Preserving stone-built cultural heritage from environmental degradation poses significant challenges, as moisture ingress and extreme weather accelerate weathering, leading to structural damage and escalating maintenance costs worldwide. While hydrophobic coatings show promise for protection, achieving long-term durability under harsh conditions remains elusive. The present research demonstrates a robust hydrophobic nanocomposite coating based on silica nanoparticles (SiNPs) functionalized with 1 H,1 H,2 H,2H-perfluorodecyltriethoxysilane (PFDTS), synthesized via alkaline hydrolysis of tetraethylorthosilicate (TEOS) and applied by spray coating to diverse heritage stones including sandstone, granite, and marble. The coatings achieve water contact angles of 130°–137° and sliding angles of 9°–10°, conferring exceptional self-cleaning properties that endure after saline exposure, wet-dry cycles, and marine simulations. Additionally, various water absorption tests, including the Karsten tube, ASTM D6489 surface uptake, ASTM C642 immersion tests, and droplet impact tests, showed a significant decrease in water absorption compared to uncoated stones. The overall results suggest that the water penetration at the coated surface was reduced by a factor of about 80–100 for the stone samples. This research study offers a scalable, cost-effective approach to enhance the longevity of cultural monuments, minimising preservation expenses and safeguarding irreplaceable historical assets for future generations.

Per- and polyfluoroalkyl substances (PFAS), the “Forever Chemicals,” with their exceptional chemical, thermal, and functional stability, have gained tremendous usability since the 1940s; therefore, over time, have become an intrinsic part of the industry-consumer nexus. These celebrated properties of PFAS have made them structurally stable and persistent in the environment. However, the toxicity, bio-cumulative/magnification properties, and solubility of these forever chemicals have raised concerns for their detection and an imperative need for their removal and remediation. Furthermore, a wide gap is still persistent in the understanding of the fate, effects, and treatment of PFAS within different stakeholders of the industry-commerce-consumer-mitigator network. To tackle this problem of forever chemicals, research has suggested and come up with many PFAS-free alternatives. Owing to the heavy reliance of many essential sectors on PFAS, the production of similarly efficient and feasible PFAS-free alternatives is a challenging task. The transition to PFAS-free alternatives requires the participation of different stakeholders with different social, economic, and legislative perspectives. Therefore, a sustainable transition to PFAS-free alternatives requires an understanding of the existing PFAS remediation technologies, social awareness about PFAS problems, dependency of industries on PFAS, and policies regulating PFAS use. This chapter explores the possibility of a PFAS-free environment by briefly analyzing different available PFAS remediation technologies, social constructs around PFAS, legislation controlling PFAS use, and the feasibility of transitioning toward the alternatives. Further, the chapter also points out the key factors that still need exploration and improvement to attain an uncertain yet hopeful PFAS-free future.

In recent times, plastic pollution had an adverse impact on the environment due to a high level of fragmentation. Consequently, as plastic waste gets accumulated in various water bodies, there is a need for sustainable and efficient mitigation techniques. The generation of plastic pollution is due to the unsustainable consumption and disposal of plastic products, which further threatens the environment, economy, as well as human health. This book chapter will discuss the possible solutions to reduce the use of single-use plastics, increase the use of biodegradable plastics, and impose a plastic tax to minimize plastic usage and plastic pollution. Typically, mismanaged waste emerges as one of the major sources of plastic pollution which can be further minimized through enhancements in the life cycle of plastics, especially during production, consumption, and disposal. The book chapter will also discuss the recent practices to manage waste plastics and minimize plastic pollution. Thus, a comprehensive approach is highly required which combines with technology advocacy and policy making to eradicate the issue of plastic pollution.

This study presents a time-efficient, two-step modification strategy to significantly enhance polybenzimidazole (PBI) membrane resistance to acids and organic solvents, targeting low-pH aqueous and organic solvent nanofiltration (OSN) for industrial applications. A green solvent-based aqueous Fenton reaction pretreats the membrane, improving chemical and thermal stability via enhanced chain interactions. Subsequent Thiol-Ene click chemistry crosslinking introduces crucial flexibility, compensating for Fenton-induced brittleness. This synergistic PBI-FT membrane demonstrates remarkable stability in 70 % HNO3 (maintaining > 80 % MgSO4 rejection) and highly polar aprotic solvents (DMAc, DMF, NMP), retaining > 97 % weight. In OSN, PBI-FT achieved 2.1 LMH/bar ethanol permeance with > 97 % Rose Bengal rejection, showing superior separation even after 168 h DMF exposure. This sustainable technique yields robust nanofiltration membranes for efficient separation processes in challenging industrial environments.

In this 21st century, water-related environmental challenges such as pollution, scarcity, and the diminishing availability of freshwater have become increasingly critical. The concept of water footprint (WF) offers a valuable useful tool to address these pressing issues. This book chapter explores the connection between freshwater consumption and key environmental challenges. The WF concept garnered significant attention from stakeholders both within and outside the scientific community. Its applications have proved to be highly versatile, particularly in assessing strategic corporate risks related to water pollution and scarcity. This chapter provides an in-depth discussion on the fundamentals of WF, tracing its origins, purpose, and operational mechanisms. It also highlights the evolvement of water footprint assessment (WFA) over the last two decades. Furthermore, this chapter demonstrates how WFA has become an effective instrument for raising awareness of global water issues among decision-makers in both government and industry sectors. The challenges associated with WF and WFA, particularly in the context of outsourced water pollution, are also critically examined. This chapter serves as a foundational resource for understanding the WF concept, emphasizing the importance of WFA, and exploring the associated challenges.

Owing to the robust chemical attributes, per- and polyfluoroalkyl substances (PFAS) were indiscriminately utilized in various sectors of the industry. However, citing environmental and human health risks, numerous types of PFAS have been gradually phased out by manufacturers. These synthetic chemicals are highly persistent in the environment. As worldwide regulation is becoming stricter for longer-chain perfluorooctanoic acid (PFOA) and perfluorooctane sulphonate (PFOS), the alternative of shorter chains and emerging PFAS have gained global attention. In this chapter, the phasing out of legacy PFAS has been thoroughly discussed along with the physicochemical properties of PFAS. Additionally, the fate and transportation mechanism of PFAS in the environment is also demonstrated. Special focus was given to the impacts of legacy PFAS on the environment and human health. Moreover, the role of short-chain PFAS chemicals as alternatives was also discussed. The book chapter highlights the PFAS pathways and bioaccumulation in aquatic systems and provides a reference for future research and development.

In the context of environmental concerns, microplastic (MPs) pollution emerges as one of the burning issues. The goal of this multifaceted analysis is to provide an up-to-date picture of MPs in the aquatic system with an emphasis on the marine environment. As of now, the growing concern of MP is due to high level fragmentation. The high surface area to volume ratio, crystallinity, and functional groups of MPs allows them to interact with a broad assortment of pollutants, including heavy metals, antibiotics, and persistent organic compounds. Understanding the origin, source, and fate of MPs in the marine environment is challenging, however, crucial for better management and regulation of MPs. Various spectroscopic and microscopic techniques can be applied to analyze MPs. This review article demonstrates the concept of MP lifecycle and footprint covering transport mechanism and pathways, possible characterization, degradation, and remediation processes. Additionally, the ecological and environmental impacts of MPs along with future directions were also highlighted. Thus, fostering global collaboration and innovative research and development can pave the path towards a healthier and cleaner earth for future generations.

Superhydrophobic coatings have broad applications across various fields but often face challenges, such as complexity, high cost, low mechanical/thermal stability, toxicity, and environmental hazards. In this study, we demonstrate a simple, scalable, eco-friendly, and durable spray-coating method using bioadhesive shellac and octadecyltrichlorosilane (OTS)-modified silica nanoparticles to create superhydrophobic surfaces. The silica nanoparticles impart superhydrophobicity by forming hierarchical micro/nanostructures and reducing surface free energy, while shellac ensures strong adhesion of the nanoparticles to a wide range of substrates, including nonwoven polypropylene fibers, glass, plastic, metal, wood, cotton, and concrete. The coating exhibits excellent superhydrophobic performance with a large contact angle (162.1°), a small sliding angle (4°), and low contact angle hysteresis (4°). The coated surface retains its superhydrophobicity even after 50 cycles of sandpaper abrasion, heat exposure up to 150 °C, and contact with acidic environments (pH ∼4.2). These biocompatible and eco-friendly superhydrophobic coatings hold promise for use in applications where safety and environmental protection are critical, such as in antifouling, food packaging, and agricultural/biomedical fields.

Forward Osmosis (FO) holds promise for treating heavy metal-contaminated groundwater, yet a suitable draw solution hinders its widespread use. This study introduced a novel draw solution (DS) for the FO process by combining hydrophilic macromolecule polyvinyl alcohol (PVA) with trivalent-charged complex EDTA-2Na. Remarkably, the incorporation of 0.7 g/L PVA into 0.3 M EDTA-2Na not only increased water flux by 24.2 %, attributed to the hydrophilic interaction between the FO membrane and the hydroxyl groups of PVA, but also significantly reduced reverse salt flux by 67.1 %, from 3.80 GMH to 1.25 GMH. This reduction can be attributed to the extended conformation of the polymer macromolecule at pH 8, acting as an effective barrier in the FO process, thereby restraining the electrophilic sodium ions of EDTA-2Na from reversing to the feed side. Moreover, the hydrophilic macromolecule coupled with the trivalent-charged complex DS has been easily regenerated by nanofiltration (NF) with a high recovery efficiency of 96 % and minimal energy input. Furthermore, the FO- NF process achieved high-quality permeate water (arsenic <0.0014 mg/L, lead <0.0029 mg/L, and iron <0.0157 mg/L) suitable for drinking water from heavy metal-contaminated groundwater. The present study therefore illustrates a facile and rational approach for integrating PVA into an EDTA-2Na solution that exhibits superior performance for heavy metal removal in groundwater via FO.

Per- and polyfluoroalkyl substances (PFAS), pervasive and toxic chemicals were found at alarming levels within living organisms and in the environment. PFAS causes several health risks such as impairment of the immune system and cancer. The distinct structural characteristics of covalent organic frameworks (COFs) including high surface area, low density, hierarchical porosity, and a rich array of active sites establish them as highly promising platforms for the adsorption and catalytic degradation of PFAS. This review outlines the current advances in chemical strategies for synthesizing stable COFs and highlights their emerging applications in the removal of PFAS. A comprehensive overview of PFAS, including their classification, regulatory landscape, and associated health risks was also documented. This review outlines the efficiency of various conventional techniques for eliminating long chain and short chain PFAS from water. A comparative study was established to show the viability of COF for PFAS remediation. Additionally, the chemistry of COF along with the factors controlling PFAS removal has been thoroughly demonstrated. This review paper discusses the design, synthesis, and application of COFs in the removal of PFAS. Various case studies of PFAS removal were also illustrated along with the experimental conditions to show the potentiality of these frameworks. Finally, the review concludes by examining the underlying mechanisms of PFAS capture by COFs and outlining future research directions.

Oil spills and oily wastewater from industries such as petrochemicals and food production release millions of tons of oil into aquatic ecosystems, causing severe environmental and ecological damage. Traditional oil/water separation methods, including centrifugation, skimming, and chemical coagulation, are often energy-intensive, costly, and can lead to secondary pollution from toxic chemicals. Membrane technology presents a promising, energy-efficient alternative with high separation performance and simple operation. However, conventional synthetic membranes made from materials like polystyrene (PS), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), and polydimethylsiloxane (PDMS) contribute to long-term environmental pollution and resource depletion. Eco-friendly biopolymer-based membranes, produced from renewable resources such as cellulose (CL), polylactic acid (PLA), polyvinyl alcohol (PVA), chitosan (CS), and sodium alginate (SA), face challenges including weak mechanical strength, low durability, and scalability issues. Recent advances in nano-biocomposite membranes that incorporate nanofillers, such as graphene oxide (GO), carbon nanotubes (CNT), and metal oxides (e.g., TiO₂, SiO₂), into biopolymer matrices have significantly improved performance, achieving oil/water separation efficiencies above 99.9 %. Polymer matrix nanocomposite membranes are widely used in membrane technology because of their practicality. Their primary components are environmentally friendly, energy-efficient, cost-effective, versatile, and practical. These membranes exhibit distinctive wettability properties, including superhydrophobicity/underwater superoleophilicity and superhydrophilicity/underwater superoleophobicity. Traits that enhance fouling resistance and selective wettability, leading to improved water rejection and oil permeation in water-in-oil emulsions, or, conversely, enhanced oil rejection and increased water permeation in oil-in-water emulsions. This review thoroughly examines the recent progress in nano-biocomposite membranes, focusing on their synthesis, performance, and environmental benefits. A Life Cycle Assessment (LCA) reveals that they produce less secondary pollution compared to synthetic membranes, underscoring their sustainability. Despite these advantages, challenges such as nanofiller aggregation, scalability, and cost persist. Future research should aim to optimize nanofiller dispersion, develop eco-friendly manufacturing processes, and conduct comprehensive LCAs to promote the industrial use of these membranes for sustainable oily wastewater treatment.

Artificial intelligence (AI) has emerged as a prominent tool in the modern day. The utilization of AI and advanced language models such as chat generative pre-trained transformer (ChatGPT) and Bard is not only innovative but also crucial for handling challenges related to water research. ChatGPT is an AI chatbot that uses natural language processing to create humanlike conversations. ChatGPT has recently gained considerable public interest, owing to its unique ability to simplify tasks from various backgrounds. Similarly, Google introduced Bard, an AI-powered chatbot to simulate human conversations. Herein, we investigated how ChatGPT and Bard (AI powdered chatbots) tools can impact water research through interactive sessions. Typically, ChatGPT and Bard offer significant benefits to various fields, including research, education, scientific publications, and outreach. ChatGPT and Bard simplify complex and challenging tasks. For instance, 50 important questions about water treatment/desalination techniques and 50 questions about water harvesting techniques were provided to both chatbots. Time analytics was performed by ChatGPT 3.5, and Bard was used to generate full responses. In particular, the effectiveness of this emerging tool for research purposes in the field of conventional water treatment techniques, advanced water treatment techniques, membrane technology and seawater desalination has been thoroughly demonstrated. Moreover, potential pitfalls and challenges were also highlighted. Thus, sharing these experiences may encourage the effective and responsible use of Bard and ChatGPT in research purposes. Finally, the responses were compared from the perspective of an expert. Although ChatGPT and Bard possess huge benefits, there are several issues, which are discussed in this study. Based on this study, we can compare the abilities of artificial intelligence and human intelligence in water sector research.

Membrane performance, regarding water flux and water recovery during membrane distillation (MD), is crucial during desalination. In this study, the membrane performance was improved using 3D-printed macro-structured feed spacers. Typically, 3D-printed feed spacers offer maximum flexibility for designing favorable geometrical transformations. The role of 3D-printed spacers in enhancing the permeate flux and recovery in direct contact membrane distillation (DCMD) has been thoroughly investigated. A comparative assessment was performed for various designs of 3D printed feed spacers with varying hydraulic diameters and filament thicknesses. An economical, biocompatible, and highly robust 3D-printed membrane spacer was developed using polylactic acid (PLA), which has a high elastic modulus. PLA is a biodegradable and environmentally friendly material. The thermal stability of PLA materials is advantageous for temperature-driven MD processes. PLA filaments were subjected to thermogravimetric analysis (TGA) for evaluating thermal stability. It provides structural support for the membranes and enhances mass movement through the membrane surface. In addition, these 3D-printed membrane spacers employing PLA have proven superior to conventional layouts in performance. These 3D-printed feed spacers were rationally designed to create a high flow disruption, which can lead to increased turbulence, thereby increasing the permeate flux. The overall results suggest that the 3D printed spacers can be ranked like TR˃DI ≈ SQ ˃ CR in terms of water flux. Eventually, the presence of 3D-printed spacers may prevent the external foulant layer onto the surface of membrane. Thus, the 3D printed spacers were ranked as TR˃DI ≈ CR≈ SQ for fouling mitigation ability. Furthermore, the used PVDF membrane with 3D printed spacers indicates lower hydrophobicity reduction, 11–14%. Therefore, this paper illustrates a facile approach to designing 3D-printed feed spacers that exhibit increased membrane performance in MD operation.

Zwitterionic materials containing equal proportions of positively and negatively charged groups have been used to provide membranes with antifouling capabilities. This study focuses on the modification of a commercially available polyamide thin-film composite membrane with a zwitterionic material and investigates its effectiveness in fouling mitigation. The zwitterionic material, sulfobetaine vinylimidazole (SBVI), was synthesized by reacting 1,3-propane sulfone with 1-vinyl imidazole. A NF90 polyamide membrane functionalized with propagyl bromide was modified by the polymerization of SBVI on its surface. Various techniques were used to verify the successful modification of membranes. The water flux and salt rejection of the pristine and modified membranes were measured under comparable stabilization conditions, and showed an increase in salt rejection and a decrease in permeability for the modified membrane because of additional membrane resistance. However, fouling tests conducted with a wide range of foulants in cross-flow filtration mode showed a lower fouling ratio and higher recovery ratio for the modified membrane than for the pristine membrane. The enhancement in the antifouling characteristics of the modified membrane was mainly attributed to the improvement in hydrophilicity resulting from the zwitterionic brushes. Our results demonstrated the fouling resistance is further reinforced in an ionic environment through the “salting-in” effect.

There is growing interest in membrane distillation (MD) as a means of desalinating seawater with 100 % theoretical salt rejection which has the capacity to address freshwater scarcity. MD has huge potential for commercial applications owing to its low operating temperature and pressure requirements. However, wetting polymeric membranes inhibits water permeance and lowers salt rejection. MXene nanosheet-incorporated polyvinylidene (PVDF) membranes have been constructed for enhanced vapor transport with high water repellence and antiwetting properties. MXene nanosheets in PVDF polymeric matrices are responsible for their high super-hydrophobicity, which can mitigate membrane fouling and wetting during the MD process. As far as experimental outcomes are concerned, the pristine PVDF membrane exhibited severe wetting with salt leakage. Ti3C2Tx MXene nanosheets allow the formation of hierarchical polymeric micro/nanostructures, changing the intrinsic hydrophilicity to super-hydrophobicity. Surface engineering of a PVDF membrane with MXene nanosheets enables efficient saline desalination during the MD process. The surface-engineered MXene/PVDF membrane demonstrated a high-water contact angle of 143° with extremely high self-cleaning characteristics as compared to that of pristine PVDF membrane. As far as the performance of the membrane is concerned, the water flux of the pristine PVDF membrane decreased from 6.5 LMH to 6 LMH after the 14th hour which can be attributed to partial pores wetting during MD operation. Eventually, the pristine PVDF membrane exhibited a continuous salt flux (SF) increase. However, MXene/PVDF membrane showed stable water flux (8 LMH) and negligible SF. The study therefore demonstrates a facile and holistic approach for constructing MXene-based PVDF membranes that exhibit superior antiwetting performance during MD operation.

An increase in population leads to an increase in the water demand. Technological advancements are racing to address water shortages. Recent advances in deep learning (DL), machine learning (ML), and artificial intelligence (AI) have enabled us to effectively manage water scarcity as well as optimize, model, automate, and predict water treatment processes. Additionally, computer-assisted support to complicated problems related to water chemistry, and membrane applications. In the sector of water treatment and desalination processes, various models such as Support Vector Machines (SVM), Random Forest (RF), Genetic Algorithms (GA), K-Nearest Neighbors (KNN), time series models, and Multi-Layer Perceptron (MLP) have been applied to address the issues ranging from optimization of treatment processes to predictive modeling as well as failure/fault detection. Presently, water quality forecasting lacks the much-needed precision and accuracy. Thus, a highly versatile MLP is engineered and designed to approximate any continuous functions and may solve issues that are not linearly separable. Typically, MLPs are used for pattern classification, forecasting performance, and approximation. This review paper presents automatic forecasting of water quality and desalination processes efficiency which resolves the issue of missing values from the data sets. Moreover, this paper examines a wide range of peer-reviewed, vital water-based applications using DL, ML, and AI, including membrane separation, water quality, and performance efficiency. A thorough review of MLP applications in water treatment and seawater desalination is presented here. Furthermore, the conventional modeling approaches are compared with the MLP model. It will also highlight the drawbacks that hinder the implementation of real-world water treatment and desalination processes. In conclusion, the latest developments in membrane processes, seawater desalination, and MLP-based water treatment have been summarised.

Novel waste treatment methods and dependable alternative energy sources must keep up with the world’s rapid population growth, urbanization’s higher living standards, and the concurrent escalation of socio-economic activities. Porous carbon materials hold the potential to be a significant contributor in both of these domains because of their proven efficiency in wastewater treatment, gas separation, and storage. In today’s water-energy nexus, there is a greater urgency to develop environmentally sustainable processes to treat contaminated water before discharge. These materials possess a controllable, nano-scale or micro-scale pore structure throughout the surface. The porous structure of carbon typically makes it an efficient filtration medium that can be applied as the support structure of membrane separation. On the other hand, significant efforts have been made over the last decade to develop low-cost, simple-to-use, and easy-to-scale porous carbon materials and composites for the production of clean and sustainable energy due to their larger surface area, rapid transport of active sites, and availability of active sites at various length scales. Additionally, they have the advantages of a variable specific surface, programmable pore structure, solid physicochemical stability, simple functionalization, and the potential to improve performance depending on the applications. Typical gas storage applications include fuel gases for automobiles, therapeutic medical gases for clinical purposes; instrument gases for industries; natural gas for long-distance transportation, and electronic gas delivery for semiconductor fabrication processes. The application of porous carbon material in water treatment and remediation and its efficiency in mechanical stability, chemical stability, permeability, and resistance to fouling will be thoroughly discussed in this book chapter. This chapter also includes an in-depth review of porous carbon materials for gas separation and storage. Even the prospects of porous carbon materials with regard to these applications will be discussed in detail.

In the modern era, deep learning (DL), and machine learning (ML), have emerged as potential technologies that are widely applied in the fields of science, engineering, and technology. These tools have been extensively used to optimize seawater desalination and water treatment processes to achieve efficient performance. Indeed, automation has played a key role in redefining the issues of water treatment and seawater desalination. Artificial intelligence (AI) has been developed as a versatile tool for processing data and optimizing smart water services while addressing the issues of monitoring, management, and labor costs. Recently, specific AI tools, such as artificial neural networks (ANNs) and genetic algorithms, have been implemented for self-monitoring and modeling applications in the field of water treatment and seawater desalination. In the present article, the application of AI in the water treatment and seawater desalination sectors is thoroughly reviewed. Additionally, conventional modeling approaches are compared with ANN modeling. Furthermore, the challenges and shortcomings are discussed, along with future prospects. Moreover, the applications of AI mechanisms in data processing, optimization, modeling, prediction, and decision-making during water treatment and seawater desalination processes are underscored. Finally, innovative trends in seawater desalination and water treatment with AI tools are summarized.

During the COVID-19 pandemic, face masks, respirators, and personal protective equipment have become common preventive measures. However, the COVID-19 pandemic has highlighted the lack of efficient and reusable face masks worldwide. Immense efforts have been dedicated to designing antidust and antidroplet masks to ensure safe breathing. In this context, electrospun nanofibrous layers have attracted considerable attention for the fabrication of antidust and antidroplet masks. During long-term usage, water droplet layers can lead to pore blockages; this remains a major concern. In this study, a three-layered sandwich structure comprising a hydrophilic spongy layer, hydrophobic support layer, and antidroplet layer was developed to address this concern. Specifically, the structure comprised polyvinylidene fluoride-silica nanoparticles-perfluorooctyl trichlorosilane/polyethylene/polybenzimidazole (PVDF-Si-NPs-PFTOS/PET/PBI) electrospun nanofibrous layers. The PBI layer was utilized as soft, hydrophilic, skin-friendly layer, as supported by the PET layer for better mechanical stability. In addition, PVDF coated with micro-nano scale Si-NPs as modified with a PFTOS nonwoven electrospun layer was used for the antifouling, antidroplet, and splash resistance capabilities. This novel electrospun nanofibrous nonwoven three-layered sandwich structure (PVDF-Si-PFTOS/PET/PBI) exhibited high performance, with competitive antidroplet abilities. Accordingly, this research can be used to fabricate face masks with antidroplet and splash resistance for personal safety and protective equipment.

In 2011, after the establishment of Ti3C2Tx MXene, it has attracted considerable attention in different areas such as photocatalysis, energy storage, electromagnetic shielding interference, and environmental applications owing to its high surface area, unique layered structure, easy functionalization, and high conductivity. This critical review paper discusses current trends in research as well as development of Ti3C2Tx MXene in desalination and water treatment processes. Additionally, the structural aspects of the MAX phase and MXene nanomaterials are illustrated along with the advancements in MXene membrane fabrication, including their synthesis, surface chemistry, and interlayer tuning. To date, very few peer-reviewed articles were published on MXene membranes for lab-scale water separation and purification. Additionally, the synthesis and characteristics of MXene nanosheets are thoroughly discussed and different types of MXene composite membranes, preparation methods and separation mechanisms are explained. Next, the gas separation, desalination, and organic solvent separation performance of MXene composite membranes as reported in earlier studies are critically evaluated. More information has been updated regarding the research gaps in the recent perception and performance of MXene-incorporated membranes. Furthermore, the limitations as well as potentials of Ti3C2Tx MXene-incorporated membranes are summarized. Recommendations and future perspectives for designing the commercial MXene composite membrane have been discussed. This holistic review article offers a fundamental basis for employing MXenes in the membrane field for water purification, organic solvent filtration and membrane desalination.

Moisture interaction and extreme weather may complicate the service life and increase the maintenance cost of various building materials. This paper investigates the performance of protective surface coatings applied to the most common building material, concrete. A novel synthesis route for producing ultrahydrophobic surface coatings is demonstrated to enhance the impermeability of concrete. The concrete specimens were chemically modified with silica sol, which was synthesized by hydrolysis of tetraethoxysilane (TEOS) under alkaline conditions, followed by treatment with hexadecyltrimethoxysilane (HDTMS) solution. The concrete specimens coated with proposed micro-composite coating were tested for hydrophobicity and self-cleaning characteristics in terms of contact angle and sliding angle at various water exposure conditions and periods of exposure. The permanency and efficiency of proposed coatings was further tested after exposure to alternate wet-dry cycles and highly saline environment. The modified specimens exhibited a contact angle of 121° – 135° and a sliding angle of 9° – 22° at various exposure conditions, depicting superior hydrophobicity. The overall findings of this study could aid in maintaining the intended longevity and performance of various concrete materials.

Owing to the inherent complications in membrane distillation (MD) operations, it has become a challenge to acknowledge swiftly and appropriately to safeguard the quality of effluent, particularly when the processing cost is a prominent concern. Membrane wetting in MD operations is a major concern during long-term performance. In this study, machine learning (ML) methodologies were utilized to overcome the limitations of conventional mechanistic modeling. ML applications have never been explored to investigate how operational factors, such as water flux and salt flux, are affected during long-term MD performance. Furthermore, time-dependent factors were neglected, making it difficult to analyze the relationship between effluent quality and operational factors. Therefore, this study demonstrates a novel ML-based framework designed to enhance the performance of MD. The ML-based framework consists of an autoregressive integrated moving average (ARIMA) and utilizes a unique pathway to explain the impact of time series among operational factors. The accuracy of forecasting has been explored by utilizing 180 h (180 datasets), that was further used and divided into training (165 datasets) and test datasets (15 datasets). Eventually, the ARIMA model demonstrated a highly precise relationship order between the model and experimental data, which can be further used to forecast membrane performance in terms of wetting and fouling. The selected ARIMA model (3,2,1) appears to be an adequate model for water and salt flux data which has been effectively used to capture the course of permeate water and salt flux by producing the smallest forecast RMSE. The RMSE values were observed to be 0.22 and 0.05 for water and salt flux respectively, which can better predict long time series with high frequency. These frameworks can be applied for the early prediction of membrane wetting if ample high-resolution data are available.

During the COVID-19 pandemic, the extensive use of face masks and protective personal equipment (PPE) kits has led to increasing degree of microplastic pollution (MP) because they are typically discarded into the seas, rivers, streets, and other parts of the environment. Currently, microplastic (MP) pollution has a negative impact on the environment because of high-level fragmentation. Typically, MP pollution can be detected by various techniques, such as microscopic analysis, density separation, and Fourier transform infrared spectrometry. However, there are limited studies on disposable face masks and PPE kits. A wide range of marine species ingest MPs in the form of fibers and fragments, which directly affect the environment and human health; thus, more research and development are needed on the effect of MP pollution on human health. This article provides a perspective on the origin and distribution of MP pollution in waterbodies (e.g., rivers, ponds, lakes, and seas) and wastewater treatment plants, and reviews the possible remediation of MP pollution related to the excessive disposal of face masks and PPE kits to aquatic environments.

Membrane fouling is a major problem that hinders the application of the membrane in water filtration. To address this issue, a novel reversed thermally induced phase separation (RTIPS) process is applied to fabricate a patterned polyethersulfone (PES) hollow fiber (HF) membrane using a structured spinneret. Surface patterning could induce turbulence, thereby preventing the accumulation of foulants on membrane surface. The RTIPS method requires lesser material with similar mechanical strength compared to that of conventional TIPS method. The fabrication process is optimized by changing the spinning conditions. A dope composition of 24 wt% PES is chosen to prepare the membrane. The chemical composition of the membrane is confirmed via sophisticated techniques such as Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) images of the sample indicates the successful formation of the pattern on the shell side of the HFs. The prepared patterned HF membranes exhibits a high rejection of 97% of bovine serum albumin (BSA), which is comparable to or higher than that of commercial membranes. Moreover, the patterned membrane demonstrates better performance, thereby confirming the effectiveness of this modification in enhancing the antifouling nature.

The threat of epidemic outbreaks like SARS-CoV-2 is growing owing to the exponential growth of the global population and the continual increase in human mobility. Personal protection against viral infections was enforced using ambient air filters, face masks, and other respiratory protective equipment. Available facemasks feature considerable variation in efficacy, materials usage and characteristic properties. Despite their widespread use and importance, face masks pose major potential threats due to the uncontrolled manufacture and disposal techniques. Improper solid waste management enables viral propagation and increases the volume of associated biomedical waste at an alarming rate. Polymers used in single-use face masks include a spectrum of chemical constituents: plasticisers and flame retardants leading to health-related issues over time. Despite ample research in this field, the efficacy of personal protective equipment and its impact post-disposal is yet to be explored satisfactorily. The following review assimilates information on the different forms of personal protective equipment currently in use. Proper waste management techniques pertaining to such special wastes have also been discussed. The study features a holistic overview of innovations made in face masks and their corresponding impact on human health and environment. Strategies with SDG3 and SDG12, outlining safe and proper disposal of solid waste, have also been discussed. Furthermore, employing the CFD paradigm, a 3D model of a face mask was created based on fluid flow during breathing techniques. Lastly, the review concludes with possible future advancements and promising research avenues in personal protective equipment.

The extreme evaporative loss of water from topsoil complicates cultivation in arid areas, and artificial plastic mulches that imitate sand mulches may minimize such water losses. However, the application of such plastic mulches is limited by their high cost and non-biodegradability. In this study, we developed superhydrophobic sand grains to reduce evaporative water loss from soil. Sea sand (SS) was coated with silica sol, which was prepared by the hydrolysis of tetraethoxysilane (TEOS) under alkaline conditions, followed by treatment with perfluorodecyltrichlorosilane (FDTS). A facile step was optimized for fabricating hydrophobic sand grains with contact angle of 151° and rolling-off angle of 9.5° to confirm the hydrophobicity and anti-droplet properties of the modified sand grains. The sands modified with engineered nanomaterials have shown the enhanced water holding and storage efficiency, and they can be applied as an oil sorbent scaffold to absorb oil (chloroform) from water selectively due to their water repelling properties. The coated superhydrophobic sand grains displayed anti-droplet and self-cleaning features, and withheld water for extended periods of time, which could benefit agriculture in arid regions and various environmental applications.

A three-layered hollow fiber (HF) membrane exhibiting enhanced permeability and wet-resistance was fabricated using polyvinylidene fluoride (PVDF) and poly(vinylidene fluoride–co-chlorotrifluoroethylene) (PVDF–CTFE) simultaneously for membrane distillation (MD). The inner, outer, and middle layers of the membrane were prepared using a macrovoid structure of PVDF–CTFE, the finger-like structure of PVDF, and thin sponge-like structure, respectively. The size of the macrovoid in the inner layer was enlarged and the permeability was enhanced using the polytetrafluoroethylenes (PTFE) as additive. However, the PTFE did not significantly change the liquid entrance pressure (LEP) of the membrane. The LEP and hydrophobicity of the inner layer of HF was increased by grafting pentafluorostyrene (PFS). The prepared membranes were characterized via several analytical tools, and the performance was evaluated using the vacuum MD (VMD) process. With 10% of PTFE, the size of the internal macrovoid increased, thus improving the flux to 137%. When PFS was grafted on the inner layer, the contact angle (CA) and liquid entry pressure (LEP) values increased to 117 and 154%, respectively, that showed an improvement in the wetting resistance. This study showed that the three-layered structure designed using the PTFE and PFS as an additive and grafting, respectively, were successfully fabricated to improve the wetting resistance and permeability.

With the emergence of membrane fouling as a prominent issue in long-term MD performance, it has become imperative to manufacture superhydrophobic membranes with antibacterial properties. In this study, a novel superhydrophobic and antibacterial membrane is fabricated using trichloro(1H,1H,2H,2H-perfluorooctyl)silane (TPFOS) and titanium dioxide nanoparticles (TiO2-NPs) as chemical modifiers. The virgin PVDF membrane was pre-treated using PEG-co-PMAA, followed by plasma treatment, to enhance the [sbnd]COOH and [sbnd]OH groups on the top layer and promote formation of coordinate bonds on the membrane surface to TiO2. TPFOS was used to impart a superhydrophobic behavior to the titanium-enriched membrane surface. Membrane characteristics were investigated using SEM-EDS, FT-IR, AFM, XPS, porosimetry, and tensile strength analysis. The PVDF/PP-PT/Ti/Si (polyvinylidene difluoride/ coated PEG-co-PMAA-plasma treated/titanium nanoparticles/perfluorooctyl silane) composite membrane showed a superior contact angle of ~152° and a better self-cleaning ability than that of the pristine PVDF membrane. Plasma treatment of the membrane results in increasing the porosity of the membrane by the mechanism of polymer ablation. Furthermore, the superhydrophobic membrane displayed superior performance due to enhanced water flux and improved salt rejection over long-term DCMD operation. It also possessed excellent antibacterial properties, exhibiting a bacterial reduction of ~99% when tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). This investigation demonstrates a simple approach to design multifunctional membranes showing anti-wetting, anti-bio-fouling, self-cleaning, and robust characteristics in MD desalination operations.

We present here a data set generated from a multinational survey on opinions of university community members on the prospect of consuming food grown with human urine as fertiliser and about their urine recycling perceptions in general. The data set comprises answers from 3,763 university community members (students, faculty/researchers, and staff) from 20 universities in 16 countries and includes demographic variables (age bracket, gender, type of settlement of origin, academic discipline, and role in the university). Questions were designed based on Ajzen's theory of planned behaviour to elicit information about three components of behavioural intention—attitudes, subjective norms, and perceived behavioural control. Survey questions covered perceived risks and benefits (attitudes), perceptions of colleagues (injunctive social norm) and willingness to consume food grown with cow urine/faeces (descriptive social norm), and willingness to pay a price premium for food grown with human urine as fertiliser (perceived behavioural control). We also included a question about acceptable urine recycling and disposal options and assessed general environmental outlook via the 15-item revised New Ecological Paradigm (NEP) scale. Data were collected through a standardised survey instrument translated into the relevant languages and then administered via an online form. Invitations to the survey were sent by email to university mailing lists or to a systematic sample of the university directory. Only a few studies on attitudes towards using human urine as fertiliser have been conducted previously. The data described here, which we analysed in “Willingness among food consumers at universities to recycle human urine as crop fertiliser: Evidence from a multinational survey” [1], may be used to further understand potential barriers to acceptance of new sanitation systems based on wastewater source separation and urine recycling and can help inform the design of future sociological studies.

Triiodide, a larger charged molecule compared to iodide, is thermodynamically favored with the presence of both iodide and iodine, and is easier to be retained by membrane processes. For the first time, iodide was recovered in the form of triiodide by forward osmosis (FO) for thin-film transistor liquid crystal display industries by preoxidation of iodide to triiodide. Partial oxidation by NaOCl was used to convert the iodide to iodine and then to form triiodide. Ethylenediaminetetraacetic acid disodium salt (EDTA-2Na), a commonly used chelating agent in the industry, was used as the draw solute because of its low reverse salt flux. The results revealed that the ideal efficiency of iodide recovery was at pH 3 with a preoxidation (adding 0.0150 M NaClO) for the 0.048 M iodide wastewater with a recovery of 98.5%. Additionally, the Pourbaix diagram and starch indicator were used to verify the formation of triiodide. Membrane distillation was demonstrated to recover the EDTA-2Na draw solute, and more than 99% of recoveries for the draw solutes with initial water flux of 12.0 L/m2 h were achieved, indicating that simultaneous recovery of the EDTA-2Na draw solute and water is feasible.

In daily life, many surfaces become contaminated owing to dust/dirt accumulation via air pollution. Self-cleaning surface modification is one of the best ways to address this problem. Therefore, ultra-hydrophobic coatings have garnered significant attention owing to their potential applications featuring water resistance and self-cleaning ability. In this study, a simple, fluorine-free, as well as eco-friendly technique was utilized to fabricate durable self-cleaning coatings. This coating material consists of fluorine-free hexadecyltrimethoxysilane-altered SiO2 nanoparticle (NPs)-coated carbon nanofibers (CNF/SiO2-HDTMS) and a commercial gelatin based adhesive emulsion. Owing to the presence of the hydroxyl (−OH) functional groups of CNFs, SiO2 NPs could accumulate on CNFs surface, hence creating hierarchical microstructures that generate air pockets for improved hydrophobicity. In this study, the developed coating was applied onto a polyethylene sheet, glass fiber membrane, and glass via dip coating. These surfaces were targeted due to over-use in day-to-day life as well as in industrial applications such as plastic tents, umbrellas, windshields of vehicles, window and door glasses, skyscrapers, membranes, fabrics, papers and the list is endless. Interestingly, after the introduction of the adhesive based CNF/SiO2-HDTMS coating, the superhydrophilic microfiber filter became highly hydrophobic, with a water contact angle of 125°. Similar effect can be seen in case of the modified glass, where the average contact angle was determined to be around 141°. The CNF/SiO2-HDTMS coated poly bag exhibited excellent anti-droplet behavior with water contact and rolling angles of 136° and 12°, respectively. The self-cleaning coatings maintained anti-droplet behavior even after tests such as sand impact abrasion, and finger touch. This study explores the possible industrial applications of self-cleaning coatings at ambient temperature to improve the feasibility of their usage.

Source-separating sanitation systems offer the possibility of recycling nutrients present in wastewater as crop fertilisers. Thereby, they can reduce agriculture's impacts on global sources, sinks, and cycles for nitrogen and phosphorous, as well as their associated environmental costs. However, it has been broadly assumed that people would be reluctant to perform the new sanitation behaviours that are necessary for implementing such systems in practice. Yet, few studies have tried to systematically gather evidence in support of this assumption. To address this gap, we surveyed 3763 people at 20 universities in 16 countries using a standardised questionnaire. We identified and systematically assessed cross-cultural and country-level explanatory factors that were strongly associated with people's willingness to consume food grown using human urine as fertiliser. Overall, 68% of the respondents favoured recycling human urine, 59% stated a willingness to eat urine-fertilised food, and only 11% believed that urine posed health risks that could not be mitigated by treatment. Most people did not expect to pay less for urine-fertilised food, but only 15% were willing to pay a price premium. Consumer perceptions were found to differ greatly by country and the strongest predictive factors for acceptance overall were cognitive factors (perceptions of risks and benefits) and social norms. Increasing awareness and building trust among consumers about the effectiveness of new sanitation systems via cognitive and normative messaging can help increase acceptance. Based on our findings, we believe that in many countries, acceptance by food consumers will not be the major social barrier to closing the loop on human urine. That a potential market exists for urine-fertilised food, however, needs to be communicated to other stakeholders in the sanitation service chain.

For the first time, an osmotic microbial fuel cell (OsMFC) was employed for simultaneous hexavalent chromium [Cr(VI)] removal, organic contaminant removal, energy production, and water reclamation. In this system, draw solutions were prepared from 0 to 1 M NaCl mixed with 12 mg/L Cr(VI). Cr(VI) reduction and power generation at different pH were studied. In terms of power generation, the results revealed that the highest power density of 6.6 mW/m2 (170 mW/m3) was obtained using the 1 M NaCl catholyte at pH 7. However, the greater Cr(VI) reduction of 44.5% and 97.6% was achieved using the 0.2 M NaCl/Cr(VI) based catholyte at pH 7 and 2, respectively. This can be attributed to the competition between Cr(VI) and oxygen reduction due to the high rate of dilution at higher concentrations of NaCl. Additionally, the highest open-circuit voltage of 0.752–0.845 V was recorded at 0.2 M NaCl/Cr(VI) as a proof to support that 0.2 M NaCl was a favorite condition for reducing Cr(VI). Moreover, through cyclic voltammetry, the signals of oxidation-reduction peaks were observed in the case of 0.2 M NaCl/Cr(VI), while, reduction peaks mostly disappeared in other cases. Additionally, more precipitate [Cr(OH)3(s)] was observed to be deposited on the surface of the cathode electrode when 0.2 M NaCl was used as the draw solution. Hence, 0.2 M NaCl was the optimal catholyte concentration for Cr(VI) reduction. The Cr(VI) removal efficiency was 97.6% for an initial pH of 2 with the 0.2 M NaCl catholyte because low pH is thermodynamically favored for Cr(VI) reduction.

Application of membrane distillation (MD) is still in its emerging stage due to membrane wetting and fouling issues. In this study, an anti-wetting and anti-fouling superhydrophobic patterned membrane was prepared utilizing patterned templet surface and subsequent chemical modifications with fluorine-based polymer. A uniform patterned polyvinylidene fluoride-co-chlorotrifluoroethylene (PVDF-CTFE) membrane was prepared using a template having a specific surface structure. It was found that the patterned membrane with a hierarchical microstructure was more hydrophobic than that with a flat surface. Long-term performance of the patterned membrane was determined through direct contact membrane distillation (DCMD). Results showed that such patterned membrane exhibited wetting resistance for a longer time compared to a pristine membrane. However, the patterned membrane showed rapid flux decline during a fouling test due to deposition of foulants such as humic acid (HA), alginate acid (AA), and bovine serum albumin (BSA). To overcome the fouling issue, a patterned membrane was chemically modified with 1H, 1H-perfluorooctyl methacrylate (FOMA) known to possess a low surface energy. After surface modification with FOMA, the superhydrophobic patterned membrane showed good stability in terms of water flux and salt rejection for more than 7 days in DCMD without wetting or fouling issue. Results of this study indicates the capability of a superhydrophobic patterned MD membrane for generating maximum water flux with excellent anti-fouling and wetting resistance properties.

The publisher regrets that in the above article Fig. 3 appeared incorrectly. The correct Fig. 3 is presented below. The online version of the article has been revised to reflect this change. The publisher would like to apologise for any inconvenience caused.

Membrane wetting in membrane distillation (MD) is a prominent issue during desalination operation, where the interfacial characteristics between the membrane surface and the feed stream are critical. In this study, an antiwetting membrane surface consisting of hierarchical microstructures was explored as a novel concept to understand the wetting behavior during the MD operation. A novel surface-engineered design of an antiwetting polyvinylidene fluoride (PVDF) membrane with micropatterned arrays obtained utilizing a 3D-printed molding phase separation method was thoroughly explored. In a novel introduction to this field, 3D-printed templates with micron-sized pillars in different shapes are used to generate air pockets when imprinted with a polymeric membrane. Additionally, hexadecyltrimethoxysilane was used as a chemical modifier for enhancing the hydrophobic characteristics. Membrane properties were thoroughly analyzed through Fourier-transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy coupled with energy-dispersive X‐ray spectroscopy, and X-ray photoelectron spectroscopy after successful fabrication of the surface and chemically engineered membrane. The chemically modified patterned membrane exhibited a higher contact angle of ~140° and superior antiwetting behavior when compared to that of the plain PVDF membrane. Moreover, the engineered membrane showed superior MD performance in terms of salt rejection and water flux. Therefore, this paper demonstrates a simplistic approach to design a micropatterned functional membrane exhibiting antiwetting and self-cleaning behavior during MD operation.

Recently, membrane distillation (MD) has emerged as a versatile technology for treating saline water and industrial wastewater. However, the long-term use of MD wets the polymeric membrane and prevents the membrane from working as a semi-permeable barrier. Currently, the concept of antiwetting interfaces has been utilized for reducing the wetting issue of MD. This review paper discusses the fundamentals and roles of surface energy and hierarchical structures on both the hydrophobic characteristics and wetting tolerance of MD membranes. Designing stable antiwetting interfaces with their basic working principle is illustrated with high scientific discussions. The capability of antiwetting surfaces in terms of their self-cleaning properties has also been demonstrated. This comprehensive review paper can be utilized as the fundamental basis for developing antiwetting surfaces to minimize fouling, as well as the wetting issue in the MD process.

The proposed work investigates a novel 3D printing technique called as Solvent based Slurry Stereolithography (3S) to fabricate membranes for filtration application. 3S process is an indirect fabrication method where the green parts are 3D printed first and densified later by sintering process. In this paper, membranes using alumina material were fabricated with a controlled thickness between 200 and 250 μm and surface roughness ranges between 0.17 and 0.18 μm. The factors that affected the entire fabrication process such as material synthesis, printing parameters, and the sintering temperature cycle are presented through empirical data. The material synthesis includes powder selection based on the morphology and optimization of the raw material. Based on the particle structure and its concentration, different slurry compositions were prepared, and green parts were 3D printed. The printed samples are characterized for thickness, roughness, porosity, and pore size followed with a brief discussion regarding filtration application.

For the first time, simultaneous iodide recovery and boron removal from thin-film transistor liquid crystal display wastewater were achieved using forward osmosis because iodide is a precious material and boron is toxic with 1 mg/L discharge standard in Taiwan. Cellulose triacetate and thin-film composite with aquaporin flat sheet membranes were tested for different feed solution, pH levels, and draw solution concentrations. The results indicated that the thin-film composite membrane had high boron and iodide rejections (98.4% and 98.3%, respectively) at a pH of 11; however, with a feed boron concentration of 600 mg/L, 9.8 mg/L boron was still present in the draw solution. Cationic surfactant cetyltrimethylammonium bromide was used to enhance the iodide recovery and boron removal efficiencies. Both efficiencies increased to 99.9% with 0.5 mM cetyltrimethylammonium bromide, and only 0.64 mg/L boron was present in the draw solution. In addition, negligible flux reduction was observed for forward osmosis process in the presence of cetyltrimethylammonium bromide. A membrane distillation system was used to concentrate and purify the MgCl2 draw solution. Thus, the hybrid forward osmosis-membrane distillation process can be applied for iodide recovery and boron removal in the thin-film transistor liquid crystal display industry.

Membrane distillation (MD) is a thermally induced membrane separation process that utilizes vapor pressure variance to permeate the more volatile constituent, typically water as vapor, across a hydrophobic membrane and rejects the less volatile components of the feed. Permeate flux decline, membrane fouling, and wetting are some serious challenges faced in MD operations. Thus, in recent years, various studies have been carried out on the modification of these MD membranes by incorporating nanomaterials to overcome these challenges and significantly improve the performance of these membranes. This review provides a comprehensive evaluation of the incorporation of new generation nanomaterials such as quantum dots, metalloids and metal oxide-based nanoparticles, metal organic frameworks (MOFs), and carbon-based nanomaterials in the MD membrane. The desired characteristics of the membrane for MD operations, such as a higher liquid entry pressure (LEPw), permeability, porosity, hydrophobicity, chemical stability, thermal conductivity, and mechanical strength, have been thoroughly discussed. Additionally, methodologies adopted for the incorporation of nanomaterials in these membranes, including surface grafting, plasma polymerization, interfacial polymerization, dip coating, and the efficacy of these modified membranes in various MD operations along with their applications are addressed. Further, the current challenges in modifying MD membranes using nanomaterials along with prominent future aspects have been systematically elaborated.

Progressive freezing is a solvent purification technology with low energy requirements and high concentration efficiency. Although these advantages make it a promising technology, the technique has never been explored for draw solution recovery for forward osmosis (FO). Hence, in this study, the progressive freezing process was used to concentrate three common diluted draw solutions: NaCl, MgCl2, and EDTA-2Na with different ice front speeds, stirring rates, and initial draw solution concentrations. Effective partition and intrinsic partition constants were also evaluated. The results reveal that the freezing process can achieve a draw solution recovery rate of 99.73%, 99.06%, and 98.65% with NaCl, MgCl2, and EDTA-2Na, respectively, using an ice front speed of 0.5 cm/h, a stirring rate of 2.62 m/s, and 30% of percentage of ice phase. Higher concentration efficiency for NaCl and MgCl2 was achieved due to the high solubility of NaCl and MgCl2 increased solute diffusion into the liquid phase solutions. The concentration factors for all three draw solutions exceeded 1.9, indicating that the draw solutes could be reused for the FO process. In addition, the two mass transfer coefficients depended on the ice front speed and the stirring rates were also obtained for scaling up the experiment in the future.

Herein, poly(sodium 4-styrenesulfonate) (PSS) with molecular weight of 70,000 (PSS-70,000) coupled with non-ionic surfactant Triton X-114 (TX-114) was exerted as draw solution (DS) in forward osmosis (FO) process for the first time to reduce salt reversal flux and enhance water recovery. In order to evaluate performances of this new type of draw solution, different concentrations of PSS-70,000 and TX-114 were prepared and implemented in FO process accordingly. When pure PSS-70,000 was used, high viscosity of 100% PS-70,000 inhibited the water flux as comparing with 50% PSS-70,000 since water passage was prevented from transferring through increasing thickness of draw solution. Interestingly, adding 1 mM TX-114 in 50% PSS-70,000 just slightly influenced on water flux but salt reversal flux was significantly reduced by 70% from 2.71 gMH to 0.92 gMH and reverse sodium was also reduced by 35.9%. Specifically, large molecular size of PSS-70,000 polyelectrolyte combining with a nucleophile ethylene oxide of TX-114 could effectively perform as a barrier to restrain electrophile sodium of PSS-70,000 reversing to the feed side. Moreover, the hydrophobic hydrocarbon tails of TX-114 retained on the hydrophobic surface of FO membrane was caused by the nonpolar–nonpolar interaction resulting in less reverse sodium. It can be concluded that the utilization of TX-114 with PSS-70,000 produced beneficial achievements since it did not only improve the performance of FO through reducing salt reversal flux but also effectively enhance the regeneration of diluted DS operated by membrane distillation (MD) process. Expressly, the repeatability of FO performance was revamped depending on the nonpolar interaction between the hydrophobic natures of 50% PSS-70,000/1 mM TX-114 based DS and hydrophobic surface of MD membrane.

With the emergence of the coronavirus disease (COVID-19), it is essential that face masks demonstrating significant anti-droplet and hydrophobic characteristics are developed and distributed. In this study, a commercial compressed-polyurethane (C-PU) mask was modified by applying a hydrophobic and anti-droplet coating using a silica sol, which was formed by the hydrolysis of tetraethoxysilane (TEOS) under alkaline conditions and hydrolyzed hexadecyltrimethoxysilane (HDTMS) to achieve hydrophobization. The modified mask (C-PU/Si/HDTMS) demonstrated good water repellency resulting in high water contact angle (132°) and low sliding angle (17°). Unmodified and modified masks were characterized using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). A drainage test confirmed the strong interaction between the mask surface and coating. Moreover, the coating had negligible effect on the average pore size of the C-PU mask, which retained its high breathability after modification. The application of this coating is a facile approach to impart anti-droplet, hydrophobic, and self-cleaning characteristics to C-PU masks.

For the first time, a nanosilver-coated hollow fiber microfiltration (MF) was fabricated by a simple chemical reduction method, then tested for membrane biofouling mitigation study under extreme high mixed liquor suspended solid (MLSS) concentration for long term. This study presents a simple and novel technique to modify a commercially available MF membrane using silver nanoparticles (AgNPs) followed by an investigation of mitigating membrane biofouling potentials using this modified membrane to compare with an unmodified membrane for 60-day operation period. The modified membranes showed that AgNPs was attached to the MF-membrane successfully with a high density of 119.85 ± 5.42 mg/m2. After long-term testing of 60 days in membrane bioreactor with a MLSS concentration of 11,000 mg/L, specific flux of the AgNPs coated MF (AgNPs-MF) decreased 59.7%, while the specific flux of the unmodified membrane dropped 81.8%, resulted from the increase of transmembrane vacuum pressure for the AgNPs-MF was lower than that of the unmodified one. The resistance-in-series model was used to calculate the resistance coefficients of membrane modules, and the result showed that the cake layer resistance coefficient of the unmodified membrane was 2.7 times higher than that of the AgNPs-MF after the 60-day operation, confirming that AgNPs displayed great antimicrobial properties to mitigate membrane biofouling under such high MLSS.

The overpopulation in the future will result in burning issues of our environment and the negative effects of global warming, environmental pollution, and habitat loss in the worldwide human community. Moreover, the nonrenewable natural resources such as fossil fuels and clear water are consumed at the speed faster than their rate of regeneration. Worldwide demand has increased year by year, which is required to exceed production from known and anticipated resources. Last but not least, the demands of water used in agriculture, industries, and supporting population growth have increased and become of the most challenges in later centuries. Under those circumstances, there are prerequisites for finding alternative renewable energy resources and cost-effective wastewater treatment technologies with less energy expenditure. Among various technologies that have been well investigated, microbial fuel cell might be the potential candidate to administer with the recent situation of wastewater–energy nexus. In general, the microbial fuel cell is a cross-disciplinary technology so that survey area has extended to energy, material sciences, biology, and environment. In this chapter, we aim to present the possibility of generating electricity in MFC from a wide range of organic waste and hazardous wastes. In addition, the integrations between microbial fuel cells and other technologies are also introduced which have supposedly made great opportunities to concurrently reach sustainable energy production, efficient wastewater treatment, and reuse.

In this era of nanotechnology, electrospun nanofibrous membranes offer versatile characteristics, such as mechanical toughness and a large surface area, making them attractive for various applications. Electrospinning is an emerging methodology for producing nanofibers. Furthermore, electrospinning yields uniform pore size, which is considered a crucial characteristic of water treatment membranes. Consequently, electrospun membranes are increasingly employed in water treatment applications such as membrane distillation and pretreatment of feed prior to reverse osmosis or nanofiltration for the removal of divalent metal ions and other contaminants. This chapter addresses the optimization of process parameters and the fabrication of electrospun, nonwoven, nanofibrous membranes and modification of their surface chemistry for desalination applications. Limitations, research challenges, and future perspectives are also discussed.

Additive manufacturing (AM), which is also commonly known as 3D printing, provides flexibility in the manufacturing of complex geometric parts at competitive prices and within a low production time. However, AM has not been used to a large extent in filtration and water treatment processes. AM results in the creation of millions of nanofibers that are sublayered on top of each other and compressed into a thin membrane. AM is a novel technique for fabricating filtration membranes with different shapes, sizes and controlled porosity, which cannot be achieved using conventional process such as electrospinning and knife casting. In this paper, we review the advantages and limitations of AM processes for fabricating ceramic membranes. Moreover, a brief background of AM processes is provided, and their future prospects are examined. Due to their potential benefits for fabrication and flexibility with different materials, AM methods are promising in the field of membrane engineering.

A novel upflow anaerobic sludge–forward osmotic membrane bioreactor was developed for simultaneous wastewater treatment, membrane fouling reduction, and nutrient recovery. An upflow anaerobic sludge blanket (UASB) reactor was incorporated into the system, suspending the anaerobic sludge at the bottom of the reactor. A forward osmosis membrane replaced the traditional three-phase separator of the UASB technology. The removals of chemical oxygen demand, PO43−, and NH4+ were all more than 95% with low membrane fouling in this system. Halotolerant Fusibacter, which can ferment organics to acetate, was increased rapidly from 0.1% to 5% in this saline environment. Acetoclastic Methanosaeta was the most dominant prokaryotes and responsible for majority of methane production. Reduction of membrane fouling in this system was verified by the fluorescence excitation-emission matrix spectrophotometry. Furthermore, phosphorus recovery and salinity build-up mitigation were achieved using periodic microfiltration to recover 57–105 mg/L phosphorus from pH 9 to 12.

BACKGROUND: For the first time, a closed-loop anaerobic osmotic membrane bioreactor–membrane distillation (AnOMBR-MD) hybrid system integrated with periodic microfiltration (MF) extraction was investigated for simultaneous nutrient and energy recovery while maintaining high water quality for reuse. In addition, phosphorus (P) was recovered as a valuable material for agricultural purposes. RESULTS: The AnOMBR-MD system exhibited excellent nutrient (>99.9%) and organic removal (almost 100%) due to double-layer filtration (FO and MD membrane). Moreover, higher methane production (0.24 L CH 4 /g COD) was achieved from the MF-AnOMBR process to supply a heat source for MD during the draw solution recovery process to reduce energy consumption. The MF permeate can significantly reduce the scaling potential caused by PO 4 3− ions in bulk solution and mitigate salt accumulation in the anaerobic reactor. The P from the MF permeate was effectively recovered with an efficacy of 60 mg L −1 when the solution pH was adjusted to 12. CONCLUSION: The overall performance of the MF-AnOMBR-MD hybrid system using 1.5 mol L −1 MgSO 4 as the draw solution demonstrates its potential application in wastewater treatment with high nutrient recovery in the closed-loop system. Moreover, this system combined with MD in AnOMBR for draw solution recovery could achieve low energy consumption when its biogas production is utilized as heat source from the anaerobic system. © 2018 Society of Chemical Industry.

Over the past decades, numerous materials have emerged as promising amenities for the fabrication of novel membranes. The current study gives insight into a modest and effective method to fabricate a crosslinked poly-vinylidene fluoride-co-hexafluoropropylene membrane with better mechanical properties and permeability for desalination. Poly-vinylidene fluoride-co-hexafluoropropylene membrane was grafted with crosslinked collagen to enhance direct contact membrane distillation used for desalination. Stiffness, rigidity and mechanical properties of the membrane were intensified by incorporating collagen (extracted from eggshells) into the membrane matrix, with glutaraldehyde crosslinkers. Furthermore, to improve water vapor diffusion, immobilized carbon nanofibers (CNF) were integrated in the membrane, casted via phase inversion technique with an optimized controlled approach. The permeate flux of CNF incorporated membrane was as high as 8 LMH, 18% higher than the unmodified poly-vinylidene fluoride-co-hexafluoropropylene membrane at 60 °C, besides minimal salt leakage. The properties of the modified membrane were characterized from its contact angle, morphological structure, surface roughness, dynamic mechanical properties, and water flux. The overall performance of the modified membranes was better than the virgin membranes. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48021.

Superhydrophobic membranes are necessary for effective membrane-based seawater desalination. This paper presents the successful fabrication of a novel electrospun nanofibrous membrane composed of polysulfone and Cera flava, which represents a novel class of enhanced performance membranes consisting of a superhydrophobic nanofibrous layer and hydrophobic polypropylene (PP). Cera flava, which helps lower the surface energy, was found to be the ideal additive for increasing the hydrophobicity of the polysulfone (PSF) polymeric solution because of its components such as long-chain hydrocarbons, free acids, esters, and internal chain methylene carbons. In the fabricated membrane, consisting of 10 v/v% Cera flava, the top PSF-CF nanofibrous layer is active and the lower PP layer is supportive. The hybrid membrane possesses superhydrophobicity, with an average contact angle of approximately 162°, and showed high performance in terms of rejection and water flux. This work also examined the surface area, pore size distribution, fiber diameter, surface roughness, mechanical strength, water flux, and rejection percentage of the membrane. The salt rejection was above 99.8%, and a high permeate flux of approximately 6.4 LMH was maintained for 16 h of operation.

Superhydrophobic membranes are essential for improved seawater desalination. This study presents the successful casting of a three-layered membrane composed of a top superhydrophobic coating onto a polypropylene (PP) mat through simple sol-gel processing of octadecyltrimethoxysilane (OTMS), and the bottom layer was casted with hydrophilic poly(vinyl alcohol) (PVA) by using a knife casting technique; this membrane represents a novel class of improved-performance membranes consisting of a top superhydrophobic coating onto a hydrophobic PP mat and a hydrophilic layer (PVA) at the bottom. OTMSs are well known low-surface-energy materials that enhance superhydrophobicity, and they were observed to be the ideal chemical group for increasing the hydrophobicity of the PP mat. The PVA layer acted as base layer absorbing the condensed vapor and thus enhancing the vapor flux across the membrane. The hybrid three-layered membrane exhibited superhydrophobicity, with an average contact angle of more than 160°, and demonstrated high performance in terms of rejection and water flux. This study also examined the pore size distribution, surface roughness, surface area, tensile strength, water flux, and salt rejection of the fabricated membrane. The salt rejection level was calculated to be 99.7%, and a high permeate flux of approximately 6.7 LMH was maintained for 16 h.

Forward osmosis (FO) has emerged as a viable technology to alleviate the global water crisis. The greatest challenge facing the application of FO technology is the lack of an ideal draw solution with high water flux and low reverse salt flux. Hence, the objective of this study was to enhance FO by lowering reverse salt flux and maintaining high water flux; the method involved adding small concentrations of Al2(SO4)3 to a MgCl2 draw solution. Results showed that 0.5 M MgCl2 mixed with 0.05 M of Al2(SO4)3 at pH 6.5 achieved a lower reverse salt flux (0.53 gMH) than that of pure MgCl2 (1.55 gMH) using an FO cellulose triacetate nonwoven (CTA-NW) membrane. This was due possibly to the flocculation of aluminum hydroxide in the mixed draw solution that constricted membrane pores, resulting in reduced salt diffusion. Moreover, average water fluxes of 4.09 and 1.74 L/m2-h (LMH) were achieved over 180 min, respectively, when brackish water (5 g/L) and sea water (35 g/L) were used as feed solutions. Furthermore, three types of membrane distillation (MD) membranes were selected for draw solution recovery; of these, a polytetrafluoroethylene membrane with a pore size of 0.45 μm proved to be the most effective in achieving a high salt rejection (99.90%) and high water flux (5.41 LMH) in a diluted draw solution.

Selection of a proper osmotic agent is important to make the forward osmosis (FO) feasible. The objective of this study was to enhance FO by lowering reverse solute flux and maintaining high water flux. Poly(propylene glycol) with molecular weight of 725 Da (PPG-725) was found to possess high osmolality, making it a strong candidate for using as a draw agent. In addition, to reduce the partial leakage of draw solute, a non-ionic surfactant (Triton X-114) has been incorporated. Typically, when the hydrophobic tails of Triton X-114 interacted with the membrane surface, a layer on the surface of membrane is produced to constrict the pores and thus minimize the reverse solute flux. In this study, different concentrations of PPG-725 incorporated with different concentrations of Triton X-114 (0.2–0.8 mM) were used to evaluate their osmotic potentials as draw solute. The specific reverse solute flux (Js/Jw) of 40% PPG-725 doped with Triton X-114 was found to be 0.01 g/L, considerably much lesser than the conventional inorganic draw agents. Finally, membrane distillation operation was utilized as the recovery system in which solute rejection of 97% was achieved for 40% PPG-725/Triton X-114. Therefore, the overall performance supported PPG-725/Triton X-114 as being an efficient draw agent for forward osmosis-membrane distillation hybrid process.

Osmotic membrane bioreactors (OsMBRs) are a recent breakthrough technology designed to treat wastewater. Nevertheless, their application in high-salinity wastewater treatment is not widespread because of the effects of saline conditions on microbial community activity. In response, this study developed an integrated sponge biocarrier-OsMBR system using highly salt-tolerant microorganisms for treating saline wastewater. Results showed that the sponge biocarrier-OsMBR obtained an average water flux of 2 L/m2 h during a 92-day operation when 1 M MgCl2 was used as the draw solution. The efficiency in removing dissolved organic compounds from the proposed system was more than 99%, and nutrient rejection was close to 100%, indicating excellent performance in simultaneous nitrification and denitrification processes in the biofilm layer on the carriers. Moreover, salt-tolerant microorganisms in the sponge biocarrier-OsMBR system worked efficiently in salt concentrations of 2.4%. A polytetrafluoroethylene MD membrane (pores = 0.45 μm) served to regenerate the diluted draw solution in the closed-loop system and produce high-quality water. The moving sponge biocarrier-OsMBR/MD hybrid system demonstrated its potential to treat salinity wastewater treatment, with 100% nutrient removal and 99.9% conductivity rejection.

Ethylenediaminetetraacetic acid disodium (EDTA-2Na) has been demonstrated as an excellent draw solution in the forward osmosis (FO) process because of its high osmotic pressure together with low reverse salt flux but its application is hindered by difficulties in the recovery of draw solution. Hence, in this study, microporous hydrophobic membranes were used in direct contact membrane distillation (DCMD) to concentrate the diluted EDTA-2Na draw solution. The MD was found to require lower operating pressures than do all other widely applied pressure-driven membrane processes, particularly in RO. This study systematically investigated the effect of different polytetrafluoroethylene membranes under various cross flow velocities of 2.67–14.67 cm/s, feed temperatures of 35–60 °C, and distillate temperatures of 10–20 °C in DCMD process for regeneration of diluted EDTA-2Na. The results revealed that DCMD system could achieve a salinity rejection rate exceeding 99.99%; furthermore, the conductivity of the permeate distillate was consistently below 6.4 µS/cm for all of the EDTA-2Na feed concentrations. More importantly, the water flux slightly decreased from 8.27 to 7.04 L/m2 h when the concentration of the EDTA-2Na feed increased from 0.1 to 0.5 M, corresponding to increased osmolality from 300 to 1411 mOsm/kg, indicating that water flux in DCMD is not significantly influenced by the osmotic pressure gradient across the membrane. This study demonstrated that MD could be an effective method for EDTA-2Na recovery in FO–MD systems and could economically utilize the wasted heat from industrial sources.

A novel superhydrophobic octadecyltrimethoxysilane (OTMS)-modified composite membrane was fabricated by incorporating recycled carbon black (CB) into a polyvinylidene fluoride (PVDF) membrane. Waste tires have been treated with extraction and high-temperature calcination to obtain recycled CB. After incorporating CB into the PVDF solution, a steep increase of 18-20% was observed in the loss and storage moduli. CB was observed to be an ideal filler for doping the PVDF solution to enhance the mechanical properties of the material. OTMSs are known for their low surface energy, which improves hydrophobicity. Moreover, OTMSs were found to be ideal agents for enhancing the superhydrophobicity of PVDF membranes. The results of surface treatment with OTMS, CB loading, particle size, and membrane properties and their effect on desalination performance were thoroughly studied. The composite membrane was observed to be superhydrophobic with a contact angle of 160° and exhibited high desalination performance in terms of permeate water flux and salt rejection. The fabricated membrane has been reused after physical cleaning in order to analyse the anti-wetting and long-term performance.

In this era of nanotechnology, electrospun nanofibrous membranes offer versatile characteristics, such as mechanical toughness and a large surface area, making them attractive for various applications. Electrospinning is an emerging methodology for producing nanofibers. Furthermore, electrospinning yields uniform pore size, which is considered a crucial characteristic of water treatment membranes. Consequently, electrospun membranes are increasingly employed in water treatment applications such as membrane distillation and pretreatment of feed prior to reverse osmosis or nanofiltration for the removal of divalent metal ions and other contaminants. This chapter addresses the optimization of process parameters and the fabrication of electrospun, nonwoven, nanofibrous membranes and modification of their surface chemistry for desalination applications. Limitations, research challenges, and future perspectives are also discussed.

Membrane technology has become a common separation technology over the past decennia. Membranes are used more and more for the production of drinkable water from groundwater, surface water and wastewater. Membranes are now competitive versus conventional techniques. Desalination is predominantly used to eradicate the problem of water scarcity. The sustainability of all desalination processes depends mainly on the reduction of energy costs (production cost) and the increase in water recovery. Forward osmosis and membrane distillation are emerging technologies for sustainable desalination. Here we review membrane processes of forward osmosis and membrane distillation and the advancements in membrane material and modules. We also discuss the capability of membrane distillation in treating highly concentrated aqueous solutions derived from other desalination processes. Furthermore, the advancements in fabrication of high-performance membrane is reviewed and the performance of different membranes and optimization of membrane distillation process are summarized.

Chennai (earlier called as Madras) was one of the key trading centers during the British days in India. As many as 14 tanneries out of a total of 25 were in Chennai, are from early 20th century. Later, more leather industries came into existence in and around the city and later grew phenomenally over the years the groundwater in these areas has become intolerably polluted with effluents and high salinity. The surface water sources have also got dried up. These tanneries generate huge quantities of solid wastes and heavy metal pollutants, e.g. Cadmium, hexavalent Chromium, Copper, Nickel and Lead on a regular basis. The concentrations of these pollutants are increasing at an alarming rate. Though there are robust methods for treatment of effluents, these are not affordable by small and medium entrepreneurs who still continue to use old technologies; limited or no treatment of the outgoing industrial effluents and direct disposal of tannery wastes into water-bodies. Ranipet in Vellore District, which has large number of leather processing units, was selected for the study. Water, soil and vegetable samples from this place were collected for analysis and the levels of heavy metals were evaluated using Atomic Absorption Spectrometer. The values obtained were compared with the Standards set up by World Health Organization (WHO) Guidelines and the deviations in those concentrations have been highlighted and their effects discussed in detail.

A novel category of improved performance membrane consisting of a hydrophobic mat and a hydrophilic electrospun layer for membrane distillation (MD) application has been presented. The nanofibrous non-woven layer was fabricated by electrospinning of polyvinylalcohol (PVA) incorporated with Triton X-100 directly onto the polypropylene (PP) mat. To render the membrane distillation process effective in terms of high permeate flux and salt rejection %, the concept of dual layer membrane is utilized with hydrophobic PP mat on top and hydrophilic PVA layer on bottom. In this study, PVA nanofibrous layer has been fabricated by incorporating non-ionic surfactant Triton X-100 for uniformity and homogeneity in fiber diameter. Additionally, the PP mat acts as a top support layer and PVA-TX nanofiber acts as base layer which absorb the water molecules (condensed vapour), that enhances the vapour flux across the membrane. The modified bilayer PP/PVA-TX membranes were characterized by the pore size distribution, permeate flux, and rejection %, then compared with original PP mat. The salt rejection of the dual layered PP/PVA-TX membrane showed > 99% and still maintained 2 times higher permeate flux compared to PP membrane for long term operation of 15 h.

Recently, water reclamation and water reuse have received considerable attention because of high water demand. Membrane processes constitute the most convenient technology for water treatment and desalination. In this study, a novel class of enhanced performance membranes consisting of a highly hydrophobic nanofibrous layer and hydrophilic cellulose filter paper (CFP) for membrane distillation (MD) was thoroughly examined. The nanofibrous layer was produced through electrospinning of polysulfone (PSF) doped with a sodium dodecyl sulfate (SDS) surfactant for uniformity and homogeneity in fiber diameter. The SDS surfactant was found to be the ideal additive for increasing the conductivity of the PSF polymeric solution, which helps in lowering the critical voltage required to initiate the electrospinning process, resulting in greater elongation of the nanofibers because of the increase in charge density. In the fabricated membranes, the PSF–SDS nanofibrous layer acts as a top active layer, whereas the CFP acts as the bottom supportive layer. Cellulose paper can absorb water molecules, which enhances vapor flux across the membrane in MD. The surface area, pore size distribution, fiber diameter, mechanical strength, water flux, and rejection percentage of the modified dual-layer PSF–SDS/CFP membranes were studied. The salt rejection of the PSF–SDS/CFP membrane was more than 99%, and a high permeate flux of approximately 9 LMH was maintained for long-term operation of 16 h.

Osmosis membrane bioreactors (OMBRs), which integrate forward osmosis (FO) and a biological process, followed by reverse osmosis or membrane distillation (MD) have been receiving increasing attention for wastewater treatment and reuse. However, OMBR application in wastewater treatment is still hindered by the accumulation of inorganic and organic salts, which affects microbial activity in the OMBR. Therefore, in this study, a novel hybrid OMBR–MD system integrated with periodic microfiltration (MF) extraction was developed for simultaneous salinity reduction and phosphorus recovery using a magnesium-based draw solute by taking advantage of magnesium salt reversal. In the OMBR system, MgCl2 was used as the draw solution to withdraw clean water passing through the FO membrane, whereby all contaminants and mineral salts, including phosphate, ammonia and magnesium reversed from the draw solution, were retained in the bioreactor. The MF membrane was used to bleed the water out of the bioreactor for salinity reduction and subsequent phosphorus recovery. The pH of the effluent from the MF containing high phosphorus was adjusted to 10 to precipitate struvite, and the amount of the produced struvite was quantitatively determined to be 41 mg per liter of the MF permeate. The MD process was used to recover the diluted MgCl2 draw solution with an initial flux of 8.2 L/m2 h under a temperature difference of 30 °C (55 °C in the feed and 20 °C in the distillate). Subsequently, the flux slightly decreased to 6.3 L/m2 h after 6 h because of the decreasing vapor pressure in the salt solution based on Raoult's law.

In this world of nanotechnology, nanofibrous structures offer specialized features, such as mechanical strength and a large surface area, which makes them attractive for many applications. Their large surface area to volume ratio also makes them highly efficient. Among all the techniques for generating nanofibers, electrospinning is an emerging and efficient process. Additionally, the electrospinning technique allows a uniform pore size, which is considered to be one of the important characteristics of membranes. Therefore, electrospun nanofibrous membranes have been used in water purification applications. Furthermore, the technique is widely utilized for generating membranes for membrane distillation and nanofiltration processes, for the removal of contaminants. However, in this review paper, more emphasis is given to the optimization of specific parameters and the preparation of polymeric solutions for fabricating specialized nanofibrous non-woven membranes, and surface modification for application in water treatment technology. Other issues, such as technology limitations, research challenges, and future perspectives, are also discussed.

A novel approach was designed to simultaneously enhance nutrient removal and reduce membrane fouling for wastewater treatment using an attached growth biofilm (AGB) integrated with an osmosis membrane bioreactor (OsMBR) system for the first time. In this study, a highly charged organic compound (HEDTA3-) was employed as a novel draw solution in the AGB-OsMBR system to obtain a low reverse salt flux, maintain a healthy environment for the microorganisms. The AGB-OsMBR system achieved a stable water flux of 3.62 L/m2 h, high nutrient removal of 99% and less fouling during a 60-day operation. Furthermore, the high salinity of diluted draw solution could be effectively recovered by membrane distillation (MD) process with salt rejection of 99.7%. The diluted draw solution was re-concentrated to its initial status (56.1 mS/cm) at recovery of 9.8% after 6 h. The work demonstrated that novel multi-barrier systems could produce high quality potable water from impaired streams.

For the first time, an innovative concept of combining sponge-based moving bed (SMB) and an osmotic membrane bioreactor (OsMBR), known as the SMB-OsMBR hybrid system, were investigated using Triton X-114 surfactant coupled with MgCl2 salt as the draw solution. Compared to traditional activated sludge OsMBR, the SMB-OsMBR system was able to remove more nutrients due to the thick-biofilm layer on sponge carriers. Subsequently less membrane fouling was observed during the wastewater treatment process. A water flux of 11.38 L/(m2 h) and a negligible reverse salt flux were documented when deionized water served as the feed solution and a mixture of 1.5 M MgCl2 and 1.5 mM Triton X-114 was used as the draw solution. The SMB-OsMBR hybrid system indicated that a stable water flux of 10.5 L/(m2 h) and low salt accumulation were achieved in a 90-day operation. Moreover, the nutrient removal efficiency of the proposed system was close to 100%, confirming the effectiveness of simultaneous nitrification and denitrification in the biofilm layer on sponge carriers. The overall performance of the SMB-OsMBR hybrid system using MgCl2 coupled with Triton X-114 as the draw solution demonstrates its potential application in wastewater treatment.

For the first time, a high charge of phosphate was used as the draw solute in a forward osmosis-membrane distillation (FO-MD) hybrid system for concentrating high-nutrient sludge. A high water flux (12.5 L/m2 h) and a low reverse salt flux (0.84 g/m2) were simultaneously achieved at pH 9 by using 0.1 M Na3PO4 as the draw solute and deionized water as the feed solution in the FO process. The specific reverse salt flux of 0.1 M Na3PO4 (Js/Jw = 0.07 g/L) was considerably less than that of 0.1 M NaCl (Js/Jw = 0.37 g/L) because the complexion between Na+ and HPO42- at pH 9 led to the reduction of free Na+ ions, which subsequently reduced the reverse salt diffusion substantially. Moreover, for a feed solution with an initial sludge concentration of 3500 mg/L, the sludge concentration could be concentrated to 19,800 and 22,000 mg/L in the pressure-retarded osmosis (PRO) and FO membrane orientations, respectively, after 15 h of operation. Four types of MD membranes were selected for draw solution recovery; of these, a polytetrafluoroethylene membrane with a pore size of 0.45 μm was the most effective in achieving a high water flux (10.28 L/m2 h) and high salt rejection (approximately 100%) in a diluted Na3PO4 draw solution.

For the first time, KOH in the waste stream of a thin film transistor liquid crystal displays (TFT-LCD) plant was utilized as a draw solution to recover iodide in the waste stream through forward osmosis (FO). In long-term operation, the pressure-retarded osmosis mode provided concentration efficiency greater than that of the FO mode. The maximum water flux achieved 11.7 LMH at pH 11 of KOH draw solution, and the iodide concentration reached 6.9% for reuse in TFT-LCD plant from the initial iodide concentration of 0.6% after 120 h. Analysis of scanning electron microscopy and energy dispersive X-ray spectroscopy images revealed a thin fouling cake layer of KI on the support layer of the membrane. The overall performance of the proposed FO system with KOH as the draw solution indicated that the FO system is promising for concentrating iodide for reuse in TFT-LCD plants. The proposed FO system offers excellent benefits: (1) the liquid discharge is minimal and (2) the cost of the FO system is extremely low because draw solution recovery is not required.

Forward osmosis is a membrane technology which is of high interest for water reclamation and desalination. To stabilize the forward osmosis (FO) process practical and cost-effective, selection of an appropriate draw solute is essential. Chlorhexidine gluconate based mouth-wash (CMW) has been determined to have high osmolality and low toxicity, rendering it applicable as a novel draw solute in future applications. The experimental data of the FO process demonstrated the advantage of using CMW compared with using conventional salt (NaCl), and parameters such as the water flux (Jw), reverse salt flux (Js), and specific reverse salt flux (Js/Jw) were considered. The specific reverse salt flux (Js/Jw) of 100% mouthwash was found to be 0.07 g/L, lower than that of 0.5 M NaCl. A thermally driven membrane distillation (MD) was used for the recovery system. Furthermore, the reusability of the draw solute was determined to be an effective agent for antifungal and antimicrobial activity. Hence, the overall performance supported CMW as a promising draw solute for FO-MD systems.

The project will study and analyse the metallic contamination found in few branded cigarettes in India. Simultaneously toxicity exposure will also be determined which may create serious health hazards. The metals selected for analysis are lead(Pb), cadmium (Cd), nickel (Ni), chromium (Cr) and mercury (Hg) which are highly toxic as well as carcinogenic in nature. The toxic metal concentration in different branded cigarettes ranges from Cd (0.045 ppm- 0.065 ppm), Pb (0.95 ppm – 1.25 ppm), Hg (2.5 ppm – 7.0 ppm), Cr (1.90 ppm – 2.50 ppm), Ni (0.29 ppm – 0.51 ppm). The concentration of above mentioned toxic metals are found to be slightly higher than the permissible limit proposed by Indian Journal of Pharmacology (IJP). This toxicity may cause various types of neurological disorders, nervous system damage and cancer. Therefore in conclusion part some sort of toxicological management and preventive measures will be emphasised for the betterment of environment point of view. Therefore different standard methodologies and instrumentations will be used to analyse the toxic metals found in cigarettes.

The project will study the effect of heavy and toxic metals present in various vegetables grown in South India (Vellore District). Simultaneously the project will make the use of different standard methodologies and analytical instrumentations for the quantitative analysis of heavy and toxic metals. In next half of the experiment Transfer Factor (TF) and Daily Intake Rate (DIR) will also be calculated. The toxicity of these metals is in part due to the fact that they accumulate in biological tissues, a process known as bioaccumulation. Even the toxicity level and reasons for increasing concentration of toxic metals were also studied for each and every vegetable for that region. This toxicity may lead to various types of paralysis, neurological disorders and cancer. Therefore in conclusion some sort of agricultural management will be suggested for the welfare of environment point of view.

The project will study the physicochemical parameters such as colour, pH, temperature, electrical conductivity, total dissolved solids (TDS), biochemical oxygen demand (BOD) and chemical oxygen demands (COD), hardness and mineral ions following the standard methods of eastern rivers of India. The project will make the use of different standard methodology, analytical instrumentations and statistical analysis for determination of physicochemical parameters. In the second half of the experiment desired treatment will be suggested for the removal of impurities. Therefore in conclusion some sort of river water management will be given for the welfare of environment point of view. © Research India Publications.