Potential human health effects of per- and polyfluoroalkyl substances (PFAS) prevalent in aquatic environment: a review
Srinithi Mayilswami, Nirav P. Raval, Rinki Tomar, Shailja Sharma, Sarva Mangala Praveena, Navish Kataria, Rangabhashiyam Selvasembian, Saravanan Ramiah Shanmugam, Ravinder Nath, Arindam Malakar, Sudeshna Dutta, Santanu Mukherjee
Journal, Environmental Science: Advances, 2025, DOI Link
View abstract ⏷
The widespread incorporation of per- and polyfluoroalkyl substances (PFAS) in various daily-use items has garnered considerable attention regarding environmental and health hazards in the last decade. Among different categories of PFAS, a paradigm shift has occurred towards short-chain PFAS alternatives like GenX, ADONA, and F53B, driven by environmental considerations and regulatory changes. Exposure to PFAS can happen through consuming contaminated food and drink, inhaling contaminated dust, or skin contact with PFAS-containing objects. Furthermore, occupational exposure might result from manufacturing and firefighting operations employing fluorinated compounds. In humans and monkeys, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) exhibit an increased affinity for plasma proteins. However, the exact extent of this affinity is still a matter of research. The buildup of PFOS in the liver might cause injury or dysfunction by interfering with its regular operation. Compared to other human tissues, the liver has been shown to accumulate higher amounts of PFOS. Although there is an absence of epidemiological studies on PFOS, a possible connection between the health disorder and elevated cholesterol levels has been established by many researchers. Considering the transition as a future environmental burden, this review aims to bring together ongoing research compilations on short-chain PFAS, delving into their persistence, prevalence, and bioaccumulative toxicity in aquatic environments and focusing on critical areas of research gaps. An extensive literature analysis assessed the relative abundance of short-chain compounds compared to their long-chain counterparts within aquatic ecosystems. US EPA has setup new guidelines specifically for drinking water for PFOA and PFOS compounds which is 4 ppt. Furthermore, this review highlights emerging regulatory measures being implemented worldwide to safeguard public health. These measures encompass a range of strategies, from the European Union's emphasis on banning certain manufacturing and production practices under the REACH regulations to establishing exposure limits and disposal protocols in the United States.
Exploring the terrestrial ecosystem hazards of perfluorooctanoic acid: a comparative acute and chronic study of Eisenia fetida responses in different soil types
Srinithi Mayilswami, Nirav Praduman Raval, Shailja Sharma, Mallavarapu Megharaj, Santanu Mukherjee
Journal, Environmental Science and Pollution Research, 2025, DOI Link
View abstract ⏷
Human activities predominantly release perfluorooctanoic acid (PFOA) and other fluorinated chemicals, which are highly persistent, leading to long-term accumulation in organisms and posing significant health risks. Therefore, it is essential to study the long-term impacts of PFOA on terrestrial ecosystems using sentinel organisms such as earthworms. This research investigated the toxicity of PFOA on earthworms (Eisenia fetida) across three different soil types. An acute toxicity assay was conducted to assess the effects of PFOA on survival, growth, cellulase activity, lysosomal membrane stability, and avoidance behaviour. Concurrently, a chronic toxicity assay examined the impact on reproduction, specifically focusing on cocoon production and juvenile emergence. For the 14-day acute toxicity study, LC50 values were found to be 823.9 mg/kg, 894.9 mg/kg, and 672.2 mg/kg in alkaline, neutral, and OECD soils, respectively. Although PFOA showed lower toxicity in neutral soils, it still caused significant sublethal effects in all soil types. Chronic exposure to a concentration of 100 mg/kg significantly affected reproduction in all soils tested. Overall, the findings suggested that earthworms were effective sentinel organisms for evaluating the toxic potential of PFOA, with reproductive effects serving as particularly sensitive indicators of PFOA contamination.
Magnetite-Doped Activated Carbon Beads and Powder Derived from Chitosan for Adsorption of Emerging Contaminants in Drinkable Water
Nirav P. Raval, Laurence Reinert, Laurent Duclaux, Nathalie Cottin, Noriko Yoshizawa, Jimmy Nicolle, Anandu Chandran, Fabrice Muller
Journal, Molecules, 2025, DOI Link
View abstract ⏷
Activated carbon beads, some of which contain Fe3O4 nanoparticles or graphene oxide, were synthesized by thermal activation (700 °C) of chitosan hydrogel beads. Materials showed a multiporous scale (micro/meso/macro) and BET specific surface areas in the 260–572 m2.g−1 range. The adsorption kinetics of beads and powders resulting from their grinding were studied for a mixture of six micropollutants (bisphenol A, carbofuran, carbamazepine, diclofenac, dimethoate and imidacloprid) dissolved in spring water. While the adsorption kinetics on the beads (pH 7.3, 25 °C, 10–100 µg.L−1) are slow (equilibrium time > 24 h), the powdered samples are more efficient: for an initial concentration of 50 μg.L−1 of each pollutant (0.1 g.L−1 of adsorbent), 50 to 99% of the micropollutants introduced into the solution were removed after 4 h of contact time. Depending on the pollutant nature, the adsorption isotherms (0.2–40 μg.L−1) studied for an activated carbon powder containing Fe3O4 (1 mass %) are either of Langmuir or Freundlich type, or they follow Henry’s law and are related to the different properties of the molecules.
Systematic evaluation of industrial greenbelts for quantifying carbon sequestration potential of afforestation activities
Nirav P. Raval, Aravind D, Ramesh, Himanshu Pandey, Pradeep Kumar Ghosal, Milind Rawal, Mrugesh H. Trivedi
Journal, Environmental Monitoring and Assessment, 2025, DOI Link
View abstract ⏷
India’s energy demand increased by 7.3% in 2023 compared to 2022 (5.6%), primarily met by coal-based thermal power plants (TPPs) that contribute significantly to greenhouse gas emissions. In line with national climate goals set under the Nationally Determined Contributions (NDCs) for 2030, India mandates 33% green cover within TPPs for carbon (C) sequestration. This study assesses the C sequestration potential of greenbelts at Tata Coastal Gujarat Power Limited (CGPL) plant (465 ha) and its township (TS, 13.86 ha). The analysis integrates field-based allometric biomass estimation with CASA modeling, supported by remote sensing (RS) and GIS-based evaluation of NDVI and NDBI indices. While the TS exhibited higher species richness (28 families, 3,706 trees), the TPP (19 families, 363,467 trees) recorded higher sequestration values (CO2-equivalent: 52.52 Mg ha⁻1 vs. 2.13 Mg ha⁻1). Statistical modeling demonstrated that biomass accumulation was the strongest predictor of carbon storage (R2 = 1 for biomass–CO2eq) across both sites indicating that larger DBH and higher total biomass consistently resulted in greater CO2eq sequestration. NDVI-based analysis indicated a consistent increase in vegetation health over 2010–2023, while NDBI showed moderate expansion in built-up area. CASA estimates annual CO2 sequestration of ~8,745 Mg ha−1 for TPP and 1058 Mg ha−1 for the TS. This study provides a reference framework for afforestation-driven carbon mitigation by optimizing green areas within industrial landscapes, thereby contributing to the achievement of the United Nations Sustainable Development Goals (SDGs).
Harnessing bio-nano hybrid column for sustainable treatment of Reverse Osmosis Concentrate: A decentralized water treatment approach
Gautam V. Priyadarshi, Nirav P. Raval, Anandu Chandran, Ashish Patel, Mrugesh H. Trivedi
Journal, Journal of Water Process Engineering, 2025, DOI Link
View abstract ⏷
Reverse osmosis concentrate (ROC), a hyper-saline byproduct of domestic RO systems, contains elevated ionic and heavy metal content, posing environmental risks. This study developed a decentralized treatment system using a fluidized-bed column packed with chitosan-impregnated zinc-oxide nanocomposite (CS@ZnO) and acid-treated resin (ATR) beads. ROC samples were collected from residential RO units in groundwater (GW) and surface water (SW) dependent regions in Gujarat, India. Physicochemical analysis revealed elevated total dissolved solids (TDS: ≥3241 mg L−1), electrical conductivity (EC: ≥5440 μS cm−1), anions, cations and heavy metals exceeding regulatory limits. A negative correlation between pH and EC/TDS revealed acidification linked to ion accumulation, informing sorbent optimization. The hybrid column, operated in upward flow (570 mL min−1), demonstrated effective stabilization of pH and removal of TDS (25.9 %) and EC (39.5 %) up to 60 L. Significant contaminant removal efficiencies included: Ca2+ (73.2 %), Mg2+ (62.4 %), Na+ (31.3 %), F− (76.6 %), Cl− (46.2 %), SO₄2− (99.7 %), NO₃− (92.1 %), Mn (100 %), Zn (65.3 %), Ni (42.5 %), Co (16.7 %), and Cd (54.5 %). The adsorption mechanism combined CS's chelation, ATR's ion-exchange, and ZnO's surface reactivity. Although Pb and Cr exceeded safe limits post-treatment, the effluent complied with standards for non-potable reuse. This column offers a scalable, low-cost method for ROC valorization, promoting sustainable water reuse and environmental protection in water-stressed areas.
Heavy metal pollution in indoor dust of residential, commercial, and industrial areas: a review of evolutionary trends
Arpita Roy, Aditya Kumar Jha, Abhishek Kumar, Tanushree Bhattacharya, Sukalyan Chakraborty, Nirav P. Raval, Manish Kumar
Journal, Air Quality, Atmosphere and Health, 2024, DOI Link
View abstract ⏷
Heavy metals (HMs) in indoor dust are among the most toxic micropollutants and have attracted mainly the attention of researchers in the last three decades concerning the environmental and human health perspectives. Hence, a thorough literature-based bibliometric analysis was inevitably needed to identify the research trend for the prevalence of HMs in indoor environments and their toxicological aspects. Accordingly, exploring publications on the Web of Science Core Collection database to identify the articles published on HM pollution in indoor dust environments revealed several peculiar findings. The review article indicates that the majority of studies conducted in this field are monitoring-based, utilizing “HMs (n = 79),” “contaminations (n = 49),” “lead (n = 49),” and “health” as primary keywords in the published articles. Among the countries, China emerged as the most active investigator in this area, followed by the USA, Middle East, Turkey, Korea, and India. Additionally, China has established collaborations with ~150 and >90 countries, respectively, solidifying its leading position in publications. Studies on HM pollution in indoor dust have evolved from initial exposure analyses in the 1990s to encompass bioavailability, bioaccessibility, exposure, risk assessment, speciation, and source apportionment assessments. Metal pollution in residential and commercial areas (schools/offices) primarily originates from in-house sources and vehicle emissions, while industrial areas, driven by anthropogenic activities (e-waste recycling/mining), face metal pollution from different sources. The analysis underscores that studies predominantly focus on risk assessment of significant metals, their bioaccessibility/bioavailability, and source apportionments. This study’s exploration of HMs in indoor dust provides explicit content and trends, offering valuable insights for researchers delving into this field. It not only suggests remedial measures but also contributes to the development of forecasting models.
Tricks and tracks of prevalence, occurrences, treatment technologies, and challenges of mixtures of emerging contaminants in the environment: With special emphasis on microplastic
Jayaraman Sethuraman Sudarsan, Kanika Dogra, Rakesh Kumar, Nirav P. Raval, Mats Leifels, Santanu Mukherjee, Mrugesh H. Trivedi, Mayur Shirish Jain, Jian Zang, Damià Barceló, Jürgen Mahlknecht, Manish Kumar
Journal, Journal of Contaminant Hydrology, 2024, DOI Link
View abstract ⏷
This paper aims to emphasize the occurrence of various emerging contaminant (EC) mixtures in natural ecosystems and highlights the primary concern arising from the unregulated release into soil and water, along with their impacts on human health. Emerging contaminant mixtures, including pharmaceuticals, personal care products, dioxins, polychlorinated biphenyls, pesticides, antibiotics, biocides, surfactants, phthalates, enteric viruses, and microplastics (MPs), are considered toxic contaminants with grave implications. MPs play a crucial role in transporting pollutants to aquatic and terrestrial ecosystems as they interact with the various components of the soil and water environments. This review summarizes that major emerging contaminants (ECs), like trimethoprim, diclofenac, sulfamethoxazole, and 17α-Ethinylestradiol, pose serious threats to public health and contribute to antimicrobial resistance. In addressing human health concerns and remediation techniques, this review critically evaluates conventional methods for removing ECs from complex matrices. The diverse physiochemical properties of surrounding environments facilitate the partitioning of ECs into sediments and other organic phases, resulting in carcinogenic, teratogenic, and estrogenic effects through active catalytic interactions and mechanisms mediated by aryl hydrocarbon receptors. The proactive toxicity of ECs mixture complexation and, in part, the yet-to-be-identified environmental mixtures of ECs represent a blind spot in current literature, necessitating conceptual frameworks for assessing the toxicity and risks with individual components and mixtures. Lastly, this review concludes with an in-depth exploration of future scopes, knowledge gaps, and challenges, emphasizing the need for a concerted effort in managing ECs and other organic pollutants.
Indian and global scenarios of Bisphenol A distribution and its new analogues: Prevalence & probability exceedance
Kanika Dogra, Dipa Lalwani, Shiwangi Dogra, Durga Prasad Panday, Nirav P. Raval, Murgesh Trivedi, Abrahan Mora, Misael Sebastian Gradilla Hernandez, Shane A. Snyder, Jürgen Mahlknecht, Manish Kumar
Journal, Journal of Hazardous Materials, 2024, DOI Link
View abstract ⏷
We compare, the prevalence, fate, and sources of Bisphenol A both globally and in India. India has the highest concentration of BPA and Bisphenol S(BPS) in general, with vegetables, particularly corn, beans, strings, and raw or canned vegetables, being the largest contributors. Among all the matrices, bisphenols (BPs) are found in the highest concentration in food, followed by surface water, wastewater, and indoor dust. BPA, BPS, and BPF are the most commonly reported analogues in India, with BPA being the most dominant category used worldwide. The highest concentration of BPs is observed in Uttar Pradesh, Punjab and Haryana that are three major agricultural states of India however, there is still a research gap regarding the dietary exposure to BPs on an individual level. Environmentally detected BPA occurs in a range of below detection to 10636 ng. L−1, with significant geographic variations. Interestingly, the order of abundance in India was maximum for BPS, which is contrary to the global average, where BPA is observed as most abundant. BPS is found to be the most common BPs analogue in surface water worldwide, with limited removal efficiency by both naturally remediation and conventional treatment methods. Similar patterns were observed in the US-India and Japan-Korea regions in terms of their source-sink-prevalence-fate dynamics. The probability of exceeding safe concentrations of BPs is higher in India and Korea, suggesting that these countries are more vulnerable to high prevalence concentrations and the subsequent public health hazards.
Chitosan supported hetero-metallic bio-nanocomposites for paracetamol removal from homogeneous solutions and heterogeneous mixtures with focused antibacterial studies
Gautam V. Priyadarshi, Nirav P. Raval, Damia Barcelo, Mrugesh H. Trivedi
Journal, International Journal of Biological Macromolecules, 2024, DOI Link
View abstract ⏷
Biopolymers infused with bimetallic nanoparticles exhibit a wide range of functionalities necessary for efficiently eliminating diverse water contaminants. However, the protracted production process requires further exploration. As such, present study seeks to optimize microwave-assisted technique for the facile synthesis of cross-linked chitosan (CTS) supported bimetallic-oxide nanoparticles, specifically zinc oxide (ZnO) and iron-oxide (Fe3O4), denoted as CTS-TTP/Zn-Fe. The primary objective is to investigate the efficacy of these beads in the removal of Paracetamol (PCM) from single and complex water matrices while also assessing their antibacterial properties. Characterization includes chemical composition, surface structures, thermal stability, and magnetic properties. The experimental results demonstrated that CTS-TPP/Zn-Fe beads achieved a remarkable PCM removal efficiency of ~99 % (qm = 4.98 mg g−1), with a Zn:Fe mole ratio of 1:1. The experimental data showed good applicability with Freundlich isotherm and chemisorption-supported rate models (R2 > 0.9). To evaluate the long-term viability and practicality of these beads, three crucial field applicability tests were conducted. These encompassed competition studies with other pharmaceuticals, desorption investigations for repeated use, and efficiency evaluations in an ionic solution. Collectively, this research provides a comprehensive understanding, spanning from material design to practical applications, with potential relevance for large-scale wastewater treatment when coupled with appropriate flux control measures.
Aggregation behaviour of black carbon in aquatic solution: Effect of ionic strength and coexisting metals
Kiran Dhangar, Manish Kumar, Marwan Aouad, Jurgen Mahlknecht, Nirav P. Raval
Journal, Chemosphere, 2023, DOI Link
View abstract ⏷
Black Carbon (BC) is an important constituent of both aquatic and terrestrial environment, but also has several adverse effects on human health, aquatic life, and contributes to the global climate change. Thus, to understand the fate and transport of BC nanoparticles (NPs) in the environment, it's important to understand the colloidal stability or aggregation behaviour and factors affecting it, under various environmental conditions, including both aquatic and atmospheric. This study investigated the individual influence of ionic strengths, valence (Na+, Ca2+ and Mg2+), metals (Zn2+, Cu2+, Ni2+ and Cd2+), and organic substances (PO43− and Humic Acid: HA) on the effective diameter or hydrodynamic diameter and zeta potential of BC-NPs in aquatic systems. A dynamic light scattering (DLS) principle-based 90 Plus Particle Size Analyzer was used for measurements of BC particle size and zeta potential at varying ionic chemistry. The results showed that strong ionic strength promotes aggregation of BC-NPs till the repulsion forces become dominant due to more negative zeta potential. The Aggregation of BC-NPs was observed to be significantly dependent on the ionic valence, where divalent ions caused more aggregation than monovalent ions. Metal ions at higher concentration (around 1 mM) promoted the aggregation rate of BC-NPs, and Cu+2 dominated among all selected metals. Conversely, organic matter (PO43− and HA) tends to promote stabilisation of BC-NPs instead of aggregation. Though this study investigated individual effect of substances, influence of possible environmental combination of substances will help to get more clear idea.
Exploration of the ameliorative effect of dietary polyphenol on Bisphenol-A prompted DNA damage by in vitro and in silico approaches
Mrugesh Trivedi, Chirag N. Patel, Druma Vaidya, Nirav P. Raval, Manish Kumar
Journal, Journal of Molecular Structure, 2023, DOI Link
View abstract ⏷
Bisphenol A (BPA), an infamous xenoestrogen, can cause the inimical environmental and health implications via generation of extremely reactive oxygen species (ROS) and/or by mimicking the endocrine activity. The intention of this study was to understand the concentration range of BPA between 0.02-200 µg mL−1 that may induce DNA damage and cytotoxicity, individually and/or through amelioration by gallic acid (GA) (10–50 µg mL−1) in HepG2 cell line by Comet, Lactate Dehydrogenase (LDH) leakage and MTT assay. The results revealed that BPA was not found genotoxic (0.02–0.2 µg mL−1) and cytotoxic at low dose exposure (0.02 µg mL−1). However, BPA at a concentration of 2-200 µg mL−1, induced significant DNA damage and cytotoxicity (p<0.05) in a dose-relying manner in HepG2 cell line. However, DNA damage and cytotoxicity were inhibited when GA (10–50 g mL-1) and BPA (200 g mL-1) were added together. To investigate the mechanism of toxicity and the binding potential of BPA/BPA-Q to DNA and GA, an in silico molecular docking approach and molecular dynamics simulation were performed. The obtained results revealed strong binding affinity between BPA/BPA-Q with DNA which induces DNA damage.
Adsorptive removal of ciprofloxacin and sulfamethoxazole from aqueous matrices using sawdust and plastic waste-derived biochar: A sustainable fight against antibiotic resistance
Rahul Silori, Jian Zang, Nirav P. Raval, Balendu Shekher Giri, Jürgen Mahlknecht, Abrahan Mora, Jaime Dueñas-Moreno, Syed Mohammad Tauseef, Manish Kumar
Journal, Bioresource Technology, 2023, DOI Link
View abstract ⏷
We produced carbon-negative biochar from the pyrolysis of sawdust biomass alone (SB) and from the co-pyrolysis of sawdust and plastic waste (SPB). The co-pyrolysis approach in this study was driven by several hypothetical factors, such as increased porosity, surface chemistry, stability, as well as waste management. We applied pyrolyzed and co-pyrolyzed biochars for the removal of ciprofloxacin (CFX) and sulfamethoxazole (SMX). Due to its more alkaline and amorphous nature, SB showed better removal efficiencies compared to SPB. The maximum removals of CFX and SMX with SB were observed as ∼95% and >95%, respectively whereas with SPB were 58.8%, and 34.9%, respectively. The primary mechanisms involved in the adsorption process were H-bonding, electrostatic and π–π electron donor–acceptor interactions. Homogenously and heterogeneously driven adsorption of both antibiotics followed the pseudo-second-order kinetic model, implying electron sharing/transfer (chemisorption) mediated adsorption. The work is highly pertinent in the context of emerging concerns related to drivers that promote antimicrobial resistance.
Aminoalkyl-organo-silane treated sand for the adsorptive removal of arsenic from the groundwater: Immobilizing the mobilized geogenic contaminants
Manish Kumar, Santanu Mukherjee, Alok Kumar Thakur, Nirav Raval, Alicia Kyoungjin An, Petros Gikas
Journal, Journal of Hazardous Materials, 2022, DOI Link
View abstract ⏷
Arsenic (As), a geogenic legacy pollutant can be present in environmental matrices (water, soil, plants, or animal) in two redox states (As(III) or As(V)). In the present study, charged mono- and di-amino functionalized triethoxy and methoxyorganosilane (TT1 and TT2- 1% and 5%) were impregnated with quartz sand particles for the treatment of As polluted water. Spectroscopic characterization of organosilane treated sand (STS) indicated the co-existence of minerals (Mg, Mn, Ti), amide, and amidoalkyl groups, which implies the suitability of silanized materials as a metal(loids) immobilization agent from water. Changes in peaks were observed after As sorption in Fourier thermal infrared and EDS images indicating the involvement of chemisorption. Batch sorption studies were performed with the optimized experimental parameters, where an increased removal (>20% for TT2–1% and >60% for TT1–1%) of As was observed with sorbate concentration (50 µg L−1), temp. (25 ± 2 ºC) and sorbent dosages (of 10 g L−1) at 120 min contact time. Among the different adsorbent dosages, 10 g L−1 of both TT1 and TT2 was selected as an optimum dosage (maximum adsorption capacity ≈ 2.91 μg g−1). The sorption model parameters suggested the possibility of chemisorption, charge/ion-dipole interaction for the removal of arsenate.
Microwave-assisted synthesis of cross-linked chitosan-metal oxide nanocomposite for methyl orange dye removal from unary and complex effluent matrices
Gautam Priyadarshi, Nirav P. Raval, Mrugesh H. Trivedi
Journal, International Journal of Biological Macromolecules, 2022, DOI Link
View abstract ⏷
Textile/Dyeing industries have been considered as one of the intense water-consuming units, resulting in the generation of a large volume of dye(s) contaminated effluent posing a heavy burden on the receiving water bodies. Therefore, the identification of methods to synthesize bulk quantity of adsorbent(s) and further their evaluation for the efficient treatment of effluent is one of the most prominent topics. Hence, microwave-assisted method was proposed for the rapid synthesis of nanocomposite (C-CS@ZnO) from natural biomolecule (chitosan-CS), a well-known crosslinker (tripolyphosphate) and metal-oxide (ZnO) nanoparticles. Detailed characterization was performed to identify the structure (SEM, XRD) and composition (FT-IR, XPS) of the sorbent. Sorption experiments with methyl orange (MO) dye solution were carried out under different pH (2.0–12.0), dye concentrations (150–350 mg L−1), reaction times (0–210 min) and temperature (25–45 °C) to establish the adsorbent at the lab-scale. The maximum sorption capacity (185.2 mg g−1) was obtained because of the ligand-exchange, Yoshida H-bonding and electrostatic interactions and was best elucidated by Freundlich (R2 ≥ 0.99) and pseudo-second-order (R2 ≥ 1) models. To simulate the field conditions, the effects of co-existing ions (anions/cations), cocktail dyes/ions mixture and regenerant were also studied. The obtained results suggest its promising applicability at a large scale for textile effluent treatment.
Development of novel Core–shell impregnated polyuronate composite beads for an eco-efficient removal of arsenic
Nirav P. Raval, Manish Kumar
Journal, Bioresource Technology, 2022, DOI Link
View abstract ⏷
Arsenic (As) can geogenically and anthropogenically contaminate the potable water resources and undoubtedly reduces its availability for human consumption. To circumvent this predicament, present study focuses on the development of a novel biosorbent by impregnating calcium cross-linked polyuronate (alginate) beads (CABs) with bilayer–oleic coated magnetite nanoparticles (CAB@BOFe) for As(V) removal. Initially, the system parameters (i.e., adsorbents dose (0.1– 3.0 g L–1), pH (4.0–13), reaction times (0–180 min) and sorbate concentrations (10–150 µg L–1)) were optimized to establish adsorbent at the lab-scale. CAB@BOFe had higher monolayer (ad)sorption capacity (∼62.5 µg g−1, 120 min) than CABs (∼17.9 µg g−1, 180 min). Electrostatic/Ion-dipole interactions and surface-complexation mechanisms mediated As(V) sorption onto CAB@BOFe mainly obeyed Langmuir isotherm (R2 ∼ 0.9) and well described by intraparticle diffusion process. Furthermore, it demonstrated an excellent arsenate removal performance from the single/multiple anionic contaminants simulated water samples which supported its prospective field applicability.
Statistical physics modeling and evaluation of adsorption properties of chitosan-zinc oxide nanocomposites for the removal of an anionic dye
Nirav P. Raval, Gautam V. Priyadarshi, Santanu Mukherjee, Hiral Zala, Dhaouadi Fatma, Adrián Bonilla-Petriciolet, Ben Lamine Abdelmottaleb, Laurent Duclaux, Mrugesh H. Trivedi
Journal, Journal of Environmental Chemical Engineering, 2022, DOI Link
View abstract ⏷
The development of rapid methods to synthesize cost-effective adsorbents for the dye removal is an emerging and relevant topic in the field of wastewater purification. This study focuses on the preparation of zinc-oxide nanoparticles (NPs) impregnated chitosan (CS@ZnO) nanocomposite beads via mechanical stirring (MS) and microwave-assisted (MA) routes. The beads were characterized and utilized for the removal of Eriochrome Black-T (EBT) dye. Results showed that the CS@ZnO-MA beads provided the best adsorption capacities for EBT removal (40.9 ± 0.83 mg g-1) at pH 3.5. The best composite (CS@ZnO-MA) can be regenerated 5 times without significantly affecting its adsorption properties and can remove 71 % of EBT dye from a multi-pollutant solution. The novelty of this study relies on the facile preparation and impregnation of the biopolymer with metal-oxide NPs, which render high adsorption capacity, mechanical strength and high specific surface area of the CS to contribute in the removal of dye molecules from textile wastewater. An enhanced statistical physics model revealed that the adsorption mechanism of EBT dye molecules on these composites was multimolecular. The study indicates an effective synthesis route that can be implemented to prepare new adsorbents using CS at a large-scale for water treatment.
Geogenic arsenic removal through core–shell based functionalized nanoparticles: Groundwater in-situ treatment perspective in the post–COVID anthropocene
Nirav P. Raval, Manish Kumar
Journal, Journal of Hazardous Materials, 2021, DOI Link
View abstract ⏷
Groundwater, one of the significant potable water resources of the geological epoch is certainly contaminated with class I human carcinogenic metalloid of pnictogen family which delimiting its usability for human consumption. Hence, this study concerns with the elimination of arsenate (As(V)) from groundwater using bilayer–oleic coated iron–oxide nanoparticles (bilayer–OA@FeO NPs). The functionalized (with high–affinity carboxyl groups) adsorbent was characterized using the state–of–the–art techniques in order to understand the structural arrangement. The major emphasis was to examine the effects of pH (5.0–13), contact times (0–120 min), initial concentrations (10–150 μg L–1), adsorbent dosages (0.1–3 g L–1), and co–existing anions in order to understand the optimal experimental conditions for the effective removal process. The adsorbent had better adsorption efficiency (∼ 32.8 μg g–1, after 2 h) for As(V) at neutral pH. Adsorption process mainly followed pseudo–second–order kinetics and Freundlich isotherm models (R2∼0.90) and was facilitated by coulombic, charge–dipole and surface complexation interactions. The regeneration (upto five cycles with 0.1 M NaOH) and competition studies (with binary and cocktail mixture of co–anions) supported the potential field application of the proposed adsorbent.
Hexametaphosphate cross-linked chitosan beads for the eco-efficient removal of organic dyes: Tackling water quality
Nirav P. Raval, Santanu Mukherjee, Nisha K. Shah, Petros Gikas, Manish Kumar
Journal, Journal of Environmental Management, 2021, DOI Link
View abstract ⏷
There is an increasing trend of developing various low-cost grafted natural amino polysaccharides for the biosorptive removal of noxious dye effluents like Malachite green (MG) and anionic Reactive Red–195 (RR-195) dyes from aqueous solution. Chemically cross-linked chitosan microsphere (CTS-HMP), a promising non-toxic biosorbent possessing high charge density and thermal stability was prepared by using hexametaphosphate as ionic cross-linker. Batch biosorption experiments were carried out under different temperatures (298, 308 and 318 K), pH (2.0–10.0), initial concentrations (25–250 mg L−1), adsorbent dosage (0.01–0.1 g) and contact times (0–180 min) to understand the optimum experimental conditions and simultaneously evaluate the adsorption isotherms and kinetics of CTS-HMP. Biosorption equilibrium was established in 120 and 60 min for MG and RR-195 removal process. The pseudo-equilibrium process was best described by the pseudo-second-order kinetic (R2 ≥ 0.98), Freundlich and Temkin isotherm model (R2 ≥ 0.90). The removal rate of MG and RR-195 gradually increased (69.40 and 148 mg g−1) at 250 mg L−1 of initial concentration till 100 and 50 min of contact period in a single contaminant system, though the removal efficiency of acid dye was ~2 times higher compared to basic dye under optimum conditions (p < 0.05; t-test). Thermodynamic parameters indicated exothermic (MG) and endothermic (RR-195) nature of spontaneous dye removal. The activation energy of sorption (Ea) was <50 kJ mol−1 which highlighted the importance of physical adsorption process. Therefore, the obtained results clearly validate the sustainable utilization of CTS-HMP as a promising functionalized chitosan microparticles/agent for removing dye effluents from the contaminated aqueous phase.
Antidrug resistance in the Indian ambient waters of Ahmedabad during the COVID-19 pandemic
Manish Kumar, Kiran Dhangar, Alok Kumar Thakur, Bhagwana Ram, Tushara Chaminda, Pradeep Sharma, Abhay Kumar, Nirav Raval, Vaibhav Srivastava, Jörg Rinklebe, Keisuke Kuroda, Christian Sonne, Damia Barcelo
Journal, Journal of Hazardous Materials, 2021, DOI Link
View abstract ⏷
The ongoing COVID-19 pandemic increases the consumption of antimicrobial substances (ABS) due to the unavailability of approved vaccine(s). To assess the effect of imprudent consumption of ABS during the COVID-19 pandemic, we compare the 2020 prevalence of antidrug resistance (ADR) of Escherichia coli (E. coli) with a similar survey carried out in 2018 in Ahmedabad, India using SARS-CoV-2 gene detection as a marker of ABS usage. We found a significant ADR increase in 2020 compared to 2018 in ambient water bodies, harbouring a higher incidence of ADR E.coli towards non-fluoroquinolone drugs. Effective SARS-CoV-2 genome copies were found to be associated with the ADR prevalence. The prevalence of ADR depends on the efficiency of WWTPs (Wastewater Treatment Plants) and the catchment area in its vicinity. In the year 2018 study, prevalence of ADR was discretely distributed, and the maximum ADR prevalence recorded was ~ 60%; against the current homogenous ADR increase, and up to 85% of maximum ADR among the incubated E.coli isolated from the river (Sabarmati) and lake (Chandola and Kankaria) samples. Furthermore, wastewater treatment plants showed less increase in comparison to the ambient waters, which eventually imply that although SARS-CoV-2 genes and faecal pollution may be diluted in the ambient waters, as indicated by low Ct-value and E.coli count, the danger of related aftermath like ADR increase cannot be nullified. Also, Non-fluoroquinolone drugs exhibited overall more resistance than quinolone drugs. Overall, this is probably the first-ever study that traces the COVID-19 pandemic imprints on the prevalence of antidrug resistance (ADR) through wastewater surveillance and hints at monitoring escalation of other environmental health parameters. This study will make the public and policyholders concerned about the optimum use of antibiotics during any kind of treatment.
Utilization of sewage sludge derived magnetized geopolymeric adsorbent for geogenic arsenic removal: A sustainable groundwater in-situ treatment perspective
Kaling Taki, Nirav P. Raval, Manish Kumar
Journal, Journal of Cleaner Production, 2021, DOI Link
View abstract ⏷
Highly compressible sewage sludge (SS) derived geopolymer was magnetized with impregnation of magnetite (Fe3O4) nanoparticles (NPs), and these newly developed and characterized adsorbents were tested in a batch mode for the sorptive removal of metalloid arsenic (As) from a significant potable water resource (groundwater). Various sorption experiments were performed under variable pH (4.0–9.0), magnetized geopolymer dosages (0.1–3 g L−1), contact time (0–180 min), initial As concentrations (10–100 μg L−1) and co–existing anions to develop a critical understanding of the optimal experimental requirements and to assess the sorption kinetics and isotherms. Magnetized geopolymer had better monolayer sorption capacity (∼51.6 μg g−1, after 3 h) for As(V) than only geopolymer (∼9.81 μg g−1, after 3 h) at near neutral pH (∼6.0). The sorption process onto magnetized geopolymer was facilitated by intraparticle diffusion as well as surface complexation mechanisms and was best explained by the pseudo second order kinetic model (R2 ≥ 0.95) and Freundlich and Temkin isotherm models (R2 ≥ 0.90). The exhausted composite adsorbent was sufficiently regenerated up to five sorption–desorption–regeneration cycles using 0.1 M NaOH. Further, it also displayed an excellent As(V) removal capacity from the cocktail mixture of the common geogenic anions and their antagonistic effect follows the order of: NO3− < Cl− < SO42− < F− < PO43−. The proposed waste derived sustainable composite material was proved to be a promising sorbent for economic As(V) removal under simulated complex environmental conditions.
Pyrimidine-Pyrazole Hybrids as Morpholinopyrimidine-Based Pyrazole Carboxamides: Synthesis, Characterisation, Docking, ADMET Study and Biological Evaluation
Mayur K. Vekariya, Rajesh H. Vekariya, Kinjal D. Patel, Nirav P. Raval, Prapti U. Shah, Dhanji P. Rajani, Nisha K. Shah
Journal, ChemistrySelect, 2018, DOI Link
View abstract ⏷
With the utilization of molecular hybridization, a series of novel morpholinopyrimidine based distinctive pyrazole carboxamides were designed and synthesized in an attempt to develop newer antimicrobial agents against the increasing bacterial resistance. Structure of final targeted compounds were confirmed by spectral analysis i. e. 1H-NMR, 13C-NMR and Mass spectra. The newly synthesized compounds were screened for their preliminary in-vitro antibacterial activity against a panel of pathogenic strains of bacteria and fungi, antituberculosis activity against Mycobacterium tuberculosis H37Rv and antimalarial activity against Plasmodium falciparum. In addition to this, In-silico molecular docking study and ADME properties were likewise studied for the targeted compounds. It was inferred that from the series, Fluorinated anilide derivatives of morpholinopyrimidine clubbed with pyrazole carboxylate emerged out as potential antimicrobial candidates from the in-vitro antimicrobial assay.
Malachite green “a cationic dye” and its removal from aqueous solution by adsorption
Nirav P. Raval, Prapti U. Shah, Nisha K. Shah
Journal, Applied Water Science, 2017, DOI Link
View abstract ⏷
Adsorption can be efficiently employed for the removal of various toxic dyes from water and wastewater. In this article, the authors reviewed variety of adsorbents used by various researchers for the removal of malachite green (MG) dye from an aqueous environment. The main motto of this review article was to assemble the scattered available information of adsorbents used for the removal of MG to enlighten their wide potential. In addition to this, various optimal experimental conditions (solution pH, equilibrium contact time, amount of adsorbent and temperature) as well as adsorption isotherms, kinetics and thermodynamics data of different adsorbents towards MG were also analyzed and tabulated. Finally, it was concluded that the agricultural solid wastes and biosorbents such as biopolymers and biomass adsorbents have demonstrated outstanding adsorption capabilities for removal of MG dye.
Synthesis, characterization and adsorption significance of novel composite (Chitosan beads loaded nickel-oxide nanoparticles)
Nirav P. Raval, Prapti U. Shah, Divya G. Ladha, Mayur K. Vekariya, Poonam M. Wadhwani, Nisha K. Shah
Journal, Desalination and Water Treatment, 2017, DOI Link
View abstract ⏷
The aim of this work was to first synthesize biocompatible nanocomposite (chitosan beads loaded nickel-oxide nanoparticles) (CTS/NiO NPs) and then study its potential application towards adsorption of anionic azo dye, Congo red (CR), from wastewater. The newly synthesized and characterized NiO nanoparticles were immobilized onto chitosan beads to prepare CTS/NiO NPs, which was characterized by using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and Fourier Transform Infrared (FT-IR) analysis. The effects of different system variables such as initial dye concentration, contact time, reaction pH, adsorbent dosage and temperature were investigated and based on the results optimal experimental conditions were ascertained. The results revealed that the amount of CR adsorbed on the adsorbent increases with increasing initial dye concentration and by decreasing pH. The Langmuir isotherm was the best-fit adsorption isotherm model for the experimental data obtained from the non-linear chi-square statistic test. Kinetic studies showed that the adsorption of CR followed pseudo-second order kinetics. Thermodynamic studies revealed that the adsorption process was spontaneous and endothermic in nature.
Comparative study of chitin and chitosan beads for the adsorption of hazardous anionic azo dye Congo Red from wastewater
Nirav P. Raval, Prapti U. Shah, Divya G. Ladha, Poonam M. Wadhwani, Nisha K. Shah
Journal, Desalination and Water Treatment, 2016, DOI Link
View abstract ⏷
Chitin (CH) and chitosan (CTS) beads used and compared for the adsorption of Congo Red (CR), an anionic azo dye, are reported in the present work. Initially, the adsorbents were prepared and characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) analysis. SEM images showed the heterogeneous and porous structure of the beads and FT-IR results confirm the presence of –OH, –NH2, and–NHCOCH3 groups which are responsible for the adsorption of CR. Further, batch studies were conducted to evaluate the adsorption capacity of CH and CTS beads and the effects of the parameters like pH, adsorbate concentration, contact time, and dosage of adsorbents on adsorption were investigated. From the analysis, it was observed that the amount of CR adsorbed on both the adsorbents increases with increasing initial dye concentration and decreasing pH. The adsorption isotherms were analyzed using the Langmuir and Freundlich isotherms. The Langmuir isotherm was the best-fit adsorption isotherm model for the experimental data obtained from the non-linear chi-square statistic test. Further, the pseudo-first-order and second-order kinetic models were used to describe the kinetic data, and the rate constants were evaluated. The dynamical data fit well with the second-order kinetic model. The results indicate that CH and CTS beads could be employed as low-cost material for the adsorption of CR from wastewater.
Nanoparticles Loaded Biopolymer as Effective Adsorbent for Adsorptive Removal of Malachite Green from Aqueous Solution
Nirav P. Raval, Prapti U. Shah, Nisha K. Shah
Journal, Water Conservation Science and Engineering, 2016, DOI Link
View abstract ⏷
In the present study, the biocompatible nanocomposite (nickel oxide nanoparticles loaded chitin beads (NiO NPs/CH)) was synthesized, characterized by using scanning electron microscopy (SEM) and Fourier transform infrared (FT–IR) analysis and then study its prospective application towards adsorption of malachite green (MG) dye. Further, batch studies were conducted to evaluate the adsorption capacity of nanocomposite, and the effects of various parameters, i.e., pH, adsorbate concentration, contact time, dosage of adsorbent and temperature, were investigated. The results revealed that the amount of MG adsorbed on the adsorbent increases with increasing initial dye concentration and by decreasing temperature. The equilibrium MG adsorption data on NiO NPs/CH were best described by the Langmuir isotherm model. Besides, the adsorption kinetics followed pseudo-second-order rate equation. Thermodynamic parameters such as free energy of adsorption (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) changes were calculated, and the results suggested that the adsorption process was spontaneous and exothermic in nature. Based on the results, it was concluded that the nanocomposite can be sustainably prepared and efficiently used for the adsorptive removal of MG from colored aqueous solutions.
Erratum: Comparative study of chitin and chitosan beads for the adsorption of hazardous anionic azo dye Congo Red from wastewater
Nirav P. Raval, Prapti U. Shah, Divya G. Ladha, Poonam M. Wadhwani, Nisha K. Shah
Journal, Desalination and Water Treatment, 2016, DOI Link
Adsorption of lead (II) ions onto novel cassava starch 5-choloromethyl-8-hydroxyquinoline polymer from an aqueous medium
Prapti U. Shah, Nirav P. Raval, Mayur Vekariya, Poonam M. Wadhwani, Nisha K. Shah
Journal, Water Science and Technology, 2016, DOI Link
View abstract ⏷
Adsorption of lead (II) ions onto cassava starch 5-choloromethyl-8-hydroxyquinoline polymer (CSCMQ) was investigated with the variation in the parameters of pH, contact time, lead (II) ions concentration, temperature and the adsorbent dose. The Langmuir and Freundlich models have been applied. CSCMQ was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Results showed that the adsorption process was better described by the Langmuir model. Adsorption kinetics data obtained for the metal ions sorption were investigated using pseudo-first-order, pseudo-second-order and intraparticle diffusion model. The maximum adsorption capacities (qm) were 46.512, 43.859 and 42.735 mg/g at 25, 35 and 45 WC, respectively. The dynamical data fit well with the second-order kinetics model. The results indicate that CSCMQ could be employed as low-cost material for the adsorption of Pb(II) ions from aqueous medium.
Adsorptive amputation of hazardous azo dye Congo red from wastewater: a critical review
Nirav P. Raval, Prapti U. Shah, Nisha K. Shah
Journal, Environmental Science and Pollution Research, 2016, DOI Link
View abstract ⏷
Increasing amount of dyes in an ecosystem has propelled the search of various methods for dye removal. Amongst all the methods, adsorption occupies a prominent place in dye removal. Keeping this in mind, many adsorbents used for the removal of hazardous anionic azo dye Congo red (CR) from aqueous medium were reviewed by the authors. The main objectives behind this review article are to assemble the information on scattered adsorbents and enlighten the wide range of potentially effective adsorbents for CR removal. Thus, CR sorption by various adsorbents such as activated carbon, non-conventional low-cost materials, nanomaterials, composites and nanocomposites are surveyed and critically reviewed as well as their sorption capacities are also compared. This review also explores the grey areas of the adsorption performance of various adsorbents with reference to the effects of pH, contact time, initial dye concentration and adsorbent dosage. The equilibrium adsorption isotherm, kinetic and thermodynamic data of different adsorbents used for CR removal were also analysed. It is evident from a literature survey of more than 290 published papers that nanoparticle and nanocomposite adsorbents have demonstrated outstanding adsorption capabilities for CR. [Figure not available: see fulltext.]
Adsorptive removal of nickel(II) ions from aqueous environment: A review
Nirav P. Raval, Prapti U. Shah, Nisha K. Shah
Journal, Journal of Environmental Management, 2016, DOI Link
View abstract ⏷
Among various methods adsorption can be efficiently employed for the treatment of heavy metal ions contaminated wastewater. In this context the authors reviewed variety of adsorbents used by various researchers for the removal of nickel(II) ions from aqueous environment. One of the objectives of this review article is to assemble the scattered available enlightenment on a wide range of potentially effective adsorbents for nickel(II) ions removal. This work critically assessed existing knowledge and research on the uptake of nickel by various adsorbents such as activated carbon, non-conventional low-cost materials, nanomaterials, composites and nanocomposites. The system's performance is evaluated with respect to the overall metal removal and the adsorption capacity. In addition, the equilibrium adsorption isotherms, kinetics and thermodynamics data as well as various optimal experimental conditions (solution pH, equilibrium contact time and dosage of adsorbent) of different adsorbents towards Ni(II) ions were also analyzed. It is evident from a literature survey of more than 190 published articles that agricultural solid waste materials, natural materials and biosorbents have demonstrated outstanding adsorption capabilities for Ni(II) ions.
Cadmium(II) removal from an aqueous solution using CSCMQ grafted copolymer
Prapti U. Shah, Nirav P. Raval, Nisha K. Shah
Journal, Desalination and Water Treatment, 2016, DOI Link
View abstract ⏷
In this work, an approach was developed to synthesize copolymer by grafting 5-Chloromethyl-8-Hydroxyquinoline on to Cassava starch for removal of Cd(II). Characterization experiments were done by scanning electron microscopy and Fourier transform infrared analysis. The study was performed under different experimental conditions of initial metal ion concentration, adsorbent dose, time, pH and temperature. Batch adsorption experiment showed that grafted copolymer had strong adsorption capacity of 51.546, 53.191, and 55.249 mg/g at 298, 308, and 318 K for Cd(II) removal. The kinetics data were analyzed using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. The pseudo-second-order model best described the adsorption of Cadmium(II) ions onto copolymer. Langmuir model fitted well and thermodynamics parameters were analyzed where results revealed that the adsorption process was a spontaneous and endothermic in nature.
