The present research examines the combined pyrolysis of rice stubble and waste motor oil, utilizing a laboratory-scale pyrolysis setup to generate alternative energy fuels. This approach leverages the hydrogen-rich nature of waste oil to improve the quality of the resulting fuel. The goal of the study is to enhance the yield of co-pyrolytic oil by optimizing process parameters such as reactor temperature (TR, °C), blending ratio (M, %), and residence time (t, min). The work also evaluates improvements in pyro-oil quality when using rice stubble alone. A maximum oil yield of 89% was achieved under optimized conditions of 500°C, 95ppele% blending ratio, and 20 min of reaction time. Besides, the absence of undesirable components like the thiols and acids or esters was found in the co-pyrolytic oil favoring its usage toward alternative fuel. Further, the alignment of the BET and FESEM results suggests that the co-pyrolytic char possesses better absorbent properties due to improved pore volume and surface area than the pyrolysis of individual feedstocks.

The rapid population, industrialization, and urbanization increase have led to a multi-fold increase in automobiles, thereby increasing the demand for lubricating oil. Among the available lubricants, automotive lubricating oil (motor oil) accounts for 57% of global lubricant demand, which is used to lubricate vehicular engine’s metal parts, reducing wear and increasing engine efficiency. However, with usage, it degrades due to (i) oxidation, (ii) thermal breakdown, (iii) micro-dieseling, (iv) additive depletion, and demands alteration with fresh motor oil. This chapter aims to discuss the characteristics of fresh and waste motor oil. Besides, it extensively explains the impact of waste motor oil (WMO) on water bodies, marine life, soil, and human health due to illegal disposal to overcome high waste management costs. Furthermore, it also focuses on the WMO hierarchy and suggests different treatment methods based on the hierarchy. However, among the available treatment methods, pyrolysis has drawn notice due to its adaptability and product diversification.

Contamination of potable water sources by emerging pollutants such as bisphenol-A and paracetamol, etc. is a major ecological concern. The present study delineates the suitability of carbon modified hexagonal boron nitride (HBCN) towards the elimination of Bisphenol-A (BPA) and paracetamol. The HBCN was obtained through an ecofriendly solvent free approach with a surface area of 224.48 m2/g which is about ∼ 11 times higher than commercially available hexagonal boron nitride (C-HBN). The HBCN possess multimodal pore network with an average pore diameter of 2 nm and an isoelectric point at pH: 4.57. The effect of process parameters like time, initial concentration and temperature were evaluated. The adsorption behaviour suited well with Langmuir isotherm suggesting monolayer adsorption with a maximum adsorption capacity of 49.75 mg g−1 (BPA) and 67.56 mg g−1 (paracetamol). The kinetic studies established chemisorption and pore filling as preferred adsorption mechanisms. The adsorption was exothermic in nature and exhibited better performance at lower temperatures making it as suitable material for domestic water purification. The HBCN demonstrated robust stability and reusability ∼ 80 % (BPA) and ∼ 71 % (paracetamol) through 5 adsorption–desorption cycles. The working adsorption mechanism being followed were confirmed through FTIR and BET studies: pre and post adsorption with HBCN.

A facile hydrothermal route was followed to obtain a ternary composite Ag@AgVO3/rGO/CeVO4 with in-situ deposition of Ag nanoparticles over the AgVO3 nano-belts. The in-situ deposition was promoted and enhanced with the introduction of GO. The as-synthesized composite demonstrated remarkable visible light harvesting efficiency greater than 75% in the visible region. The charge separation and light harvesting properties were achieved through the Z-scheme mechanism mediated through rGO and the electron trapping/Schottky barrier effect from Ag nanoparticles. The reduction in the width of space charge region (∼2.5 times) and simultaneous increase in the density of charge carriers (2.3∗1018) promoted the LED irradiated photocatalytic performance. The decay time of the charge carriers were prolonged in the order of 4.46 s implying the enhancement in the charge separation. The studies were extended to charge trapping and the band structure modelling. The later emphasized on the prominence of Z-scheme mechanism with hole mediated degradation pathway. The LED photocatalysis demonstrated a removal efficiency of 87.20% for MB and 55.51% for phenol with a average AQE of 29.28% (MB) and 13.90% (phenol) for the ternary. The mineralization efficiency determined through TOC analysis was found to be 71.72%, and 66.43% for MB and phenol system respectively.

Photocatalytic removal of toxic contaminants is one of the emerging techniques for water remediation, but it suffers from low redox ability, charge recombination and poor light harvesting efficiency. The present work reports a simultaneous S-scheme promoted by CeVO4/g-C3N4/Ag@AgVO3. The formation of the S-scheme mechanism enhanced the generation of photogenerated carriers and also improved the redox ability of the electrons and holes in the reduction and oxidation photocatalysts. The ternary demonstrated remarkable photo switching properties along with efficient charge separation which was achieved through dual interfacial interaction within the ternary (Ag@AgVO3/g-C3N4 and CeVO4/g-C3N4). The heterojunction formation was verified through the shift in binding energy spectra in the X-ray Photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy analysis (HR-TEM). The ternary demonstrated reduced PL intensity, width of space charge region and an upsurge in photogenerated current density in the order of 93 μA/cm2 (∼6X higher than all the pristine). This resulted in efficient removal of methyl orange, methylene blue and endocrine disruptive bisphenol-A with a removal rate of 0.02 min−1, 0.03 min−1 and 0.0087 min−1 and an apparent quantum yield of 4.6 × 10−9 (Methylene Orange), 6.89 × 10−9 (Methylene Blue) and 2 × 10−9 (Bisphenol A/H2O2).

The present study outlines the transformation of non-photoresponsive hexagonal boron nitride (HBN) into a visible-light-responsive material. The carbon modification was achieved through a solid-state reaction procedure inside a tube furnace under nitrogen atmosphere. In comparison to HBN (bandgap of 5.2 eV), the carbon-modified boron nitride could efficiently absorb LED light irradiation with a light harvesting efficiency of ≈90% and a direct bandgap of 2 eV. The introduction of carbon into the HBN lattice led to a significant change in the electronic environment through the formation of C–B and C–N bonds which resulted in improved visible light activity, lower charge transfer resistance, and improved charge carrier density (2.97 × 1019 cm−3). This subsequently enhanced the photocurrent density (three times) and decreased the photovoltage decay time (two times) in comparison to those of HBN. The electronic band structure (obtained through Mott–Schottky plots) and charge trapping analysis confirmed the dominance of e−, O2 −•, and •OH as dominant reactive oxygen species. The carbon modification could effectively remove 93.83% of methylene blue (MB, 20 ppm solution) and 48.56% of phenol (10 ppm solution) from the aqueous phase in comparison to HBN which shows zero activity in the visible region.

A natural polymer, silk fibroin (Bombyx mori) was used as base anode material and was further modified by coating varied concentrations of Polydopamine for enriched MFC power generation. The performances of the modified anodes were compared to that of the base anode. The resultant anodes were all conductive, flexible, of 3D geometry with enriched macroporosity, biocompatibility and hydrophilicity. It was also observed that with an increase in the polymerization cycle the porosity of the anode has increased along with conductivity. A maximum bacterial colonization and power production was observed for the anode with the highest Polydopamine concentration (SFPDA-6) and lowest for the base (control). SFPDA-6 produced about 6x (56 mA/m2) more current density compared to that of the control (7 mA/m2). The predominant microbial colonies present in the anode and anolyte were analyzed by 16S rRNA sequencing and was found that the Bacillus dominated over the rest. The highest COD removal in the order of 84% was reported for SFPDA-6 anode. An analysis on cost estimation was carried out to reveal the commercial viability of the fabricated anodes for the large-scale MFC application and was found to be ∼$ 27.93 for SF anode and ∼$ 48.47 for SFPDA-6 with a working area of 15.71 cm2. Thus, the obtained results showed the potential of the Polydopamine modified silk fibroin anode as an effective anode material for real-time MFC operation.

The authors would like to regret that there was a unit conversion error in the power density unit value of the published article. The power density previously given in W/m2 should be read as mW/m2. The Fig. 6(c) is corrected to mW/m2. The corrections would not affect any of the discussions and conclusions of the original article. The authors would like to apologize for any inconvenience caused.

Conventional metal oxide and its composites embrace the long-standing problem of using the combined visible and near-infrared (NIR) light. Doping with suitable impurities of metal, nonmetal, or its combinations for visible light enhancement is very well studied. However, the quantum efficiency of these photocatalysts does not produce an exciting appearance toward visible and NIR light when irradiated through either artificial or natural light. Furthermore, owing to the limited availability of solar light, challenges arise from the implication of these developed nano-photocatalysts. Therefore, the hybridized concept was developed for the effective use of either full or partial solar spectrum, even functioning in dark conditions. The present review focuses on the challenges of hybridized photocatalysts in storing and discharging the harvested photons obtained from the solar spectrum. The review vividly emphasizes the evolution of light-driven nanomaterials since its innovation and significant breakthroughs in brief, while a detailed presentation of the implications of hybrid photocatalysts for full solar applications, including the mechanistic features, charging-discharging characteristics, work function, charge carrier mobility, and interactions, follows. The article also delivers the substantial contribution of these materials in regard to energy and environmental application.

In current scenario, the world is heading through challenging environmental concerns like greenhouse gas (GHG) emission, water security, clean energy, etc. Although numerous alternatives were practiced to counter the issue, a permanent relief was not drawn. As a result, a breakthrough in nanotechnology has laid a pathway for the evolution of light-driven energy materials. Since then they have gained popularity in numerous sectors of industrial application and some of the most demanding are solar cell, water treatment, hydrogen production, CO2 reduction, destruction of war fare chemicals, etc. They easily attracted multiple sectors owing to their sustainable characteristics, durability, and reusability potential over the conventional. Moreover, these materials allow reconstruction flexibility in accordance to the need and demand of the day-to-day world. Although these nanomaterials were seen as solution providers for the most prevailing concerns, majority of the remarkable achievements attained in this field were at bench scale. Hence, this chapter exclusively niches on the robust near and full industrial-scale applications of these nanomaterials for clean energy and environment.

The advent of nanotechnology has led to the development of new nanomaterials with enriched material properties over the conventional. These nanomaterials find wide application in numerous fields including environmental predominantly on water purification. Carbon nanotubes (CNT) are one among the nanomaterials widely employed for such application. Therefore, the present review emphasizes on the exceptional abilities of CNT especially in the removal of organics and inorganics from aquatic streams. Though numerous reviews were published in this subject most of them focused on the synthesis and specific applications. The authors learned that there is a wider gap on the review that presents the mechanistic features like the development of active sites, the effect of curvature, inclusion of heteroatoms, methods for the enhancement of affinity and selectivity through functionalization, the introduction of defects and the chemistry involved in their interaction with various category of pollutants. Hence, the present review delivers a clear understanding of the above-said factors in a comprehensive way. The article explicits on the various surface modification techniques (i.e covalent, non-covalent, defect and endohedral) along with their effects on the sorption efficiency. Further, the review also provides a clear picture of the toxicological aspects of the CNT. The authors strongly believe that the present review will aid in the understanding and design of multifunctional CNT towards environmental application in a comprehensive manner.

Hexagonal boron nitride, known as white graphene has attracted the water industry as a replacement to both classical bulk and nano-adsorbent. Its structural resemblance to graphene, resistance to corrosion, chemical oxidation, high thermal stability has attracted the focus of the researchers. On top of that its intrinsic material properties such as porosity, surface functional groups, band gap, etc. can be engineered to complement the real-time applications. All the aforementioned strengthened their potential candidature as alternative nano-adsorbent as well as energy material. The distinct characteristics like high selectivity, affinity, and the polar nature are auxiliary benefits for the adsorptive process. Further, the higher thermal stability of the material paves facile and ease regeneration. However, the wider band position limits its attributes as energy materials and was resolved by simple doping with suitable impurities. The authors drafted review, learning the vacuum that consolidates the mechanistic features like the development of nanoarchitecture, porosity, and bandgap engineering of the said material. Hence, the present review unambiguously discusses the role of various governing parameters for the development of novel porous Hexagonal boron nitride, along with characteristics of typical energy materials.

The twin associates, pollution and energy are the bottleneck for the sustainable development of present and future. Visible light driven nanomaterials have emerged as sustainable and eco-friendly outlook to address these burning issues. Metal-organic frameworks [MOFs] that was widely considered for gas storage and separations, notably for hydrogen have overlooked the conventional light driven nanomaterials owing to their excellence in materials characteristics; enormous surface area, analogous reactive sites and tuneable functionality. They soared slowly and gained interest as visible light photo catalyst, for driving the photocatalysis and can perform versatile reactions like elimination of aquatic organics, general organic synthesis, water split for hydrogen production, CO2 reduction and etc. Owing to their demand, we articulated the present review on MOFs as light driven nanomaterial that comprises of its evolution, synthesis, structure, functionality, application, and its future.