Synthesis of ternary-based visible light nano-photocatalyst for decontamination of organic dyes-loaded wastewater

Biopolymer‑carbonaceous composites, progress, and adsorptive mitigation of water pollutants

Chitin is the second most abundant natural biopolymer, which is composed of N-acetyl glucosamine units linked by β-(1 → 4) Chitosan is an N-deacetylated product of chitin. Properties of chitosan and chitin, such as biocompatibility, non-toxic nature, and biodegradability, make them successful alternatives for energy and environmental applications. However, their low mechanical properties, small surface area, reduced thermal properties, and greater pore volume restrict the potential for adsorption applications. Multiple investigations have demonstrated that these flaws can be prevented by fabricating chitosan and chitin with carbon-based composites. This review presents a comprehensive analysis of the fabrication of chitosan/chitin carbon-based materials. Furthermore, this review examines the prevalent technologies of functionalizing chitosan/chitin biopolymers and applications of chitin and chitosan as well as chitosan/chitin carbon-based composites, in various environmental fields (mitigating diverse water contaminants and developing biosensors). Also, the subsequent regeneration and reuse of adsorbents were also discussed. Finally, we summarize a concise overview of the difficulties and potential opportunities associated with the utilization of chitosan/chitin carbon-based composites as adsorbents to remove water contaminants.

Investigation on humic substance and tetracycline interaction mechanism: biophysical and theoretical studies and assessing their effect on biological activity

Tetracycline (TC) is a widely used antibiotic, and evaluating its interaction with humic substances (HS) that act as a complexing agent in the environment is essential to understanding the availability of this contaminant in the environment. This study evaluated the interaction between HS and TC using different spectroscopic techniques, theoretical studies, and biological assays simulating environmental conditions. TC interacts with HS, preferably by electrostatic forces, with a binding constant of 9.2 × 103 M-1 (30 °C). This process induces conformational changes in the superstructure, preferably in the HS, like protein fraction. Besides, studies using the 8-anilino-1-naphthalene sulfonate (ANS) probe indicated that the antibiotic alters the hydrophobicity degree on HS's surface. Synchronized fluorescence shows that the TC interaction occurs preferentially with the protein-like fraction of soil organic matter (KSV = 26.28 ± 1.03 M-1). The TC epitope was evaluated by 1H NMR and varied according to the pH (4.8 and 9.0) of the medium, as well as the main forces responsible for the stabilization of the HS-TC complex. The molecular docking studies showed that the formation of the HS-TC complex is carried out spontaneously (ΔG = -7.1 kcal mol-1) and is stabilized by hydrogen bonds and electrostatic interactions, as observed in the experimental spectroscopic results. Finally, biological assays indicated that HS influenced the antimicrobial activity of TC. Thus, this study contributed to understanding the dynamics and distribution of TC in the environment and HS's potential in the remediation of antibiotics of this class in natural systems, as these can have adverse effects on ecosystems and human health.

Insight into microplastics in the aquatic ecosystem: Properties, sources, threats and mitigation strategies

Globally recognized as emergent contaminants, microplastics (MPs) are prevalent in aquaculture habitats and subject to intense management. Aquaculture systems are at risk of microplastic contamination due to various channels, which worsens the worldwide microplastic pollution problem. Organic contaminants in the environment can be absorbed by and interact with microplastic, increasing their toxicity and making treatment more challenging. There are two primary sources of microplastics: (1) the direct release of primary microplastics and (2) the fragmentation of plastic materials resulting in secondary microplastics. Freshwater, atmospheric and marine environments are also responsible for the successful migration of microplastics. Until now, microplastic pollution and its effects on aquaculture habitats remain insufficient. This article aims to provide a comprehensive review of the impact of microplastics on aquatic ecosystems. It highlights the sources and distribution of microplastics, their physical and chemical properties, and the potential ecological consequences they pose to marine and freshwater environments. The paper also examines the current scientific knowledge on the mechanisms by which microplastics affect aquatic organisms and ecosystems. By synthesizing existing research, this review underscores the urgent need for effective mitigation strategies and further investigation to safeguard the health and sustainability of aquatic ecosystems.

Recent advances in visible light-activated photocatalysts for degradation of dyes: A comprehensive review

The rapid development in industrialization and urbanization coupled with an ever-increasing world population has caused a tremendous increase in contamination of water resources globally. Synthetic dyes have emerged as a major contributor to environmental pollution due to their release in large quantities into the environment, especially owing to their high demand in textile, cosmetics, clothing, food, paper, rubber, printing, and plastic industries. Photocatalytic treatment technology has gained immense research attention for dye contaminated wastewater treatment due to its environment-friendliness, ability to completely degrade dye molecules using light irradiation, high efficiency, and no generation of secondary waste. Photocatalytic technology is evolving rapidly, and the foremost goal is to synthesize highly efficient photocatalysts with solar energy harvesting abilities. The current review provides a comprehensive overview of the most recent advances in highly efficient visible light-activated photocatalysts for dye degradation, including methods of synthesis, strategies for improving photocatalytic activity, regeneration and their performance in real industrial effluent. The influence of various operational parameters on photocatalytic activity are critically evaluated in this article. Finally, this review briefly discusses the current challenges and prospects of visible-light driven photocatalysts. This review serves as a convenient and comprehensive resource for comparing and studying the fundamentals and recent advancements in visible light photocatalysts and will facilitate further research in this direction.

Recent advances in cellulose-based sustainable materials for wastewater treatment: An overview

Water pollution presents a significant challenge, impacting ecosystems and human health. The necessity for solutions to address water pollution arises from the critical need to preserve and protect the quality of water resources. Effective solutions are crucial to safeguarding ecosystems, human health, and ensuring sustainable access to clean water for current and future generations. Generally, cellulose and its derivatives are considered potential substrates for wastewater treatment. The various cellulose processing methods including acid, alkali, organic & inorganic components treatment, chemical treatment and spinning methods are highlighted. Additionally, we reviewed effective use of the cellulose derivatives (CD), including cellulose nanocrystals (CNCs), cellulose nano-fibrils (CNFs), CNPs, and bacterial nano-cellulose (BNC) on waste water (WW) treatment. The various cellulose processing methods, including spinning, mechanical, chemical, and biological approaches are also highlighted. Additionally, cellulose-based materials, including adsorbents, membranes and hydrogels are critically discussed. The review also highlighted the mechanism of adsorption, kinetics, thermodynamics, and sorption isotherm studies of adsorbents. The review concluded that the cellulose-derived materials are effective substrates for removing heavy metals, dyes, pathogenic microorganisms, and other pollutants from WW. Similarly, cellulose based materials are used for flocculants and water filtration membranes. Cellulose composites are widely used in the separation of oil and water emulsions as well as in removing dyes from wastewater. Cellulose's natural hydrophilicity makes it easier for it to interact with water molecules, making it appropriate for use in water treatment processes. Furthermore, the materials derived from cellulose have wider application in WW treatment due to their inexhaustible sources, low energy consumption, cost-effectiveness, sustainability, and renewable nature.

Synthesis of Oval-Shaped Bi2Al4O9 Nanoparticles and Their Applications for the Degradation of Acid Green 25 and as Fuel Additives

The present study was designed to synthesize an oval-shaped bimetallic bismuth aluminate (Bi2Al4O9) nanoparticles through a solvothermal approach. The resulting structure and morphology of synthesized materials were characterized through X-ray diffraction and scanning electron microscopy. The catalytic performance of Bi2Al4O9 was investigated using acid green 25 (AG-25) as the model dye. The effect of various parameters like catalyst dose, H2O2 concentration, and temperature on dye degradation was studied. The Bi2Al4O9 nanocomposite exhibited the maximum removal of 95% within 50 min at 0.3 M H2O2 concentration, 0.05 mg/mL catalyst dose, and 315 K temperature. The photocatalytic removal of AG-25 followed pseudo-first-order kinetics. The thermodynamics study exposed that thermal catalytic degradation is a spontaneous, endothermic, as well as entropy-driven reaction that moves in the forward direction at the higher temperatures. The Bi2Al4O9 composite was further applied as fuel additives in order to study combustion and physical characteristics of the modified fuel. The efficacy of modified fuel was studied by investigating the fuel parameters at different Bi2Al4O9 dosages. Results revealed that synthesized NPs are excellent photocatalysts and could possibly be used for the removal of toxic pollutants.

Solar light driven degradation of textile dye contaminants for wastewater treatment - studies of novel polycationic selenide photocatalyst and process optimization by response surface methodology desirability factor

The unplanned anthropogenic activities and raced industrial revolution detrimentally causes serious threat to terrestrial and aquatic life. A high discharge of wastewater from industries using dyes affects living organisms and the environment. This paper presents studies on polycationic selenides (PCS) synthesized by hydrothermal methods for photocatalytic degradation of dyes. The synthesized PCS were confirmed by various characterization techniques such as FTIR, SEM, EDX, UV/Vis, and XRD. The FTIR spectra revealed characteristic band at 843, 548 cm^-1, and 417 cm^-1 due to the M - Se stretching and intrinsic stretching vibrations, respectively. The optical bandgap of polycationic selenide lies in the visible light region (2.36 eV). The SEM images showed that PCS has a spherical shape with an average crystallite size of 29.23 nm calculated from XRD data using Scherer's equation. The PCS has a point of zero charge (PZC) at pH 7. The efficiency of synthesized PCS photocatalyst was confirmed in terms of its activity towards Eosin (EY) and Crystal violet (CV) dyes mineralization. The photocatalytic degradation for EY and CV dyes at optimum conditions was 99.47% and 99.31% and followed second order reactions kinetics with 1.4314 and 0.551 rate constant, respectively. The polynomial quadratic model is the best-fitted response surface methodology (RSM) model having a maximum desirability factors value and significant terms, with R² (0.9994) and adj R² values (1.0).

Preparation and characterization of single perovskite microplates and its sunlight assisted photodecolorization activity, validated by response surface methodology

Perovskites overtaking simple metal oxides as solar light harvesting material due to their excellent photocatalytic efficiency and superior stability. An efficient visible light responsive, K₂Ba_0.3Cu_0.7O₃ single perovskites oxides (SPOs) photocatalyst was fabricated by a facile hydrothermal method. The fabricated SPOs was characterized by various techniques. SEM analysis confirm the cubic morphology of SPOs, the average length and diameter of SPOs were 27.84 and 10.06 μm calculated from SEM images. FT-IR analysis confirmed the presence of M-M and M - O bonds. EDX showed prominent peaks of the constituent elements. The average crystallite size of SPOs calculated by Scherrer and Williamson-Hall equation was 14.08 and 18.47 nm respectively. The optical band gap value lies in visible region of spectrum (2.0 eV) determined from the Tauce's plot. The fabricated SPOs was applied for photocatalytic degradation of methylene blue (MB) dye. Maximum degradation 98.09% of MB was achieved at 40 min irradiation time, 0.01 g catalyst dose, 60 mg L^-1 MB concentration and pH 9. The photocatalytic degradation of MB follows first order kinetic. RSM modeling of MB removal was also caried out. Reduce quadratic model was best fitted model having F-value = 300.65, P-value = < 0.0001,R² = 0.9897, predicted R² = 0.9850 and adjusted R² = 0.9864.

Biomimetic Electrochemical Sensors Based on Core-Shell Imprinted Polymers for Targeted Sunset Yellow Estimation in Environmental Samples

Magnetic molecularly imprinted polymers (MMIPs) contain the predesigned specialized recognition capability that can be chosen to build credible functional materials, that are easy to handle and have a good degree of specificity. Hence, the given piece of work is intended to design a novel electrochemical sensor incorporating magnetite-based molecularly imprinted polymers. The building materials consisted of a cross-linker (EGDMA), reaction-initiator (AIBN), monomer (methylene succinic acid-MSA), and template molecule (Sunset Yellow-SY dye). MMIPs exhibited a diameter of 57 nm with an irregular shape due to the presence of cavities based on SEM analysis. XRD patterns exhibited crystallinity, as well as amorphous peaks that are attributed to polymeric and non-polymeric frameworks of MMIPs. The crystallite size of the MMIPs from XRD analysis was found to be 16.28 nm based on the Debye-Scherrer's equation. Meanwhile, the FTIR bands showed the synthesis of MMIPs using monomer and methylene succinic acid. The sorption data at the optimized operating conditions (pH 2, sorbent dosage 3 mg, time 18 min) showed the highest sorption capacity of 40 mg/g. The obtained data best fitted to the Langmuir sorption isotherm and followed the pseudo-second-order kinetics. The magneto-sensors were applied for ultrasensitive, rapid, and simple sensing of SY dye. The electrochemical experiments were run at the operating condition range of (scan rate 10-50 mV/s, tads 0-120 s, pH 5-9, potential range 1-1.5 V for CV and 1-1.3 V for SWAdASV). The linear range of detection was set to 1.51 × 10^-6 M to 1.51 × 10^-6 M posing LOD and LOQ values of 8.6242 × 10^-5 M and 0.0002874 M, respectively. The regression analysis value for the calibration was found to be 0.950. Additionally, high adsorption efficiency, selectivity, reusability, and strong structural stability of the magneto-sensors showed potential use for SY detection in real samples. These characteristics make MMIPs a viable electrochemical substrate for the detection of chemical contaminants in the environment and in health-related products.

BiOI-SnO2 Heterojunction Design to Boost Visible-Light-Driven Photocatalytic NO Purification

The efficient, stable, and selective photocatalytic conversion of nitric oxide (NO) into harmless products such as nitrate (NO3-) is greatly desired but remains an enormous challenge. In this work, a series of BiOI/SnO2 heterojunctions (denoted as X%B-S, where X% is the mass portion of BiOI compared with the mass of SnO2) were synthesized for the efficient transformation of NO into harmless NO3-. The best performance was achieved by the 30%B-S catalyst, whose NO removal efficiency was 96.3% and 47.2% higher than that of 15%B-S and 75%B-S, respectively. Moreover, 30%B-S also exhibited good stability and recyclability. This enhanced performance was mainly caused by the heterojunction structure, which facilitated charge transport and electron-hole separation. Under visible light irradiation, the electrons gathered in SnO2 transformed O2 to ·O2- and ·OH, while the holes generated in BiOI oxidized H2O to produce ·OH. The abundantly generated ·OH, ·O2-, and 1O2 species effectively converted NO to NO- and NO2-, thus promoting the oxidation of NO to NO3-. Overall, the heterojunction formation between p-type BiOI and n-type SnO2 significantly reduced the recombination of photo-induced electron-hole pairs and promoted the photocatalytic activity. This work reveals the critical role of heterojunctions during photocatalytic degradation and provides some insight into NO removal.

Cellulose/inorganic nanoparticles-based nano-biocomposite for abatement of water and wastewater pollutants

Nanostructured materials offer a significant role in wastewater treatment with diminished capital and operational expense, low dose, and pollutant selectivity. Specifically, the nanocomposites of cellulose with inorganic nanoparticles (NPs) have drawn a prodigious interest because of the extraordinary cellulose properties, high specific surface area, and pollutant selectivity of NPs. Integrating inorganic NPs with cellulose biopolymers for wastewater treatment is a promising advantage for inorganic NPs, such as colloidal stability, agglomeration prevention, and easy isolation of magnetic material after use. This article presents a comprehensive overview of water treatment approaches following wastewater remediation by green and environmentally friendly cellulose/inorganic nanoparticles-based bio-nanocomposites. The functionalization of cellulose, functionalization mechanism, and engineered hybrid materials were thoroughly discussed. Moreover, we also highlighted the purification of wastewater through the composites of cellulose/inorganic nanoparticles via adsorption, photocatalytic and antibacterial approach.

Self-propelled nanojets an interfacial Schottky junctions modulated oxygen vacancies enriched for enhanced photo-Fenton degradation of organic contaminant: Improving H2O2 generation, Fe3+/Fe2+ cycle and enhancing plant metabolism

The study reports an innovative approach on sunlit driven heterostructure photocatalytic generation of H₂O₂ and removal of cefixime. In the present work, we have fabricated Mn/Mg doped CoFe₂O₄ modified CaCr₂O₄ decorated by Ag₃PO₄ quantum dots (Ag₃PO₄ QDs), a p-n-p nano heterojunction. The study promotes the photocatalytic production of H₂O₂ and self-Fenton photocatalytic degradation of cefixime. Egg white-assisted synthesis of Mn-doped CoFe₂O₄ causes the lattice oxygen defect, which enhances the photocatalytic activity. Lattice oxygen defect enable the adsorption of O₂, which enable the conversion of •O² in the valence band of CoFe₂O₄ for the endogenous production of H₂O₂. The higher in the surface area enhance the photocatalytic activity under visible light irradiation. Mn-CoFe₂O₄-CaCr₂O₄-Ag₃PO₄ QDs enables the complete photocatalytic degradation of cefixime (99.9%) and the complete removal was determined by total organic carbon (TOC) removal and it was around 99.4%. Meanwhile the photocatalytic degradation pathway of cefixime was determined by LC-MS/MS. Reusability of the nano heterojunction was determined by six cycle test, and the reusability of the nano heterojunction was 99.8%. Further, the toxicity of the nanomaterial was studied in maize plant and the results shows that the nanoheterojunction enhances the maize growth. The study systematically reveals the robust activity of nano heterojunction for sustainable water treatment.

Environmental assessment of wastewater management via hybrid nanocomposite matrix implications-an organized review

Pollution of water is currently a significant worry for scientific communities all over the world, and it is imperative that this problem be solved as quickly as possible. It is today recognized to be one of the most important foci of research worldwide. The present dilemma of clean, fresh waste is being addressed by the subsequent ejection of impurities from polluted water following recycling. There are several effective solutions that have been promoted as a solution to this problem. Even if the present procedures for wastewater treatment degrade a wide variety of effluents efficiently, these protocols still have some kind of restrictions. The most cutting-edge research in this area is being done on the subject of nanotechnology, which has an astounding number of potential uses, one of which is the treatment of wastewater. One of the value-added alternatives utilized for water purification by eliminating the many types of pollutants found in wastewater is the green synthesis of nanocomposites in adsorbents, magnetic separation, photocatalysts, and other similar processes. Within the scope of this study, the most significant discoveries of nanocomposites to date that have been made towards the remediation of wastewater are highlighted.

Biodegradation of environmental pollutants using catalase-based biocatalytic systems

The synergistic combination of biocatalysts and nanomaterials provides a new interface of a robust biocatalytic system that can effectively remediate environmental pollutants. Enzymes, such as catalase-based constructs, impart the desired candidature for catalytic transformation processes and are potential alternatives to replace conventional remediation strategies that have become laborious and somewhat inefficient. Furthermore, the controlled or uncontrolled discharge of various emerging pollutants (EPs) into water bodies is equally proportional to the fast-growing population and extensive urbanization. EPs affect the entire living being and continuously deteriorate the environmental system, directly or indirectly. The occurrence of EPs (even released after partial treatments, but still in bioactive forms) disturbs ecological integrity. Due to the ineffectiveness of in-practice traditional remediation processes, new and robust treatment measures as effective and sustainable remediation have become a meaningful goal. In this context, special attention has been shifted to engineering an enzyme (catalase)-based biodegradation system with immense prospects in environmental cleanup. The unique synergistic combination of nanomaterials (having multifunctional attributes) with enzymes of interest makes them a state-of-the-art interface that can further ameliorate bio-catalysis and biodegradation performance. This review covers current research and scientific advancement in developing and deploying catalase-based biocatalytic systems to mitigate several EPs from the environment matrices. The biocatalytic features of catalase, along with the mechanistic insight into H₂O₂ neutralization, several nano-based materials loaded with catalase, including nanoparticles (NPs), carbon nanotubes (CNTs), metal-organic frameworks (MOFs), polymeric-based composites, oxime-functionalized cryo-gel disks, electro-spun nanofibrous membranes, and other hybrid materials have also been discussed with suitable examples.

Design strategies, surface functionalization, and environmental remediation potentialities of polymer-functionalized nanocomposites

Inorganic nanoparticles (NPs) have a tunable shape, size, surface morphology, and unique physical properties like catalytic, magnetic, electronic, and optical capabilities. Unlike inorganic nanomaterials, organic polymers exhibit excellent stability, biocompatibility, and processability with a tailored response to external stimuli, including pH, heat, light, and degradation properties. Nano-sized assemblies derived from inorganic and polymeric NPs are combined in a functionalized composite form to import high strength and synergistically promising features not reflected in their part as a single constituent. These new properties of polymer/inorganic functionalized materials have led to emerging applications in a variety of fields, such as environmental remediation, drug delivery, and imaging. This review spotlights recent advances in the design and construction of polymer/inorganic functionalized materials with improved attributes compared to single inorganic and polymeric materials for environmental sustainability. Following an introduction, a comprehensive review of the design and potential applications of polymer/inorganic materials for removing organic pollutants and heavy metals from wastewater is presented. We have offered valuable suggestions for piloting, and scaling-up polymer functionalized nanomaterials using simple concepts. This review is wrapped up with a discussion of perspectives on future research in the field.

Facile synthesis of multifunctional zinc vanadate/polyaniline composite for photocatalytic degradation and supercapacitor applications

Multifunctional Zn₃V₂O₈/Polyaniline (ZnV/PANI) composite was prepared by in-situ oxidative polymerization method. The formation of ZnV and ZnV/PANI composite was proved by various characterization tools including such as FTIR, XRD, SEM, BET, VSM, TEM and XPS analysis. The average crystalline size calculated using Scherrer equation of ZnV and ZnV/PANI were found to be 45 nm and 92 nm respectively. From the Tauc plots the bandgap values (E_g) were found to be 2.4 eV and 2.0 eV for ZnV and ZnV/PANI respectively. The FE-SEM images clearly show the flakes incorporated cluster-like morphology. The BET surface area of ZnV and ZnV/PANI was found to be 22 m² g^-1 and 40 m² g^-1. The XPS results also confirm the successful formation of ZnV/PANI composite. The as-prepared samples were utilized as photocatalyst and electrode materials for energy applications. The ZnV/PANI composite showed an outstanding photocatalytic activity (94%) in the degradation of aqueous RhB dye under visible light irradiation. The optimum catalyst dosage for the degradation of 50 mL of 1 × 10^-5 M RhB dye aqueous solution was 50 mg. The Langmuir-Hinselwood (L-H) kinetic model proves that the photodegradation mechanism follows pseudo-first order kinetics. Further, the supercapacitive behavior of the ZnV/PANI composite was tested using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) techniques in 1 M KOH electrolyte at the potential window of 0-0.55 V. ZnV/PANI electrode displayed a specific capacitance (C_sp) of 664 F g^-1 at 1 A/g. The satisfactory performance of ZnV/PANI composite is mainly ascribed to the synergistic effect of ZnV-PANI matrixes with the occurrence of multiple electroactive sites in the composite. The cycling stability test proved that ZnV/PANI electrode material retained 92% of its initial capacitance even after 6000 GCD cycles at 2 A/g. The finding of this study will help to determine the most efficient and cost-effective method for the removal of dyes from textile industry wastewater and also as an effective material for supercapacitor applications.

Fabrication, characterization, and photocatalytic degradation potential of chitosan-conjugated manganese magnetic nano-biocomposite for emerging dye pollutants

The release of toxic dyes from different industries through industrial effluents cause hazardous effects to human and aquatic life. Therefore, the detoxification of such toxic pollutants is very important for a clean environment. In this regard, chitosan conjugated Mn-magnetic nano-biocomposite (Mn-CCMN) was synthesized, characterized, and applied for the photocatalytic decontamination of crystal violet (CV) dye in the contaminated aqueous system and industrial wastewater. The characterization was performed using SEM, XRD, EDX and FTIR spectroscopic techniques and determine PZC. The data shows the successfully synthesis of the resultant nano-biocomposite with amorphous nature and Fe and Mn were present therein. The SEM study revealed the flat and irregular shaped structure with porous surface and 87 ± 4 nm as mean particle size. The application of as-synthesized nano-biocomposite was determined as a photocatalyst for the eradication of CV in the aqueous environment under UV light illumination. The different photocatalysis conditions were studied for maximum degradation of CV and under the best experimental factors, tremendous CV degradation was attained in the real samples and industrial wastewater. The synthesized Mn-CCMN sustain excellent photocatalytic performance for four successive batches. The photocatalytic data was fitted to the pseudo-first-order kinetic model (R² = 0.992) having 0.007672 min^-1 and 0.0549 ppm/min as k and reaction rate, respectively. The statistical models such as response surface methodology (RSM) and artificial neural network-genetic algorithm (ANN-GA) were also applied for confirmation of the experimental data and the results showed a good agreement. It is deduced that the synthesized Mn-CCMN could be an excellent alternative to the present photocatalysts for the decontamination of toxic organic dyes from contaminated water and industrial wastewater.

Analytical perspective and environmental remediation potentials of magnetic composite nanosorbents

The synthesis and application of magnetic nanosorbents to remove emerging pollutants have been considered the best environmental remediation and sustainability option. Incorporating magnetism shortens the treatment time and allows the sorbent to be recovered quickly using external magnetic with many cycles. The implementation of magnetic solid-phase extraction (MSPE) using magnetic materials of different shapes, sizes, and surface morphology can be a valuable tool in applying materials to prepare analytical samples. In MSPE applications, materials with strong magnetic domain can be used as precursors for constructing magnetic composite as a promising sorbent. This article focuses on the most recent and exceptional applications of magnetic adsorbents for preconcentration and removal purposes. Magnetic adsorbents, such as nanoparticles (NPs), foam, sponges, nanocomposites, hydrogels, and beads with multifunctional attributes have been comprehensively studied in terms of preparation procedures, limitations, advantages, and interactions between pollutants and magnetic composites. The role of magnetic sorbents in sample preparation methods, such as simple solid-phase extraction and microextraction, as well as sorptive extraction using a stir bar, was also examined. The use of magnetic adsorbents with analytical techniques, such as solid-phase extraction and solid-phase microextraction improves the method for preparing samples concerning the influential role of magnetic adsorbents. Towards the end, promising features and future outlook are also directed.

Graphene-based nanocomposites and nanohybrids for the abatement of agro-industrial pollutants in aqueous environments

Incessant release of a large spectrum of agro-industrial pollutants into environmental matrices remains a serious concern due to their potential health risks to humans and aquatic animals. Existing remediation techniques are unable to remove these pollutants, necessitating the development of novel treatment approaches. Due to its unique structure, physicochemical properties, and broad application potential, graphene has attracted a lot of attention as a new type of two-dimensional nanostructure. Given its chemical stability, large surface area, electron mobility, superior thermal conductivity, and two-dimensional structure, tremendous research has been conducted on graphene and its derived composites for environmental remediation and pollution mitigation. Various methods for graphene functionalization have facilitated the development of different graphene derivatives such as graphene oxide (GO), functional reduced graphene oxide (frGO), and reduced graphene oxide (rGO) with novel attributes for multiple applications. This review provides a comprehensive read on the recent progress of multifunctional graphene-based nanocomposites and nanohybrids as a promising way of removing emerging contaminants from aqueous environments. First, a succinct overview of the fundamental structure, fabrication techniques, and features of graphene-based composites is presented. Following that, graphene and GO functionalization, i.e., covalent bonding, non-covalent, and elemental doping, are discussed. Finally, the environmental potentials of a plethora of graphene-based hybrid nanocomposites for the abatement of organic and inorganic contaminants are thoroughly covered.