Chitosan-capped ternary metal selenide nanocatalysts for efficient degradation of Congo red dye in sunlight irradiation

Carbon based nanocomposites, surface functionalization as a promising material for VOCs (volatile organic compounds) treatment

Urban residential and industrial growth development affects sustainable and healthful indoor environments. Environmental issues are a global problem. The deterioration of indoor air quality has prompted the creation of several air cleansing techniques. This review explains how carbon-based materials have influenced the development of air purification systems using photocatalysis. These carbon-based materials offer unique properties and advantages in VOC removal processes. Biochar, produced from biomass pyrolysis, provides an environmentally sustainable solution with its porous structure and carbon-rich composition. Carbon quantum dots, with their quantum confinement effects and tunable surface properties, show promise in VOC sensing and removal applications. Polymers incorporating reduced graphene oxide demonstrate enhanced adsorption capabilities owing to the synergistic effects of graphene and polymer matrices. Activated carbon fibers, characterized by their high aspect ratio and interconnected porosity, provide efficient VOC removal with rapid kinetics. With their unique electronic and structural properties, graphitic carbon nitrides offer opportunities for photocatalytic degradation of VOCs under visible light. Catalysts integrated with MXene, a two-dimensional nanomaterial, exhibit enhanced catalytic activity for VOC oxidation reactions. Using various carbon-based materials in VOC removal showcases the versatility and effectiveness of carbon-based approaches in addressing environmental challenges associated with indoor air pollution. Metal-organic-framework materials are carbon-based compounds. It examines the correlation between VOC mineralization and specific characteristics of carbon materials, including surface area, adsorption capability, surface functional groups, and optoelectronic properties. Discussions include the basics of PCO, variables influencing how well catalysts degrade, and degradation mechanisms. It explores how technology will improve in the future to advance studies on healthy and sustainable indoor air quality.

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.

Bio-inspired magnetic chitosan/Iron oxide macromolecules for multiple anionic dyes adsorption from aqueous media

Organic anionic dyes are major water pollutants due to their low degradability caused by complex aromatic structures. Not only do they exert toxic, mutagenic, teratogenic, tumorigenic, and genotoxic effects, but they also decrease fertility and cause irritation to the skin and respiratory system in humans. This long-term toxicity has detrimental effects on aquatic organisms and their surroundings, resulting in an imbalanced ecosystem. In this study, a Cs@Fe3O4 magnetic biosorbent was synthesised to uptake three anionic dyes and characterised for FTIR, BET/BJH, XRD, TGA, VSM, and FESEM analyses. The biosorbent average surface area was confirmed to be 52.6524 m2/g, with average pore sizes of 7.3606 nm and 6.9823 nm for adsorption-desorption processes, respectively. Batch adsorption studies pH values, contact times, temperature, initial dye concentrations, and adsorbent dosages were examined. Several isotherm and kinetic models were studied to determine the adsorption mechanism. The adsorption data of these dyes at equilibrium was observed to match Langmuir's isotherm and pseudo-second-order kinetic models. The thermodynamic study revealed that the adsorption process for these dyes was an exothermic reaction. Maximum adsorption capacities for congo red, methyl orange, and metanil yellow were 117.77 mg/g, 137.77 mg/g, and 155.57 mg/g, respectively. The reusability of recovered Cs@Fe3O4 after dye adsorption was evaluated up to five continuous adsorption-desorption cycles for its possible industrial applications.

Robust polymer hybrid and assembly materials from structure tailoring to efficient catalytic remediation of emerging pollutants

A massive amount of toxic substances and harmful chemicals are released every day into the outer environment, imposing serious environmental impacts on both land and aquatic animals. To date, research is constantly in progress to determine the best catalytic material for the effective remediation of these harmful pollutants. Hybrid nanomaterials prepared by combining functional polymers with inorganic nanostructures got attention as a promising area of research owing to their remarkable multifunctional properties deriving from their entire nanocomposite structure. The versatility of the existing nanomaterials' design in polymer-inorganic hybrids, with respect to their structure, composition, and architecture, opens new prospects for catalytic applications in environmental remediation. This review article provides comprehensive detail on catalytic polymer nanocomposites and highlights how they might act as a catalyst in the remediation of toxic pollutants. Additionally, it provides a detailed clarification of the processing of design and synthetic ways for manufacturing polymer nanocomposites and explores further into the concepts of precise design methodologies. Polymer nanocomposites are used for treating pollutants (electrocatalytic, biocatalytic, catalytic, and redox degradation). The three catalytic techniques that are frequently used are thoroughly illustrated. Furthermore, significant improvements in the method through which the aforementioned catalytic process and pollutants are extensively discussed. The final section summarizes challenges in research and the potential of catalytic polymer nanocomposites for environmental remediation.

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.

Synergistic molecular mechanism of degradation in dye wastewater by Rhodopseudomonas palustris intimately coupled carbon nanotube - Silver modified titanium dioxide photocatalytic composite with sodium alginate

The intimately coupled photocatalysis and biodegradation (ICPB), which combined the advantages of high oxidation capacity of photocatalysis and high mineralization rate of biodegradation, has demonstrated excellent removal performance in the degradation of azo dyes with highly toxic, refractory, mutagenic and carcinogenic. In order to explore the metagenomics mechanism of the ICPB system, a novel ICPB was prepared by coupling Rhodopseudomonas palustris (R. Palustris), carbon nanotube - silver modified titanium dioxide photocatalytic composite (CNT-Ag -TiO2, CAT) and sodium alginate (SA) (R. palustris/CAT@SA, R-CAT). Metagenomics sequencing was used to investigate the molecular mechanism of adaptation and degradation of dyes by photosynthetic microorganisms and the adaptive and synergistic interaction between photosynthetic microorganisms and photocatalyst. Experiments on the adaptability and degradability of photosynthetic microorganisms have proved that low concentration azo dyes could be utilized as carbon sources for growth of photosynthetic microorganisms. Metagenomics sequencing revealed that R. palustris was the main degrading bacterium in photosynthetic microorganisms and the functional genes related to carbohydrate metabolism, biological regulation and catalytic activity were abundant. It was found that the addition of photocatalyst significantly up-regulated the functional genes related to the catabolic process, electron transport, oxidoreductase activity and superoxide metabolism of organic matter in the photosynthetic microorganisms. Moreover, many key gene such as alpha-amylase, 1-acyl-sn-glycerol-3-phosphate acyltransferase, aldehyde dehydrogenase enrichment in microbial basal metabolism, such as enoyl-CoA hydratase, malate dehydrogenase, glutathione S-transferase enrichment in degrading azo dyes and electron transport, and many key gene such as undecaprenyl-diphosphatase, carbon storage regulator, DNA ligase enrichment in response to dyes and photocatalysts were discovered. These findings would contribute to a comprehensive understanding of the mechanism of degradation of dye wastewater by ICPB system, a series of genes was produced to adapt to environmental changes, and played synergistic role in terms of intermediate product degradation and electron transfer for degrading azo dyes. The photosynthetic microorganisms might be a promising microorganism for constructing ICPB system.

Enzyme-triggered approach to reduce water bodies' contamination using peroxidase-immobilized ZnO/SnO2/alginate nanocomposite

Enzyme immobilization on solid support offers advantages over free enzymes by overcoming characteristic limitations. To synthesize new stable and hyperactive nano-biocatalysts (co-precipitation method), ginger peroxidase (GP) was surface immobilized (adsorption) on ZnO/SnO2 and ZnO/SnO2/SA nanocomposite with immobilization efficacy of 94 % and 99 %, respectively. Thereafter, catalytic and biochemical characteristics of free and immobilized GP were investigated by deploying various techniques, i.e., FTIR, PXRD, SEM, and PL. Diffraction peaks emerged at 2θ values of 26°, 33°, 37°, 51°, 31°, 34°, 36°, 56°, indicating the formation of SnO2 and ZnO. The OH stretching of the H2O molecules was attributed to broad peaks between 3200 and 3500 cm-1, whereas ZnO/SnO2 spikes occurred in the 1626-1637 cm-1 range. SnO stretching mode and ZnO terminal vibrational patterns have been verified at corresponding wavelengths of 625 cm-1 and 560 cm-1. Enzyme entrapment onto substrate was verified via interactions between GP and ZnO/SnO2/SA as corroborated by signals beneath 1100 cm-1. GP-immobilized fractions were optimally active at pH 5, 50 °C, and retained maximum activity after storage of 4 weeks at -4 °C. Kinetic parameters were determined by using a Lineweaver-Burk plot and Vmax for free GP, ZnO/SnO2/GP and ZnO/SnO2/SA/GP with guaiacol as a substrate, were found to be 322.58, 49.01 and 11.45 (μM/min) respectively. A decrease in values of Vmax and KM indicates strong adsorption of peroxidase on support and maximum affinity between nano support and enzyme, respectively. For environmental remediation, free ginger peroxidase (GP), ZnO/SnO2/GP and ZnO/SnO2/SA/GP fractions effectively eradicated highly intricate dye. Multiple scavengers had a significant impact on the depletion of the dye. In conclusion, ZnO/SnO2 and ZnO/SnO2/SA nanostructures comprise an ecologically acceptable and intriguing carrier for enzyme immobilization.

A review on the lignocellulosic derived biochar-based catalyst in wastewater remediation: Advanced treatment technologies and machine learning tools

Wastewater disposal in the ecosystem affects aquatic and human life, which necessitates the removal of the contaminants. Eliminating wastewater contaminants using biochar produced through the thermal decomposition of lignocellulosic biomass (LCB) is sustainable. Due to its high specific surface area, porous structure, oxygen functional groups, and low cost, biochar has emerged as an alternate contender in catalysis. Various innovative advanced technologies were combined with biochar for effective wastewater treatment. This review examines the use of LCB for the synthesis of biochar along with its activation methods. It also elaborates on using advanced biochar-based technologies in wastewater treatment and the mechanism for forming oxidizing species. The research also highlights the use of machine learning in pollutant removal and identifies the obstacles of biochar-based catalysts in both real-time and cutting-edge technologies. Probable and restrictions for further exploration are discussed.

Titanium doped cobalt ferrite fabricated graphene oxide nanocomposite for efficient photocatalytic and antibacterial activities

Dyes and microbes are the main sources of water pollution and their treatment with titanium doped cobalt ferrite nanoparticles (CoTixFe2-xO4 NPs) is highly challenging due to the recombination ability of their electron-hole pairs which could be mitigated by making their composite with graphene oxide (GO). In the present study, titanium doped cobalt ferrite was fabricated on GO (CoTi0.2Fe1.8O4/GO NC) via the facile ultrasonication method and its confirmation was done by various analytical studies. Homogeneous dispersion of spherical CoTi0.2Fe1.8O4 NPs on the GO surface was realized by SEM analysis. Excellent crystallinity was corroborated by XRD while a Zeta Potential value -21.52 mV depicted exceptional stability. The photocatalytic power of CoTi0.2Fe1.8O/GO NC against Congo Red (CR) dye showed 91% degradation efficiency after 120 min visible light irradiation under optimum conditions of pH 9 and dye concentration 1 mg L-1 which was reasonably higher as compared to bare CoTi0.2Fe1.8O NPs (78% degradation efficiency). The improved photocatalytic performance is accredited to its narrow bandgap value (1.07 eV) and enhanced charge separation as indicated by the Tauc plot and Photoluminescence analysis, respectively. Additionally, CoTi0.2Fe1.8O/GO NC could be readily regenerated and reused five times with only ∼2% performance loss. Meanwhile, MICs of CoTi0.2Fe1.8O4/GO NC against P. aeruginosa and S. aureus were 0.046 and 0.093 mg mL-1 while MBCs were 0.093 and 0.187 mg mL-1, respectively. Thereby, optimized NC can open new avenues for the degradation of dyes from polluted water besides acting as a promising antimicrobial agent by rupturing the cell walls of pathogens.

Adsorption-photocatalytic degradation abilities of γ-irradiated chitosan-ZnO-AgNP composite for organic dye removal and antibacterial activity

We synthesized a γ-irradiated chitosan-ZnO-AgNPs (ICZA) composite by using a simple hydrogels method. We evaluated its adsorption/photocatalytic degradation abilities for the removal of an organic dye and its antibacterial activity. The XRD, SEM, TEM, EDS, and FTIR techniques were used to characterize the obtained samples. Based on the adsorption and degradation of methylene blue (MB) in the dark and under UV light irradiation, the adsorption and the photocatalytic activity of the as-obtained samples were evaluated. The optimum conditions for synthesizing the composite were as follows: contact time of 210 min, a dosage of 2 g/L, MB concentration of 40 mg/L, and a solution pH of 8.0. The ICZA had a high adsorption capacity, which was suitable for removing MB from the aqueous solutions; it showed a maximum adsorption capacity (qm) of 92.59 mg/g. The fit of the adsorption isotherms with the Langmuir model was satisfactory. The photocatalytic degradation ability of the composite was also better than that of other catalysts in the presence of UV light, with an apparent rate constant (kapp) of 3.08 × 10-2. The synthesized ICZA also showed good antibacterial activity against Staphylococcus aureus, with a minimum inhibitory concentration (MIC) and a minimum bactericidal concentration (MBC) of 12.5 g/mL and 50 g/mL under light-incubation and dark-incubation conditions. Finally, we discussed the hypothesized mechanism of the adsorption/photocatalytic activity and antibacterial activity of the ICZA composite in this study.

Cellulose nanofibers decorated with SiO2 nanoparticles: Green adsorbents for removal of cationic and anionic dyes; kinetics, isotherms, and thermodynamic studies

Cellulose nanofibers decorated with SiO2 nanoparticles (SiO2-CNF) were prepared by the extraction of cellulose nanofibers from Yucca leaves, followed by modification with SiO2 nanoparticles, and used as efficient materials for the removal of both anionic and cationic dyes from the aqueous solution. Prepared nanostructures were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction powder (XRD), Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and transmission electron microscopy (TEM) analysis. The adsorption capacity of the nanostructures was investigated for the removal of both cationic (Methylene Blue, MB, and Crystal Violet, CV) and anionic (Eriochrome Black-T, EB) dyes. The kinetics of adsorption were investigated using some well-known models, including intraparticular diffusion (IPD), pseudo-first-order (PFO), pseudo-second-order (PSO), and Elovich. The adsorption isotherms were also explored using the Langmuir, Freundlich, Temkin, and Redlich-Peterson models. The obtained results revealed that the adsorption processes follow PSO kinetic and Langmuir isotherm models. Thermodynamic parameters of the adsorption were measured at different temperatures, indicating the feasibility and spontaneity of the adsorption. The pH and salt effects on adsorption were also explored. Finally, according to the reusability tests, the prepared adsorbents showed high recoverability without considerable loss in adsorption efficiency after five repeated runs.

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).

One-pot synthesis of CdS/CeO2 heterojunction nanocomposite with tunable bandgap for the enhanced advanced oxidation process

Herein, a binary nanocomposite CdS/CeO₂ has been fabricated via a one-pot co-precipitation method for the degradation of Rose Bengal (RB) dye. The structure, surface morphology, composition, and surface area of the prepared composite were characterized by transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, Brunaur-Emmett-Teller analysis UV-Vis diffuse reflectance spectroscopy and photoluminescence spectroscopy. The prepared CdS/CeO₂(1:1) nanocomposite has a particle size of 8.9 ± 0.3 nm and a surface area of 51.30 m²/g. All the tests indicated the agglomeration of CdS nanoparticles over the surface of CeO₂. The prepared composite showed excellent photocatalytic activity in the presence of hydrogen peroxide under solar irradiation towards the degradation of Rose Bengal. Near to about complete degradation of 190 ppm of RB dye could be achieved within 60 min under optimum conditions. The enhanced photocatalytic activity was attributed to the delayed charge recombination rate and a lower bandgap of the photocatalyst. The degradation process was found to follow pseudo-first-order kinetics with a rate constant of 0.05824 min^-1. The prepared sample showed excellent stability and reusability and maintained about 87% of the photocatalytic efficiency till the fifth cycle. A plausible mechanism for the degradation of the dye is also presented based on the scavenger experiments.

Enhanced Visible-Photocatalytic Activities in Strong Acids and Strong Alkalis of Flexible Iron-SrTiO3 Nanofibrous Membranes

Traditional SrTiO₃ (STO) materials have high brittleness and poor deformation resistance. In this work, macroscopically flexible iron-doped SrTiO₃ (SFTO) nanofibrous membranes were prepared by electrospinning and calcination, which can be easily isolated and can maintain integrity to recycle as photocatalysts. Moreover, the SFTO nanofibrous membranes showed enhanced photocatalytic performance under strong acids (pH = 2) and strong alkalis (pH = 12). The SFTO nanofibrous membranes increased the catalytic rate of Congo red (CR) dye by about 10 times in visible light. The mechanism of photocatalytic activity enhancement was discussed by the combined effects of hydroxyl radicals and superoxide radicals. The successful preparation of SFTO nanofibrous membranes has offered a simple and economical approach to photocatalysis as well as environmental remediation.

Cocatalyst loaded Al-SrTiO3 cubes for Congo red dye photo-degradation under wide range of light

The continued pollution, waste, and unequal distribution of the limited amount of fresh water on earth are pushing the world into water scarcity crisis. Consequently, development of revolutionary, cost-effective, and efficient techniques for water purification is essential. Herein, molten flux method was used for the preparation of micro-sized Al-doped SrTiO₃ photocatalyst loaded with RhCr₂O₃ and CoOOH cocatalysts via simple impregnation method for the photo-assisted degradation of Congo red dye under UV and visible irradiation compared with P25 standard photocatalyst. In addition, photoelectrochemical analysis was conducted to reveal the separation and transfer efficiency of the photogenerated e^-/h⁺ pairs playing the key role in photocatalysis. SEM and TEM analyses revealed that both P25 and the pristine SrTiO₃ have spherical shapes, while Al-doped SrTiO₃ and the sample loaded with cocatalysts have cubic shapes with a relatively higher particle size reaching 145 nm. In addition, the lowest bandgap is due to Al⁺³ ion doping and excessive surface oxygen vacancies, as confirmed by both UV-Vis diffuse-reflectance and XPS analyses. The loading of the cocatalysts resulted in a change in the bandgap from n-type (pristine SrTiO₃ and Al-SrTiO₃) into p-type (cocatalyst loaded sample) as exhibited by Mott-Schottky plots. Besides, the cocatalyst-loaded sample exhibited good performance stability after 5 cycles of the photocatalytic removal of Congo red dye. OH^· radical was the primary species responsible for CR degradation as confirmed by experiments with radical scavengers. The observed performance of the prepared samples under both UV and visible light could foster the ongoing efforts towards more efficient photocatalysts for water purification.

Coupling of carboxymethyl starch with 2-carboxyethyl acrylate: A new sorbent for the wastewater remediation of methylene blue

Textile and printing industries play a vital role in the economy of any country. But the effluents of these industries, which contain toxic Methylene Blue (MB) dye when mixed with fresh water, make it unfit for human health and aquatic life. For the removal of MB, different adsorbents were used, but they were expensive, non-biodegradable or less effective. In this research, novel carboxymethyl starch grafted poly 2-carboxyethyl acrylate (CM-St-g-P2CEtA) was synthesized by reacting carboxymethyl starch with 2-carboxyethyl acrylate. The reaction followed a free radical polymerization mechanism. The structure and properties of CM-St-g-P2CEtA were investigated by advanced analytical techniques. The CM-St-g-P2CEtA was employed for the remediation of Methylene Blue (MB) dye from wastewater. The removal percentage (%R) of MB was checked under different parameters, like different pH levels, different initial concentrations of dye, different adsorbent doses, and different contact times. The results obtained during the experiment were subjected to different adsorption and kinetic models. In the kinetic investigation, the experimental results were best represented by the pseudo-second-order kinetic model due to its high R² value of 0.999. Similarly, with a regression coefficient (R²) value of 0.947, the Langmuir adsorption isotherm was best represented by the experimental results. The Langmuir adsorption model showed that MB dye was adsorbed on the surface of CM-St-g-P2CEtA in a monolayer pattern. The pseudo 2nd order kinetic model suggested that the adsorption process favored chemisorption mechanism. The CM-St-g-P2CEtA showed maximum percentage removal efficiency (%R) of 99.3% for MB dye.

Comparative robustness and sustainability of in-situ prepared antimony nanoarchitectonics in chitosan/synthesized carboxymethyl chitosan in environmental remediation perspective

Due to the rapid race of industrialization natural assets like fresh water has been deteriorated causing lethal effects in living organisms. In the current study robust and sustainable composite of in-situ antimony nanoarchitectonics in chitosan/synthesized carboxymethyl chitosan matrix were synthesized. To improve solubility, metal adsorption and water decontamination, chitosan was modified into carboxymethyl chitosan and the modification was confirmed through various characterization techniques. The characteristic bands in the FTIR spectrum confirm substitution of carboxymethyl group in the chitosan. This was further illustrated that the characteristic proton peaks of CMCh observed at δ = 4.097 to 4.192 ppm, suggesting O-carboxy methylation of chitosan by ¹H NMR. The second order derivative of potentiometric analysis confirmed 0.83 degree of substitution. The antimony (Sb) loaded modified chitosan were confirmed by FTIR and XRD analysis. The potential effectiveness of chitosan matrix was determined and compared toward reductive removal of the Rhodamine b dye. Rhodamine b mitigation is following first order kinetics with R² value of 0.9832 and 0.969 with a constant rate of 0.0977 and 0.2534 ml/min for Sb loaded chitosan and carboxymethyl chitosan respectively. The Sb/CMCh-CFP enables us to achieve 98.5 % mitigation efficiency within 10 min. The CMCh-CFP chelating substrate was found stable and efficient even after 4th batches of cycles with <4 % decrease in efficiency. The in-situ synthesized material was found tailored composite, in terms of dyes remediation, reusability and biocompatibility as compared to chitosan.

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.

Eco-friendly cubic-ZnS coupled Cu7S4 spines on chitosan matrix: Unravelling defect-engineered nanoplatform for the photodegradation of p-chlorophenol

Novel ZnS-Cu₇S₄ nanohybrid supported on chitosan matrix, as an ideal photocatalyst, was fabricated by the sonochemical method wherein high-resolution transmission electron microscopy (HRTEM) and X-ray powder diffraction (XRD) analysis confirmed the co-existence of both ZnS and Cu₇S₄; presence of vacancy sites in ZnS was verified by electron paramagnetic resonance (EPR) analysis and their introduction could promote two-photon excitation facilitated visible light response and charge transport/separation. The type II interface is formed in the ZnS-Cu₇S₄/Chitosan heterojunction owing to interstitial states that promote charge separation. The ZnS-Cu₇S₄/Chitosan was used for the photodegradation of a pharmaceutical pollutant, p-chlorophenol (PCP); over 98.8% of PCP photodegradation was achieved under visible-light irradiation where the ensued ·O₂^- and ·OH serve a key role in the photodegradation of PCP. In vitro cytotoxicity studies substantiated that the ZnS-Cu₇S₄/Chitosan is nontoxic to the ecosystem and human beings and endowed with promising photodegradation properties and accessibility via an environmentally friendly design, bodes well for its potential remediation applications.

Chitosan functionalized bismuth oxychloride/zinc oxide nanocomposite for enhanced photocatalytic degradation of Congo red

The industrial discharge of dye pollutant contaminated wastewater is the major cause of water and soil pollution. Photocatalysis is a promising and green remediation technology, which has received widespread attention in the remediation of hazardous dyes from aqueous environment and convert them into harmless compounds. Herein, we report the synthesis of chitosan (CS) functionalized bismuth oxychloride/zinc oxide (BiOCl/ZnO) nanocomposite by a modified hydrothermal route. The physiochemical characterization revealed that the synthesized nanocomposite have crystalline, agglomerated spherical along with rod shaped morphology and size range from 35 to 160 nm. FTIR peaks at 825, 727, 662 and 622 cm^-1 specified the presence of BiO and ZnO bonds, whereas peak at 1635 cm^-1 revealed the existence of amine groups which confirms the presence of CS in the synthesized CS-BiOCl/ZnO nanocomposite. Catalytic property of synthesized nanocomposite was evaluated by the degradation of Congo red (CR) under UV-light irradiation. CR dye degradation percentage was found to be 93 % within a short period of 40 min by utilizing UV-light. Furthermore, reusability of CS-BiOCl/ZnO photocatalyst was also investigated, and it remained significant photocatalytic activity after three consecutive cycles. Hence, the results obtained in this study revealed that CS-BiOCl/ZnO nanocomposite can be used as a potential photocatalyst to remediate organic pollutants in various industries.

Enhanced PMS/O2 activation by self-crosslinked amine-gluteraldehyde/chitosan-Cu biocomposites for efficient degradation of HEPES as biological pollutants and selective allylic oxidation of cyclohexene

Optimization and mechanism elucidation of the catalytic degradation of HEPES and selective aerobic oxidation of cyclohexene by Cu@cross-linked magnetic chitosan.

Facile synthesis of CoFe2O4@MIL-53(Al) nanocomposite for fast dye removal: Adsorption models, optimization and recyclability

The global occurrence of textile dyes pollution has recently emerged, posing a serious threat to ecological systems. To abate dye contamination, we here developed a novel magnetic porous CoFe₂O₄@MIL-53(Al) nanocomposite by incorporating magnetic CoFe₂O₄ nanoparticles with MIL-53(Al) metal-organic framework. This nanocomposite possessed a surface area of 197.144 m² g^-1 and a pore volume of 0.413 cm³ g^-1. The effect of contact time (5-120 min), concentration (5-50 mg L^-1), dosage (0.1-1.0 g L^-1), and pH (2-10) on Congo red adsorption was clarified. CoFe₂O₄@MIL-53(Al) could remove 95.85% of Cong red dye from water with an accelerated kinetic rate of 0.6544 min^-1 within 10 min. The kinetic and isotherm models showed the predominance of Bangham and Temkin. According to Langmuir, the maximum uptake capacities of CoFe₂O₄@MIL-53(Al), CoFe₂O₄, and MIL-53(Al) adsorbents were 43.768, 17.982, and 15.295 mg g^-1, respectively. CoFe₂O₄@MIL-53(Al) was selected to optimize Cong red treatment using Box-Behnken experimental design. The outcomes showed that CoFe₂O₄@MIL-53(Al) achieved the highest experimental uptake capacity of 35.919 mg g^-1 at concentration (29.966 mg L^-1), time (14.926 min), and dosage (0.486 g L^-1). CoFe₂O₄@MIL-53(Al) could treat dye mixture (methylene blue, methyl orange, Congo red, malachite green, and crystal violet) with an outstanding removal efficiency of 81.24% for 30 min, and could be reused up to five cycles. Therefore, novel recyclable and stable CoFe₂O₄@MIL-53(Al) is recommended to integrate well with real dye treatments systems.

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.

In-house fabrication of macro-porous biopolymeric hydrogel and its deployment for adsorptive remediation of lead and cadmium from water matrices

A novel adsorbent was prepared by blending chitosan (CS) and acrylic acid (AA) while using formaldehyde as a cross linker in the form of hydrogel beads. The adsorption properties of these hydrogel beads for the removal of toxic metal ions (Pb²⁺ and Cd²⁺) from aqueous solutions were evaluated. The hydrogel beads have a 3D macro-porous structure whose -NH₂ groups were considered to be the dominant binding specie for Cd and Pb ions. The equilibrium adsorption capacity (q_e) of beads was significantly affected by the mass ratio of sorbent and sorbate. The percentage removal of Cd and Pb ions was observed to be enhanced with the increase in sorbate concentration. The hydrogel beads maintained good adsorption properties at adsorption-desorption equilibrium. The Langmuir and Freundlich models were used to elaborate the isotherms as well as isotherm constants. Adsorption isothermal data is well explained by the Freundlich model. The data of experimental kinetics is interrelated with the second-order kinetic model, which showed that the chemical sorption phenomenon is the rate limiting step. The results of intraparticle diffusion model described the adsorption process occurred on a porous substance that proved chitosan/Formaldehyde beads to be the favorable adsorbent.

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.

Designing, characterization, and evaluation of chitosan-zinc selenide nanoparticles for visible-light-induced degradation of tartrazine and sunset yellow dyes

Employing dyes in different industrial sectors has produced a serious threat to the environment and living organisms of water bodies and land. For the decontamination of such toxic dyes, efforts have been made to develop an efficient, feasible, and low maintenance processes. In this context, chitosan-zinc selenide (CS-ZnSe) nanoparticles were prepared through chemical reduction method as the efficient photocatalysts for the decontamination of toxic dyes through photocatalysis. Photocatalyst's synthesis was confirmed with the help of FTIR spectroscopy. XRD indicated the hexagonal crystal structure of the CS-ZnSe with a crystallite size of 12 nm. SEM micrographs showed the average nano photocatalyst size as 25 nm. EDX analysis was employed to determine the elemental composition of the CS-ZnSe. An excellent photocatalytic degradation efficiency for tartrazine and sunset yellow dyes was obtained using CS-ZnSe. The results showed a 98% and 97% degradation efficiency for tartrazine dye and sunset yellow (SY) dye at optimized conditions of time (3 h), pH (5), dye concentration (30 ppm), catalyst dosage (0.09 g and 0.01 g) , and at a temperature of 35 °C. Findings of the photocatalytic degradation process fitted well with first-order kinetics for both the dyes. Rate constant, 'K' value was found to be 0.001362 min^-1 and 0.001257 min^-1 for tartrazine and SY dyes, respectively. While value for (correlation coefficient, R²) was 0.99307 and 0.99277 for tartrazine and sunset yellow dyes, respectively. Recyclability of the photocatalyst was confirmed using it for consecutive cycles to degrade organic dyes. Results showed that the CH-ZnS possesses excellent efficiency in decontaminating organic dyes from industrial wastewater.

Photocatalytic activity of calcined chicken eggshells for Safranin and Reactive Red 180 decolorization

One of the most important problems affecting the environment today is the inability to adequately treat wastewater containing dyes. Among of the many treatment processes used in the treatment of dye-containing wastewater, photocatalytic based wastewater treatment processes attract the attention of scientists as a new, economically feasible, and promising approach which has been in practice for a few decades. However, in order to use these processes in wider areas, cheap and effective catalysts are still being developed today. In this study, the photocatalytic activity of eggshell-CaO produced from waste chicken eggshells was investigated for decolorization of Safranin (Basic Red 2) and Reactive Red 180 (RR180) dyes. First, sintering process was applied to the waste chicken eggshells at different temperatures (300, 600, 900 °C) in order to observe CaO formation from the eggshells. Second, the parameters such as photocatalyst amount, pH, concentration of dyes, and reaction time were optimized on dye removal efficiency in photocatalytic experiments. The optimum conditions were performed under visible light and found to be 1 g/L of catalyst amount (sintered at 900 °C), original solution pH (6.80 for Safranin and 6.60 for RR180), and 5 mg/L of dye concentration. The photocatalytic removal efficiencies of Safranin and RR180 dyes were 100% and 97.90%, respectively, under the determined optimum experimental conditions. The adsorption efficiency of the dyes that could be realized during the photocatalytic experiment was measured as 20.99% and 9.99% for Safranin and RR180 dyes, respectively.

Magnetically recoverable poly (methyl methacrylate-acrylic acid)/iron oxide magnetic composites nanomaterials with hydrophilic wettability for efficient oil-water separation

Due to the environmental and production problems of emulsion, it is important to efficiently separate oil-water emulsion to meet the refinery requirement and clean up oil spills. Synthesis of a universal demulsifier is not an easy task because the physical properties of crude oil vary, which makes its characterization and demulsification procedure difficult. To overcome this problem, hydrophilic and magnetically recoverable poly (methyl methacrylate-acrylic acid)/iron oxide magnetic composite nanoparticles ((P(MMA-AA)/Fe₃O₄ NPs) were developed as an efficient and economical demulsifier via soap-free emulsion polymerization. To characterize the magnetic composite NPs for their appropriate surface morphology and magnetic domain, TEM, FTIR, VSM, and TGA analyses were carried out. The newly synthesized NPs displayed good hydrophilic properties as they migrated quickly to the aqueous emulsion phase, which was also reassured by their water contact angle of 75°. They exhibit strong magnetic characteristics (20 amu/g) in the oil-water emulsion, makings the hydrophilic wettability capable and attractive to the external magnet. Experimental results revealed that the prepared magnetic composite NPs separated 99% of the water from stable emulsion in 30 min and could be recycled 8 times through magnetic separation. The recycled magnetic composite NPs maintain their hydrophilic wettability and efficiency in separating oil-water emulsion, making them economical and commercially viable. The migration of magnetic composite NPs to the aqueous phase in the stable emulsion with a strong magnetic domain explains the coalescence of emulsified water droplets and their quick separation from the stable emulsions through the external magnet.

Robust bioinspired surfaces and their exploitation for petroleum hydrocarbon remediation

The current improvement in science and engineering, actively dealing with surfaces and interfaces, turns into a functioning control with a thriving advancement propensity. Superlyophobic/superlyophilic phenomena in surface sciences have pulled in broad considerations of researchers and specialists. Inspired by the natural and living organism, researchers have designed different biomimetic materials with exceptional surface wettability, such as the smart wetting of asymmetric spider silk surfaces. These smart materials with superlyophobic/superlyophilic wettability are generally utilized for water assortment, self-cleaning, fluid transportation and separation, and many researchers' domains. Among them, emulsion separation, including division of oil-water blend, mixtures of immiscible liquids and oil-water emulsions, is highlighted by an increasing number of researchers. Numerous materials with one- and two-dimensional morphology, smart surfaces, and super wettability have been effectively designed and utilized in various scientific research applications. We expect that these bioinspired materials with super wettability can have promising applications in practical for emulsion destabilization and liquid transportation.

Core-shell magnetic molecularly imprinted polymer for selective recognition and detection of sunset yellow in aqueous environment and real samples

Magnetic Molecularly imprinted polymers (MMIPs) have been recently recognized as an exceptional tool for monitoring and decontamination of environmental and biological samples of diverse nature. Based on the potential applications as sorbents and biomimetic sensors, herein, a core-shell magnetic-molecularly imprinted polymer (MMIP) was developed as a selective material for separation and sensing of sunset yellow (SY) dye in an aqueous environment and real samples. The MMIP was synthesized via precipitation polymerization using SY as a template, MAA as a functional monomer (chosen based on simulation studies), EGDMA as a cross-linking agent, and AIBN as an initiator. To elaborate the specificity of MMIP, a comparative agent, magnetic non-imprinted polymer (MNIP) was also synthesized. The XRD results showed that the MMIP showed both crystalline and amorphous structure attributed to the presence and polymeric and non-polymeric groups. The FTIR spectra confirmed synthesis of intermediate and final MMIP product. The SEM results showed spherical morphology and porous structure of the MMIP with an average particle size of 0.636 μm in diameter. The MMIP was first employed as a sorbent for the removal of SY from the aqueous environment. The binding experiments performed at optimized operating conditions (pH 2; time 30 min; sorbent dosage 3 mg; sorbate concentration 80 ppm) showed more selectivity when compared with MNIP. The data fitted best to Langmuir's sorption isotherm (Q_o 359.8 mg/g) and followed the pseudo-second-order kinetic model. The synthesized MMIP was also used as an electrochemical sensor for detection of SY dye in the aqueous environment, which exhibited a linear range of detection as (1.51 × 10^-6 - 1.5 × 10^-3 M). The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.00413 M and 0.0137 M, respectively. While the R² value was found to be 0.997 at optimized analytical conditions. These results suggested that the synthesized MMIP can be applied for the selective separation and quantification of SY dye in sample of diverse nature.

Historical development and prospect of intimately coupling photocatalysis and biological technology for pollutant treatment in sewage: A review

Through the synergistic effect of photocatalysis and biodegradation, intimately coupling photocatalysis and biological (ICPB) technology could improve the removal rate and mineralization rate of refractory pollutants and reduce the toxicity of intermediate products. ICPB system was characterized with the advantages of simple operation, low energy consumption and high treatment efficiency. As a new sewage treatment technology, ICPB system has shown great potential in the treatment of refractory pollutants, and has been widely concerned. In this study, the research progress of photocatalyst, carrier and biofilm in ICPB system were discussed, and the degradation mechanism was introduced. The shortcomings of the current ICPB system were pointed out, and the possible research directions of ICPB in the future were proposed. This review aimed to deepen the understanding of ICPB technology and promoted the further development of ICPB technology in the treatment of refractory pollutants.

Rapid degradation of Congo red wastewater by Rhodopseudomonas palustris intimately coupled carbon nanotube - Silver modified titanium dioxide photocatalytic composite with sodium alginate

With a large number of Congo red used in textiles, Congo red wastewater was not easily degraded, resulting in environmental and health-related problems. In order to improve the degradation efficiency of Congo red wastewater, A novel intimately coupled photocatalysis and biodegradation (ICPB) system was prepared by coupling Rhodopseudomonas palustris (R. Palustris), carbon nanotube - silver modified titanium dioxide photocatalytic composite (CNT-Ag -TiO₂, CAT) and sodium alginate (SA) (R. palustris/CAT@SA). Compared with immobilized CAT and R. palustris, the R. palustris/CAT@SA improved the degradation and removal rates of Congo red by 14.3% and 42.1%, and the COD removal rates by 76% and 44.6%, respectively. The mechanism of the degradation of Congo red by the new ICPB was that the Congo red on the surface of the support was degraded into long-chain alkanes by the superoxide and hydroxyl radicals of CAT product, and then the long-chain alkanes were completely mineralization by R. Palustris, which reduced the accumulation of intermediates in the photocatalysis. Most of the Congo red was adsorbed to the interior of the carrier was degraded into aromatic hydrocarbons by R. Palustris, and then oxidized and degraded by CAT, and a small part of the Congo red would be directly mineralized by R. Palustris. A novel technical solution of R. palustris/CAT@SA provided a potential application to the degradation of dye wastewater.

Cerium oxide decorated 5-fluorouracil loaded chitosan nanoparticles for treatment of hepatocellular carcinoma

Reactive oxygen species (ROS) play a crucial role in the mammalian system in both normal and pathological conditions. Hence, this work prepared and characterized the ROS responsive cerium oxide nanoparticles (CeO₂ NPs) decorated 5-fluorouracil (5FU) loaded chitosan (CS) nanoparticles (CS-5FU NPs) for enhanced anticancer activity in hepatocellular carcinoma (HepG2 cells). CeO₂ NPs decorated CS-5FU NPs were found to be spherical in shape and black dense aggregated particles sized 200 nm. The functional properties and cubic crystalline structure of CeO₂ NPs were studied by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis, respectively. Further, CS-5FU-CeO₂ NPs attenuated the 2,2'-Azobis (2-methylpropionamidine) dihydrochloride (AAPH) induced ROS formation in mouse embryonic fibroblasts (NIH3T3 cells) while enhancing apoptotic cell death in HepG2 cells by controlled delivery of 5FU. Furthermore, CS-5FU-CeO₂ NPs have not exhibited toxicity to red blood cells (RBCs) and chick chorioallantoic membrane (CAM). Hence, this work concluded that CeO₂ NPs decorated CS-5FU NPs synergistically enhanced anticancer activity in HepG2 cells through the regulation of ROS.

Solar-Energy-Driven Cu-ZnO/TiO2 Nanocomposite Photocatalyst for the Rapid Degradation of Congo Red Azo Dye

This study effectively demonstrates the sonochemical synthesis of visible-light-responsive Cu-ZnO/TiO2 ternary Z-scheme heterojunction nanocomposite photocatalyst. The as-prepared photocatalyst was comprehensively characterized by techniques including high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray analysis (EDX) and elemental dot mapping, X-ray diffraction (XRD), UV-Vis-diffuse reflectance spectroscopy (UV-Vis-DRS), Brunauer–Emmett–Teller (BET) surface area, and Fourier-transform infrared spectroscopy (FTIR). The photocatalytic activity of the Cu-ZnO/TiO2 nanocomposite photocatalyst was assessed for the degradation of Congo red (CR), an azo dye, under direct sunlight. The pseudo-first-order rate constant for CR degradation was found to be 0.09 min−1. The outcome implies that the synthesised nanocomposite photocatalyst demonstrates excellent photocatalytic activity under direct sunlight as 98% degradation of CR dye was achieved in approximately 20 min using the Cu-ZnO/TiO2 nanocomposite photocatalyst. Furthermore, its high recoverability and reusability of five times indicate its excellent catalytic potential.

Utilization of a double-cross-linked amino-functionalized three-dimensional graphene networks as a monolithic adsorbent for methyl orange removal: Equilibrium, kinetics, thermodynamics and artificial neural network modeling

Herein, it is aimed to develop a high-performance monolithic adsorbent to be utilized in methyl orange (MO) adsorption. Therefore, amino-functionalized three-dimensional graphene networks (3D-GN_f) fulfilling the requirements of reusability and high capacity have been fabricated via hydrothermal self-assembly approach followed by a double-crosslinking strategy. The potential utilization of 3D-GN_f as an adsorbent for removal MO has been assessed using both batch-adsorption studies and an artificial neural network (ANN) approach. Graphene oxide sheets have been amino-functionalized and cross-linked, by ethylenediamine (EDA) during hydrothermal treatment, following the glutaraldehyde has used as a double-crosslinking agent to facilitate the crosslinking of architecture. The successful fabrication of 3D-GN_f has been confirmed by field-emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR), Raman and X-ray photoelectron spectroscopy (XPS). Moreover, N₂ adsorption/desorption isotherms have revealed the high specific surface area (1015 m² g^-1) with high pore volume (1.054 cm³ g^-1) and hierarchical porous structure of 3D-GN_f. The effect of initial concentration, contact time, and temperature on adsorption capacity have been thoroughly studied, and the kinetics, isotherms, and thermodynamics of MO adsorption have been modelled. The MO adsorption has been well defined by the pseudo-second-order kinetic model and Langmuir isotherm model with a monolayer adsorption capacity of 270.27 mg g^-1 at 25 °C. The thermodynamic findings have revealed MO adsorption has occurred spontaneously with an endothermic process. The Levenberg-Marquardt backpropagation algorithm has been implemented to train the ANN model, which has used the activation functions of tansig and purelin functions at the hidden and output layers, respectively. An optimum ANN model with high-performance metrics (coefficient of determination, R² = 0.9995; mean squared error, MSE = 0.0008) composed of three hidden layers with 5 neurons in each layer was constructed to forecast MO adsorption. The findings have shown that experimental results are consistent with ANN-based data, implying that the suggested ANN model may be used to forecast cationic dye adsorption.

Solvothermal synthesis of 3D hierarchical Cu2FeSnS4 microspheres for photocatalytic degradation of organic pollutants

In this work, we prepared Cu₂FeSnS₄ (CFTS) microspheres via solvothermal method and studied their photocatalytic performance towards the degradation of organic pollutants. With increasing solvothermal temperature from 160 °C to 180 °C, the morphology of CFTS changes from irregular 2D to hierarchical 3D shapes. Hierarchical 3D CFTS microspheres packed with 2D nanosheets were successfully prepared at 180 °C. During the solvothermal process, octadecyl amine (ODA) acts as a capping agent to prevent the aggregation of particles, while L-cystine functions as an environmentally friendly sulfur source and complexing reagent. The large surface area and mesoporous structure of the as-prepared 3D hierarchical CFTS microspheres provide more active sites, enhance visible light absorption and promote charge separation and transfer, leading to the improved photodegradation performance for RhB and MB compared to the samples prepared at the temperature lower than 180 °C. This work provides a simple and low-cost method for the synthesis of 3D hierarchical CFTS towards photocatalytic applications.

Multi-object optimization of Navy-blue anodic oxidation via response surface models assisted with statistical and machine learning techniques

This study aims to model, analyze, and compare the electrochemical removal of Navy-blue dye (NB, %) and subsequent energy consumption (EC, Wh) using the integrated response surface modelling and optimization approaches. The Box-Behnken experimental design was exercised using current density, electrolyte concentration, pH and oxidation time as inputs, while NB removal and EC were recorded as responses for the implementation and analysis of multiple linear regression, support vector regression and artificial neural network models. The dual-response optimization using genetic algorithm generated multi-Pareto solutions for maximized NB removal at minimum energy cost, which were further ranked by employing the desirability function approach. The optimal parametric solution having total desirability of 0.804 is found when pH, current density, Na₂SO₄ concentration and electrolysis time were 6.4, 11.89 mA cm^-2, 0.055 M and 21.5 min, respectively. At these conditions, NB degradation and EC were 83.23% and 3.64 Wh, respectively. Sensitivity analyses revealed the influential patterns of variables on simultaneous optimization of NB removal and EC to be current density followed by treatment time and finally supporting electrolyte concentration. Statistical metrics of modeling and validation confirmed the accuracy of artificial neural network model followed by support vector regression and multiple linear regression anlaysis. The results revealed that statistical and computational modeling is an effective approach for the optimization of process variables of an electrochemical degradation process.

Valorization of spent brewery yeast biosorbent with sonication-assisted adsorption for dye removal in wastewater treatment

The effluent of textile industries containing synthetic dyes contributed to substantial pollution to water bodies. The biosorption process of Congo Red dye was successfully performed by integrating ultrasonication in the adsorption step with spent brewery yeast as a novel and renewable biosorbent. The adsorption process was hindered when ultrasonication was employed together with the biosorbent, indicating that desorption process had occurred. The adsorption process showed that 4 g/L of biosorbent was the optimum dosage for adsorption of 50 mg/L of Congo Red dye, and that the adsorption equilibrium fitted to the Langmuir model, with kinetics best fitted with pseudo-second order model. The maximum capacity of the adsorption was 52.6 mg/g, showing the potential of spent brewery yeast to aid in removing wastewater pollutants. Maximal Congo Red dye recovery (100%) was achieved in the sonication-assisted desorption studies using 0.01M NaOH as the eluting agent. The ultrasonication effects contributed to the efficient recovery of dye and good conversion of spent brewery yeast to biosorbent can be beneficial for treating pollution from textile wastewater.

Environmental impacts of hazardous waste, and management strategies to reconcile circular economy and eco-sustainability

The rise in living standards and the continuous development in the global economy led to the depletion of resources and increased waste generation per capita. This waste might posture a significant threat to human health or the environmental matrices (water, air, soil) when inadequately treated, transported, stored, or managed/disposed of. Therefore, effective waste management in an economically viable and environmentally friendly way has become meaningful. Prominent technology is the need of the day for circular economy and sustainable development to reduce the speed of depletion in resources and produce an alternative means for the future demands in the different sectors of science and technology. In order to meet the potential requirements for energy production or producing secondary raw material, solid waste may be the prime source. The activities of living organisms convert waste products in one form or another in which electronic waste (e-waste) is a modern-day problem that is growing by leaps and bounds. The disposal protocols of the e-waste management need to be given proper attention to avoid its hazardous impacts. The e-waste is obtained from any equipment or devices that run by electricity or batteries like laptops, palmtops, computers, televisions, mobile phones, digital video discs (DVD), and many more. E-waste is one of the rapidly growing causes of world pollution today. Plenty of research is available in the scientific literature, which shows different approaches being set up and followed to manage and dispose of waste products. These strategies to manage waste products designed by the states all over the globe revolves around minimal production, authentic techniques for the management of waste produced, reuse and recycling, etc. The virtual survey of the available literature on waste management shows that it lacks specificity regarding the management of waste products parallel to ecological sustainability. The presented review covers the sources, potential environmental impacts, and highlights the importance of waste management strategies to provide the latest and updated knowledge. The review also put forward the countermeasures that need to be taken on national and International levels addressing the sensitive issue of waste management.

The state of art on the prediction of efficiency and modeling of the processes of pollutants removal based on machine learning

During the last few years, important advances have been made in big data exploration, complex pattern recognition and prediction of complex variables. Machine learning (ML) algorithms can efficiently analyze voluminous data, identify complex patterns and extract conclusions. In chemical engineering, the application of machine learning approaches has become highly attractive due to the growing complexity of this field. Machine learning allows computers to solve problems by learning from large data sets and provides researchers with an excellent opportunity to enhance the quality of predictions for the output variables of a chemical process. Its performance has been increasingly exploited to overcome a wide range of challenges in chemistry and chemical engineering, including improving computational chemistry, planning materials synthesis and modeling pollutant removal processes. In this review, we introduce this discipline in terms of its accessible to chemistry and highlight studies that illustrate in-depth the exploitation of machine learning. The main aim of the review paper is to answer these questions by analyzing physicochemical processes that exploit machine learning in organic and inorganic pollutants removal. In general, the purpose of this review is both to provide a summary of research related to the removal of various contaminants performed by ML models and to present future research needs in ML for contaminant removal.

Highly Efficient and Sustainable ZnO/CuO/g-C3N4 Photocatalyst for Wastewater Treatment under Visible Light through Heterojunction Development

Dye-containing pollutants are currently a threat to the environment, and it is highly challenging to eliminate these dyes photocatalytically under visible light. Herein, we designed and prepared a ZnO/CuO/g-C3N4 (ZCG) heterostructure nanocomposite by a co-crystallization procedure and applied it to eliminate pollutants from wastewater via a photocatalytic scheme. The structural and morphological features of the composite confirmed the formation of a ZCG nanocomposite. The photocatalytic capability of the ZCG photocatalyst was investigated via the decomposition of methylene blue dye. The outstanding activity level of 97.46% was reached within 50 min. In addition, the proficiency of the ZCG composite was 753%, 392%, 156%, and 130% higher than photolysis, g-C3N4, CuO, and ZnO, respectively. Furthermore, the photodeterioration activity on Congo red was also evaluated and found to be excellent. The enhanced catalytic achievement is attributed to the construction of heterojunctions among the constituent compounds. These properties boost the charge transfer and decrease the recombination rate. Moreover, the reusability of the ZCG product was explored and a negligible photoactivity decline was detected after six successful runs. The outcomes suggest the as-prepared nanocomposite can be applied to remove pollutants, which opens a new door to practical implementation.

Efficient adsorption of methylene blue on carboxylate-rich hydrochar prepared by one-step hydrothermal carbonization of bamboo and acrylic acid with ammonium persulphate

Hydrochar (AAHC) with rich carboxylate groups was prepared by one-step hydrothermal carbonization (HTC) of bamboo and acrylic acid with the presence of ammonium persulphate, and then activated by a sodium hydroxide solution. AAHC was featured by elemental analysis, SEM, XPS, FTIR, Zeta potential analysis and N₂ adsorption-desorption isotherms, and applied to test adsorptive ability of methylene blue (MB) by batch sorption experiments. Despite a small Brunauer-Emmett-Teller (BET) surface area of 5.03 m²·g^-1, AAHC has excellent MB adsorbing capacity owing to the richness of carboxylate groups. Compared with hydrochar produced without adding ammonium persulphate, AAHC exhibits larger BET surface, pore volume and carboxylate groups, indicating a small amount of ammonium persulfate plays an important role in HTC in addition to the free radical initiator. This work provides a facile and cheap method combining HTC and polymerization for preparation of carboxylate-rich hydrochar.

Separation and remediation of environmental pollutants using metal-organic framework-based tailored materials

Metal-organic frameworks (MOFs) are a polymer hybrid family of compounds comprising metal ions that have been deliberately incorporated in organic ligands to form several multi-dimensional structures with unique structural and functional attributes. They have the typical properties of brittleness, major porosity, and randomly crystalline. These three factors hampered their potential incorporation into modern technologies. However, with the discovery of their polymers, hope was rekindled. Polymers, unlike their counterparts, are versatile and malleable and can be tailored into solids with a wide range of technical applications. MOFs can be effectively incorporated into polymer structures, resulting in polymers with enhanced properties and increased demand, according to recent studies. This review focuses on the synthetic procedures of MOFs used to create hybrid materials, as well as their potential environmentally related applications. Desalination, hazardous heavy metal removal and mitigation, gas and liquid separations and purifications, and dye removal will all be extensively discussed as applications. To assemble this review, we will add insight from recent papers and discoveries, as well as seminal reports from experts on the advancement of MOF-polymers.

Preparation and applications of chitosan and cellulose composite materials

Chitosan is a natural fiber, chemically cellulose-like biopolymer, which is processed from chitin. Its use as a natural polymer is getting more attention because it is non-toxic, renewable, and biocompatible. However, its poor mechanical and thermal strength, particle size, and surface area restrict its industrial use. Consequently, to improve these properties, cellulose and/or inorganic nanoparticles have been used. This review discusses the recent progress of chitosan and cellulose composite materials, their preparation, and their applications in different industrial sectors. It also discusses the modification of chitosan and cellulose composite materials to allow their use on a large scale. Finally, the recent development of chitosan composite materials for drug delivery, food packaging, protective coatings, and wastewater treatment are discussed. The challenges and perspectives for future research are also considered. This review suggests that chitosan and cellulose nano-composite are promising, low-cost products for environmental remediation involving a simple production process.

Adsorptive remediation of environmental pollutants using magnetic hybrid materials as platform adsorbents

Effective separation and remediation of environmentally hazardous pollutants are burning areas of research because of a constant increase in environmental pollution problems. An extensive number of emerging contaminants in the environmental matrices result in serious health consequences in animals, humans, and plants, even at trace levels. Therefore, it is of paramount significance to quantify these undesirable pollutants, even at a very low concentration, from the natural environment. Magnetic solid-phase extraction (MSPE) has recently achieved huge attention because of its strong magnetic domain and easy separation through an external magnetic field compared with simple solid-phase extraction. Therefore, MSPE appeared the most promising technique for removing and pre-concentration of emerging pollutants at trace level. Compared to the normal solid-phase extraction, MSPE as magnetic hybrid adsorbents offers the unique advantages of distinct nanomaterials and magnetic hybrid materials. It can exhibit efficient dispersion and rapid recycling when applying to a very complex matrix. This review highlights the possible environmental applications of magnetic hybrid nanoscale materials as effective MSPE sorbents to remediate a diverse range of environmentally toxic pollutants. We believe this study tends to evoke a variety of research thrust that may lead to novel remediation approaches in the forthcoming years.