Highly efficient Sr/Ce/activated carbon bimetallic nanocomposite for photoinduced degradation of rhodamine B

Enhanced photocatalytic degradation of Rhodamine B using polyaniline-coated XTiO3(X = Co, Ni) nanocomposites

In this study, novel polyaniline-coated perovskite nanocomposites (PANI@CoTiO3 and PANI@NiTiO3) were synthesized using an in situ oxidative polymerization method and evaluated for the photocatalytic degradation of Rhodamine B (RhB) a persistent organic pollutant. The nanocomposites displayed significantly enhanced photocatalytic efficiency compared to pure perovskites. The 1%wt PANI@NiTiO3 achieved an impressive 94% degradation of RhB under visible light after 180 min, while 1wt.% PANI@CoTiO3 reached 87% degradation under UV light in the same duration. X-ray diffraction (XRD) confirmed that the crystalline structures of CoTiO3 and NiTiO3 remained intact post-polymerization. At the same time, Fourier transform infrared spectroscopy (FTIR) verified the successful deposition of PANI through characteristic functional group vibrations. Diffuse reflectance spectroscopy (DRS) revealed reduced band gaps of 2.63 eV for 1wt.% PANI@NiTiO3 and 2.46 eV for 1wt.% PANI@CoTiO3, enhancing light absorption across UV and visible ranges. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis demonstrated the uniform distribution of PANI, ensuring consistent surface activity and efficient charge transfer. The photocatalytic test confirmed a pseudo-first-order degradation mechanism. The study elucidates the degradation mechanism through intermediate identification via HPLC-MS analysis, highlighting N-de-ethylation, aromatic ring cleavage and eventual mineralization into CO2 and H2O as critical pathways. Furthermore, the 1wt.%PANI@NiTiO3 nanocomposite demonstrated excellent stability and recyclability, maintaining its degradation efficiency over four consecutive cycles with minimal change. These findings highlight the potential of PANI@XTiO3 nanocomposites for sustainable and efficient wastewater treatment, addressing diverse environmental challenges by tailoring photocatalysts to specific light sources.

Synthesis of vanillin via oxidation of kenaf stalks in the presence of CeO2: tuning the catalytic behaviour of CeO2 via nanostructure morphology

Different CeO2 nanostructures were synthesized using a hydrothermal method and treated with alkaline NaOH, followed by drying at 120 °C for 16 h and calcined at 400 °C for the direct oxidation of kenaf stalks to vanillin under microwave irradiation. The catalysts were characterized for their physicochemical properties using XRD, BET, Raman spectroscopy, TPR, TPO, and XPS. All synthesized CeO2 nanostructures show diffraction peaks corresponding to the formation of cubic fluorite, which agrees with Raman spectra of the F2g mode. The N2 adsorption-desorption isotherms showed that all catalysts possess a type IV isotherm, indicating a mesoporous structure. TPR and TPO analyses display formation peaks corresponding to surface-to-bulk reducibility and the oxidized oxygen ratio, which is responsible for the redox properties of ceria nanostructures. The XPS analysis of CeO2 nanostructures proved that Ce exists in the Ce3+ and Ce4+ oxidation states. All catalysts were tested for direct oxidation of kenaf stalks under microwave irradiation with the highest vanillin yield obtained by the CeO2-Nps-400 heterogeneous catalyst at 3.84%, whereas 4.66% vanillin was produced using 2 N NaOH as a homogeneous catalyst.

Fabrication of bio-inorganic metal nanoparticles by low-cost lychee extract for wastewater remediation: a mini-review

INTRODUCTION

This review article gives an overview of the biogenic synthesis of metal nanoparticles (mNPs) while using Litchi chinensis extract as a reducing and stabilizing agent. The subtropical fruit tree i.e lychee contains phytochemicals such as flavonoids, terpenoids, and polyphenolic compounds which act as reducing agents and convert the metal ions into metal atoms that coagulate to form mNPs.

METHODOLOGY

Different methodologies adopted for the synthesis of lychee extract and its use in the fabrication of mNPs under different reaction conditions such as solvent, extract amount, temperature, and pH of the medium have also been discussed critically in detail.

TECHNIQUES

Different techniques such as FTIR, UV-visible, XRD, SEM, EDX, and TEM adopted for the analysis of biogenic synthesis of mNPs have also been discussed in detail. Applications of mNPs: Applications of these prepared mNPs in various fields due to their antimicrobial, antiinflammatory, anticancer, and catalytic activities have also been described in detail.

A waste-to-wealth conversion of plastic bottles into effective carbon-based adsorbents for removal of tetracycline antibiotic from water

Currently, plastic waste and antibiotic wastewater are two of the most critical environmental problems, calling for urgent measures to take. A waste-to-wealth strategy for the conversion of polyethylene terephthalate (PET) plastic bottles into value-added materials such as carbon composite is highly recommended to clean wastewater contaminated by antibiotics. Inspired by this idea, we develop a novel PET-AC-ZFO composite by incorporating PET plastic-derived KOH-activated carbon (AC) with ZnFe2O4 (ZFO) particles for adsorptive removal of tetracycline (TTC). PET-derived carbon (PET-C), KOH-activated PET-derived carbon (PET-AC), and PET-AC-ZFO were characterized using physicochemical analyses. Central composite design (CCD) was used to obtain a quadratic model by TTC concentration (K), adsorbent dosage (L), and pH (M). PET-AC-ZFO possessed micropores (d ≈ 2 nm) and exceptionally high surface area of 1110 m2 g-1. Nearly 90% TTC could be removed by PET-AC-ZFO composite. Bangham kinetic and Langmuir isotherm were two most fitted models. Theoretical maximum TTC adsorption capacity was 45.1 mg g-1. This study suggested the role of hydrogen bonds, pore-filling interactions, and π-π interactions as the main interactions of the adsorption process. Thus, a strategy for conversion of PET bottles into PET-AC-ZFO can contribute to both plastic recycling and antibiotic wastewater mitigation.

Synthesis of CuO, ZnO nanoparticles, and CuO-ZnO nanocomposite for enhanced photocatalytic degradation of Rhodamine B: a comparative study

Water pollution, arising from the presence of toxic dyes and chemicals, is a global challenge, urging the need for eco-friendly solutions in water decontamination. This study focused on the synthesis of copper oxide nanoparticles (CuO NPs), zinc oxide nanoparticles (ZnO NPs), and a bimetallic CuO-ZnO nanocomposite (CZ NC) through an environmentally friendly method employing Tragia involucrata L. leaf extract. Comprehensive analysis of structural and optical properties involved using various analytical techniques such as XRD, FT-IR, XPS, UV-DRS, PL, FE-SEM, EDAX, TEM, SAED, zeta potential, TGA, and BET. In comparison to pristine CuO and ZnO NPs, the CZ-NC demonstrated notably enhanced photocatalytic activity in the degradation of Rhodamine B dye (RhB). The optimum conditions for RhB degradation were found to be a pH of 9 and a catalyst dosage of 1 mg/mL for a concentration of 10 ppm. Under these conditions, CuO NPs, ZnO NPs, and CZ-NC demonstrated high efficiencies of 78%, 83%, and 96.1% respectively over 105 min. Through LC-HRMS, the identification of degradation products offered valuable insights into the pathway of photocatalytic degradation. Furthermore, toxicity analysis of intermediates, conducted through ECOSAR software, indicated the formation of non-toxic by-products (ChV/LC50/EC50 > 100) after the completion of the reaction. Furthermore, the recycled catalysts exhibited sustained stability for up to 4 cycles, with only a minor decrease in activity of up to 6.8%. This confirms their catalytic efficacy in purifying polluted water. This research significantly contributes to the progress of environmentally friendly nanocomposites, enhancing their efficacy in the realm of environmental remediation.

Construction of magnetic MoS2/NiFe2O4/MIL-101(Fe) hybrid nanostructures for separation of dyes and antibiotics from aqueous media

In this study, MoS2/NiFe2O4/MIL-101(Fe) nanocomposite was synthesized by hydrothermal method and used as an adsorbent for the elimination of organic dyes and some antibiotic drugs in aqueous solutions. The synthesized nanocomposite underwent characterization through different techniques, including scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) surface area analysis, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), zeta potential analysis, vibrating sample magnetometry (VSM), and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). These results demonstrated the successful insertion of MoS2within the cavities of MIL-101(Fe). The as-prepared magnetic nanocomposite was used as a new magnetic adsorbent for removing methylene blue (MB) and rhodamine B (RhB) organic dyes and tetracycline (TC) and ciprofloxacin (CIP) antibiotic drugs. For achieving the optimized conditions, the effects of initial pH, initial dye and drug concentration, temperature, and adsorbent dose on MB, TC, and CIP elimination were investigated. The results revealed that at a temperature of 25 °C, the highest adsorption capacities of MoS2/NiFe2O4/MIL-101(Fe) for MB, TC, and CIP were determined to be 999.1, 2991.3, and 1994.2 mg g-1, respectively. The pseudo-second-order model and Freundlich model are considered suitable for explaining the adsorption behavior of the MoS2/NiFe2O4/MIL-101(Fe) nanocomposite. The magnetic nanocomposite was very stable and had good recycling capability without any change in its structure.

Transition-state defect structure: A new strategy for TiO2-based porous materials to enhance photodegradation of pollutants

The aim of this paper is to investigate the derived structure and properties of Zeolitic Imidazolate Framework-8 (ZIF-8), and the effect of residual structural on the catalytic properties after loading with Titanium Dioxide (TiO2). For this purpose, we ingeniously prepare C-ZIF-8@TiO2 with a transition-state defect structure and apply it for efficiently degrading organic dye wastewater represented by Rhodamine B (Rh-B). Thanks to the transition-state defect structure loaded with TiO2 and ZIF-8 self-derived Carbon (C) and Zinc Oxide (ZnO), the catalytic performance of C-ZIF-8@TiO2 is superior to that of TiO2 and normal TiO2/ZIF-8 composites, and it is effective in degrading a variety of antibiotics and dyes. The related characterization also shows good photovoltaic properties and long-term durability for C-ZIF-8@TiO2. The mechanism on free radical action is elucidated and the possible degradation pathway for Rh-B is speculated. Therefore, C-ZIF-8@TiO2 provides a new strategy for the degradation of organic pollutants in water bodies.

Ce/N @BC prepared based on plant metallurgy strategy: A novel activator of peroxymonosulfate for the degradation of sulfamethoxazole

A novel carbon catalyst was created based on plant metallurgy strategy for organic pollutants removal. Plants rich in CeO2 NPs in water were used as carbon precursors and pyrolyzed with urea to obtain Ce/N co-doped carbon catalysts, which were used in the degradation of sulfamethoxazole (SMX) by active peroxymonosulfate (PMS). The results showed that the Ce/N @BC/PMS system achieved to 94.5% degradation of SMX in 40 min at a rate constant of 0.0602 cm-1. The activation center of PMS is widely dispersed Ce oxide nanocrystals, and CeO2 NPs promote the formation of oxygen centered PFR with enhanced catalytic ability and longer half-life. In addition, N-doping facilitates the transfer of π-electrons within the sp2 carbon of biochar, increasing active sites and thus improving PMS activation efficiency. The degradation process was contributed to by both radical and non-radical activation mechanisms including 1O2 and direct electron transfer, with O2•- serving as 1O2's precursor. Through the DFT calculations, LC-MS and toxicological analyses, the degradation pathway of pollutants and the toxicity changes throughout the entire degradation process were further revealed, indicating that the degradation of SMX could effectively reduce ecological toxicity.

Fabrication of nano-sized Pd catalyst supported on sodium carboxymethyl cellulose/gum Arabic/sodium alginate functionalized microspheres for catalytic reduction of nitro compounds, organic dyes, K3[Fe(CN)6], and chromium(VI) pollutants

The rapid development of industrialization and urbanization, along with the increasing human population, has led to serious water pollution. Among water pollutants, organic and inorganic pollutants cause serious problems for both the environment and human health due to their toxicity and carcinogenic properties. One of the best ways to eliminate these pollutants is to develop eco-friendly, efficient, and long-life catalysts. For this purpose, in this study, environmentally friendly microspheres containing sodium alginate (SA), sodium carboxymethyl cellulose (Na-CMC), and gum Arabic (GA) were fabricated as potential stabilizers (SA/Na-CMC/GA). Subsequently, newly heterogeneous catalyst system was designed by immobilizing Pd nanoparticles on them and characterized (Pd@SA/Na-CMC/GA). The catalytic reduction ability of Pd@SA/Na-CMC/GA was then investigated against the reduction of 4-nitroaniline (4-NA), 4-nitrophenol (4-NP), 2-nitroaniline (2-NA), 4-nitro-o-phenylenediamine (4-NPDA), methylene blue (MB), methyl orange (MO), Rodamin B (RhB), potassium hexacyanoferrate(III) (K3[Fe(CN)6]), and hexavalent chromium (Cr(VI)) using NaBH4. The Pd@SA/Na-CMC/GA effectively catalyzed these contaminants in a short period of time under mild reaction conditions. As a result of the performed kinetics studies, rate constants were found to be 0.009 s-1, 0.016 s-1, 0.027 s-1, 0.018 s-1, 0.043 s-1, 0.058 s-1, 0.038 s-1 and 0.041 s-1 for the reduction of 4-NP, 2-NA, 4-NA, 4-NPDA, MO, RhB, K3[Fe(CN)6], and Cr(VI), respectively. Additionally, MO was immediately reduced by Pd@SA/Na-CMC/GA. The microsphere nature of Pd@SA/Na-CMC/GA allowed for easy recovery through simple filtration and successful reuse for up to six cycles.

Pd:In-Doped TiO2 as a Bifunctional Catalyst for the Photoelectrochemical Oxidation of Paracetamol and Simultaneous Green Hydrogen Production

The integration of clean energy generation with wastewater treatment holds promise for addressing both environmental and energy concerns. Focusing on photocatalytic hydrogen production and wastewater treatment, this study introduces PdIn/TiO2 catalysts for the simultaneous removal of the pharmaceutical contaminant paracetamol (PTM) and hydrogen production. Physicochemical characterization showed a high distribution of Pd and In on the support as well as a high interaction with it. The Pd and In deposition enhance the light absorption capability and significantly improve the hydrogen evolution reaction (HER) in the absence and presence of paracetamol compared to TiO2. On the other hand, the photoelectroxidation of PTM at TiO2 and PdIn/TiO2 follows the full mineralization path and, accordingly, is limited by the adsorption of intermediate species on the electrode surface. Thus, PdIn-doped TiO2 stands out as a promising photoelectrocatalyst, showcasing enhanced physicochemical properties and superior photoelectrocatalytic performance. This underscores its potential for both environmental remediation and sustainable hydrogen production.

Remediation of organic pollutant from the aqueous environment using in-house fabricated polyaniline-based hybrid composite (PANI-MnPBA/NiCoMnS) materials

Polyaniline-based hybrid material (PANI-MnPBA/NiCoMnS) was prepared by hydrothermal-solvothermal approach. Synthesized hybrid material was characterized through FTIR-spectroscopy, p-XRD, SEM, EDX, BET, and Zetasizer techniques. Hybrid material as adsorbent for removal of Congo red (CR) from water system showed excellent results such as 98 % removal efficiency and 254 mg/g adsorption capacity. Furthermore, various studies like adsorption isothermal, kinetic, thermodynamic, and statistical analysis were performed to understand the adsorption phenomenon. From various kinetic models, pseudo-first and second-order kinetic models, intra-particle and liquid film diffusion kinetic models, pseudo-first-order kinetic model, and liquid-film diffusion kinetic model both are most suitable for explaining the adsorption phenomenon due to the greater value of R2 (0.955) for CR. According to these kinetic models, physio-sorption and diffusion play a basic role in the adsorption of CR. Moreover, ΔG (-1779.508 kJ mol-1) and ΔH (61,760.889 kJ mol-1) values explained the spontaneous and exothermic nature of the adsorption process, respectively. Furthermore, for support of the adsorption mechanism via electrostatic attractions before and after the adsorption process FTIR results of as-synthesized adsorbent were measured (NH peaks before 3668.88, after 3541.41 cm-1). These results confirm electrostatic attraction for the adsorption process. Finally, the statistical model was added (n < 1), according to this model, adsorption follows a multi-anchorage approach and adsorbent contains enough sites for adsorption of CR.

Improved photocatalytic degradation of rhodamine B by g-C3N4 loaded BiVO4 nanocomposites

Photocatalytic degradation has emerged as one of the most efficient methods to eliminate toxic dyes from wastewater. In this context, graphitic nitride (g-C3N4) loaded BiVO4 nanocomposites (5 wt% g-CN@BiVO4 and 10 wt% g-CN@BiVO4) have been fabricated by the wet impregnation method, and their efficiency towards photocatalytic removal of rhodamine B have been investigated under visible light irradiation. These hybrid composites have been characterized by XRD, FESEM, HRTEM, EDS-mapping, UV-Vis DRS, DLS, XPS and BET, etc. The HRTEM images revealed that BiVO4 has a decagonal shape covered by a layered nanosheet-like structure of g-C3N4. BET measurements suggest increasing the proportion of g-C3N4 results enhancement of the specific surface area. Among different photocatalysts, the 10 wt% g-C3N4@BiVO4 hybrid possesses the best catalytic activity with 86% degradation efficiency after 60 min of reaction time. The LC-MS studies suggest that the degradation reactions follow the de-ethylation pathway. Even after five cycles, the heterostructure shows only a 14% decrease in photocatalytic activity, confirming its stability. As a result, the binary composite can be regarded as a promising catalyst for the degradation of pollutants due to its ease of preparation, high stability and superior catalytic activity.

Hybrid Polymer-Silica Nanostructured Materials for Environmental Remediation

Due to the ever-growing global population, it is necessary to develop highly effective processes that minimize the impact of human activities and consumption on the environment. The levels of organic and inorganic contaminants have rapidly increased in recent years, posing a threat to ecosystems. Removing these toxic pollutants from the environment is a challenging task that requires physical, chemical, and biological methods. An effective solution involves the use of novel engineered materials, such as silica-based nanostructured materials, which exhibit a high removal capacity for various pollutants. The starting materials are also thermally and mechanically stable, allowing for easy design and development at the nanoscale through versatile functionalization procedures, enabling their effective use in pollutant capture. However, improvements concerning mechanical properties or applicability for repeated cycles may be required to refine their structural features. This review focuses on hybrid/composite polymer-silica nanostructured materials. The state of the art in nanomaterial synthesis, different techniques of functionalization, and polymer grafting are described. Furthermore, it explores the application of polymer-modified nanostructured materials for the capture of heavy metals, dyes, hydrocarbons and petroleum derivatives, drugs, and other organic compounds. The paper concludes by offering recommendations for future research aimed at advancing the application of polymer-silica nanostructured materials in the efficiency of pollutant uptake.

Efficient activation of peroxymonosulfate via Cu2+/Cu+ cycle enhanced by hydroxylamine for the degradation of Rhodamine B

The application of Cu²⁺/peroxymonosulfate (PMS) process for the elimination of refractory pollutants in industrial wastewater is limited by the slow transformation from Cu²⁺ to Cu⁺. In this research, hydroxylamine (HA) was employed to improve the degradation capacity of the Cu²⁺/PMS process. Rhodamine B (RhB) was selected as the target compound to indicate the performance of HA/Cu²⁺/PMS process. Compared with the Cu²⁺/PMS process, the reduction of Cu²⁺ to Cu⁺ was effectively promoted by HA in the HA/Cu²⁺/PMS process, which increased the decomposition rate of PMS by 29.2%, correspondingly, promoted the removal rate of RhB by 77.6%. The degradation of RhB followed pseudo-second-order kinetics in the proposed process. The active species analysis subsequently indicated hydroxyl radicals (·OH) and sulfate radicals (SO₄·^-) played important roles for degrading RhB with ·OH as the dominant active radical. The effects including initial pH, RhB concentration, PMS concentration, and Cu²⁺ concentration on the degradation of RhB were further investigated and discussed in detail. Additionally, the HA/Cu²⁺/PMS process exhibited effective RhB removal in simulated wastewater. From the perspective of waste utilization (Cu²⁺) and the remediation of organic contamination, the work would provide a valuable and promising process.

Excellent photocatalytic and antibacterial activities of bio-activated carbon decorated magnesium oxide nanoparticles

Green production of nanomaterials are restrict toxic substances and motivated the noxious free environment. Photocatalysis and antibacterial resistance are more promising and efficient fields for their chemical reductants and clean environment. Herein, we adopted a green and simple method for the biosynthesis of MgO NPs using Manilkara zapota as a bio source. Recently, the green synthesis of magnesium oxide nanoparticles has been a keen interest amongst researchers and scientists due to its simplicity eco-friendliness, non-toxic, inexpensive and potential to perform as an antibacterial agent. Activated carbon/Magnesium oxide (AC/MgO) photocatalyst was blended through a simple solution evaporation method. The surface electron microscopy (SEM) study reviles that AC/MgO had smooth and aggregated particles. The Fourier transform infrared (FT-IR) and x-ray diffraction (XRD) study confirms the structural formation and incorporation of nanoparticles into the AC matrix. Results confirmed the flourishing integration of MgO NPs over the activated carbon matrix. The electron movement and valency of AC/MgO photocatalyst reduced the bandgap and their findings were characterized by ultra visible diffuse reflectance spectroscopy (UV-DRS) and x-ray photoelectron spectroscopy (XPS). The blended AC/MgO photocatalyst was analyzed for photodegradation of Rhodamine- B (Rh-B) dye using a UV-visible spectrophotometer. The degradation study projects that the AC/MgO photocatalyst degrades (Rh-B) dye with 99% efficiency under simulated solar irradiation. This efficient degradation of (Rh-B) dye by AC/MgO photocatalyst is ascribed to the synergetic AC as catalytic support and adsorbent and MgO as photocatalyst. Finally, the photocatalytic material shows a better bactericidal effect in both gram-positive bacteria Escherichia coli-745 and gram-negative bacteria Staphylococcus aureus-9779. The AC/MgO photocatalyst is effectively used in bacteriocidal and photocatalytic removal of dyes and can be used for further development of water reuse and bio-medical fields. In addition, this research shows a viable method for synthesizing a cheap and effective AC/MgO for the photocatalytic destruction of organic pollutants.

Efficient Degradation of Congo Red in Water by UV-Vis Driven CoMoO4/PDS Photo-Fenton System

In order to improve the catalytic activity of cobalt molybdate (CoMoO₄), a PDS-activated and UV-vis assisted system was constructed. CoMoO₄ was prepared by coprecipitation and calcination, and characterized by XRD, FTIR, Raman, SEM, TEM, XPS, TGA Zeta potential, BET, and UV-Vis DRS. The results showed that the morphology of the CoMoO₄ nanolumps consisted of stacked nanosheets. XRD indicated the monoclinic structures with C2/m (C³_2h, #12) space group, which belong to α-CoMoO₄, and both Co²⁺ and Mo⁶⁺ ions occupy distorted octahedral sites. The pH of the isoelectric point (pHIEP) of CMO-8 at pH = 4.88 and the band gap of CoMoO₄ was 1.92 eV. The catalytic activity of CoMoO₄ was evaluated by photo-Fenton degradation of Congo red (CR). The catalytic performance was affected by calcination temperature, catalyst dosage, PDS dosage, and pH. Under the best conditions (0.8 g/L CMO-8, PDS 1 mL), the degradation efficiency of CR was 96.972%. The excellent catalytic activity of CoMoO₄ was attributed to the synergistic effect of photo catalysis and CoMoO₄-activated PDS degradation. The capture experiments and the ESR showed that superoxide radical (·O₂^-), singlet oxygen (¹O₂), hole (h⁺), sulfate (SO₄^-·), and hydroxyl (·OH^-) were the main free radicals leading to the degradation of CR. The results can provide valuable information and support for the design and application of high-efficiency transition metal oxide catalysts.

Efficient degradation of organic pollutants using peroxydisulfate activated by magnetic carbon nanotube

The magnetic composite of Fe₃O₄ and carbon nanotube (MCNT) was fabricated in a facile one-pot solvothermal method and employed to activate peroxydisulfate (PDS) for degradation of Rhodamine B (RhB) and other pollutants. The effects of operational factors including MCNT dosage and PDS dosage were studied, and high removal efficiencies of 84.2-99.5% were achieved for these pollutants with 0.3 g/L MCNT and 4 mM PDS. The effects of environmental factors including initial pH, inorganic cations, inorganic anions, humic acid and water matrix were also studied. Reusability test showed that the removal efficiency declined in four consecutive runs, which was attributed to the adsorbed oxidation products on the catalyst surface. Based on quenching experiments, solvent exchange (H₂O to D₂O), inductively coupled plasma and open circuit potential tests, it was concluded that radicals of ^·OH/SO₄^·- and the non-radical electron-transfer pathway were involved in the MCNT/PDS system, and the contributions of O₂^·-, ¹O₂, high-valent iron-oxo species and homogenous activation were insignificant. Moreover, the orbital-weighted Fukui functions of RhB were calculated by density functional theory, and its plausible degradation pathway was proposed based on the calculation results. Finally, toxicity evaluation of the degradation products was performed in the quantitative structure-activity relationship approach.

Fe-Ti bimetal oxide adsorbent for removing low concentration H2S at room temperature

ABSTRACTHerein, a series of Fe-Ti bimetal oxide adsorbents were prepared by reduction-co-precipitation method, and their performance in removing low concentration H₂S at room temperature was investigated. The adsorbents were characterized by X-Ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Ultraviolet Visible diffuse reflectance spectroscopy (UV-Vis-DRS), X-Ray photoelectron spectroscopy (XPS) and N₂ adsorption-desorption. The results showed that the addition of Ti increased the specific surface area, pore volume and small oligomeric Fe₂O₃ of ferrihydrite. When the Fe/Ti molar ratio was 8:1, Fe-Ti bimetal oxide formed a large amount of oligomeric Fe₂O₃, and its specific surface area and pore volume reached 344.99 m²/g and 0.34 cm³/g, respectively. At this time, Fe-Ti bimetal oxide exhibited the highest breakthrough sulfur capacity of 222.8 mg/g. High temperature calcination caused Fe-Ti bimetal oxide to form small specific surface area and pore volume, and produced crystalline α-Fe₂O₃. And the breakthrough sulfur capacity of Fe-Ti bimetal oxide decreased with the increasing calcination temperature. In addition, the desulfurization process conformed to the unreacted shrinking nucleus model.

Application of visible light active photocatalysis for water contaminants: A review

Organic water pollutants are ubiquitous in the natural environment arising from domestic products as well as current and legacy industrial processes. Many of these organic water pollutants are recalcitrant and only partially degraded using conventional water and wastewater treatment processes. In recent decades, visible light active photocatalyst has gained attention as a non-conventional alternative for the removal of organic pollutants during water treatment, including industrial wastewater and drinking water treatment. This paper reviews the current state of research on the use of visible light active photocatalysts, their modified methods, efficacy, and pilot-scale applications for the degradation of organic pollutants in water supplies and waste streams. Initially, the general mechanism of the visible light active photocatalyst is evaluated, followed by an overview of the major synthesis techniques. Because few of these photocatalysts are commercialized, particular attention was given to summarizing the different types of visible light active photocatalysts developed to the pilot-scale stage for practical application and commercialization. The organic pollutant degradation ability of these visible light active photocatalysts was found to be considerable and in many cases comparable with existing and commercially available advanced oxidation processes. Finally, this review concludes with a summary of current achievements and challenges as well as possible directions for further research. PRACTITIONER POINTS: Visible light active photocatalysis is a promising advanced oxidation process (AOP) for the reduction of organic water pollutants. Various mechanisms of photocatalysis using visible light active materials are identified and discussed. Many recent photocatalysts are synthesized from renewable materials that are more sustainable for applications in the 21st century. Only a small number of pilot-scale applications exist and these are outlined in this review.

Crystal Plane Impact of ZnFe2O4-Ag Nanoparticles Influencing Photocatalytical and Antibacterial Properties: Experimental and Theoretical Studies

This paper describes the crystal interphase impact of ZnFe₂O₄-Ag in the photodegradation of Rhodamine B. Prepared ZnFe₂O₄ nanoparticles (NPs) were deposited with Ag NPs to offer ZnFe₂O₄-Ag (0-2.5%). An X-ray diffraction peak corresponding to the Ag NPs was detected if the particle content reached about 2.0%, observing multiple crystalline interphases in HR-TEM. Magnetic saturation (Ms) was increased ∼160% times for ZnFe₂O₄-Ag (7.25 to 18.71 emu/g) and ZnFe₂O₄ (9.62 to 25.09 emu/g) if the temperature is lowered from 298 to 5.0 K; while for Fe₃O₄ (91.09 to 96.19 emu/g), the Ms increment was just about 5.6%. After analyzing the DFT-Density of State, a decrease of bandgap energy for ZnFe₂O₄-Ag₆ from the influence of the size of Ag cluster was seen. Quantum yield (Φ) was 0.60 for ZnFe₂O₄, 0.25 for ZnFe₂O₄-Ag (1.0%), 0.70 for ZnFe₂O₄-Ag (1.5%), 0.66 for ZnFe₂O₄-Ag (2.0%), and 0.66 for ZnFe₂O₄-Ag (2.5%), showing that the disposition of Ag NPs (1.5-2.5%) increases the Φ to >0.60. The samples were used to photo-oxidize RhB under visible light assisted by photopowered Langmuir adsorption. The degradation follows first-order kinetics (k = 5.5 × 10^-3 min^-1), resulting in a greater k = 2.0 × 10^-3 min^-1 for ZnFe₂O₄-Ag than for ZnFe₂O₄ (or Fe₃O₄, k = 1.1 × 10^-3 min^-1). DFT-total energy was used to analyze the intermediates formed from the RhB oxidation. Finally, the ZnFe₂O₄-Ag exhibits good antibacterial behavior because of the presence of Zn and the Ag components.

Visible-light driven dual heterojunction formed between g-C3N4/BiOCl@MXene-Ti3C2 for the effective degradation of tetracycline

In the present study, we have successfully formulated a dual heterojunction of g-C₃N₄/BiOCl@MXene-Ti₃C₂ (GCBM) which was found to be highly active in the visible region. GCBM was found to be highly efficient for the degradation of an antibiotic, tetracycline (TC) as compared to the individual constituting units; g-C₃N₄ and BiOCl. Maximum of 97% TC degradation rate was obtained within 90 min of visible light irradiation for initial concentration of 10 mg/L of TC. Optical analysis exhibited that the synthesized heterojunction showed high absorption in the complete spectrum. The reactive species specified by the scavenger study showed the major involvement of ^•O₂^- and ^•OH radicals. The charge transfer mechanism showed that 2 schemes were majorly involvement in which Z-scheme was formed between g-C₃N₄ and BiOCl and Schottky junction was formed between g-C₃N₄ and Mxene-Ti₃C₂. The formation of Schottky junction helped in inhibiting the back transfer of photogenerated charges and thus, helped in reducing the recombination rate. The synthesized photocatalyst was found to be highly reusable and was studied for consecutive 5 cycles that generalized the high proficiency even after repetitive cycles.

Green synthesis of silver nanoparticles from plant latex and their antibacterial and photocatalytic studies

The present work describes a facile synthesis of silver nanoparticles from calotropis procera (CP-AgNPs). The CP-AgNPs were well characterized by many methods. The synthesized CP-AgNPs are stable for more than 5 months. Then we have used CP-AgNPs as photo catalysts for the degradation of methyl orange (MO) dye. The photocatalytic degradation efficiency was 0.0076. Moreover, we also have studied the antibacterial activity against pseudomonas aeruginosa (PA), klebsiella pneumonia (KP), staphylococcus aureus (SA) and bacillus subtilis (BS) bacteria. Interestingly, all four different bacteria causing biofilm were inhibited by CP-AgNPs by 80%. To the best of our knowledge, this is the first report for the synthesis of silver nanoparticles from calotropis procera plant latex. Furthermore, CP-AgNPs effectively were applied as photo catalysts for the degradation of MO dye and also as anti-biofilm agents.

Chemically modified sugarcane bagasse-based biocomposites for efficient removal of acid red 1 dye: Kinetics, isotherms, thermodynamics, and desorption studies

Novel eco-friendly and economically favourable chemically modified biosorbents and biosomposites from sugarcane bagasse (SB) has been investigated for the first time for efficient removal of Acid red 1 dye from wastewater. As fabricated biosorbents and biocomposites were characterized analytically. Batch adsorption experiments has been performed to optimize operating parameters and the determined optimum conditions are; pH: 2, dose: 0.05 g, contact time: between 60 and 75 min, initial dye concentration: 400 mg L^-1, and temperature: 30 °C, at which maximum Acid red 1 dye removal capacities were found (within range of 143.4-205.1 mg g^-1) by as-designed SB-derived chemically modified biosorbents and biocomposites. This high adsorption capacity was accompanied due to its large specific surface area (30.19 m² g^-1) and excessive functional active binding sites. In terms of the nature of adsorption process, kinetic and isothermal studies demonstrated that experimental data shows greater fitness with pseudo 2nd order and Langmuir model. Thermodynamics analysis revealed that the adsorption process is spontaneous, feasible, and exothermic in nature. Adsorption selective studies signifies that lower concentration of co-existing metallic ions were not interfered during the removal of Acid red 1 dye, which confirms that under optimized adsorption conditions the biosorbents and biocomposites exhibited greater affinity for dye molecules. The excessive quantity (82%) of loaded dye molecules within the adsorbents were extracted within the NaOH eluting media which predicts that as designed biocomposites could have capability of reusability. Hence, it is anticipated that this type of novel SB-derived biocomposites could be considered as greener potential candidate material for commercial scale dye removal applications from industrial wastewater.

Precipitation of (Mg/Fe-CTAB) - Layered double hydroxide nanoparticles onto sewage sludge for producing novel sorbent to remove Congo red and methylene blue dyes from aqueous environment

Preparation of new sorbent from precipitation of nano-sized (Mg/Fe-CTAB)- layered double hydroxide (LDH) on the surfaces of sewage sludge byproduct to remove the anionic and cationic dyes was the focal point of this work. The presence of nanoparticles and enlarged of interlayers by CTAB intercalation have increased the sludge surface area from 5.34 to 10.32 m²/g. The CTAB mass 0.03 g/50 mL, sludge dosage 1 g/50 mL and (Mg/Fe) molar ratio 2 were the best preparation conditions required to obtain effective sorbent with efficiencies exceeded 93% for MB and CR dyes. These efficiencies were obtained under operational conditions for batch study of 0.5 g coated sludge per 50 mL colored dye solution, initial pH 3 (for CR) and 12 (for MB), and time 3 h for 10 mg/L dyes at 200 rpm. Models of Langmuir and pseudo second-order have a high capability in the representation of sorption records with maximum capacities of adsorption 163.6 and 132.6 mg/g for CR and MB dye, respectively. The X-ray diffraction analysis proved that the calcite occurred mainly at 2θ = 29.8° while quartz corresponded to the 21, 26.6, 36.4, 36.9, 50.1, 60.01 and 68.4°. Characterization tests showed that nano-sized particles of magnesium/iron were precipitated on the sludge due to the formation of hydrotalcite-like compounds with an increase in the percentages of Mg and Fe from 0.87 and 1.36 to 4.25 and 3.03%, respectively. The results showed that the electrostatic attraction, intra-particle diffusion and hydrogen bonding were predominant mechanisms for removal of CR and MB onto coated sludge.

Preparation of magnetic chitosan corn straw biochar and its application in adsorption of amaranth dye in aqueous solution

In this study, the magnetic chitosan biochar (MCB) was magnetized by chemical coprecipitation after loading chitosan with Schiff base reaction. The prepared MCB was used to remove amaranth dye in solution. The synthesized MCB was characterized to define its surface morphology and specific elements. The amaranth dye adsorption system was optimized by varying the contact time, pH, and initial concentration. The adsorption of MCB on amaranth dye was measured in a wide pH range. According to Zeta potential, the surface of MCB was positively charged in the acidic pH region, which was more conducive to the adsorption of anionic amaranth dye. In addition, the adsorption data was fitted with the pseudo-first-order model and Langmuir adsorption model and the maximum adsorption capacity reached 404.18 mg/g. The adsorption efficiency of MCB was still above 95% after three cycles of adsorption and desorption. The removal percentage in the real sample of amaranth dye by MCB was within 94.5-98.6% and the RSD was within 0.14-1.08%. The MCB adsorbent with advantages of being easy to prepare, easy to separate from solution after adsorption, has good adsorption performance for amaranth dye and is effective potential adsorbent to remove organic anionic dye in wastewater.

MXene quantum dots decorated Ni nanoflowers for efficient Cr (VI) reduction

Nickel@MXene quantum dots (Ni@MQDs), as novel flower-like hybrid materials, were firstly prepared through a simple reduction method. The Ni@MQDs exhibited an outstanding catalytic performance for Cr (VI) reduction with a low activation energy (E_a = 18.9 kJ mol^-1) and a high kinetic constant (k = 0.4779 min^-1) in the presence of formic acid (HCOOH). Density functional theory calculations demonstrated that Ni@MQDs exhibited an upshift of d-band center of active Ni atoms to promote the adsorption of both HCOOH and active H atoms, as well as an improved conductivity to boost the catalytic reaction kinetics, leading to the most favorable catalytic performance. This work may open up a new avenue towards the design and synthesis of novel MQDs-based hybrid catalysts for wastewater treatment.

Fabrication of biochar-based hybrid Ag nanocomposite from algal biomass waste for toxic dye-laden wastewater treatment

Dual functional innovative approaches were developed to tackle the algal scum problem in water by utilizing the algal (Spirogyra sp.) biomass waste for organic dye-laden industrial wastewater treatment, a global problem, and challenge. Therefore, an algal biochar-based nanocomposite (nAgBC) was synthesized and employed as a low-cost adsorbent for Congo red (CR) removal. Surface morphology, physicochemical characteristics, elemental composition, phase, and stability of the nanocomposite was analyzed using BET, FESEM-EDX, FTIR, XRD, XPS, and TGA. The nanocomposite was found to be thermostable, mesoporous with large and heterogeneous surface area, containing nAg as doped material, where -OH, NH, CO, CC, SO, and CH are the surface binding active functional groups. Maximum adsorption efficiency of 95.92% (18 mg L^-1 CR) was achieved (qe = 34.53 mg g^-1) with 0.5 g L^-1 of nanocomposite after 60 min, at room temperature (300 K) at pH 6. Isotherm and kinetic model suggested multilayer chemisorption, where adsorption thermodynamics indicated spontaneous reaction. Fluorescens spectral analysis of CR confirmed the formation of CR supramolecule, supporting enhanced adsorption. Furthermore, the result suggested a 5th cycle reusability and considerable efficacy towards real textile industrial effluents. Synergistic effects of the active surface functional groups of the biochar and nAg, along with the overall surface charge of the composite lead to chemisorption, electrostatic attraction, H-bonding, and surface complexation with CR molecules. Thus, synthesized nAgBC can be applicable to mitigate the wastewater for cleaner production and environment.

A comprehensive review on the removal of noxious pollutants using carrageenan based advanced adsorbents

Rapid industrial development is associated with high discharge of toxic pollutants into the environment. The industries discharge their wastewater containing organic pollutants directly into the water system without treating them that has posed many serious threats to environmental protection. The use of bioadsorbents for the removal of such toxic pollutants from the waste water due to its simple synthesis, easy operation, effectiveness, and economic viability have emerged a new dimension in the wastewater treatment approaches. Various adsorbents have been prepared to examine their adsorption capacity against different adsorbates, but, to attain sustainability, biocompatibility, and biodegradation, bio-adsorbents have been found to won the battle. Seaweed derived polysaccharide; Carrageenan (CR) has been proven to be an excellent adsorbent for the wastewater treatment. It has been successfully modified with various components to form CR based-magnetic composites, hydrogels, nanoparticle modified CR composites and many others to enrich and diversify its properties. In this review, we have explained the adsorption behaviour of various carrageenan based adsorbents for the removal of different dyes. The influence of various parameters such as the effect of initial concentration, adsorbent dosage, contact time, pH, temperature, and ion concentration on dye adsorption is well explained. This paper also summarizes the structure, morphology, swelling ability, and thermal stability of carrageenan. The data also expounds on the adsorption capacity, kinetic model, isotherm model, and nature of the adsorption process. Different types of solvents are used for the regeneration and reusability of carrageenan adsorbents and their regeneration studies and desorption efficiency is well-explained. The adsorption mechanism of dyes onto carrageenan based adsorbents has been well described in this review. This review provides a deep insight about the use of carrageenan based adsorbents for the wastewater treatment.

Adsorption of cationic dyes onto carrageenan and itaconic acid-based superabsorbent hydrogel: Synthesis, characterization and isotherm analysis

Polysaccharide-based hydrogels offer a great overlook for environmental applications and help in the elimination of various noxious pollutants from the water system. Novel carrageenan and itaconic acid-based superadsorbent hydrogel having appreciable swelling properties and adsorption capacity towards Methylene blue (MB), Crystal violet (CV), and Methyl Red (MR) was synthesized by suspension polymerization technique. The swelling study showed the dependency upon the temperature in which the swelling rate increased with increasing temperature with a maximum swelling rate of 417% at 318 K. For ascertaining the maximum adsorption capacity, various influential parameters such as contact time, adsorbent dose, dye concentration, and temperature were systematically studied. Maximum adsorption capacity as calculated from the Langmuir isotherm was 2439.02, 1111.11, and 666.68 mg/g for MB, CV, and MR, respectively. Thermodynamic studies revealed the spontaneous nature of the undertaken dye adsorption experiment. Overall, the present study reveals that the synthesized superadsorbent hydrogel can be used as an efficient adsorbent for the removal of dyes from an aqueous solution.

Accelerated charge transfer in well-designed S-scheme Fe@TiO2/Boron carbon nitride heterostructures for high performance tetracycline removal and selective photo-reduction of CO2 greenhouse gas into CH4 fuel

Designing and fabrication of smart hybrid multifunctional materials for energy/fuel production and environmental detoxification is indeed of great significance for sustainable development. Herein, we synthesized a new well-structured S-scheme heterostructure Fe@TiO₂/Boron Carbon nitride (FT/BCN) with high performance tetracycline degradation and selective CO₂ photo-reduction to CH₄. Under visible light irradiation, 96.3% tetracycline was degraded in 60 min using best performing FT30/BCN sample with a high 83.2% total organic carbon removal in 2 h. The tetracycline degradation rate for FT30/BCN composite catalyst was ∼7 times than bare boron carbon nitride (BCN). The impact of reaction parameters as pH, presence of interfering electrolytes, light source and water matrix was also investigated. The FT30/BCN photocatalyst shows dramatic improvement in CO₂ photoreduction as exhibited in 24.7 μmol g^-1 h^-1 CH₄ and 2.4 μmol g^-1 h^-1 CO evolutions with optimal 91.1% CH₄ selectivity. Pure BCN shows a poor 39.1% selectivity. Further, effect of alkali activation, CO₂/H₂O feed ratio, reducing agent and light source onto CH₄ production and selectivity was also investigated. The CH₄ evolution and selectivity was improved because of enhanced visible light absorption, high adsorption potential, charge carrier separation and high reducing power of photogenerated electrons induced by an effective S-scheme heterojunction between Fe@TiO₂ and boron carbon nitride. An S-scheme (step-scheme) charge transfer mechanism is here operative both during tetracycline removal and CO₂ reduction. The drug degradation route and photocatalytic mechanism for antibiotic removal and CO₂ reduction was also predicted.

Carbon quantum dots sensitized 2D/2D carbon nitride nanosheets/bismuth tungstate for visible light photocatalytic degradation norfloxacin

A novel carbon quantum dots (CQDs) sensitized 2D/2D carbon nitride nanosheets and bismuth tungstate composite (CQD-CNs/BWO) was successfully prepared via the facile hydrothermal method and used for the photocatalytic degradation of norfloxacin (NOR). During 120 min irradiation test, CQD-CNs/BWO exhibited 9 and 1.76 times higher photocatalytic activity than CNs and BWO, respectively. CQDs and constructed 2D/2D structure could not only improve the light harvesting but also promote the generation and separation of electron-holes. The existing inorganic ions in solution (e.g. bicarbonate ions, chlorine ions, and sulfate ions) could inhibit NOR degradation. Based on the electron spin resonance and free radicals inhibition tests, the holes and superoxide radicals rather than hydroxyl radicals were the main reactive species. The intermediates and possible pathways were proposed, and the antibacterial activity of the treated solution after the reaction was evaluated via bacteriostatic tests. The prepared composite material with high photocatalytic activity and stability is potentially effective for the degradation of antibiotics in wastewater.

Polyvinyl Alcohol Polymer Functionalized Graphene Oxide Decorated with Gadolinium Oxide for Sequestration of Radionuclides from Aqueous Medium: Characterization, Mechanism, and Environmental Feasibility Studies

Uranium (U(VI)) and thorium (Th(IV)) ions produced by the nuclear and mining industries cause water pollution, thereby harming the environment and human health. In this study, gadolinium oxide-decorated polyvinyl alcohol-graphene oxide composite (PGO-Gd) was developed using a simple hydrothermal process to treat U(VI) and Th(IV) ions in water. The developed material was structurally characterized by highly advanced spectroscopy and microscopy techniques. The effects of pH, equilibration time and temperature on both radionuclides (U(VI) and Th(IV)) adsorption by PGO-Gd were examined. The PGO-Gd composite adsorbed both metal ions satisfactorily, with adsorption capacities of 427.50 and 455.0 mg g-1 at pH 4.0, respectively. The adsorption properties of both metal ions were found to be compatible with the Langmuir and pseudo-second-order kinetic models. Additionally, based on the thermodynamic characteristics, the adsorption was endothermic and spontaneous. Furthermore, the environmental viability of PGO-Gd and its application was demonstrated by studying its reusability in treating spiked surface water. PGO-Gd shows promise as an adsorbent in effectively removing both radionuclides from aqueous solutions.

Rational design of novel three-dimensional reticulated Ag2O/ZnO Z-scheme heterojunction on Ni foam for promising practical photocatalysis

Direct Z-scheme heterojunctions composed of Ag₂O nanoparticles and ZnO nanorods were immobilized on Ni foam (AZN) via combined hydrothermal and precipitation methods to successfully construct 3D reticulated composites, and their photocatalytic performance were evaluated under simulated sunlight. Just as expected, the AZN samples exhibited excellent photocatalytic effects of 99.26% for the model pollutant (rhodamine B) in water after loading with Ag₂O, which was 2.77 times higher than that of regular ZnO NAs/Ni foam composites. Meanwhile, the surface wettability of composite was remarkably enhanced. Besides, a series of photoelectrochemical measurements showed a significant improvement in the charge separation efficiency of AZN, which was attributed to the synergistic effect of direct Z-scheme heterojunction, matched energy band structure as well as 3D porous structure. Moreover, the AZN sample presented satisfactory stability after four cycles, meanwhile it displayed good removal performance against different types of antibiotics (Tetracycline, Sulfadiazine and Ciprofloxacin). The applicability and durability of AZN for rhodamine B degradation were evaluated by sequential batch experiments in a homemade simulated flowing water device. More importantly, the lower value of electrical energy per order indicated the photocatalyst/simulated sunlight system was more energy efficient and effective. Accordingly, this work provided a new strategy for designing 3D reticulated composites with low-dimensional nanomaterials to decompose organic pollutants in impaired waters.

Trimetallic@Cyclodextrin Nanocomposite: Photocatalyst for Degradation of Amoxicillin and Catalyst for Esterification Reactions

The industry is looking for new materials which can respond to specific applications that exclusively advance materials can provide. In this context, nanoparticles and nanocomposites opened an interesting method for designing specific properties which can be modulated according to the requirements. The preparation of biomolecules supported trimetallic nanoparticles and some other derives is a good example of the complex systems that can be designed for getting exclusive properties. This study is based on the preparation of new cyclodextrin supported Fe/La/Zn trimetallic nanocomposite by the microemulsion technique. Photocatalytic degradation of amoxicillin was performed using cyclodextrin-Fe/La/Zn. 78% of amoxicillin photodegradation along 4 hours of photoirradiation was achieved. Finally, the catalytic nature of new material was explored for oxidation and esterification reactions. The present study revealed that this advanced multifunctional nanomaterial can be successfully employed for environmental remediation and catalytic activities.

Global soil pollution by toxic elements: Current status and future perspectives on the risk assessment and remediation strategies - A review

The aim of this article is to review and present the state of the arte about the status of toxic elements (TEs) in soils and assess the potential risk using single and total complex pollution indices in a global scale. We compiled, integrated, and analyzed soil TE pollution data over almost a decade through key maps, which have not been reviewed up to date. All the in-situ and ex-situ remediation treatments have been also reviewed, illustrated, and compared, for the first time. The future perspectives have been discussed and summarized. This review demonstrates that the cornerstone maps and integrated information provide reliable geographical coordinates and inclusive information on TEs pollution, particularly in China. In-situ treatment approaches for TEs polluted soils are more cost-effective and applicable than ex-situ treatment trials. Selecting a feasible remediation strategy should to take the extent of contamination, treatment objectives, site characteristics, cost-efficiency, and public suitability into account. The summarized findings in this review may help to develop innovative and applicable methods for assessing the global soil pollution by TEs. Also, these findings may help to develop innovative, applicable, and feasibly economic methods for sustainable management of TEs contaminated soils to mitigate the environmental and human health risk.

Construction of Z-scheme CuFe2O4/MnO2 photocatalyst and activating peroxymonosulfate for phenol degradation: Synergistic effect, degradation pathways, and mechanism

Photocatalysis coupled with sulfate radical-based advanced oxidation process (SR-AOPs) is an efficient strategy to enhance the degradation efficiency of organic pollution. Herein, a Z-scheme CuFe₂O₄/MnO₂ composite catalyst was successfully fabricated by the hydrothermal method. A series of characterizations demonstrated that the higher CuFe₂O₄ particle dispersion and larger BET surface area of CuFe₂O₄/MnO₂ catalyst contributed to a high catalytic activity toward the phenol removal compared with pure CuFe₂O₄. The effects of catalyst concentration, pH, and peroxymonosulfate (PMS) concentration were studied according to the Box-Behnken Design (BBD) method. The results indicated that 100 mg/L 100 mL phenol could be degraded completely at 0.5 g/L CuFe₂O₄/MnO₂ catalyst, pH = 4.8 and 0.5 mM PMS within 30 min. Moreover, the excellent reusability and stability of CuFe₂O₄/MnO₂ were indicated by the results of recycling degradation and ion leaching test. The free radical quenching experiments and electron spin resonance (ESR) confirmed that h⁺, SO₄^•-, and ^•OH were the main reaction species for phenol oxidation. Based on the results of gas chromatography-mass spectrometry (GC-MS) and ion chromatography, the degradation pathway of phenol was proposed, and the toxicity of phenol degradation intermediates was evaluated. This work may provide new insights into the design of heterojunction photocatalysts for PMS activation to remove organic pollutants.

Adsorptional-photocatalytic removal of fast sulphon black dye by using chitin-cl-poly(itaconic acid-co-acrylamide)/zirconium tungstate nanocomposite hydrogel

In the present work, the removal of fast sulphon black (FSB) dye from water was executed by using chitin-cl-poly(itaconic acid-co-acrylamide)/zirconium tungstate nanocomposite hydrogel (Ch-cl-poly(IA-co-AAm)-ZrW NCH). The Ch-cl-poly(IA-co-AAm)-ZrW NCH was fabricated proficiently by microwave-induced sol-gel/copolymrization method. The zirconium tungstate (ZrW) photocatalyst was prepared by co-precipitation method using sodium tungstate and zirconium oxychloride in ratio (2:1). The polymeric hydrogel part has been used to support the ZrW, and it acted as an adsorbent for adsorptive removal of FSB dye. The band gap for nanocomposite hydrogel was found about 4.18 eV by using Tauc equation. The Ch-cl-poly(IA-co-AAm)-ZrW NCH was characterized by various techniques as FTIR (Fourier-transform infrared spectroscopy), X-ray diffraction (XRD), transmittance electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM). The adsorptional-photocatalytic remediation experiment of FSB dye was optimized for reaction parameters as FSB dye and Ch-cl-poly(IA-co-AAm)-ZrW NCH concentration, and pH. The maximum percentage removal for FSB dye was observed at 92.66% in 120 min under adsorptional-photocatalysis condition.