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Selenium (Se) release from anthropogenic activities such as mining, power generation, and agriculture poses considerable environmental and ecological risks. Increasing prevalence and awareness of Se-related issues have driven the development of many innovative Se treatment technologies. Photocatalysis has shown promise towards Se removal from industrial wastewaters with minimal residuals, and is generally considered a low-cost, robust, non-toxic, and potentially solar-powered method. Despite this, its real-world application towards environmental remediation remains extremely limited. This is because research into practical considerations, such as photocatalyst stability and reusability, is often overlooked or understudied in favor of developing academically interesting but impractical materials. In this work, commercial anatase TiO 2 is stress tested through fifteen cycles of reuse towards the photocatalytic reduction and removal of selenate in synthetic mining-influenced brine (SMIB) without washing or regeneration. Remarkably, selenate removal exceeds 99.3% throughout all cycles. In situ Se-TiO 2 heterojunction formation, and changes to its properties including Se loading, particle size, and crystal phase, are characterized through X-ray absorption spectroscopy, scanning transmission electron microscopy, and diffuse reflectance UV/vis, while their effects on catalyst performance are elucidated. This work underscores the importance of catalyst recyclability for practical photocatalytic environmental remediation and discusses the effects of extensive use on photocatalyst performance., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

In this research, the dimensional catalysts of pure g-C 3 N 4 photocatalysts (1D, 2D, and 3D) were investigated for the reduction of the highly toxic/carcinogenic Cr(VI) under visible light irradiation. The catalysts underwent explanation through various surface analysis techniques. According to the BET data, the specific surface area of the 3D catalyst was 1.3 and 7 times higher than those of the 2D and 1D CN catalysts, respectively. The 3D catalyst demonstrated superior performance, achieving an efficiency greater than 99% within 60 min under visible light irradiation in the presence of EDTA due to the abundance of active sites. The study also delved into the influence of factors such as the amount of EDTA-hole scavenger, pH, catalyst dosage, and temperature on the photocatalytic reduction of Cr(VI). Moreover, the 3D catalyst showed excellent reusability, maintaining an efficiency of more than 80% even after 10 cycles, and performed effectively in real water samples. The 3D CN catalyst, with its facile synthesis process, excellent visible light harvesting properties, high reduction efficiency that sustains over multiple cycles, and outstanding performance in real water samples, presents a significant advancement for practical applications in environmental remediation. This research contributes to a new understanding of developing efficient degradation methods for heavy metals in polluted water, highlighting the potential of 3D g-C3N4 catalysts in environmental cleanup efforts. [Display omitted] • Dimensional g-C 3 N 4 photocatalysts was synthesized for Cr(VI) reduction. • 3D catalyst showed 1.3 to 7 times greater surface area than 1D/2D counterparts. • 3D catalyst enhanced Cr(VI) reduction through more efficient electron transfer. • 3D catalyst showed superior reusability and effectiveness in real water samples. [ABSTRACT FROM AUTHOR]

Abstract Antibiotics and heavy metals often coexist in polluted environment, and the harm of combined pollution is greater than that of single pollution. In this study, a series of graphene supported p-n heterojunction rGO@Cu 2 O/BiVO 4 composites are synthesized with different Cu 2 O doping for simultaneous detoxification of Cr(VI) and antibiotics. The obtained photocatalysts (rGO@Cu 2 O/BiVO 4) with proper loading amount of Cu 2 O shows the a high photocatalytic degradation activity for simultaneously efficient Cr(VI) reduction and sulfamethoxazole (SMZ) oxidation under LED light at neutral pH. The Cr(VI) was completely transformed to Cr(III) rather than simply Cr(VI) adsorbed on the surface of rGO@Cu 2 O/BiVO 4. The photocatalytic activity of composites can be attributed to excellent electrical conductivity of rGO and the p-n heterojunction between Cu 2 O and BiVO 4 , which promotes the spatial separation of photogenerated charges at the heterojunction boundary and inhibits of the photogenerated h + and e − recombination. It's confirmed that h +, O 2 − and OH are the main reactive species for the photocatalytic SMZ oxidation, and the most important reactive species is h +. Finally, the tentative degradation pathways of SMZ are proposed based on the liquid chromatography-triple quadrupole mass spectrometry analysis. This work provides an effective approach for the treatment of water that contains SMZ and Cr(VI) under LED light. Graphical abstract Image 1 Highlights • rGO@Cu 2 O/BiVO 4 p-n heterojunction photocatalysts were successfully prepared. • Simultaneous and efficient Cr(VI) reduction and SMZ oxidation. • The joint photocatalysis enhances the degradation activity of Cr(VI) and SMZ. • O 2 − and OH are major reactive species. • The degradation pathways of SMZ are proposed based on the LC-MS-MS analysis. [ABSTRACT FROM AUTHOR]

Heavy metals and radionuclides in water are a global environmental issue, which has been receiving considerable attention worldwide. Water-stable MOFs are green and recyclable materials to eliminate the environmental impacts caused by the hazardous heavy metal ions and radionuclides in water. This paper presents a systematical review on the current status of water-stable MOFs that capture and convert a wide range of heavy metal ions (e.g., As(III)/As(V), Pb(II), Hg(II), Cd(II), and Cr(III)/Cr(VI)) and radionuclides (e.g., U(VI), Se(IV)/Se(VI) and Cs(I)) in aqueous solution. Water-stable MOFs and MOF-based composites exhibit the superior adsorption capability for these metal species in water. Significantly, MOFs show high selectivity in capturing target metal ions even in the presence of multiple water constituents. Mechanisms involved in capturing metal ions are described. MOFs also have excellent catalytic performance (photocatalysis and catalytic reduction by formic acid) for Cr(VI) conversion to Cr(III). Future research is suggested to provide insightful guidance to enhance the performance of the MOFs in capturing target pollutants in aquatic environment. [ABSTRACT FROM AUTHOR]

Abstract: A series of Bi3+-doped TiO2 (Bi3+–TiO2) catalysts with a doping concentration up to 2wt% were prepared by a sol–gel method. The prepared photocatalysts were characterized by different means to determine their chemical composition, surface structure and light absorption properties. The photocatalytic activity of different Bi3+–TiO2 catalysts was evaluated in the photocatalytic reduction of nitrate in aqueous solution under UV illumination. In the experiments, formic acid was used as a hole scavenger to enhance the photocatalytic reduction reaction. The experiments demonstrated that nitrate was effectively degraded in aqueous Bi3+–TiO2 suspension by more than 83% within 150min, while the pH of the solution increased from 3.19 to 5.83 due to the consumption of formic acid. The experimental results indicate that the presence of Bi3+ in TiO2 catalysts substantially enhances the photocatalytic reaction of nitrate reduction. It was found that the optimal dosage of 1.5wt% Bi3+ in TiO2 achieved the fastest reaction of nitrate reduction under the experimental condition. Bismuth ions deposit on the TiO2 surface behaves as sites where electrons accumulate. Better separation of electrons and holes on the modified TiO2 surface allows more efficient channeling of the charge carriers into useful reduction and oxidation reactions rather than recombination reactions. Two intermediate products of nitrite and ammonia during the reaction were also monitored to explore the possible mechanisms of photoluminescence quenching and photocatalytic reduction in the context of donor–acceptor interaction with electron trapping centers. [Copyright &y& Elsevier]

Currently, Tetrabromobisphenol A (TBBPA) has been regarded as an emerging organic pollutant and efficient TBBPA elimination technology has been attracting increasing attention. In this work, a novel photocatalyst, MoS 2 /SnIn 4 S 8 , was synthesized through hydrothermal method by introducing few-layer MoS 2 nanosheets and then employed to establish an integrated photocatalytic reduction/oxidation system for the remediation of TBBPA under visible light. The characterization results demonstrated that the few-layer MoS 2 nanosheets were well combined with SnIn 4 S 8 and significantly lowered the recombination rate of the photo-induced electron and holes, leading to outstanding photocatalytic performance of MoS 2 /SnIn 4 S 8 composite. Besides, the MoS 2 /SnIn 4 S 8 composite also exhibited excellent reusability (over 10 runs) and stability. The TBBPA degradation experiments showed that the integrated photocatalytic reduction/oxidation system was able to completely degrade TBBPA and mineralize its byproducts (60.2 ± 2.9%). In the photocatalytic reduction, due to the cleavage of C–Br bonds by photo-induced electrons, TBBPA underwent stepwise debromination and finally transferred into BPA in 6 h. In the following photocatalytic oxidation, under the attack of reactive oxygen species (1O 2 , h+, OH and O 2 −), BPA was first decomposed into aromatic products (such as phenol, benzoic acid, p -hydroxybenzyl alcohol and so on) via C–C bond cracking and hydroxylation, and then further oxidized into organic acids like maleic acid and muconic acid through ring-opening, and finally mineralized into CO 2 and H 2 O. What was noteworthy was that the final effluent from the photocatalytic reduction/oxidation system showed no toxicity to the luminescent bacteria. [Display omitted] • Structure and photocatalytic performance of MoS 2 /SnIn 4 S 8 were studied. • TBBPA could be fully degraded during photocatalytic reduction/oxidation. • Stepwise debromination of TBBPA occurred during photocatalytic reduction. • O 2 − and h+ were the main species during photocatalytic oxidation of BPA. • The final effluent from the system were proved to nontoxic. [ABSTRACT FROM AUTHOR]

Heavy metals pollution in water is a global environmental issue, which has threatened the human health and environment. Thus, it is important to remove them under practical water environment. In recent years, metal-organic frameworks (MOFs) with water-stable properties have attracted wide interest with regard to the capture of hazardous heavy metal ions in water. In this review, the synthesis strategy and postsynthesis modification preparation methods are first summarized for water-stable MOFs (WMOFs), and then the recent advances on the adsorption and photocatalytic reduction of heavy metal ions in water by WMOFs are reviewed. In contrast to the conventional adsorption materials, WMOFs not only have excellent adsorption properties, but also lead to photocatalytic reduction of heavy metal ions. WMOFs have coupling and synergistic effects on the adsorption and photocatalysis of heavy metal ions in water, which make it more effective in treating single pollutants or different pollutants. In addition, by introducing appropriate functional groups into MOFs or synthesizing MOF-based composites, the stability and ability to remove heavy metal ions of MOFs can be effectively enhanced. Although WMOFs and WMOF-based composites have made great progress in removing heavy metal ions from water, they still face many problems and challenges, and their application potential needs to be further improved in future research. Finally, this review aims at promoting the development and practical application of heavy metal ions removal in water by WMOFs. • Heavy metal ion pollution of water bodies has led to serious harm. • The removal of heavy metal ions in water by WMOFs is summarized. • Adsorption and photocatalytic reduction of heavy metal ions by WMOFs are reviewed. • Synthesis strategies and postsynthesis modification of WMOFs are summarized. [ABSTRACT FROM AUTHOR]