Heterogeneous photocatalytic activation of electrogenerated chlorine for the production of reactive oxygen and chlorine species: A new approach for Bisphenol A degradation in saline wastewater

Biodegradation of bisphenol A by a Pichia pastoris whole-cell biocatalyst with overexpression of laccase from Bacillus pumilus and investigation of its potential degradation pathways

Bisphenol A (BPA), an endocrine disrupter with estrogen activity, can infiltrate animal and human bodies through the food chain. Enzymatic degradation of BPA holds promise as an environmentally friendly approach while it is limited due to lower stability and recycling challenges. In this study, laccase from Bacillus pumilus TCCC 11568 was expressed in Pichia pastoris (fLAC). The optimal catalytic conditions for fLAC were at pH 6.0 and 80 °C, with a half-life T1/2 of 120 min at 70 °C. fLAC achieved a 46 % degradation rate of BPA, and possible degradation pathways were proposed based on identified products and reported intermediates of BPA degradation. To improve its stability and degradation capacity, a whole-cell biocatalyst (WCB) was developed by displaying LAC (dLAC) on the surface of P. pastoris GS115. The functionally displayed LAC demonstrated enhanced thermostability and pH stability along with an improved BPA degradation ability, achieving a 91 % degradation rate. Additionally, dLAC maintained a degradation rate of over 50 % after the fourth successive cycles. This work provides a powerful catalyst for degrading BPA, which might decontaminate endocrine disruptor-contaminated water through nine possible pathways.

Photodegradation of bisphenol A (BPA) in coastal aquaculture waters: Influencing factors, products, and pathways

Bisphenol A (BPA), an endocrine-disrupting contaminant, is ubiquitous in the environment due to its presence in plastics, wastewater, and agricultural runoff. This study investigated the photodegradation behavior of BPA in coastal aquaculture waters near Qingdao, China. Lower salinity promoted BPA photodegradation, while higher salinity has an inhibitory effect, suggesting slower degradation in seawater compared to ultrapure water. Triplet-excited dissolved organic matter (3DOM*) was identified as the primary mediator of BPA degradation, with additional contributions from hydroxyl radicals (•OH), singlet oxygen (1O2), and halogen radicals (HRS). Alepocephalidae aquaculture water exhibited the fastest degradation rate, likely due to its high DOM and nitrate/nitrite (NO3-/NO2-) content, which are sources of 3DOM* and •OH. A positive correlation existed between NO3-/NO2- concentration and the BPA degradation rate. Ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) analysis identified the primary BPA photodegradation products, formed mainly through oxidative degradation, hydroxyl substitution, nitration, and chlorination pathways. Elucidating these photodegradation mechanisms provides valuable insights into the environmental fate and potential ecological risks of BPA in aquaculture environments. This knowledge can inform strategies for marine environmental protection and the development of sustainable practices.

Developing In2S3 upon modified MgTiO3 anchored on nitrogen-doped CNT for sustainable sensing and removal of toxic insecticide clothianidin

Herein, the study introduces a novel bifunctional In2S3/MgTiO3/TiO2@N-CNT (IMTNC) nanocomposite, which is poised to revolutionize the detection and removal of clothianidin (CLD) from aquatic environments by synergistic adsorption and photodegradation. Confirmation of the material's synthesis was done using structural, optical, morphological, and chemical characterizations. An outstanding sensitivity of 2.168 μA/nM.cm2 with a linear range of 4-100 nM and a LOD of 0.04 nM, along with an exceptional elimination efficiency of 98.06 ± 0.84% for about 10 ppm CLD within 18 min was demonstrated by the IMTNC nanocomposite. Extensive studies were carried out to appraise the material's effectiveness in the presence of various interfering species, such as cations, anions, organic compounds, and different water matrices, and a comprehensive assessment of its stability throughout several cycles was made. Response Surface Methodology (RSM) study was used to determine the ideal removal conditions for improved performance. In addition, the catalytic performance in removing various other pollutants was also analyzed. Adding In2S3 and developing N-doped Carbon Nanotubes (N-CNT) increased conductivity and higher electrochemical sensing skills, improving charge transfer and increasing photocatalytic activity. This research underscores the potential of the IMTNC nanocomposite as a promising candidate for advanced environmental sensing and remediation applications.

Insights into the efficient mineralization of antibiotic trimethoprim in aqueous media by Fe2+ catalytically enhanced vacuum-UV irradiation: Kinetics, mechanisms, and toxicity evaluation

The widespread existence of antibiotics in the environment has attracted growing concerns regarding the potential adverse effects on aquatic organisms, ecosystems, and human health even at low concentrations. Extensive efforts have been devoted to developing new methods for effective elimination of antibiotics from wastewater. Herein, a novel process of Fe2+ catalytically enhanced vacuum ultraviolet (VUV) irradiation was proposed as a promising approach for the removal of antibiotic trimethoprim (TMP) in water. Compared with UVC photolysis, VUV photolysis, and UVC/Fe2+, VUV/Fe2+ could increase the pseudo-first-order reaction rate constant of TMP removal by 6.6-38.4 times and the mineralization rate by 36.5%-59.9%. The excellent performance might originate from the synergistic effect of VUV and Fe2+, i.e., VUV irradiation could effectively split water and largely accelerate the Fe3+/Fe2+ cycle to generate more reactive oxygen species (ROS). EPR results indicated that •OH and O2•- were identified as the main ROS in the UVC/Fe2+ and VUV/Fe2+ processes, while •OH, O2•-, and 1O2 were involved in the VUV process. The operating parameters, such as Fe2+ dosage and initial TMP contents, were evaluated and optimized. Up to 8 aromatic intermediates derived from hydroxylation, demethylation, carbonylation, and methylene group cleavage were identified by UPLC-QTOF-MS/MS technique, the possible pathways of TMP degradation were proposed. Finally, the acute and chronic toxicity of intermediates formed during TMP degradation in the VUV/Fe2+ process were also evaluated.

Emerging technologies for the removal of pesticides from contaminated soils and their reuse in agriculture

Pesticides are becoming more prevalent in agriculture to protect crops and increase crop yields. However, nearly all pesticides used for this purpose reach non-target crops and remain as residues for extended periods. Contamination of soil by widespread pesticide use, as well as its toxicity to humans and other living organisms, is a global concern. This has prompted us to find solutions and develop alternative remediation technologies for sustainable management. This article reviews recent technological developments for remediating pesticides from contaminated soil, focusing on the following major points: (1) The application of various pesticide types and their properties, the sources of pesticides related to soil pollution, their transport and distribution, their fate, the impact on soil and human health, and the extrinsic and intrinsic factors that affect the remediation process are the main points of focus. (2) Sustainable pesticide degradation mechanisms and various emerging nano- and bioelectrochemical soil remediation technologies. (3) The feasible and long-term sustainable research and development approaches that are required for on-site pesticide removal from soils, as well as prospects for applying them directly in agricultural fields. In this critical analysis, we found that bioremediation technology has the potential for up to 90% pesticide removal from the soil. The complete removal of pesticides through a single biological treatment approach is still a challenging task; however, the combination of electrochemical oxidation and bioelectrochemical system approaches can achieve the complete removal of pesticides from soil. Further research is required to remove pesticides directly from soils in agricultural fields on a large-scale.

Green synthesis of ZnO nanocubes from Ceropegia omissa H. Huber extract for photocatalytic degradation of bisphenol An under visible light to mitigate water pollution

Plastic pollution has become a major environmental problem because it does not break down and poses risks to ecosystems and human health. This study focuses on the environmentally friendly synthesis of ZnO nanocubes using an extract from Ceropegia omissa H. Huber plant leaves. The primary goal is to investigate the viability of these nanocubes as visible-light photocatalysts for the degradation of bisphenol A (BPA). The synthesized ZnO nanocubes have a highly crystalline structure and a bandgap of 3.1 eV, making them suitable for effective visible-light photocatalysis. FTIR analysis, which demonstrates that the pertinent functional groups are present, demonstrates the chemical bonding and reducing processes that take place in the plant extract. The XPS method also studies zinc metals, oxygen valencies, and binding energies. Under visible light irradiation, ZnO nanocubes degrade BPA by 86% in 30 min. This plant-extract-based green synthesis method provides a long-term replacement for traditional procedures, and visible light photocatalysis has advantages over ultraviolet light. The study's results show that ZnO nanocubes may be good for the environment and can work well as visible light photocatalysts to break down organic pollutants. This adds to what is known about using nanoparticles to clean up the environment. As a result, this study highlights the potential of using environmentally friendly ZnO nanocubes as a long-lasting and efficient method of reducing organic pollutant contamination in aquatic environments.

Insight into roles of carbon anodes for removal of refractory organic contaminants in electro-peroxone system: Mechanism, performance and stability

Electro-peroxone (EP) is a novel technique for the removal of refractory organic contaminants (ROCs), while the role of anode in this system is neglected. In this work, the EP system with graphite felt anode (EP-GF) and activated carbon fiber anode (EP-ACF) was developed to enhance ibuprofen (IBP) removal. The results showed that 91.2% and 98.6% of IBP was removed within 20 min in EP-GF and EP-ACF, respectively. Hydroxy radical (O⋅H) was identified as the dominant reactive species, contributing 80.9% and 54.0% of IBP removal in EP-ACF and EP-GF systems, respectively. The roles of adsorption in EP-ACF and direct electron transfer in EP-GF cannot be ignored. Due to the differences in mechanism, EP-GF and EP-ACF systems were suitable for the removal of O⋅H-resistant ROCs (e.g., oxalic acid and pyruvic acid) and non-O⋅H-resistant ROCs (e.g., IBP and nitrobenzene), respectively. Both systems had excellent stability relying on the introduction of oxygen functional groups on the anode, and their electrolysis energy consumption was significantly lower than that of EP-Pt system. The three degradation pathways of IBP were proposed, and the toxicity of intermediates were evaluated. In general, carbon anodes have a good application prospect in the removal of ROCs in EP systems.

Degradation mechanisms and toxicity determination of bisphenol A by FeOx-activated peroxydisulfate under ultraviolet light

Ultraviolet light (UV)-assisted advanced oxidation processes (AOPs) are commonly used to degrade organic contaminants. However, this reaction system's extensive comprehension of the degradation mechanisms and toxicity assessment remains inadequate. This study focuses on investigating the degradation mechanisms and pathways of bisphenol A (BPA), generation of reactive oxygen species (ROS), and toxicity of degradation intermediates in UV/PDS/ferrous composites (FeOx) systems. The degradation rate of BPA gradually increased from the initial 11.92% to 100% within 120 min. Sulfate radicals (SO 4 . - ), hydroxyl radicals (.OH), superoxide anions (O 2 . - ), and singlet oxygen (1O2) were the primary factors in the photocatalytic degradation of BPA in the UV/PDS/FeOx systems. The main reactions of BPA in this system were deduced to be β-bond cleavage, hydroxyl substitution reaction, hydrogen bond cleavage, and oxidation reaction. A trend of decreasing toxicity for the degradation intermediates of BPA was observed according to the toxicity investigations. The efficient degradation of BPA in UV/PDS/FeOx systems provided theoretical data for AOPs, which will improve the understanding of organic contaminants by FeOx in natural industry wastewater.

Cellulose beads supported CoFe2O4: A novel heterogeneous catalyst for efficient rhodamine B degradation via advanced oxidation processes

In this study, a novel mechanical process was used to produce cellulose beads (CB). These beads were then doped with cobalt ferrite nanoparticles (CoFe2O4 NPs) to serve as catalysts for the degradation of rhodamine B (RhB) through peroxymonosulfate (PMS) activation. The physical and chemical properties of CoFe2O4 and CoFe2O4@CB catalysts were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) combined with energy dispersive X-ray spectrometer (EDX), scanning transmission electron microscopy (STEM) techniques, and thermogravimetric analysis (TGA). To optimize RhB degradation efficiency, Response Surface Methodology (RSM) was employed, utilizing the Box-Behnken design (BBD). Under the optimized conditions of a catalyst dosage of 0.40 g/L, PMS dosage of 0.98 mM, RhB concentration of 40 mg/L, pH of 5.27, and reaction time of 60 min, a remarkable degradation efficiency of 98.51 % was achieved at a temperature of 25 °C. In quenching experiments, 1O2, SO4•-, and HO• species are produced in the CoFe2O4@CB/PMS system, with 1O2, and SO4•- species dominating RhB degradation. Remarkably, the new CoFe2O4@CB catalyst has demonstrated exceptional stability and reusability, validated by recycling tests (up to 78 % of RhB degradation efficiency after a 5-cycle experiment) and subsequent characterizations (FTIR, SEM, and EDX) emphasizing unchanged bands, uniform distribution, and consistent composition after reuse cycles. These results demonstrate the effectiveness of mechanically produced CoFe2O4@CB catalysts for advanced oxidation processes (AOPs), with promising applications in wastewater treatment.

Effect of UV/peroxymonosulfate pretreatment on disinfection byproduct (DBP) formation during post-chlorination of humic acid

UV/peroxymonosulfate (UV/PMS) is a promising advanced oxidation technology in water treatment. This study aimed to investigate the impact of UV/PMS on humic acid (HA) and the influence of PMS dosage, pretreatment time, pH pretreatment, nitrate, nitrite, ammonium, and bicarbonate influencing factors on disinfection byproduct (DBP) formation during post-chlorination. With increased PMS dosage or pretreatment time, the UV/PMS treatment significantly reduced ultraviolet absorbance and increased mineralization. It altered the fractional constituent as humic substances were gradually transformed into building blocks and low-molecular-weight acids. However, most DBP formation increased initially and then decreased after subsequent chlorination. Rising nitrate or nitrite concentrations markedly promoted halonitromethane (HNM) formation. The presence of ammonia had a more significant impact on dichloroacetonitrile (DCAN) formation. Bicarbonate in UV/PMS pretreatment increased carbonated disinfection byproduct (C-DBP) formation, whereas it had a negligible impact on nitrogenous disinfection byproduct (N-DBP) formation. The present study revealed the impact of a series of influencing factors on DBP formation in UV/PMS reaction systems, providing comprehensive insights on applying UV/PMS in actual practice.

Comparative study of electro-Fenton and photoelectro-Fenton processes using a novel photocatalytic fuel cell electro-Fenton system with g-C3 N4 @N-TiO2 and Ag/CNT@CF as electrodes

In this study, a novel photocatalytic fuel cell electro-Fenton (PFC-EF) system was constructed using g-C3 N4 @N-TNA and Ag/CNT@CF as electrodes. The composition, structure, and morphology of the electrodes were obtained. The g-C3 N4 @N-TNA, with its 2.37 eV band gap and 100 mV photovoltage, has excellent excitation properties for sunlight. Ag/CNT@CF with abundant pores, CNT 3D nanostructures, and Ag crystals on the surface can improve the electro-Fenton efficiency. A comparative study of rhodamine B (RhB) degradation was performed in this system. It has been shown that electric fields can greatly enhance the oxidation efficiency of both anode photocatalysis and the cathode electro-Fenton process. Under optimal conditions, RhB can be completely removed by the photoelectro-Fenton (PEF) process. The energy consumption of the PEF system was obtained. The electrical energy per order (EE/O) is only 9.2 kWh/m3 ·order, which is only 16.5% of EF and 2.2% of PFC-EF system. The mineralization current efficiency (MCE) of the PEF system reached 93.3% for a 2-h reaction. Therefore, the PEF system has the advantage of saving energy. The kinetic analysis shows that the RhB removal follows a first-order kinetic law, and the reaction rate constant reaches 0.1304 min-1 , which is approximately 5.2 times larger and 4.0 times larger than the electro-Fenton and PFC-EF processes, respectively. RhB removal is a coupling multimechanism in which an electric field enhances photoelectron migration, Ag loading improves H2 O2 generation, UV light coupled with H2 O2 promotes hydroxyl radical (٠OH) generation, and the nanoconfinement effect of CNTs promotes ٠OH accumulation in favor of RhB degradation. PRACTITIONER POINTS: Novel efficiency photocatalytic fuel cell electro-Fenton system was constructed. The electric field greatly enhances the photocatalytic fuel cell electro-Fenton system. Multiple coupling mechanisms of UV/H2O2, UV/Fenton and photo-electro-Fenton have been revealed.

Reasonable decoration of CuO/Cd0.5Zn0.5S nanoparticles onto flower-like Bi5O7I as boosted step-scheme photocatalyst for reinforced photodecomposition of bisphenol A and Cr(VI) reduction in wastewater

Building S-scheme heterostructures is a sophisticated approach to receiving outstanding catalysts for environmental detoxification. Herein, ternary CuO/Cd0.5Zn0.5S/Bi5O7I (CO/CZS/BOI) nanocomposites were constructed by in-situ decorating of CuO and Cd0.5Zn0.5S nanoparticles onto Bi5O7I micro-sphere in a facile route. The optimal CO/CZS/BOI reflected reinforced bisphenol A (BPA) photo-oxidation (95% in 70 min) and Cr(VI) photo-reduction (96.6 in 60 min) under visible light. Besides, CO/CZS/BOI afforded 5.10 (4.44), 4.42 (3.71), and 6.60 (5.27) fold reinforcement in the BPA (Cr(VI)) photo-reaction rate compared to BOI, CZS, and CO, respectively. This behavior was linked to the development of S-scheme mechanisms resulting from the co-effects of BOI, CZS, and CO in retaining the optimum redox capacity, facilitating the dissolution of photo-carriers, increasing reactive sites, and strengthening the visible-light response. The parameters influencing the catalytic reaction of CO/CZS/BOI, such as light intensity, catalyst dosage, and pH, were deeply studied. The quenching tests declared the prominent roles •O2- and •OH in the breaking down of BPA and the participation of electrons and •O2- in the photocatalytic conversion of Cr(VI). The cyclic tests verified the robust photostability of CO/CZS/BOI, which is associated with the reintegration process between the free h+ coming from CZS and the photo-induced e- of CO and BOI in the S-scheme system. In conclusion, the present study provides a profound understanding of the photo-reaction mechanism of CO/CZS/BOI and introduces a novel concept for constructing a superior dual-Scheme system for efficient wastewater detoxification.

Impact of vacuum ultraviolet (VUV) intensity on the performance of VUV irradiation for the mineralization of trimethoprim in neutral media: Kinetics, mechanisms, and by-products formation

A comparative study on the mineralization of antibiotic trimethoprim (TMP) in neutral medium was investigated by applying irradiation with five types of ultraviolet lamps. Among these lamps, the whole envelope of one lamp contained ordinary quartz, which could only transmit ultraviolet-C (UVC) light. For the other four lamps, approximately one tenth, a quarter, a half, and full of envelopes were comprised of high-purity synthetic quartz, which can transmit both vacuum ultraviolet (VUV) and UVC light. TMP decay was well fitted to pseudo-first-order reaction kinetics and occurred more quickly as the VUV intensity increased. Poor mineralization was achieved in the absence of VUV light, whereas the mineralization efficiency was also enhanced with increasing VUV intensity. The presence of hydroxyl radicals (•OH), superoxide radicals (O2•-) and singlet oxygen (1O2) during VUV photolysis of water was confirmed by electron paramagnetic resonance (EPR) analysis. Appropriate radical quenching experiments and fluorescent molecular probe detection provided the evidence that •OH played a significant role in TMP mineralization. Higher VUV intensity favored the generation of H2O2 and •OH. The evolution of NH4+ and NO3- as well as carboxylic acids (formic, acetic, oxalic, and oxamic acids) released in the treated solution were quantified. Ten aromatic intermediates were also identified by UPLC-QTOF-MS. Thereby, a plausible reaction sequence for TMP mineralization in VUV/UVC photolysis was finally proposed.

Boron nitride quantum dots-enhanced laser desorption/ionization mass spectrometry analysis and imaging of bisphenol A

Bisphenol A (BPA) displays harmful effects on the human health, including potent endocrine activity and potential impact on the development of cancer. Analysis BPA residues in water and plastic products attracted considerable attention in the past decades. However, dominantly used conventional analysis techniques are unable to directly and non-destructively identify the correct species of BPA in plastic products. Hence, this study demonstrates the effective utilisation of boron nitride quantum dots (BNQDs) as an inorganic matrix in matrix-assisted laser desorption/ionization mass spectrometry analysis and imaging (MALDI-MS & MSI) for BPA. The presence of abundant hydroxyl and amino groups on the BNQDs' surface is favourable for the formation of hydrogen bonds with BPA, and increases their ionization and chemoselectivity. Intriguingly, the BNQDs matrix offers a distinct signal for phenolic hazardous molecules featuring different hydroxyl groups. The method was applied to detect BPA at nanomolar level in environmental water, and also allowed non-destructive and in situ mapping of BPA in plastics and pacifiers. This research provides a novel strategy for adapting nanomaterials as inorganic matrices for analysis of small molecular pollutants in environmentally relevant samples using MALDI-MS & MSI.

Photochemistry of the Fe(III)-iminodiacetic acid complex under UVA and UV/Vis irradiation: synthesis and characterisation

The photochemistry of Fe(III)-Iminodiacetic acid complex (Fe(III)-IDA) was studied under UVA and UV/Vis irradiation. The synthesis was realised via molar ratio method modified by reaction of IDA as ligand with Fe(III) as metal. The interaction of Fe(III) with IDA was characterised using Fourier-transform infrared (FTIR) and spectroscopy UV-visible. The results confirmed the stability of the complex at pH > 5; with constant of stability (Log β = 10.02) and stoichiometry Fe(III): IDA = 1:1. In addition, the redox potential was calculated at 521 mV, which is significantly lower than E° for the Fe(III)/Fe(II) couple. The photolysis of this complex in the presence of UVA light and UV/Vis light at different pHs was carried out. This photolysis was followed by several assay Fe(II) and •OH. The results show that the Fe(III)-IDA complex present a photo-reactivities under either light source and the phenomenon is faster when the UV/Vis was used. The initial conversion rate (r0) decreased with increasing of initial pH. The formation of hydroxyl radicals via the Fenton reaction was improved at pH = 2.12 for both irradiation sources used. Reduction of total organic carbon was also studied using the total organic carbon (TOC). The feasibility of amino iron complexes to improve the Fenton process under irradiation was confirmed. Additionally, our research also evidenced the optimal conditions for the formation of hydroxyl radicals; which are the key factor in remove pharmaceuticals pollutants in aqueous media. Based on the results obtained, the Fe(III)-IDA complex could be efficiently photolysis under UV/Vis light.

Facile and Sustainable Synthesis of ZnO Nanoparticles: Effect of Gelling Agents on ZnO Shapes and Their Photocatalytic Performance

The present work involves investigating an unexplored soft-chemical method for synthesizing nanostructured ZnO through biopolymer gelation. Our objective was to exploit (i) the difference in the gelation mechanism of four tested biopolymers, namely, alginate, chitosan, carboxymethylcellulose (CMC), and pectin and (ii) numerous experimental parameters that govern this process in order to allow the control of the growth of nanostructured ZnO, with a view to using the prepared oxides as photocatalysts for the oxidation of the Orange G dye. So, the effect of biopolymer's nature on the microstructural, morphological, and textural properties was examined by thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field-emission gun-scanning electron microscopy-high resolution (FEG-SEM) with energy-dispersive spectrometry (SEM-EDS), ultraviolet-visible (UV-vis) spectroscopy, and N₂ adsorption/desorption. As-prepared oxides were crystallized in a hexagonal wurtzite structure, with a clear difference in their morphologies. The sample prepared by using chitosan has a specific surface area of around 36.8 m²/g in the form of aggregated and agglomerated nanostructured minirods and thus shows the best photocatalytic performance with 99.3% degradation of the Orange G dye in 180 min.

Enhanced degradation of reactive black 5 via persulfate activation by natural bornite: Influencing parameters, mechanism and degradation pathway

Reactive black 5 (RBk5) is a refractory azo dye that constitutes a serious threat to the environment and humans. Herein, natural bornite (Nbo) was utilized to activate persulfate (PDS) for the RBk5 removal. The particle size of the Nbo catalyst was optimized and the RBk5 degradation rate constant that responded positively to the particle size of the Nbo catalyst was exhibited. Then, the operational factors affecting RBk5 removal were comprehensively investigated. With the addition of 1.5 g·L^-1 Nbo and 1.5 mM PDS, 99.05% of the RBk5 (20 mg·L^-1) was removed in 150 min compared with 0.46% removal with PDS only, which was caused by the additional reactive oxygen species (ROS) produced by the synergistic action of Fe-Cu bimetallic metal and reductive sulfur species. The Nbo catalyst presented high stability and reusability toward RBk5 removal. Identification of reactive oxygen species revealed that SO₄^·-, ·OH, O₂^·- and ¹O₂ collectively participated in RBk5 removal. Additionally, a possible degradation pathway for RBk5 was proposed, including cleavage of the azo, C-S and S-O bonds, hydroxylation, hydrolyzation, direct oxidation and other pathways. This work developed a highly effective and low-cost natural mineral-based bimetallic sulfide material for PDS activation for the degradation of contaminants and environmental remediation.

Formation, toxicity, and mechanisms of halonitromethanes from poly(diallyl dimethyl ammonium chloride) during UV/monochloramine disinfection in the absence and presence of bromide ion

Bromide ion (Br^-) is known as a prevalent component in water environments, which exhibits significant impacts on halonitromethanes (HNMs) formation. This study was performed to explore and compare the formation, toxicity, and mechanisms of HNMs from poly(diallyl dimethyl ammonium chloride) (PDDACl) in the absence and presence of Br^- in the UV/monochloramine (UV/NH₂Cl) disinfection process. The results showed that chlorinated HNMs were found in the absence of Br^-, while brominated (chlorinated) HNMs and brominated HNMs were found in the presence of Br^-. Furthermore, the peaks of total HNMs were promoted by 2.0 and 2.4 times, respectively when 1.0 and 2.0 mg L^-1 Br^- were added. Also, the peaks of total HNMs were enhanced with the increase of the NH₂Cl dosage, which were reduced with the increase of pH. It should be noted that Br^- induced higher toxicity of HNMs, and the cytotoxicity and genotoxicity of HNMs with the addition of 2.0 mg L^-1 Br^- were 78.0 and 3.7 times those without the addition of Br^-, respectively. Meanwhile, both the reaction mechanisms of HNMs produced from PDDACl were speculated in the absence and presence of Br^-. Finally, different HNMs species and yields were discovered in these two real water samples compared to those in simulated waters. These findings of this work will be conducive to understanding the significance of Br^- affecting HNMs formation and toxicity in the disinfection process.

Control of particle growth and enhancement of photoluminescence, adsorption efficiency, and photocatalytic activity for zinc sulfide and cadmium sulfide using CoAl-layered double hydroxide system

The fabrication of zinc sulfide (ZnS) and cadmium sulfide (CdS) hybrids was carried out by the sulfidization of Zn(II) or Cd(II) adsorbed in dodecylsulfate modified CoAl-layered double hydroxide through solid-liquid reaction. The TEM images showed the nanocrystals of ZnS (2.61 nm) or CdS (3.29 nm) orderly distributed on the nanosheets. The BET surface area of ZnS (1.13 m²/g) and CdS (0.78 m²/g) was largely improved by intercalating in the interlayer space of CoAl-layered double hydroxide system (15-20 m²/g). The spectroscopic observations further confirmed the formation of ZnS or CdS nanoparticles in the hybrid as the evidence of the blue-shifted absorption onset (39-44 nm), and the increase of the photoluminescence intensity (3-4 times) relative to those of bare ZnS and CdS. The nanohybrids could be applicable as the adsorbent and photocatalyst on purifying wastewater contaminated with Congo red dye. By the adsorptive removal, the hybrids exhibited the maximum adsorption capacity of 216-234 mg/g, resulting from the effect of CoAl-layered double hydroxide. In addition, the photocatalytic degradation was completely conducted by using CdS hybrid with the rate constant of 0.0115 min^-1, because the host-guest and/or guest-guest interactions promoted the greater optical performance, and adsorption and photocatalytic efficiencies.

Potassium Poly(heptazine imide) Coupled with Ti3C2 MXene-Derived TiO2 as a Composite Photocatalyst for Efficient Pollutant Degradation

The photocatalytic degradation of pollutants is an effective and sustainable way to solve environmental problems, and the key is to develop an efficient, low-cost, and stable photocatalyst. Polymeric potassium poly(heptazine imide) (K-PHI), as a new member of the carbon nitride family, is a promising candidate but is characterized by a high charge recombination rate. To solve this problem, K-PHI was in-situ composited with MXene Ti₃C₂-derived TiO₂ to construct a type-II heterojunction. The morphology and structure of composite K-PHI/TiO₂ photocatalysts were characterized via different technologies, including TEM, XRD, FT-IR, XPS, and UV-vis reflectance spectra. Robust heterostructures and tight interactions between the two components of the composite were verified. Furthermore, the K-PHI/TiO₂ photocatalyst showed excellent activity for Rhodamine 6G removal under visible light illumination. When the weight percent of K-PHI in the original mixture of K-PHI and Ti₃C₂ was set to 10%, the prepared K-PHI/TiO₂ composite photocatalyst shows the highest photocatalytic degradation efficiency as high as 96.3%. The electron paramagnetic resonance characterization indicated that the^·OH radical is the active species accounting for the degradation of Rhodamine 6G.