Iron sulfides-based advanced oxidation processes (AOPs) have attracted significant attention owing to their intrinsic ability to drive efficient self-enhanced Fe(II)/Fe(III) cycling. Currently, researchers have investigated the efficacy and mechanisms of iron sulfides-based catalysts (mainly including FeS and FeS2) in activating various advanced oxidants (hydrogen peroxide, sodium percarbonate, peroxydisulfate, peroxymonosulfate, peracetic acid, and periodate) for efficient pollutant degradation. These investigations have demonstrated the activation mechanisms of oxidants by iron sulfides-based catalysts, elucidating the efficiency and pathways of pollutant degradation, providing valuable insights for researchers. Although some reviews of environmental applications of iron sulfides-based catalysts exist, a comprehensive review that systematically analyzes the application of iron sulfides-based catalysts in various AOPs has not been published yet. This work contributes to addresses this gap by thoroughly examining the fundamental properties of iron sulfides-based catalysts and oxidants, catalytic mechanisms categorized by oxidant type, and the latest advancements in pollutant degradation. Additionally, it highlights current challenges, such as catalyst stability and oxidant selectivity, while proposing potential solutions, including surface modification and hybrid material design. This review will provide guidance for the application of iron sulfide-based catalysts in activating various oxidants (including less common oxidants sodium percarbonate, peracetic acid, and periodate) for pollutant removal.

Floodplain wetlands are important carbon sinks, yet drought-induced water level declines threaten this function by triggering widespread mudflat-to-meadow conversion that alters soil organic carbon (SOC) stocks and stability. Microtopography shapes wetland hydrology and vegetation; however, its interactive effects with vegetation on microbial necromass carbon (MNC)—the main component of stable SOC—remain unknown. Combining amino sugar biomarkers, amplicon and metagenomic sequencing, we investigated MNC distribution and factors in meadow and mudflat soils (0–30 cm) across dish-shaped depressions, delta and riparian slopes in Poyang Lake floodplains. In the top 10 cm, mudflat-to-meadow conversion increased SOC content by 80% but decreased MNC/SOC from 27% to 19%, shifting MNC dominance from bacterial necromass carbon (BNC) to fungal necromass carbon (FNC). This conversion also increased the activities of cellulose-hydrolyzing enzymes and aerobic lignin-degrading genes, and enriched saprotrophic and symbiotrophic fungi (mainly Ascomycota and Basidiomycota). These processes acidified the soil, suppressing bacterial richness and functions critical for carbon, nitrogen, and sulfur cycling. Microtopographic regulation of MNC/SOC ratio depended on vegetation and soil depth. In the top 10 cm, delta meadow had higher FNC/SOC than other meadows, associated with enriched recalcitrant dissolved organic matter (DOM) content. Well-drained riparian mudflat had higher BNC/SOC than other mudflats at this depth, linked to lower mineral nitrogen and labile DOM with reduced carbon emissions. Below 10 cm, oxygen limitation favored BNC over FNC. Therefore, delta meadow and riparian mudflat had higher BNC/SOC than other meadows and mudflats, respectively, with SOC/(clay+silt) ratio as the key factor. Overall, mudflat-to-meadow conversion restructured topsoil microbial communities and altered the dominant MNC source. Slope wetlands exhibited higher MNC/SOC ratio than depressions, with primary driving factors shifting from substrate availability to mineral protection with depth. These findings provide mechanistic insights into predicting and enhancing wetland SOC persistence under drought, highlighting the role of plant-microbe-mineral interactions across microtopographic units.

Freshwater littoral wetlands are hydrologically dynamic interfaces that regulate nitrogen (N) metabolism (e.g., removal, retention, and N2O emission); however, the effect of seasonal water-level fluctuations on N2O emissions and nitrogen multifunctionality (NMF) remains poorly quantified. This hydrological variability challenges accurate estimates of greenhouse gas (GHG) emissions and complicates ecosystem management strategies that aim to balance climate mitigation with ecosystem functions and sustainability. Here, using a water-level controlled mesocosm at Poyang Lake Wetland Research Station, China, we combine static-chamber measurements, 15N isotope pairing, metagenomic binning, and an interpretable causal machine learning framework to elucidate the microbial mechanisms and environmental thresholds governing the trade-off between limiting N2O emissions and maintaining NMF. N2O flux (-27.678 to 86.791 μg m-2 h-1) was observed at the source-sink transition with rising water levels, whereas NMF was higher in both the continuously dry (0.379) and wet (0.158) zones than in zones subject to water-level fluctuations. A functional quadrant plot revealed the asynchronous relationship between N2O emissions and NMF maintenance. Metagenomic binning demonstrated that distinct dominant microbial taxa mediated N2O and NMF and their trade- off via cooperative and competitive interactions. Moreover, key thresholds, including soil organic matter contents and abundances of hao, hzsABC, nosZII, nirKS, and nasAB genes, drive the system toward a low-emissions and high-function state. This study clarifies the trade-off mechanisms between N2O emissions and NMF maintenance, and provides an ecological basis for reconciling climate mitigation with ecosystem functions in aquatic ecosystems.

Urban lakeshore zones characterized by highly spatiotemporal heterogeneity serve as critical hotspots for N2O emissions. While nosZI communities contribute to nitrous oxide (N2O) sink potential, their regulatory mechanisms in the urban lakeshores remain unexplored. Here, we investigated the variations and driving patterns of N2O fluxes and nitrogen (N) removal rates in continuously flooded (CF), semi-flooded (SF), and non-flooded (NF) zones of Pipa Lake in China during both summer and winter. Results revealed that CF zones exhibited seasonal N2O sink-source shifts (-14.73 and 9.00 mu g m(-2) hr(-1) for summer and winter, respectively) and higher potential denitrification rates (0.63-43.73 nmol N g(-1) hr(-1)) compared to SF and NF zones. These shifts were likely driven by seasonal variations in nosZI community abundance and composition in CF zones, for example, significantly reduced nosZI gene abundance (P < 0.05), and remarkably enriched taxa Azospirizaceae (40.43%) in the winter. Additionally, sediment carbon and nitrogen substrates exerted stronger direct effects on N2O emissions than indirect effects mediated by nosZI communities, while moisture regulated N2O emissions by suppressing nosZI abundance and enhancing carbon substrates. Under projected urban expansion scenarios, the CF zone would be a potential hotspot for N2O emissions, thereby exacerbating climate change. Consequently, managing sediment carbon and nitrogen substrates to modulate nosZI communities would present a viable strategy for N2O mitigation in urban lakeshores. Plain Language Summary As a potent greenhouse gas, nitrous oxide (N2O) emissions significantly contribute to the global greenhouse effect. The production and consumption of N2O are closely linked to nutrient cycling, thereby making nutrient-rich urban lakeshore areas hotspots for N2O emissions. While microbial communities carrying the nosZI gene regulate N2O emissions, their seasonal and hydrological control mechanisms remain unclear. This study investigated N2O fluxes and regulatory factors in a typical urban lake using genomics and isotope tracer techniques. Results indicated that denitrification process dominated nitrogen removal, with highest potential rates in continuously flooded (CF) zones. Seasonal N2O sink-source shifts at CF zones were driven by reduced nosZI gene abundance and enriched key microbial taxa. Sediment carbon and nitrogen substrates exerted stronger direct effects than nosZI-mediated indirect effects on N2O emissions and denitrification. Sediment moisture regulated N2O emissions via carbon substrates and nosZ1 communities. The CF zones in urban littoral areas might serve as potential N2O emission hotspots, but manipulating sediment carbon and nitrogen substrates could effectively regulate nos21 communities, thereby mitigating N2O emissions.

Climate change-induced extreme heat, flooding and drought events influence the carbon and nitrogen cycling, including the denitrifying anaerobic methane oxidation (DAMO) process which couples the nitrogen removal and methane (CH4) mitigation. To assess the impacts of 2022 record-breaking flash drought (summer FD) on the DAMO process, we collected bulk soils and Carex cinerascens-associated soils in the littoral wetlands of Poyang Lake during summer FD and winter drought. The in situ CH4 fluxes and potential DAMO rates were determined using static-chamber technique and 13C stable isotope method. The abundance, composition and metabolic pathways of DAMO archaeal and bacterial communities were investigated using quantitative PCR, high-throughput and metagenomic sequencing techniques. Higher DAMO rates (8.73 ± 3.79 and 16.03 ± 7.45 nmol 13CO2 g-1 d-1 for nitrate-DAMO and nitrite-DAMO respectively) were observed during summer FD compared to winter drought, and nitrite-DAMO (52%∼74%) dominated the DAMO processes. DAMO bacterial pmoA genes (4.7 × 104∼1.1 × 106 copies g-1 dry soil) were more abundant than DAMO archaeal mcrA genes (1.4 × 103∼1.3 × 104 copies g-1 dry soil). Nitrate- and nitrite-DAMO rates were mainly driven by temperature, available nitrogen substrate and the abundance of DAMO archaea and bacteria, possibly contributing to CH4 consumption in the littoral wetlands of Poyang Lake. Several reconstructed metagenome-assembled genomes possessing genes involved in anaerobic methane oxidation and nitrate/nitrite reduction could potentially participate in cooperative DAMO process. This study elucidates the DAMO process and microbial mechanisms under flash droughts, providing a novel insight for the carbon-nitrogen coupling and mitigation of greenhouse gases in aquatic ecosystems.

Arsenic-calcium residue (ACR) is a highly hazardous solid waste produced through the lime neutralizationprecipitation treatment of waste sulfuric acid and poses considerable environmental risks. This study proposes a sustainable stabilization strategy for the ACR by utilizing magnetite tailings and carbide slag as sources of iron (III) and neutralizing agents, respectively, to immobilize As in the form of stable scorodite. A pure magnetite reagent was initially used to explore the mechanisms and optimal conditions for As fixation within the ACR through the generation of scorodite. In contrast, magnetite tailings were subsequently employed to validate the technical feasibility of the approach. The XRD, FTIR, and FE-SEM results revealed that scorodite formation is governed by the controlled release of Fe3+ from magnetite. The slow Fe3+ supply modulates Fe-As supersaturation and promotes crystallization into environmentally stable scorodite. The stabilization process using magnetite tailings achieved a high As fixation efficiency of 97.29% in the ACR. Subsequent neutralizationprecipitation with carbide slag further reduced the concentrations of Zn, As, Pb, Cu, and Cd in the residual water to approximately 0.24, 0.28, 0.26, 0, and 0 mg/L, respectively. Both the treated solid residues and the residual water complied with Chinese environmental regulatory standards, demonstrating the industrial applicability of the proposed method. This work offers an efficient, environmentally sustainable, and cost-effective approach for stabilizing hazardous ACR.

Siderite tailings is a potentially cost-free iron (Fe) source for arsenic (As) fixation in hazardous arsenic-calcium residues (ACR) as stable scorodite. In this study, a pure siderite reagent was employed to investigate the mechanism and optimal conditions for As fixation in ACR via scorodite formation, while the waste siderite tailings were used to further demonstrate the cotreatment method. The cotreatment method starts with an introduction of sulfuric acid to the ACR for As extraction and gypsum precipitation, and is followed by the addition of H 2 O 2 to oxidize As(III) in the extraction solutions and finalized by adding siderite with continuous air injection for scorodite formation. The dissolution-oxidation of siderite can slowly produce Fe(III) to control aqueous As(V)-Fe(III) precipitation supersaturation for continuous scorodite crystallization. Chemical analyses show that the extraction efficiency of As from the ACR reaches 94.55%, while the precipitation yield of extracted As via scorodite formation arrives at 99.63% and 99.47%, leading to fixation efficiency of 94.20% and 94.04% in terms of the total As in the ACR by using siderite reagent and tailings, respectively. The final solid products show desirable TCLP stability and long-term stability, meeting the requirement for safe storage (GB 5085.3-2007). XRD, FTIR, and TEM results reveal that such high stability is attributable to the formation of scorodite and the surface adsorption of As on the raw siderite and secondary maghemite. This innovative and economical application of siderite tailings for the treatment of hazardous ACR can be extended to the management of hydrometallurgical wastes. (c) 2024 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Developing efficient, scalable electrocatalysts for the hydrogen evolution reaction (HER) is crucial for industrial H 2 production. Herein, ultrafine (≈1.7 nm) ruthenium‐cobalt (RuCo) alloys anchored on Sulfur‐vacancy‐rich 1T phase molybdenum disulfide (1T phase MoS 2‐x ) nanosheets (denoted as Ru 2 Co 1 ‐4@E‐MoS 2‐x ) are synthesized via ultrasonic microreactor (USMR) technology. The USMR strategy concurrently achieves a reduced alloy size, accelerated Ru reduction kinetics, and improved metal dispersion, endowing the resulting catalysts with high metal loading and abundant accessible active sites. Experimental and theoretical analyses reveal that Co incorporation optimizes RuCo electronic structure and strengthens interfacial coupling with 1T phase MoS 2‐x , lowering the Gibbs free energy of H * adsorption (ΔG H* ) on both Ru and Co sites. This synergistic interaction establishes bimetallic active centers that overcome the adsorption–desorption trade‐off in single‐metal systems. In situ Raman spectroscopy further confirms that Co promotes water dissociation and hydrogen desorption at Ru sites under alkaline conditions. Consequently, Ru 2 Co 1 ‐4@E‐MoS 2‐x exhibits exceptional HER activity, achieving record‐low overpotentials of 31 mV in acidic and 36 mV in alkaline media at 10 mA·cm −2 , significantly outperforming 20 wt% Pt/C (45 and 53 mV, respectively). Moreover, the USMR approach is universal, generating highly active RuM@E‐MoS 2‐x catalysts (M = Fe, Ni, Cu). This work establishes a novel “bimetallic active sites/engineered carrier” paradigm for advanced electrocatalytic water splitting.

This study investigates the effect of various SO4 2- concentrations (0, 50, and 100 mM) on the phase transformation of hydrous ferric arsenate (HFA) and partitioning behaviors of As(v), Fe(iii), and SO4 2- under ambient (25 °C, 15 d) and subsequent elevated temperature (80 °C, 35 d) conditions. The results revealed that the primary factor controlling the transformation of HFA into crystalline scorodite was the pH, whereas the SO4 2- concentration played a secondary, pH-dependent role. More specifically, at pH 4 and under ambient temperature, SO4 2- enhanced the release of As(v) and Fe(iii) into the solution. By contrast, at pH 6 and 8, SO4 2- promoted the formation of basic ferric arsenate sulfate, which immobilized As(v), and later dissolved upon heating. SO4 2- incorporation into the solid phase occurred across all pH levels and was enhanced at higher concentrations and temperatures. Thus, SO4 2- modulates As(v) mobility via structural incorporation and ion competition, with distinct behaviors at acidic versus circumneutral pH. These findings offer guidance for risk assessment and design of sulfate-rich, mining-impacted remediation systems.

Nitrous oxide （N2O） is one of the important greenhouse gases contributing to the global warming trend. As important nitrogen removal pathways， microbially mediated denitrification and anaerobic ammonia oxidation （ANAMMOX） in the rhizospheres of wetland plants can reduce nitrogen load in freshwater wetlands， and the denitrification process is the major N2O source. Littoral zone of urban lakes is an ecotone between terrestrial and aquatic ecosystems and an important area for nitrogen input and transformation. The investigation of plant-microbially mediated nitrogen removal processes and N2O emissions in the littoral zone of urban lakes is of great significance for maintaining the stability of lake ecosystems， strengthening nitrogen management， and controlling N2O emission， as well as realizing sustainable urban development. In this study， the littoral zone of Xuanwu Lake （a typical urban lake in Nanjing） was selected to compare the in situ N2O emission fluxes， potential denitrification and ANAMMOX rates， as well as the abundance， diversity， and composition of functional microbial communities associated with three dominant plants （i.e.， Nelumbo nucifera， Phragmites australis， and Dichondra micrantha） using 15N isotope pairing， real-time quantitative PCR， and high-throughput sequencing techniques. In addition， the influences of different driving factors on the potential denitrification and ANAMMOX rates and N2O fluxes were further explored in the littoral zone. The results showed that the N2O emission fluxes in the littoral zone of Xuanwu Lake ranged from 6.20 to 15.03 μg·（m2·h）-1 （D. micrantha&gt;N. nucifera&gt;P. australis）. Potential denitrification and ANAMMOX rates in the rhizosphere sediments of the three wetland plants were （8.92±4.33） nmol·（g·h）-1 and （1.03±1.17） nmol·（g·h）-1， respectively （N. nucifera&gt;D. micrantha&gt;P. australis）， and denitrification （65.55%-97.82%） was the dominant nitrogen removal process. There were significant differences in the community composition of nirK and nirS in rhizosphere sediments of the three wetland plants （ANOSIM， P&lt;0.005）， and Nitrobacteraceae （28.57%） and Zoogloeaceae （14.63%） were the dominant families in the nirK and nirS communities. The abundances of the nirS gene （1.09×109 copies·g-1） were 2 orders of magnitude higher than those of the nirK gene （3.00×107 copies·g-1）， indicating that nirS-denitrifier played a more important role in N2O emission （P&lt;0.05）. Moreover， pH， C/N， NH4+-N， and NO3--N contents drove the changes of N2O fluxes， while NO2--N， LOI， and TN contents were the main regulators of potential denitrification and ANAMMOX rates in the littoral zone of Xuanwu Lake.

The appearance of recalcitrant organic pollutants such as antibiotics in water bodies has gained a lot of attention owing to their adverse effects on organisms and humans. The current study aims to develop a novel approach to eliminate antibiotic tetracycline (TC) from a synthetic aqueous solution based on the advanced oxidation process triggered by MnSO4-catalyzed NaIO4. A single-factor experiment was performed to observe the impact of pH, NaIO4 concentration, and MnSO4 dosage on TC decomposition, and a three-factor, three-level response surface experiment with TC removal rate as the dependent variable was designed based on the range of factors determined from the single-factor experiment. The single-factor experiment revealed that the ranges of pH, NaIO4 concentration, and MnSO4 dosage need to be further optimized. ANOVA (analysis of variance) results showed that the data from the response surface experiment were consistent with the quadratic model with high R2 (0.9909), and the predicted values were very close to the actual values. After optimization by response surface methodology, the optimal condition obtained was pH = 6.7, [NaIO4] = 0.39 mM, and [MnSO4] = 0.12 mM, corresponding to a TC removal of 96.56%. This optimization condition was fully considered to save the dosage of the high-priced chemical NaIO4.

Smart dressings integrated with bioelectronics have attracted considerable attention and become promising solutions for skin wound management. However, due to the mechanical distinction between human body and the interface of electronics, previous smart dressings often suffered obvious degradation in electrical performance when attached to the soft and curvilinear wound sites. Here, we report a stretchable dressing integrated with temperature and pH sensor for wound status monitoring, as well as an electrically controlled drug delivery system for infection treatment. The wound dressing was featured with the deployment of liquid metal for seamless connection between rigid electrical components and gold particle-based electrodes, achieving a stretchable soft-hard interface. Stretching tests showed that both the sensing system and drug delivery system exhibited good stretchability and long-term stable conductivity with the resistance change rate less than 6% under 50% strain. Animal experiments demonstrated that the smart dressing was capable of detecting bacterial infection via the biomarkers of temperature and pH value and the infection factors of wound were significantly improved with therapy through electrically controlled antibiotics releasing. This proof-of-concept prototype has potential to significantly improve management of the wound, especially those with dynamic strain.

Rapid and precise detection of harmful substances in food products is essential for ensuring public health and safety. This study introduces a novel surface-enhanced Raman spectroscopy (SERS) substrate, composed of a molybdenum disulfide-silver nanocomposite, applied to flexible, water-resistant filter paper for detecting melamine and bisphenol A (BPA) in milk. Optimized molybdenum disulfide (NMS) nanoflowers (NFs) were synthesized through hydrothermal methods and high-temperature annealing, then modified with silver (Ag) nanoparticles to form the NMS-Ag nanocomposite (NMSA6). This substrate greatly enhances the Raman signal, achieving an enhancement factor of approximately 1.49 x 107 and a detection limit as low as 10-11 M for simultaneous multi-component analysis. Finite-difference time-domain (FDTD) simulations confirm the enhancement mechanism. The NMSA6 substrate demonstrates remarkably low detection limits for BPA and melamine, facilitating the analysis of various hazardous substances. These findings highlight the substrate's potential for highly sensitive, label-free detection, presenting a viable tool for food safety monitoring.

The attenuation of acidic Se(IV)-rich wastewater, including those associated with acid mine drainage (AMD) and nonferrous metallurgical wastewater (NMW), presents a serious environmental challenge. This study investigates the effects of diverse factors from pH values to Se(IV)/Fe(III) molar ratios, initial Se(IV) concentrations, and alkali neutralization agents on the direct co-precipitation of ferric selenites in AMD and NMW systems involving different orders of Fe(III) and alkali addition. Our results show that amorphous sulfate-substituted ferric (hydrogen) selenite and Se(IV)-bearing ferrihydrite-schwertmannite are the major Se(IV)-attenuation solids except that gypsum is an additional phase in the NMW system with Ca(OH)2 neutralization. Produced ferric selenites achieve 98-99.8% of Se(IV) immobilization under optimal conditions of pH 4.5, Se(IV)/Fe(III) molar ratios of 0.0625-0.5, and initial Se(IV) concentrations of 0.15-1.3 mmol·L-1. Moreover, completing FeSO4+ and FeHSeO32+/FeSeO3+ complexes as well as different ferric selenite co-precipitates are shown to collectively control aqueous Se(IV) remaining. Specifically, three distinct trends of aqueous Se(IV) concentrations separately correspond to changes in the four factors. The co-precipitation in the NMW system via pH adjustment followed by Fe(III) addition is more efficient for Se(IV) fixation than that in the AMD system because of minimal complexation, concurrent Fe(III) hydrolysis, and enhanced ferric selenite co-precipitation in the former.

Arsenic-alkali slag (AAS) is one of the most hazardous solid wastes generated by the antimony smelting process, posing a significant environmental risk. However, the economic method for effective As immobilization in AAS is still lacking. In this study, we proposed an economical and novel method for the removal of As from AAS using siderite (FeCO3). After the sodium carbonate is recovered from the AAS leaching liquor, the process continues. Aqueous As(V) is immobilized as scorodite via continuous dissolution-oxidation of siderite (FeCO3) by air injection. The residual As(V) is immobilized via Fe-As coprecipitation by lime neutralization. The dissolution-oxidation of siderite produces Fe(III), ensuring continuous Fe(III)-As(V) coprecipitation and scorodite crystallization. The results showed that the removal efficiency of As from AAS reached 99.98%. The mixture of scorodite and Fe-As coprecipitation demonstrated good As stability in the Toxicity Characteristic Leaching Procedure (2.6 mg/L) and at pH 4 (1.84 mg/L), pH 6 (2.13 mg/L), and pH 8 (3.20 mg/L) in a 50-d long-term stability test. Combined results from chemical analysis, X-ray diffraction, and infrared spectroscopy revealed that the existence of high ionic strength Na+ and Cl- were the critical factors in the dissolution of siderite and the crystallization of scorodite. This study provides an effective treatment method for the removal and fixation of arsenic in metallurgical AAS.

Atomically ordered intermetallic compounds (OICs) have aroused remarkable interests for wide applications and are considered as very promising materials for electrocatalysis owing to the strict stoichiometry, well-defined atom binding environment, and the specific crystalline phase. However, the tunable synthesis of the intermetallics remains a giant challenge. Herein, this study reports the preparation of the Pd-Sn OICs composed of an interconnected nanowire network structure with adjustable molar ratios of elements Pd and Sn. The co-reduction of Pd(acac)2 and SnCl2·2H2O in ethylene glycol (EG) in the presence of sodium hypophosphite (NaH2PO2) as the reducing agent affords OICs of three phases: hexagonal Pd3Sn2-P63/mmc, orthorhombic PdSn-Pnmb, and orthorhombic PdSn2-Aba2. Also, the pure phase can convert to two mixed phases (Pd3Sn2/PdSn and PdSn/PdSn2) by just altering the feed ratio. It is found that orthorhombic PdSn-Pnmb OIC has a large electrochemically active surface area (ECSA), excellent electrocatalytic performance (4857 mA mgPd−1), and outstanding stability toward ethanol oxidation reaction (EOR), which could be attributed to its optimal electronic structure. These results demonstrate that the phase engineering of OICs with desired components is an excellent way for catalysts design.

Water environment pollution caused by a large amount usage of bisphenol A (BPA) in industry has attracted widespread attention, since BPA may destroy the endocrine system of organisms and even the human body. Peroxymonosulfate (PMS) catalyzed by biochar (BC) for the removal of emerging pollutants (including BPA) from water body has entered the researcher's field of vision. A ferric chloride- modified rice husk BC was prepared via one pot method and characterized by BET, SEM, XPS, and Raman spectroscopy. A series of batch experiments were conducted to investigate the performance, influencing factors, and reaction mechanism of BC/PMS system for the degradation of BPA. The results showed that more than 97 % of BPA was removed with 1.0 g/L F2BC3 and 1.6 g/L PMS from the artificial solution containing 20 mg/L BPA within 150 min at different pH (3, 6, and 10); the degradation of BPA was not associated with humic acid (HA), was inhibited by HCO3-, NO3-, H2PO4-, and Cl- (at low concentration), and was promoted by Cl- (at high concentration) based on the concentration range set in this study; the removal rate of BPA by F2BC3/PMS decreased from 94.3 % to 84.8 % after four cycles of F2BC3, which meant stable performance was demonstrated. It could be confirmed that BPA was degraded into intermediates and final products H2O and CO2 via co-attack of major free radicals (SO4 center dot-, (OH)-O-center dot, and O-2(center dot-)) and minor non-radical O-1(2). Therefore, F2BC3/PMS system could be considered as a potential process for the treatment of BPA.

Hydrometallurgical iron-arsenic (Fe–As) coprecipitation residue (FACR), a massive industrial solid waste, is a potentially cheapest Fe(III) source for the removal and fixation of As in waste sulfuric acid (WSA) as stable scorodite. This study innovatively proposed a method by controlling a low supersaturation degree of ferric arsenate in WSA via stepwise addition and slow dissolution of FACR, ensuring continuous ferric arsenate precipitation and scorodite crystallization. The results showed that As removal efficiency in WSA reached 99.92%. The decrease in the weight of solid waste was up to 37.1%. X-ray diffraction and infrared spectroscopy results indicated that scorodite is the principal crystalline As mineral in the products. The solid products displayed excellent stability with the TCLP concentrations of leached As and divalent metals (CuII, PbII, ZnII, and CdII) far below the US-EPA regulatory limits. Scanning/Transmission electron microscopy and X-ray photoelectron spectroscopy results revealed that such high TCLP stability could be ascribed to the adsorption of As and trace divalent metals on the raw/secondary Fe-(oxy)hydroxide minerals, such as FeO(OH), goethite, and ferrihydrite. This work provides an economical and efficient method for simultaneous treatment of WSA and FACR, which can support the sustainable development of the hydrometallurgical industry.