Deciphering the structure-activity relationship of ternary transition metal chalcogenides is crucial for the development of heterogeneous Fenton-like catalysts. However, the facet-dependent mechanism of ternary metal sulfides such as Cu2WS4 in Fenton-like systems has not yet been elucidated. Herein, we report a facet-controlled Cu2WS4 catalyst synthesized through a one-pot solvothermal strategy, aiming to reveal the structure-activity relationship during H2O2 activation. The results demonstrate that Cu2WS4 dominated by the {101} facet (L-Cu2WS4) exhibits excellent tetracycline (TC) degradation performance, with degradation rates being 6.15- and 1.24-fold higher than those of its {001}-exposed counterpart (S-Cu2WS4) and the classical Fenton system (Fe2+/H2O2), respectively. Theoretical calculations combined with experimental analysis indicate that the {101} facet possesses stronger adsorption affinity and a lower H2O2 activation energy barrier, which promotes the formation of high-valent copper through non-radical pathways, while the {001} facet is prone to adsorb O2, inhibiting the effective utilization of H2O2 and resulting in reduced catalytic activity. The Cu(III)-dominated mechanism enables the L-Cu2WS4/H2O2 system to operate over a wide pH range (4.08-9.05), exhibit exceptional stability over 5 cycles, and maintain excellent catalytic activity in complex water bodies. Additionally, toxicity tests confirm the detoxification of the treated TC solution, and continuous-flow experiments further demonstrate the application potential of this system in actual water treatment. This study deepens the understanding of the facet-dependent mechanism in Fenton-like reactions and establishes a paradigm for the precise design of copper-based catalysts for water purification.

This study developed a self-supported, binder-free fluorine-modified ferric phosphate (F-FeP) cathode to enhance heterogeneous electro-activation of peroxymonosulfate (PMS) for the degradation of sulfamethazine (SMT). Compared with the iron foam (IF) as the cathode system, the F-FeP/PMS/EC system demonstrated a significant reduction of 98.6% in iron leaching rate, resulting in a much lower iron leaching amount of 0.47 mg/L, while achieving complete degradation of SMT (5 mg/L) within 30 min. It demonstrated that the F-FeP cathode exhibited improved stability and effectively accelerated the Fe2+/Fe3+ cycle on its surface. Quenching experiments identified sulfate radicals (SO4 center dot-) and high-valent iron (Fe(IV)) as the dominant reactive species responsible for SMT degradation in F-FeP/PMS/EC system. Degradation pathways of SMT were proposed based on the intermediates detected. Furthermore, the luminescent bacteria test and toxicity prediction of intermediates indicated that the biotoxicity of SMT was reduced through the degradation. Finally, the practicality evaluation results demonstrated that the F-FeP/PMS/EC process is a promising approach for the rapid remediation of antibiotic-contaminated water.

There exists a mutually reinforcing relationship between sludge and corn cob, and their combined treatment products have high potential for application. This paper focuses on the comprehensive characterization of the properties of the combined high-temperature carbonization products of sludge and corn cob and explores the effectiveness of high-temperature carbonization on the main pollutant indexes in the water treatment process. The optimal ratio (W sludge: W corncob = 4:1) of dried corn cob sludge high-temperature carbonization (SJC) prepared at pyrolysis temperature (800 degrees C), heating rate (5 degrees C/min) and holding time (120 min) was used as the experimental group, and pure sludge high-temperature carbonization (SSC) was used as the control group, and the adsorption effect and adsorption mechanism of SJC and SSC on COD and NH4'-N in the concentration range of simulated domestic wastewater were investigated. The adsorption effects of SJC and SSC on COD and NH4'-N in the concentration range of simulated domestic wastewater were investigated. The results showed that the adsorption amount of COD and NH4'-N by SJC was larger than that of SSC, and the removal rate of SJC for COD solution with an initial concentration of 300 mg/L could be more than 50% at 298 K, and that of NH4'-N solution with a concentration of 40 mg/L could be up to 70%.

This study presents a novel Basalt-based grafted graphitic carbon nitride composite (Basalt–MTES/g-C3N4) for the efficient pretreatment of Cr(VI) in ethylene wastewater. The composite was synthesized by the acid purification of natural Basalt, surface modification with hydroxymethyl triethoxysilane (MTES), and the subsequent grafting of g-C3N4. Characterization confirmed the uniform distribution of nano-sized g-C3N4 particles on a Basalt surface with intact chemical bonding, where 82.63% of melamine participated in g-C3N4 crystallization. The material exhibited a high specific surface area (403.55 m2/g) and mesoporous structure (34.29 nm). Acidic conditions promoted the protonation of amino groups in g-C3N4, significantly enhancing Cr(VI) adsorption via ion exchange. Adsorption kinetics followed the pseudo-second-order model, while isotherm data fitted the Langmuir monolayer adsorption mechanism. The composite achieved 97% Cr(VI) recovery through chromatographic extraction and retained 96.87% removal efficiency after five regeneration cycles. This work demonstrates a cost-effective, recyclable green pretreatment material for high-sensitivity Cr(VI) monitoring in ethylene industry wastewater, offering dual benefits in environmental remediation and regulatory compliance. The design synergizes natural Basalt’s stability with g-C3N4’s adsorption affinity, showing practical potential for sustainable wastewater treatment technologies.

In situ chemical oxidation (ISCO) is a promising technology to remove the organic pollutants from groundwater on site. In order to ensure the sustainable and long-term treatment performance, the oxidant controlled-release materials (CRMs) are required. In this study, a novel environmentally friendly and low-cost peroxydisulfate CRM (XG/CS-PDS) was synthesized via the mixing and mold method with xanthan, polyvinyl alcohol and chitosan as the binders for the first time. The XG/CS-PDS possessed significantly stable controlled-release properties under different pH and co-anions. 80% PDS in the CRMs could continuously and slowly release within 50 days. The simulation of PDS controlled-release process indicated that the process was controlled by the non-Fickian diffusion. Then the as-prepared CRM was applied to remove tetracycline (TC) from synthesized groundwater with nanoscale zero-valent iron (nZVI) as the PDS activator. The XG/CS-PDS/nZVI system could achieve 100% removal efficiency at different initial TC concentrations (5-40 mg/L) and had a good anti-interference ability to pH, inorganic co-anions and humic acid. The quenching experiments and electron spin resonance (ESR) revealed that SO4 center dot-, center dot OH and 1O2 were the main reactive oxygen species (ROS) for the degradation of TC, while SO4 center dot- played the more dominant role. The intermediates and possible degradation pathway of TC were proposed and the toxicity of TC and its intermediates were evaluated. This study provided a new conception for the design of controlled-release material and theoretical strategies for in-situ remediation of groundwater.

Numerous chlorinated disinfection by-products (DBPs) are produced during the chlorination disinfection of water. Among them, chloroacetic acids (CAAs) are of great concern due to their potential human carcinogenicity. In this study, effective electrocatalytic dechlorination of trichloroacetic acids (TCAA), a typical CAAs, was achieved in the electrochemical system with the three-dimensional (3D) self-supported CoP on cobalt foam modified by carbon nanotubes (CNT/CoP/CF) as the cathode. At a 10 mA cm-2 current density, 74.5% of TCAA (500 μg L-1) was converted into AA within 100 min. In-situ growth of CoP increased the effective electrochemical surface area of the electrode. Electrodeposited CNT promoted electron transfer from the electrode surface to TCAA. Therefore, the production of surface-adsorbed atomic hydrogen (H*) on CNT/CoP/CF was improved, further resulting in excellent electrochemical dechlorination of TCAA. The dechlorination pathway of TCAA proceeded into acetic acids via direct electronic transfer and H*-mediated reduction on CNT/CoP/CF electrode. Additionally, the electroreduction efficiency of CNT/CoP/CF for TCAA exceeded 81.22% even after 20 cycles. The highly efficient TCAA reduction performance (96.57%) in actual water revealed the potential applicability of CNT/CoP/CF in the complex water matrix. This study demonstrated that the CNT/CoP/CF is a promising non-noble metal cathode to remove chlorinated DBPs in practice.

Currently, the pharmaceutical and personal care products (PPCPs) have posed great challenge to advanced oxidation techniques (AOTs). In this study, we decorated sponge iron (s-Fe0) with Cu and Pd (s-Fe0-Cu-Pd) and further optimized the synthesis parameters with a response surface method (RSM) to rapidly degrade diclofenac sodium (DCF). Under the RSM-optimized conditions of Fe: Cu: Pd = 100: 4.23: 0.10, initial solution pH of 5.13, and input dosage of 38.8 g/L, 99% removal of DCF could be obtained after 60 min of reaction. Moreover, the morphological structure of trimetal was characterized with high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS). Electron spin resonance (ESR) signals have also been applied to capture reactive hydrogen atoms (H*), superoxygen anions, hydroxyl radicals, and single state oxygen (1O2). Furthermore, the variations of DCF and its selective degradation products over a series of s-Fe0-based bi(tri)metals have been compared. Additionally, the degradation mechanism of DCF has also been explored. To our best knowledge, this is the first report revealing the selective dechlori-nation of DCF with low toxicity over Pd-Cu co-doped s-Fe0 trimetal.

Electrocatalytic denitrification is an attractive and effective method for complete elimination of nitrate (NO3-). However, its application is limited by the activity and stability of the electrocatalyst. In this work, a novel bimetallic electrode was synthesized, in which N-doped graphitized carbon sealed with Cu and Fe nanoparticles and immobilized them on nickel foam (CuFe NPs@N-C/NF) without any chemical binder. The immobilized Cu-Fe nanoparticles not only facilitated the adsorption of the reactant but also enhanced the electron transfer between the cathode and NO3 -, thus promoting the electrochemical reduc-tion of NO3 -. Therefore, the as-prepared electrode exhibited enhanced electrocatalytic activity for NO3 - reduction. The composite electrode with the Cu/Fe molar ratio of 1:2 achieved the highest NO3- removal (79.4 %) and the lowest energy consumption (0.0023 kW h mg-1). Furthermore, the composite electrode had a robust NO3- removal capacity under various conditions. Benefitting from the electrochlorination on the anode, this electrochemical system achieved nitrogen (N2) selectivity of 94.0 %. Moreover, CuFe NPs@N-C/NF exhibited good stability after 15 cycles, which should be attributed to the graphitized car-bon layer. This study confirmed that CuFe NPs@N-C/NF electrode is a promising and inexpensive elec-trode with long-term stability for electrocatalytic denitrification.(c) 2022 Elsevier Inc. All rights reserved.

The conventional Fenton-like system (Fe(III)/H2O2) is severely limited by the inferior activity of Fe(III) on H2O2 activation to produce highly active species and the sluggish regeneration rate of Fe(II). This work significantly enhanced the oxidative breakdown of the target organic contaminant bisphenol A (BPA) by Fe(III)/H2O2 by introducing cheap CuS at a low dose of 50 mg/L. The BPA removal (20 mg/L) in CuS/Fe(III)/H2O2 system reached 89.5 % within 30 min under the optimal conditions: CuS dosage 50 mg/L, Fe(III) concentration 0.05 mM, H2O2 concentration 0.5 mM and pH 5.6. Compared to CuS/H2O2 and Fe(III)/H2O2 systems, the reaction constants had a 47- and 12.3-fold enhancement, respectively. Even compared with the conventional Fe(II)/H2O2 system, the kinetic constant also increased more than twice, further confirming the distinctive superiority of constructed system. Element species change analyses showed that Fe(III) in solution was adsorbed onto the CuS surface, and then Fe(III) was rapidly reduced by Cu(I) in the CuS lattice. Combining CuS and Fe(III) (in-situ formed CuS-Fe(III) composite) created a robust co-effect on the activation of H2O2. Also, S(-II) and its derivatives, e.g., Sn2- and S0 (as an electron donor), could quickly reduce Cu(II) to Cu(I) and ultimately oxidize to the harmless product SO42-. Notably, a mere 50 μM of Fe(III) was sufficient to maintain enough regenerated Fe(II) to effectively activate H2O2 in CuS/Fe(III)/H2O2 system. In addition, such a system achieved a broad range of pH applications and was more suitable for real wastewater containing anions and natural organic matter. Scavenging tests, electron paramagnetic resonance (EPR), and probes further verified the critical role of •OH. This work provides a new approach to solving the problems of Fenton systems through a solid-liquid-interfacial system design and exhibits considerable application potential in wastewater decontamination.

Salts including NaCl are the most common food flavoring agents so they are often accumulated in food waste (FW) and have potential impact on anaerobic digestion (AD) of FW. In this study, the enhanced biogas production from two-stage anaerobic digestion (TSAD) of FW by microscale zero-valent iron (ZVI) under different salinity (3, 6, 9, and 15 g NaCl/L) was evaluated. Under salinity stress, ZVI becomes a continue-release electron donor due to the enhanced corrosion and dissolution effect and the slow-down surface passivation, further improving the performance of TSAD. Experimental results revealed that the biogas production including H2 and CH4 from TSAD with 10 g/L ZVI addition was promoted under salinity stress. The maximum H2 and CH4 yield (303.38 mL H2/g-VS and 253.84 mL CH4/g-VS) were observed at the salinity 9 g NaCl/L. Compared with that of zero salinity, they increased by 40.94% and 318.46%, respectively. Additionally, Sedimentibacter, an exoelectrogen that can participate in the direct interspecies electron transfer, also exhibited the highest relative abundance (34.96%) at the salinity 9 g NaCl/L. These findings obtained in this study might be of great importance for understanding the influence of salinity on the enhanced AD by ZVI.

The practical application of the traditional Fenton system (Fe(II)/ H2O2) is seriously hampered by the sluggish Fe(III)/Fe(II) cycle and the stringent acidic reaction condition. In this work, we found that trace-dissolved S(-II) (DS( II), 5 mu M) could significantly accelerate the Fe(III)/Fe(II) cycle and trigger a rapid H(2)O(2 )activation process in the Fe(III)/H2O2 system. Thus, more hydroxyl radicals (OH) were generated for the rapid removal of various organic pollutants such as bisphenol A (BPA) and sulfamethoxazole (SMX) from water. Besides, the additive DS(-II) effectively broadened the application pH range of the Fenton or Fenton like system. The constructed Fe(III)/DS(-II)/H2O2 system showed extensive applicability to different water matrices and maintained high BPA removal in the actual water sources. Furthermore, the toxicity assessment revealed that the toxicity of the target contaminant was diminished. The harmless SO42- was the final product of DS(-II) in the Fe(III)/DS(-II)/H2O2 system, and the residual DS(-II) was less than the threshold limit value for fresh or saltwater (0.5 mg/L). This discovery is expected to promote the large-scale practical application of iron-based Fenton or Fenton-like systems in practical organic wastewater purification.

Carbonaceous material is not only the excellent adsorbent for organic contaminants removal, but also the effective activator for peroxydisulfate (PDS) activation. In this study, a nitrogen-doped hierarchical porous carbon material (NHGBC-800) presented the attractive bifunctional properties was developed for the removal of model organic contaminant antibiotic tetracycline (TC). On the one aspect, the NHGBC-800 had a large specific surface area (1178.0 m2/g) and achieved good TC removal with a maximal adsorption capacity (Qm) of 629.76 mg/g at 303 K. On the other aspect, TC-saturated NHGBC-800 could effectively activate PDS with itself as the activator, by which the mineralization of desorbed TC and in-situ regeneration of exhausted adsorbent were achieved simultaneously. The Qm of NHGBC-800 recovered 90.61% after first regeneration and still retained 77.18% even after the 6th adsorption-regeneration cycles. Moreover, the as-prepared material maintained good adsorption and regeneration performance under a wide range of pH conditions (3.02-9.83) and in the presence of inorganic anions such as Cl-, SO42-, NO3- , H2PO4- , HCO3- . The electro spin resonance (ESR), reactive oxygen species (ROS) quenching studies and electrochemical measurement revealed that the electron-transfer and single oxygen mediated the non-radical pathways dominated the TC degradation during the regeneration process. Compared with the conventional thermal and electrochemical regenerations, the in-situ regeneration of bifunctional carbon materials induced by PDS activation is more effective, sustainable and environmental-friendly.

The cathode with low-energy consumption and long-term stability is pivotal to achieve the conversion of nitrate (NO3-) to nitrogen (N2) by electrocatalytic denitrification. Herein, a binder-free electrode was synthesized by directly immobilizing N-doped graphitized carbon layer-encapsulated NiCu bimetallic nanoparticles on nickel foam (NF) (NiCu@N-C/NF) and served as the cathode for electrocatalytic NO3- reduction. Morphological characterization indicated that Ni and Cu nanoparticles were encapsulated by the N-doped graphitized carbon layer and well-dispersed on the surface of NF. Compared with monometallic composite cathode (Cu@N-C/NF and Ni@N-C/NF), NiCu@N-C/NF exhibited better NO3- removal performance (98.63 %) and lower energy consumption (0.007 kW.h mmol(-1)), which should be attributed to its strong adsorption ability to NO(3)(- )and excellent electron transfer property. Meanwhile, its electrocatalytic performance could be maintained in wide initial NO(3)(- )concentration (1.79-7.14 mM) and solution pH (3-11). With the assistance of electrochlorination, the N-2 selectivity of electrochemical system was up to 99.89 % in the presence of 0.028 M Cl-. More importantly, NiCu@N-C/NF electrode displayed an ultra-high stability during ten recycling experiments. This study indicated that the binderless composite cathode NiCu@N-C/NF had great potential in electrocatalytic NO3- removal from wastewater.

A nitrogen(N)-rich hierarchical porous graphite carbon (NHC) was synthesized at different hydrothermal carbonization temperature (400, 600 and 800 C) using a template-free and solvent-free method. The as prepared materials possessed perfect bifunctional performance for tetracycline (TC) removal via synergistic adsorption and catalytic activation of peroxydisulfate (PDS). The carbonization temperature had a significant effect in the material structure and property adjustment. The carbonaceous material prepared at 800 C (NHC800) showed optimal adsorption and catalytic activation of PDS efficiency with 451.62 mg/g maximum TC adsorption capacity and 69.5% TC mineralization rate within 180 min. The pseudo-first-order rate constant for NHC-800 (0.0406 min-1) was 111.54-folders higher than NHC-400 (3.6400 x 10-4 min-1). Moreover, the NHC800/PDS system had a good anti-interference ability to pH, inorganic anions and humic acid. The investigation of catalytic mechanism revealed that the nonradical process governed PDS activation process with defective edges, C--O, graphitic N and pyridinic N as the active redox sites, while the large surface area of NHC-800 or the activated C(+) supported the adsorption of pollutants or PDS, further facilitated the electron-transfer process. Finally, the possible degradation pathway was proposed and the acute toxicity of degradation intermediates was assessed. This study not only provides a facile route for the synthesis carbonaceous materials, but also gives a detailed insight in N species and other reactive sites of carbonaceous materials in adsorption and catalytic degradation process.

The activation of peroxymonosulfate (PMS) by Fe(II) or Fe(III) for environmental decontamination is severely limited by the low conversion rate from Fe(III) to Fe(II). Here, we found that this puzzling problem could virtually be solved by introducing trace amounts of S2-. With the addition of 0.2 mM S2-, the bisphenol A (BPA) degradation efficiency and total organic carbon (TOC) removal in PMS/Fe(III) system were improved by 3.8 and 6.0 times, respectively. Meanwhile, the kobs and PMS utilization efficiency also markedly increased by 650% and 160%, respectively. The constructed PMS/Fe(III)/S2- system exhibited a good applicability to a wide pH range (3.2 ~ 9.5) and high resistance to humic acid, Cl- and NO3-. The main reactive oxidant species in PMS/Fe(III)/S2- system were identified by scavenging experiments, electron paramagnetic resonance measurement, chemical probe approach, and 18O isotope-labeling technique. The identification results revealed that FeIVO2+ was the primary reactive oxidant species, while •OH, SO4•-, O2•- and 1O2 were also involved in the degradation of BPA. Finally, the generalizability of PMS/Fe(III)/S2- system was evaluated by varying the target pollutants, oxidants, and reducing S species. The construction of PMS/Fe(III)/S2- system provides some insights into the treatment of organic wastewaters containing S2-, e.g., from refineries and tanneries.

Achieving advanced treatment of phosphorus (P) to prevent water eutrophication and meet increasingly stringent wastewater discharge standard is an important goal of water management. In this study, a low-cost, high-efficiency phosphate adsorbent zirconium-modified biochar (ZrBC) was successfully synthesized through co-precipitation method, in which the biochar was prepared from the pyrolysis of peanut shell powder. ZrBC exhibited strong adsorption ability to low-concentration phosphate (< 1 mg·L−1) in water, and the phosphate removal reached 100% at the investigated dosage range (0.1–1.0 mg·L−1). The adsorption process could be described well by pseudo-second-order model and Langmuir isotherm model, indicating that the phosphate adsorption by ZrBC was mainly a chemical adsorption and single-layer adsorption process. The calculated static maximum phosphate adsorption capacity was 58.93 mg·g−1 at 25 °C. The ligand exchange between surface hydroxyl groups and phosphate was the main mechanism for the phosphate adsorption on ZrBC. The presence of coexisting anions except for SO42− had little effect on the phosphate removal. At the column experiment, ZrBC showed superior treatment capacities for simulated secondary effluents and the breakthrough time for 0.5 mg·L−1 effluent phosphate concentration reached 190 h. ZrBC highlights the potential as an effective and environment-friendly adsorbent for the removal of low-concentration phosphate from secondary effluents of municipal wastewater treatment plants (WWTPs).

Although Co3O4-based non-noble metal electrodes have caused wide concern in electrochemical denitrification, the electrocatalytic activity and stability of these materials are still unsatisfied. In this work, a self-supported electrode (Co3O4/CF) was first fabricated via in-situ growth of needle-like Co3O4 on the cobalt foam (CF) and then used as cathode for electrochemical denitrification. The physicochemical and electrochemical characters of Co3O4/CF could be regulated by calcination temperature. Owing to the needle-like structure and the internal contact between Co3O4 and CF, the as-prepared Co3O4/CF-600 electrode exhibited excellent electrochemical performances for NO3- removal. The influences of current density, initial NO3- concentration, solution pH, and additive Cl- concentration on electrochemical NO3- reduction were considered. A high NO3- removal efficiency (72.9%) and N2 selectivity (96.2%) were achieved by Co3O4/CF-600 electrode under the optimum conditions: current density 5 mA/cm2, Cl- concentration 1500 mg/L and initial NO3- concentration 50 mg N/L. The cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) confirmed that electrochemical denitrification was mainly realized via Co2+-Co3+-Co2+ redox process instead of H*-mediated indirect process. Moreover, the Co3O4/CF electrode material could keep its electrochemical properties even after 10 cycles.

Focusing on low biogas yields in the anaerobic co-digestion of waste activated sludge and food waste, the enhancing effects and mechanisms of microscale zero valent iron (mZVI) on anaerobic co-digestion was investigated. The results indicated that the addition of mZVI enhanced the methanogenesis stage of co-digestion but had no significant effect on the solubilization, hydrolysis, and acidification stages. With a dosage of 10 g·L-1 mZVI, the cumulative methane yield (based on VS) within 15 days reached 238.68 mL·g-1, which was 20.05% higher than the control group. The mechanism analysis showed that mZVI promoted electron transport system (ETS) activity (based on INTF/TS), which increased to 21.50 mg·(g·h)-1 with 10 g·L-1 mZVI compared to 13.43 mg·(g·h)-1 in the control group. Furthermore, mZVI enhanced direct interspecies electron transfer (DIET) between specific bacteria and methanogens. Microbial community analysis demonstrated that the abundance of DIET-related microorganisms, such as Syntrophomonas, Methanosarcina, and Methanobacterium, was higher in presence of mZVI.