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[Display omitted] • ∼100 % PFOA and 80.01 % PFOS defluorination were observed within 3 h. • The ROS couldn't initiate the PFOA degradation without additional energy. • The US/EO/ROS together initiated the first-step for complete PFOA defluorination. • The indirect ROS oxidation was dominant instead of the direct EO oxidation. • The US enhanced the ROS generation and direct oxidation ability of EO. Ultrasound (US)-assisted electrochemical oxidation (EO) has previously demonstrated its ability to degrade perfluorooctanoic acid (PFOA). However, the mechanisms of direct electron transfer and indirect oxidation by reactive oxygen species (ROS), as well as the involvement of these ROS, are unclear, particularly with the peroxydisulfate (PDS) electrolyte and the added effect of US. In this study, an US/EO/PDS system was first investigated, achieving nearly 100 % and 80.01 % defluorination for PFOA and perfluorooctane sulfonate, respectively (within 3 h). This US/EO/PDS system exhibited remarkable stability, pH tolerance, and practicality. Further experimental and theoretical studies revealed that the predominant mechanism of PFOA defluorination was indirect oxidation via ROS, rather than direct oxidation at the anode. Although none of these ROS could initiate the degradation of PFOA without additional energy, both ROS (S O 4 ∙ - ＞ •OH ＞ 1O 2 ＞ O 2 ∙ -) and US/EO contributed to the initial step of PFOA defluorination. Furthermore, US enhanced the generation of ROS and the direct oxidation (electron transfer) ability of EO. The electrons were transferred from PFOA to PDS via the electrode assembly. This study clarified, for the first time, the synergistic effect of US/EO/PDS and the involvement of direct and indirect ROS oxidation in defluorination of PFOA, which shows potential for developing US and EO technology for complete degradation of polyfluoroalkyl substances. [ABSTRACT FROM AUTHOR]

[Display omitted] • Organic and inorganic OBPs were formed during electrochemical oxidation of wastewater. • Wastewater (Cl-, organic matter) and anode ((non)active) types affect OBPs formation. • Optimizing operate parameters (acidic pH and low current) can reduce OBPs formation. • Quenching free chlorine and developing chlorine-inert anode minimize OBPs formation. • The formed OBPs can be post-treated by electrochemical or microbial reduction. Electrochemical oxidation (EO) is an emerging technology for treating recalcitrant wastewater owing to its high efficiency and mild operational conditions. However, the formation of toxic oxidation byproducts (OBPs) poses a great challenge in EO applications. This paper aims to provide a comprehensive review of OBPs formation and potential control strategies, both qualitatively and quantitatively. Correlation analyses reveal that the concentrations of Cl- and types of organic matter have significant effects on organic OBPs formation, while electrode materials influence inorganic OBPs formation. Some experiences learned from disinfection byproducts could help better understand OBP toxicity and develop potential removal methods. OBPs may be controlled through minimizing OBPs formation or post-treatment of the formed OBPs. Both acidic pH and lower current density help mitigate OBPs production. Free chlorine can be quenched through electrochemically generated H 2 O 2 to decrease OBPs formation. Chlorine-inert anode electrodes like graphene-based materials are being developed to achieve efficient EO performance without OBPs formation. Post-treatment technologies include electrochemical reduction and microbial reduction, which can be synergistically integrated with EO. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel heterogeneous Fenton system based on Cu species was established. • Significant role of pH adjustment in removing HA and FA from Landfill Leachate was revealed. • Removal efficiency of HA component reached 100% according to PARAFAC. Mature landfill leachate contains large quantities of a wide range of hazardous and refractory pollutants, especially humic acid-like (HA) and fulvic acid-like (FA) substances. These have poor biodegradability and a considerable ultraviolet-light quenching capacity, severely inhibiting the performance of wastewater treatment and post ultraviolet-light disinfection, but this aspect has attracted little previous research. The Fenton reaction has proved to be a feasible method for removing ultraviolet-quenching substances (UVQSs) but in conventional systems it is unable to completely mineralize organic contaminants. In this study, a novel electro-oxidation process was developed consisting of a flow-through reactor with a Cu 2 O cathode to catalyze Fenton-type reactions, and oxidation at a RuO 2 anode. The combination of pH adjustment and electro-oxidation was evaluated for the treatment of real ultrafiltration (UF) filtrate of mature landfill leachate. A series of analytical techniques were used to determine the performance for the removal of HA and FA. Under optimal conditions, the elimination of fluorescence characteristics of HA and FA reached 100 % and 99.3 %, respectively, according to PARAFAC results based on EEM spectra. TOC was removed by 25.5 %∼30.4 % during the pH adjustment step and 51 % by electrochemical oxidation. Changes in the molecular weight distribution and fluorescence content showed that pH adjustment played an important and significant role in removing UVQSs, and the remaining TOC after electrochemical oxidation was attributed to bioavailable amino acid-like substances. Overall, the results have demonstrated the successful development of an effective method of treating the UF filtrate from mature landfill leachate, with particular respect to the removal of the problematic HA and FA content. [ABSTRACT FROM AUTHOR]

[Display omitted] • ED was coupled with AC for enhancing chlorine-resistant bacteria inactivation. • ED/AC had synergistic effects on chlorine-resistant/sensitive bacteria inactivation. • ED/AC had ∼ 2.5 times lower energy consumption for cell inactivation than AC alone. • EP/AC prompted the formation of neutral HClO molecules and free chlorine radicals. • ED/AC enabled oxidative damage of cell structures for bacterial inactivation. The widespread use of chlorination prompts the selection of chlorine-resistant bacteria in drinking water, posing a great threat to public health. Herein, according to sequential electrochemical oxidation/reduction (Ox/Red) processes with a flow-through mode, electrochemical devices (ED) with sequential Ox-Red, Red-Ox and Ox-Red-Ox processes were coupled with chlorination (AC) to evaluate their synergistic effects and mechanisms for inactivation of chlorine-resistant bacteria in drinking water. ED/AC enabled ∼ 3.0 log of synergistic effect and ∼ 2.5 times lower energy consumption for inactivation of various chlorine-sensitive/-resistant bacteria and gram-positive/-negative bacteria in DI and tap waters. Especially, ED/AC with Ox-Red-Ox device exhibited the best disinfection performance with achieving over 6.7 log inactivation of Bacillus cereus at 4.0 V and 0.5 mg/L-Cl 2 as compared with ED alone (∼1.25 log) and AC (∼2.67 log) disinfection. The electrochemical oxidation on Ti 4 O 7 -based anode promoted the generation of free chlorine radicals and H+ ions, which was accompanied with the formation of neutral HClO molecules. Characterizations of SEM and flow cytometer suggested that oxidative species of neutral HClO molecules and free chlorine radicals enhanced the bacterial inactivation via severe damages of cell structures. This work provided a promising strategy via coupling electrochemical oxidation and chlorination for eliminating chlorine-resistant bacteria in drinking water. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Ir-doped SnO 2 anode is fabricated via a thermal decomposition process. • Ir-SnO 2 efficiently produces reactive chlorine species via Cl− oxidation. • Ir-SnO 2 treats urine wastewater more efficiently than commercial anodes. • Ir-SnO 2 shows sustained stability over 100 h of continuous electrolysis. The prevalence of nitrogen pollutants in urine wastewater has become a pressing environmental issue. Among various methods for addressing this concern, electrochemical oxidation processes that generate reactive chlorine species (RCS) from chloride ions commonly found in urine wastewater stand out as a promising approach. Despite the exploration of diverse anode materials, existing options still suffer from low selectivity in RCS generation, poor stability, and considerable energy consumption. In this study, we synthesized iridium-doped tin oxide (Ir-SnO 2) as an efficient, durable, and energy-conserving anode and systematically evaluated its electrochemical activity for RCS-mediated removal of nitrogen pollutants in urine wastewater. The Ir-SnO 2 anode outperformed counterparts such as IrO 2 , SnO 2 , and Sb-SnO 2 , demonstrating its superior electrochemical performance characterized by high current density, low charge transfer resistance, and substantial active surface area. It also achieved exceptional current efficiency of 91.7 % and energy efficiency of 7.79 mmol/Wh for RCS generation at 30 mA cm−2 in diluted 0.1 M chloride solution. Computational analysis based on density functional theory additionally supported experimental results, revealing that Ir doping to SnO 2 enhances chlorine adsorption through electronic structure modification, significantly lowering the overpotential and improving electrocatalytic activity for chlorine evolution reactions. In the electrolysis of synthetic urine wastewater at 30 mA cm−2 for 5 h, the Ir-SnO 2 anode demonstrated remarkable efficacy in degrading ammonia nitrogen (NH 3 -N), total nitrogen (TN), and chemical oxygen demand (COD) with efficiencies of 100 %, 97.8 %, and 89.1 %, respectively. These results were comparable to those achieved by IrO 2 (dimensional stable anode, DSA) and exceeded the performance of the boron-doped diamond (BDD) anode. Moreover, Ir-SnO 2 exhibited the lowest energy consumption compared to benchmark DSA and BDD anodes in the treatment of urine wastewater. In stability assessments, furthermore, the Ir-SnO 2 electrode maintained stable anodic cell potential for 100 h of continuous electrolysis in a 0.1 M NaCl electrolyte at 30 mA cm−2 and remained functional over five cycles without any signs of deactivation. This study provides valuable insights into the development of a suitable anode for energy-efficient urine wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Design of nanoflower rod-like SnO 2 -Sb supported on TiO 2−x for PPCPs degradation. • A Ti3+/O vs -related TiO 2−x was fabricated. • The effects of O vs on conductivity and the ·OH formation were studied via DFT. • Providing new insights into the electrochemical degradation mechanism for AMX. The fabrication of Sb-doped SnO 2 electrode with high catalytic activity and excellent durability for decomposition PPCPs (Pharmaceuticals and personal care products, PPCPs) is challenging. Herein, a Ti3+/O vs -related TiO 2−x is prepared by short-time annealing at low temperature in mixed gas with Zr as a cocatalyst. DFT calculations indicate that the introduction of Ti3+/O vs defects could promote the formation of more ·OH. Then, the nanoflower rod-like SnO 2 -Sb catalytic layer supported on dual-defects TiO 2−x is successfully synthesized by one-step pulse electrodeposition (PLED) combined with hydrothermal methods (H). This newly pulse electrodeposition technique solves the short lifetime problem of SnO 2 -Sb nanoflower electrodes current hydrothermal-based methods. 1O 2 and ·OH are found to be the primary reactive oxygen species (ROSs) by radical quenching tests and electron paramagnetic resonance analysis. The optimized Ti foam/TiO 2−x /SnO 2 -Sb electrode could degrade over 96.3 % of 20 mg L−1 amoxicillin (AMX) within 30 min, corresponding kinetic constant 0.10228 min−1. This will provide inspiration for the construction of defect engineering and new insights for the development of low-cost and high electrooxidation activity Sb-doped SnO 2 electrode. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Pt/NbC membrane based nanofluid reactor was developed for ammonia oxidization. • Removal of NH 4 + of 100 % & selectivity of N 2 of 88.09 % were achieved in a short HRT. • The high removal efficiency originated from high mass transferring efficiency. • An oxidation mechanism of NH 4 +→NH 3 → NH 2 → N → N 2 was explored through DFT. Electrochemical oxidation has garnered increasing attention for its potential in treating ammonia in wastewater. However, achieving both high conversion and high nitrogen selectivity simultaneously, while maintaining a short hydraulic retention time (HRT), remains a significant challenge. In this study, we constructed an efficient niobium carbide (NbC) nanoporous membrane reactor by incorporating metal platinum as a catalyst for the electrochemical oxidation of ammonia. The electrocatalytic oxidation process occurred within the nanochannels of the membrane. This design allowed for enhanced single-pass removal of ammonia due to the short diffusion distance on the nanometer scale, which subsequently increased the mass transfer efficiency. Remarkably, we achieved highly controllable pore sizes in the NbC membrane, ranging from 200 to 8.3 nm by dip-coating method. Without the addition of any oxidants, the single-pass removal of ammonia reached 100 % when the applied potential was set at 4 V vs. SCE on a membrane with a pore size of 8.3 nm, and an HRT of 249 s. The primary product obtained from this process was nitrogen, displaying a selectivity of 88.09 %, with a small percentage of nitrate production (selectivity of 11.91 %). By decreasing the applied potential or increasing the pore size, the selectivity of nitrogen can be further improved, reaching 100 %. However, this adjustment may lead to a decrease in the conversion of ammonia. DFT results have revealed that the production of nitrogen on the Pt (1 1 1) surface occurs through the NH 4 +→NH 3 → NH 2 → N → N 2 pathway. This finding contributes to the understanding of the electrochemical process for ammonia removal in water, and provides a viable option for the design of efficient nanomembrane reactors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Combining PM and 3D electrode process showed a remarkable synergy for DCF removal. • GAC and organic contaminants promoted the conversion of MnO 2 and PM to Mn(III) aq. • GAC act as a mediator transferring electrons from organic contaminants to PM. • Mn(III) aq and colloidal MnO 2 mainly contributed to ECs removal. • GAC particles exhibited a stable catalytic performance after 10 cycles. Currently, the electro-activated permanganate (PM) process, as one of the reactive manganese species (RMnS)-based advanced oxidation processes, has shown great potential for environmental remediation. However, the activation efficiency of PM in the electro-activated PM (E-PM) process is limited due to the poor mass transfer and electron transfer efficiency in the two-dimensional (2D) process. In this study, to overcome these drawbacks, granular activated carbon (GAC) was introduced as particle electrodes, establishing an efficient three-dimensional (3D) electrode process (E-GAC-PM), which promoted the generation of RMnS. Comparative experiments exhibited the significant synergy between PM and the 3D electrode process, resulting in the highest diclofenac (DCF) removal (90.2 %) with the lowest energy consumption. Electrochemical impedance spectroscopy and Tafel curve showed that the addition of GAC greatly attenuated the electrochemical impedance, facilitating the activation of PM. Further studies revealed that GAC can serve as an electron mediator, transferring electrons from contaminants to PM, thereby generating Mn2+ and promoting Mn(III) aq formation. Meanwhile, in-situ generated Mn2+ can also be oxidized by the anode and particle electrodes into Mn(III) aq. Besides, the in-situ generated MnO 2 facilitates the performance via oxidation and catalysis effects. Under the protection of the electric field, GAC showed a relatively stable performance which could be regenerated and maintain active after 10 cycles. All these results demonstrated that the E-GAC-PM process was an efficient, energy-saving, and sustainable method for refractory organic contaminants removal, which showed potential for practical application. [ABSTRACT FROM AUTHOR]

[Display omitted] • Degradation of ultrashort- to long-chain PFAS with chain lengths C1-C13. • Application of a realistic individual PFAS content of 0.2 µg L−1. • Use of multi-solute systems with 24 C1-C13 PFAS and 8 C1-C8 PFAS. • Higher PFAS decay in real water matrices up to a given content of organics. • Need for current densities higher than 20 mA cm−2 to maximize the decay of most PFAS. The current study aimed to investigate major knowledge gaps regarding the application of the anodic oxidation (AO) process with boron-doped diamond (BDD) anodes for the remediation of water matrices contaminated with per- and polyfluoroalkyl substances (PFAS). This included: (i) the degradation of ultrashort-chain (C1-C3) and long-chain (C9-C13) PFAS in addition to short- and medium-chain (C4-C8) PFAS, (ii) the application of multi-solute systems with different PFAS content (0.2 µg L−1 versus 2.0 µg L−1) and diversity (24 C1-C13 versus 8 C1-C8) in addition to single-solute systems, (iii) the use of real water matrices in addition to pure water, and (iv) the application of current densities (j) up to 250 mA cm−2 in addition to usual j (≤20 mA cm−2). C1-C4 PFAS with a sulfonated headgroup were the most recalcitrant compounds. By contrast, PFAS ≥ C9 with a sulfonated headgroup and PFAS ≥ C12 with a carboxylic headgroup were potentially instantaneously degraded. The content and diversity of PFAS mainly affected the degradation kinetics of PFEtS (C2), PFPrA (C3), and PFBA (C4). Four real water matrices were under focus: drinking water (DW), urban wastewater after secondary treatment (UWW), and nanofiltration concentrate (NF) and reverse osmosis concentrate (RO) from urban wastewater polishing step. PFAS degradation typically benefited from using real matrices primarily due to the presence of chloride ions and consequent electrogeneration of active chlorine species. However, for waters with a high organic content, namely a chemical oxygen demand (COD) of 319 mg O 2 L−1, PFAS degradation was hindered. Furthermore, the removal of most PFAS benefited from the application of j > 20 mA cm−2, and some specific PFAS required the use of j ≥ 250 mA cm−2 to have maximized removal rates. [ABSTRACT FROM AUTHOR]

• Titanium foam/IrO 2 electrode is more suitable for use in sewer network treatment. • A decrease in flow rate or an increase in current density will accelerate in-situ oxygen production. • The most significant effect on DO concentration is attributed to HCO 3 −, followed by PO 4 3−, NH 4 +, and COD. • Electrochemical in-situ oxygen generation technology has wide applicability in sewer engineering. Hydrogen sulfide (H 2 S) causes corrosion of pipeline network and endangers sewer's normal operation, while the rehabilitation or replacement of sewer network incurs expensive manpower and material costs. Conventional chemical dosing strategies such as oxygen injection and caustic soda addition, confront issues with transport and storage of chemical reagents as well as dose control. In contrast, electrochemical treatment techniques have evoked growing attention in sewer management due to its capacity of in-situ effective agent production, real-time dose control and amenability to automation. In this study, the performances of anodic oxygen production using Ti/IrO 2 and Titanium foam/IrO 2 as electrodes were investigated. Titanium foam/IrO 2 electrode exhibited the superior oxygen evolution capacity, with the dissolved oxygen (DO) level attained in the range 8–9 mg L-1 (i.e., higher than that of 5–6 mg L-1 by Ti/IrO 2 electrode). It was also indicated that a decrease in flow rate or an increase in current density would accelerate its in-situ oxygen production. DO production with the presence of COD, NH 4 +, HCO 3 −, H 2 PO 4 −/HPO 4 2− was approximately 6.78–8.37 mg L-1. Moreover, this electrochemical method was illustrated to successfully achieve sulfide removal efficiency of 90 % in the simulated sewage experiment. The cathode compartment simultaneously produced caustic soda (∼0.4 wt% in 210 min), thereby contributing to further sulfide removal. Additionally, the effect of real sewage with different conductivities on sulfide removal proved the wide applicability of electrochemical technology in sewer management. Overall, this study demonstrated the practical potential of concurrent in-situ anodic oxygen production and cathodic caustic soda generation for sulfide control in sewers. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electro-oxidation of N-heterocycles produces N 2 , N H 3 / N H 4 + , N O 3 - , C O and C O 2. • N H 3 / N H 4 + and an apparent N 2 yield correlate linearly with carbon removal. • Both apparent N 2 and N O 3 - form directly from organic intermediates rather than N H 3 / N H 4 +. • Higher concentrations of parent compounds promote a higher apparent N 2 selectivity. • N O 3 - dominates when oxidation of carbon is mass transfer-limited or at basic pH. We report for the first time the carbon and nitrogen product distribution during the electrochemical oxidation (EO) of pyrazine and related N-heterocyclic compounds (NHCs) present in the hard-to-treat wastewater from a biofuel production process. The experimental study was carried out using a boron-doped diamond anode. Identified and quantified intermediate products included oxamic acid, formamide, oxalic acid, and formic acid. Analysis of the C and N yields as a function of the extent of carbon removal reveals the influence of the current- and mass transfer-control operating regimes on product distribution. Carbon monoxide, which was detected among the gaseous products, suggests a possible decarbonylation pathway in the current-controlled regime. An apparent nitrogen gas and ammonium yields correlated linearly with the carbon removal, while nitrate yields significantly increased in the mass transfer-controlled regime. Nitrate and apparent nitrogen gas appear to form directly from organic nitrogen intermediates, rather than from the ammonium that also forms in the process. The research gives new insights into the NHCs degradation pathways, product distribution, and final water composition as a function of operating regime in the EO of recalcitrant wastewater. [ABSTRACT FROM AUTHOR]

• MIT was electrochemical degraded by a Ti/SnO 2 -Sb 2 O 3 /α, β-PbO 2 electrode. • Electrochemical treatment required low energy consumption and no chemical addition. • 68.8% of electrons that used for MIT oxidation was utilized to mineralize MIT into CO 2. • The sulfur atom can be oxidized into SO 4 2− and separated from MIT ring structure. Methylisothiazolinone (2-methyl-4-isothiazolin-3-one) (MIT) is a commonly used biocide in wastewater treatment processes. Residual MIT in wastewater leads to high environmental risks and toxicity. The degradation of MIT via electrochemical oxidation, including kinetics, energy efficiency, oxidation mechanism and degradation pathway, was investigated in this study. Findings from energy and cost evaluation by using electrochemical technology were compared with those of other technologies. Experimental results indicate that electrolyte, current density and initial concentration can significantly affect MIT degradation. The lowest electrical energy per order was less than 3.85 kWh m−3 when NaCl was used as the electrolyte. Electrochemical degradation is advantageous because it can be easily applied without adding chemicals into wastewater and has relative low costs. The oxygen evolution, production of recalcitrant byproducts, and the mass transfer limitation resulted in the decrease of instantaneous current efficiency and mineralization current efficiency. Electron efficiency analysis demonstrated that 68.8% of the electrons used for MIT oxidation were effectively utilized to mineralize MIT into CO 2. The proportion of direct and indirect oxidation of MIT during electrochemical degradation was quantitatively determined as 37.7% and 62.3%, respectively. HO was the most effective species for MIT degradation. MIT degradation pathway was proposed, in which the C C bond in MIT was broken down. C 3 H 7 NOS and C 3 H 7 NO 4 were detected, indicating the occurrence of ring opening reaction. Sulfur was oxidized into SO 4 2− and cleaved from C 3 H 7 NOS. [ABSTRACT FROM AUTHOR]

Graphical abstract The mechanism diagram of CES. Highlights • CES can simultaneously remove COD, TN and available chlorine. • The formation and removal of available chlorine in CES is discussed. • The changes of organics and cytotoxicity during electrolysis are demonstrated. • CES can reduce the volume of electrocoagulation precipitates and increase their sedimentation capacity. Abstract This study presents a combinatorial electrochemical system (CES) for the treatment of refractory organic wastewater containing nitrogen and chloride ion. The CES was composed of iron anode reactor (IAR), Ti/RuO 2 anode reactor (TAR) and available chlorine removal reactor (CRR). Biologically treated landfill leachate (BTLL) was selected as the treatment object to evaluate the performance of CES. The results showed that CES could simultaneously remove chemical oxygen demand (COD) and total nitrogen (TN) by 94.6% and 98.3%, respectively. Reduction of nitrite-N by cathode in IAR and oxidation of ammonium-N by available chlorine in TAR were the major pathways for TN removal. Fluorescence spectroscopy and parallel factor analysis (PARAFAC) showed that the main organic components in BTLL were humic-like substances and soluble microbial degradation products. These substances were removed by CES and the remaining organics were some hydrocarbons and carboxylic acids. The available chlorine was rapidly reduced into chloride ion by IAR precipitates, thus decreasing the cytotoxicity. In addition, the formation of stable Fe3+ crystals was promoted by the oxidation of available chlorine in CRR, which increased the density of the precipitates and reduced their volume. Therefore, the CES is a promising solution for the treatment of refractory organic wastewater containing nitrogen and chlorine ion. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Perchloroethylene can be removed from methanol solutions by electrolysis with BDD. • NaCl or NaOH can be used to increase the conductivity of the methanol solution. • All reaction intermediates are oxidized during the electrolytic tests. • Adding sodium hydroxide to methanol seems to produce a faster removal of intermediates. • Total removal of perchloroethylene from aqueous and methanol media is attained. Abstract Removal of perchloroethylene using combined granular active carbon (GAC) adsorption and electrolysis is evaluated in this research. There is an interest in the regeneration of GAC using methanol solutions, because this process can obtain the almost complete desorption of the pollutant retained during the treatment of gaseous flows. In this work, the electrolysis of perchloroethylene (used not only as a hazardous pollutant but also as a model of organic pollutant) in methanol media containing sodium chloride and sodium hydroxide is evaluated and results are compared to those obtained during the electrolysis of this pollutant in aqueous media. Results demonstrate the feasibility of this treatment technology, which does not only remove the raw molecule but it is also capable to remove all the intermediates detected by GC-ECD, allowing the possibility of the reuse of the methanol solution for further regeneration steps. [ABSTRACT FROM AUTHOR]

[Display omitted] • DOM in ROCLL includes BP (>18 kDa), HS (0.45–18 kDa) and LMWS (<0.45 kDa) fractions. • RSM experiments showed that pH was the most critical parameter for EO treatment. • Removal of DOC fractions was controlled by charge transfer process. • Elimination of chromophores and fluorophores was limited by mass transport process. • BP-C1, HS-C2 and LMWS-C1 subfractions required further treatment after EO process. Electrochemical oxidation (EO) is a viable option for the advanced treatment of reverse osmosis concentrated landfill leachate (ROCLL). This work characterized dissolved organic matter (DOM) in ROCLL with size exclusion chromatography (SEC) and then investigated the impact of operating parameters on the removal of DOM fractions with response surface methodology (RSM). The SEC chromatograms revealed that the DOM fractions in ROCLL comprised of biopolymers (BP, > 18 kDa), humic substances (HS, 0.45–18 kDa) and low molecular weight substances (LMWS, < 0.45 kDa). For the EO configuration with different anodes, the BDD film anode showed the highest removal efficiency for DOM in terms of COD, DOC, UVA254 and fluorescence indices, followed by Ti, graphite, Ti/RuO 2 -IrO 2 and Ti/SnO 2 -Sb 2 O 5 anodes. The RSM experiments suggested that pH was the most critical factor to enhance the removal of all DOM fractions, and acidification pretreatment could remove approximately 50% BP and 30% HS fractions due to the pH-induced precipitation. The DOC removal kinetics of DOM fractions could be described by pseudo-zero kinetic model with rates in the order of HS > LMWS > BP, which were controlled by charge transfer process. Differently, the elimination of chromophores and fluorophores followed pseudo-first kinetics, which was limited by mass transport process. Via nonnegativity matrix factorization (NMF) deconvolution of the SEC-OCD chromatograms, BP-C1, HS-C2 and LMWS-C1 subfractions required to be removed through further treatment after EO process. This work demonstrates the potential for SEC analysis coupled with mathematical approaches to give informative insights into the evolution of DOM and provide optimization strategies for the EO treatment of complex ROCLL. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel reactive electrochemical ceramic membrane (RECM) system was designed. • RECM system has dual functions of membrane filtration and contaminant degradation. • rTNA/SnO 2 -Sb/PbO 2 anode has excellent electrochemical property, stability and safety. • RECM system can efficiently and sustainably eliminate enrofloxacin from wastewater. A novel reactive electrochemical ceramic membrane (RECM), assembled by ceramic membrane and reduced TiO 2 nanotube arrays (rTNA) based PbO 2 membrane anode with a Sb-SnO 2 interlayer (rTNA/Sb-SnO 2 /PbO 2), was developed in this study with the dual functions of low-pressure membrane filtration and efficient removal of antibiotics from wastewater. Compared with Ti/Sb-SnO 2 and rTNA/Sb-SnO 2 membrane anodes, rTNA/Sb-SnO 2 /PbO 2 anode exhibited higher oxygen evolution potential, larger active surface area and promising electrochemical stability, owing to the introduction of rTNA structure and PbO 2 layer. The rTNA/Sb-SnO 2 /PbO 2 RECM also achieved a higher electrochemical degradation performance than Ti/Sb-SnO 2 and rTNA/Sb-SnO 2 RECMs, as well as a lower energy consumption. The antibiotic enrofloxacin (ENR) removal of the rTNA/Sb-SnO 2 /PbO 2 RECM in the flow-through mode was 5.4 times higher than that in the flow-by mode. These results were ascribed to the improved mass transfer of ENR towards anode surface and reactive oxygen species (i.e., H 2 O 2 , O 2 −, and OH) production. According to theoretical computations and the detection results of intermediates, the degradation pathway involved the defluorination, hydroxylation, decarboxylation, and breakage of quinolone and/or piperazine rings of ENR under the attack of hydroxyl radicals in the RECM system. The findings demonstrated the application potential of the rTNA/Sb-SnO 2 /PbO 2 RECM in removing ENR from wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • The addition of CeO 2 and CoFe 2 O 4 would accelerate the electron transfer. • A hetero-EF/Cl- system was found to be highly efficient for NOR degradation. • ·OH, ClO·, and 1O 2 were determined to be predominant ROS/RCS. • Overall toxicity was reduced during NOR degradation. • Providing a method to treat pharmaceutical wastewater containing chloridion. To utilize the chloridion in practical pharmaceutical wastewater and to minimize the negative impact of chloridion on the aerobic bacteria in the biochemical pool, a composite electrocatalyst consisting of CeO 2 and CoFe 2 O 4 loaded on electrospun carbon nanofibers (CeO 2 /CoFe 2 O 4 @C-NCNFs-800) was prepared and employed for NOR degradation in the heterogeneous electro-Fenton/Cl- (hetero-EF/Cl-) system. A superior NOR degradation efficiency was discovered in the hetero-EF/Cl- system than in the hetero-EF system, which benefited from the generation of more selective oxidants (ClO·) when hydroxyl radical (·OH) and Cl- were present simultaneously. The 20 min operation allowed 99.54% NOR removal under the appropriate conditions (pH = 6.05, current = 40 mA, and [Cl-] = 0.1 M) with a reaction rate constant (k obs) of 0.3032 min-1. According to the quenching and the probe experiments, ·OH, ClO·, and singlet oxygen (1O 2) were confirmed to be predominance during NOR degradation, whose steady-state concentrations were 2.00 × 10-11 M, 1.39 × 10-11 M, and 1.19 × 10-11 M, respectively. In short, this study offered a probable method to utilize chloridion in practical pharmaceutical wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • Manganese oxide increased the electrocatalytic activity of the graphene electrodes. • Amino group doping improves manganese oxide functionalization stability in graphene. • Graphene sponges removed E. coli from tap water without chlorine formation. • E. coli were inactivated irreversibly via low-voltage electroporation. • Storing the treated samples enhanced the removal from 2.7 to 4.7 log of E. coli. Low-cost reduced graphene oxide sponges functionalized with manganese oxide were used as electrodes for the disinfection of Escherichia coli in water. Manganese oxide was doped with amino groups (Mn x O y NH 2) to strengthen the bond with the graphene coating and improve the electrochemical stability of the sponge. The Mn II and Mn III incorporated into the graphene coating favored the formation of oxygen vacancies and enhanced the electric and catalytic properties of the anode. Electrooxidation of real tap water at 29 A/m−2 resulted in 2.2 log removal of E. coli. After storing the treated samples for 18 h at 25 and 37 °C, the removal of E. coli increased to 3.3 and 4.6 log, respectively, demonstrating the irreparable damage to the bacterial cells via low-voltage electroporation, and the key role of storage temperature in their further inactivation. The energy consumption of the system treating real low conductivity tap water was 1.2–1.6 kWh m−3. Finally, experiments with intermittent current suggest the contribution of the pseudo-capacitance of the graphene sponge to electrochemical disinfection during the OFF periods. This study demonstrates the feasibility of manganese oxide-functionalized graphene sponges for the chlorine-free disinfection of water. [ABSTRACT FROM AUTHOR]

Highly performed electrode is one of the key factors affecting the efficiency of electrochemical oxidation toward organic pollutants. In the present work, three-dimensional porous PbO 2 -CeO 2 composite electrodes (3D/PbO 2 -CeO 2 ) were fabricated by composite electrodeposition method using oxygen bubbles as template, to eliminate neonicotinoid thiamethoxam in aqueous solution. The surface morphology, structure, and composition of the 3D/PbO 2 -CeO 2 electrodes were well characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). Then the influence of the applied current density, the initial concentration of thiamethoxam, the concentration of supporting electrolyte, and initial pH value on the thiamethoxam removal ratio were also optimized. Amount to twenty deductive intermediates of thiamethoxam degradation were identified by HPLC-MS analysis, and dechlorination, hydrogen abstraction, denitration, and hydroxylation were observed in electrochemical oxidation process of thiamethoxam. Based on these identified byproducts, a hypothetical degradation mechanism has been proposed, which was divided into two parallel pathways according to the different initial oxidation position on thiamethoxam, such as chlorine atom on thiazole ring and nitro group on 1,3,5-oxadiazinane ring. All the intermediates were ultimately mineralized into H 2 O and CO 2 . The electrochemical oxidation based on 3D/PbO 2 -CeO 2 electrodes in this work is a promising approach to effective removal of thiamethoxam. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI)-based conductive polymers are promising electrode candidates for energy storage, but they suffer the common hurdle of poor cycling stability due to structural rupture during the doping and de-doping processes. Electro-oxidation of phenol is an attractive method for removing phenol from contaminated wastewaters, but the method usually suffers from electrode fouling due to formation of non-conductive polymers on the anode. Here, we propose an environmentally benign strategy that addresses these two issues simultaneously, which can substantially enhance the cycling stability of PANI and prevent passivation of the electrode. We show that, in comparison with the bare graphite brush (GB) electrode, the PANI-GB electrode (aniline electropolymerized on GB) enables high selectivity of phenol conversion to the redox-active benzoquinone (BQ)/hydroquinone (HQ). These species are largely immobilized on the electrode, as evidenced via chemical identification and physicochemical characterization. Meanwhile, the P/40-PANI-GB electrode (obtained from CV scans of phenol on PANI-GB over 40 cycles) achieves a larger specific capacitance and, more importantly, a remarkably higher capacitance retention rate compared to the PANI-GB electrode. Such improvements are demonstrated to be caused by the availability of a second BQ/HQ redox system and the strong affinity between PANI and BQ/HQ via the interactions of π–π stacking, hydrogen bonding, and chemical doping. [ABSTRACT FROM AUTHOR]

The treatment of a real wastewater characterized by low conductivity was performed by anodic oxidation at boron doped diamond (BDD) in both conventional and microfluidic cells. The electrolyses carried out in conventional cells without supporting electrolyte were characterized by very high TOC removals but excessively high energetic consumptions and operating costs. The addition of sodium sulphate, as supporting electrolyte, allowed to strongly reduce the cell potentials and consequently the energetic consumptions and the operating costs. However, under various operating conditions, the addition of Na 2 SO 4 caused a lower removal of the TOC. The best results in terms of both TOC removal, energetic consumptions and operating costs (about 1 €/m 3 ) were obtained using a cell with a very low inter-electrode distance (50 µm) with no addition of a supporting electrolyte. [ABSTRACT FROM AUTHOR]

The treatment of 0.348 mM carbofuran solutions in 0.050 M Na 2 SO 4 at pH 3.0 has been studied by electrochemical oxidation with electrogenerated H 2 O 2 (EO-H 2 O 2 ), electro-Fenton (EF) and photoelectro-Fenton (PEF). The trials were performed in a 2.5 L pre-pilot plant equipped with a filter-press cell, which contained a RuO 2 -based anode and an air-diffusion cathode, connected to an annular photoreactor with a 160 W UVA lamp in PEF. The oxidizing species were the OH generated at the anode from water oxidation and in the bulk from Fenton’s reaction between added Fe 2+ and H 2 O 2 produced at the cathode. The oxidation power of treatments rose in the order EO-H 2 O 2  ≪ EF < PEF, demonstrating the preponderant role of OH in the bulk. The drug decay always obeyed a pseudo-first order kinetics. Similar TOC abatements of 82%–88% were found in PEF operating at different current densities and carbofuran concentrations, ascribed to the additional photolytic action of UVA light to remove photoactive intermediates, also allowing a gradual detoxification. In matrices with Cl − , active chlorine was also produced as oxidant and its quick reaction with carbofuran caused its faster decay at increasing Cl − content. However, lower mineralization was achieved because of the accumulation of recalcitrant chloroderivatives. GC–MS analysis of treated solutions with 0.070 M NaCl corroborated the formation of 6 chloroderivatives, whereas 5 heteroaromatics were detected in 0.050 M Na 2 SO 4 . Oxalic acid was accumulated in the latter medium since its Fe(III) complexes were stable in EF and rapidly mineralized by UVA light in PEF. The mineralization of urban wastewater spiked with carbofuran by PEF in the pre-pilot plant was partial due to the recalcitrant chloroderivatives formed from carbofuran and natural organic matter. [ABSTRACT FROM AUTHOR]

This paper deals with an experimental and modelling study on the electrochemical oxidation of refractory pharmaceuticals using a boron-doped diamond (BDD) anode. Different parameters have been investigated, such as the role of salts (sulfates), the presence of other organics, and the influence of applied current intensity. Ciprofloxacin (CIP), Sulfamethoxazole (SMX) and Salbutamol (SALBU) were used for models of pharmaceuticals, and urea as a model for a common organic. The complete removal of pharmaceuticals was observed in all electrolyses under galvanostatic conditions. The presence of common organic waste or other pharmaceutical has no significant impact on the degradation of the CIP target molecule. A mathematical model predicting the temporal concentration variation of organics with electroxidation time has been developed. In this model, different oxidation pathways have been considered: the transfer of electrons (direct oxidation) or of oxygen atoms via the reaction with either hydroxyl radicals or/and with strong electrogenerated oxidants. Excellent correlation with experiments is obtained under all experimental conditions. [ABSTRACT FROM AUTHOR]

Boron-doped diamond anodes are widely used for electrochemical oxidation of contaminants, due to their excellent capability to form hydroxyl radicals as well as inorganic radicals such as chloride, phosphate, and sulfate radicals, electrogenerated when their corresponding anions are present in the influent water. Addition of sulfate increases the electrooxidation rates of organic pollutants at boron-doped diamond (BDD) anode. However, the effect of chloride on the electrooxidation is considered to be less straightforward. The anodic oxidation of chloride yields chlorine and hypochlorous acid/hypochlorite, besides chloride radicals, and may form toxic chlorine oxyanions at higher applied potentials. The present study investigates such implications of chloride ions to the electrooxidation of a natural organic matter surrogate, resorcinol, in the presence of sulfate. The presence of sulfate yielded up to eightfold enhancement in the removal of resorcinol and total organic carbon (TOC) at both acidic and neutral pH. Chloride addition to Na 2 SO 4 inhibited the resorcinol oxidation and mineralization, whereas it enhanced resorcinol oxidation in NaNO 3 . However, sulfate inhibited the electrogeneration of chlorinated organics by ∼2–4 folds compared to nitrate at low chloride concentrations (i.e., [SO 4 2− ]:[Cl − ] > 1). Although increasing the pH from pH 2 to pH 7 yielded a two times lower amount of chlorinated organics, electrolysis in Na 2 SO 4 anolyte enhanced the generation of undesired chlorate and perchlorate at both acidic and neutral pH. [ABSTRACT FROM AUTHOR]

A novel electrochemical filter has been prepared for the effective adsorption and electrochemical oxidation of aqueous organic pollutants. The adsorptive electrode utilized in the electrochemical filter was a porous Graphite-RuO 2 electrode decorated with multi-walled carbon nanotubes (MWCNTs) adsorption layer, which was prepared by sol–gel coating, thermal decomposition, and vacuum filtration synthesis. The morphology and composition of adsorptive electrode characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) revealed a uniform distribution of RuO 2 active coating and MWCNTs adsorption layer. Electrochemical measurements indicated that the adsorptive electrode possessed a favorable oxygen evolution potential (OEP) of 1.42 V and inner voltammetric charge 170.05 mC·cm −2 , which were higher than that of non-MWCNTs electrode. Furthermore, the mass transfer of adsorptive electrode was enhanced as high as 4.6-fold in the electrochemical filter. The optimal operation parameters obtained was 3 mA·cm −2 and 7 g·L −1 Na 2 SO 4 . Under this condition, the electrochemical filter can remove > 97% of pyrrole and >75% of total organic carbon. The pyrrole oxidation mechanism of electrochemical filter was also investigated, revealed three dominant reaction stages: adsorption (≤0.3 V), direct oxidation (0.3–1.2 V) and indirect oxidation (>1.2 V). In general, the high electrochemical performance of Graphite-RuO 2 -MWCNTs filter on pyrrole removal resulted from the enhanced mass transfer, which attributed to the synergistic effect of adsorption from MWCNTs, electrochemical oxidation and convection by filtration. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ciprofloxacin and clarithromycin were detected in KTR water. • Antibiotic persistence gives rise to antibiotic-resistance genes and bacteria. • PbO 2 electrode showed good stability and activity on antibiotics removal. • The generated SO 4 − and OH radical can efficiently degrade antibiotics. • The electron transferred from antibiotics to the SO 4 2−. The widespread occurrence of antibiotics in the environment is a global problem, but their occurrence and spatiotemporal distribution, as that of their associated antibiotic-resistant genes and bacteria in Hong Kong estuaries and coast, are poorly understood or documented. Here, the long-term influences of ciprofloxacin (CIP) and clarithromycin (CLR) along the Kai Tak River (KTR) nullah, a man-made channel transporting treated effluents from two wastewater treatment plants, were monitored from December 2019 to April 2021. The results revealed that these antibiotics were widely distributed, exhibiting seasonal variations around median concentrations of 1693.8 ng L−1 for CIP and 632.1 ng L−1 for CLR. The ecological risk assessment indicated that ciprofloxacin and clarithromycin are the predominant ecological risk contributors to aquatic organisms in KTR water. The antibiotic resistance genes (ARGs) of acrB-1, acrA-2, mexF, acrA-1, and mexE persist in the sampled water along with CIP, CLR, and CIP/CLR-resistant bacteria. In addition, a PbO 2 thin film electrode of superb stability and electrochemical activity was fabricated by an electrodeposition method and used for the electrochemical oxidation of antibiotic water pollutants. As a result, CIP and CLR were rapidly removed and degraded within fifteen minutes by electron transfer and reactive oxygen species, thus, mitigating ARG contamination in the nullah. [ABSTRACT FROM AUTHOR]

The degradation of 150 mL of 0.561 mM tetracaine hydrochloride at pH 3.0 by electrochemical oxidation with electrogenerated H 2 O 2 (EO-H 2 O 2 ) has been studied at a low current density of 33.3 mA cm −2 in three different matrices: 0.050 M Na 2 SO 4 , real urban wastewater and a simulated matrix mimicking its electrolyte composition. Comparative trials were performed in an undivided cell with a 3 cm 2 boron-doped diamond (BDD), Pt, IrO 2 -based or RuO 2 -based anode and a 3 cm 2 air-diffusion cathode that allowed continuous H 2 O 2 electrogeneration. In 0.050 M Na 2 SO 4 , much faster and overall removal of tetracaine occurred using BDD because of the large oxidation ability of BDD( OH) formed from anodic water oxidation. In either simulated matrix or real wastewater, the RuO 2 -based anode yielded the quickest tetracaine decay due to a large production of active chlorine from anodic oxidation of Cl − . For the mineralization of the organic matter content, the BDD/air-diffusion cell was the best choice in all aqueous matrices, always reaching more than 50% of total organic carbon abatement after 360 min of electrolysis, as expected if BDD( OH) mineralizes more easily the chloroderivatives formed from tetracaine oxidation in the presence of active chlorine. The initial N of tetracaine was partly transformed into NO 3 − , although the total nitrogen of all solutions always decayed by the release of volatile by-products. In the Cl − -containing matrices, significant amounts of ClO 3 − and ClO 4 − were obtained using BDD, whereas active chlorine was much largely produced using the RuO 2 -based anode. Five aromatic by-products, one of them being chlorinated, along with low concentrations of oxalic acid were identified. The change in toxicity during EO-H 2 O 2 with BDD in the sulfate and simulated matrices was also assessed. [ABSTRACT FROM AUTHOR]

The biologically pretreated cellulosic ethanol wastewater poses a serious environmental concern because of its refractory and color compounds. The decolorization of electrochemical oxidation using Sb doped Ti/SnO 2 electrode for advanced treatment of cellulosic ethanol wastewater under different current density (5–30 mA·cm −2 ), initial pH (3–8.9) and supporting electrolyte (0–0.25 M NaCl) was investigated in this study. Complete decolorization, 8.5% chemical oxygen demand (COD) and 69.1% dissolved organic carbon removal efficiencies were achieved under the optimal conditions (20 mA·cm −2 , pH 5 and supporting electrolyte of 0.1 M NaCl) after 150 min. The energy consumption required to meet National Discharge Standard (GB 27631-2011) is 93.8 kWh kg COD −1 . Further investigation revealed that hydroxyl radicals played a primary role in the degradation of organic contaminants, while active chlorine formed from chloride oxidation played a less important role. Direct anodic oxidation and indirect reaction via peroxodisulfate generated from sulfate oxidation could be negligible. The formation of chlorination by-products appeared to be low since the final total Trihalomethanes concentration detected was 263 µg L −1 , with the detection of chloroform as the main Trihalomethanes. [ABSTRACT FROM AUTHOR]

This paper reports the electrochemical treatment of poly- and perfluoroalkyl substances (PFASs) in the effluent from an industrial wastewater treatment plant (WWTP). While most of the previous research focused on the electrochemical degradation of perfluorooctanoic acid and perfluorooctane sulfonate in model solutions, this work studies the simultaneous removal of 8 PFASs at environmentally relevant concentrations in real industrial emissions, which also contained organic matter and inorganic anions. The overall PFASs content in the WWTP effluent was 1652 µg/L, which emphasized the need to develop innovative technologies for the management of PFASs emissions. 6:2 fluorotelomer sulfonamide alkylbetaine (6:2 FTAB) and 6:2 fluorotelomer sulfonate (6:2 FTSA) were the major contributors (92% w/w) to the overall PFASs content, that also contained significant amounts of short-chain perfluorocarboxylic acids (PFCAs). Using a boron doped diamond (BDD) anode of 0.0070 m 2 , the effluent (2 L) was treated by applying a current density of 50 mA/cm 2 for 10 h, that resulted in 99.7% PFASs removal. The operation at lower current densities (5 and 10 mA/cm 2 ) evidenced the initial degradation of 6:2 fluorotelomers into perfluoroheptanoic and perfluorohexanoic acids, that were later degraded into shorter chain PFCAs. The high TOC removal, >90%, and the fluoride release revealed that PFASs mineralization was effective. These results highlight the potential of the electrochemical technology for the treatment of PFASs contained in industrial wastewaters, which nowadays stands as the main source of this group of persistent pollutants into the environment. [ABSTRACT FROM AUTHOR]

The worldwide presence of harmful micropollutants in water resources drives the development of innovative and energy-efficient water treatment technologies. Herein, a novel carbon-nanotube-(CNT)-based hollow fiber membrane, with a sandwich-like structure in its cross section, is designed and prepared for expanded micropollutant removal under electrochemical assistance. The CNT membranes consist of (1) outer CNT layer as separation layer, (2) middle porous polyvinylidene fluoride layer and (3) inner CNT layer as support. Apart from their intrinsic functions as separation membranes, they can construct a complete electrochemical system, in which two CNT layers are also designed as electrodes and the PVDF layer as insulating separator. Low-concentration microcystin-LR can be cost-efficiently and continuously removed (>99.8%) by these CNT ultrafiltration membranes through facile switches between adsorption and desorption/electrochemical oxidation. Such switches can be achieved at a high flux of 500 L m −2 h −1 without terminating filtration process. Degradation product analysis has evidenced the breaking of Mdda chains that are largely responsible for the toxicity of microcystins. This work synergistically combines adsorption and electrochemistry with membrane separation, and highlights their potentials for advanced wastewater treatment and drinking water purification. [ABSTRACT FROM AUTHOR]

Three-dimensional Ti-Sn/γ-Al 2 O 3 particle electrodes were prepared for the efficient degradation of chloramphenicol (CAP) in wastewater. To observe the surface morphology and structural characteristics of the Ti-Sn/γ-Al 2 O 3 particle electrodes, Fourier transform infrared spectroscopy, X-ray fluorescence, scanning electron microscopy, and X-ray diffraction were used for characterization. Parameters affecting the degradation efficiency and energy consumption of the Ti-Sn/γ-Al 2 O 3 particle electrodes, such as conductivity, initial pH of wastewater, current density, air flow, and initial CAP concentration (100 mg·L −1 ), were examined. Results showed that the optimal conditions were 0.1 A current intensity, 1.0 L·min −1 air flow, 6000 μS·cm −1 conductivity, and pH 6. More than 70% of CAP was degraded under the optimal conditions. Based on the reaction intermediate products identified, a possible pathway for the electrochemical oxidation of CAP by the Ti-Sn/γ-Al 2 O 3 particle electrodes was proposed. [ABSTRACT FROM AUTHOR]

Surfactant enhanced soil washing (SW) and soil flushing are efficient processes for polycyclic aromatic hydrocarbons removal from contaminated soils. However, management of soil washing solutions is a complex challenge for environmental engineering. This study investigated the implementation of a combined process coupling anodic oxidation (AO) – an electrochemical advanced oxidation process – and aerobic biological treatment (BT) for proper handling of a synthetic SW solution containing phenanthrene, Tween® 80 and humic acids. As a sole process, AO required a treatment duration of 5 h and a current intensity of 1 A to remove 95% of phenanthrene and Tween® 80 as well as 71% of COD. Such operating conditions resulted in high electrical energy consumption (67 kWh (kg COD) −1 ). In contrast, BT alone allowed a total degradation of both phenanthrene and Tween® 80, but an insufficient removal of COD (44%) was observed due to the production of non-biodegradable by-products. In order to promote synergistic effects, AO and BT were combined and two different treatment strategies were investigated depending on whether AO was used as pre- or post-treatment. The production of more biodegradable by-products was observed after short AO pre-treatment (3 h, 500 mA), resulting in 80% COD removal after BT. The opposite combination (with AO post-treatment) led to 76% and 93% COD removal after the AO post-treatment at 500 mA for 3 h and 5 h, respectively. Therefore, such combined process appears as a sustainable way to enhance both quality of treated effluent and process cost-effectiveness. [ABSTRACT FROM AUTHOR]

[Display omitted] • Efficient degradation of NAs was achieved by EC/PMS/Fe(III) system. • The redox cycle of Fe(III)/Fe(II) was triggered on the cathode. • The chemical structures of NA molecules affect their reactivity. • •OH, SO 4 •− and 1O 2 are the main reactive species in EC/PMS/Fe(III) system. • CHA degradation pathways and byproducts were revealed. In this study, an electrochemical/peroxymonosulfate/Fe(III) (EC/PMS/Fe(III)) system was established for efficient degradation of four naphthenic acids (NAs) compounds including cyclohexanecarboxylic (CHA), heptanoic (HPA), benzoic (BA) and 2-methylhexanoic acids (2-MHA). The introduction of electric field enhances the redox cycle of Fe(III)/Fe(II) to activate PMS for degredation of NAs. Complete degradation of NAs compounds (5 mg/L) has been achieved within 30 min in the EC/PMS/Fe(III) system. The results of electron paramagnetic resonance (EPR) analysis, scavenging experiment, and chemical probe experiments indicated hydroxyl radical (•OH), sulfate radical (SO 4 •−) and singlet oxygen (1O 2) are primary reactive oxygen species (ROS) in the EC/PMS/Fe(III) system. NAs compounds with different structures exhibit inconsistent degradation efficiency in current system (k CHA > k BA > k HPA > k 2-MHA), depending on the selectivity of the different ROS and stability of respective intermediate organic radicals. Besides, multiple degradation pathways of CHA, mainly including hydroxylation and carbonylation, were proposed by combining the results of mass spectrometry analysis with the calculated Fukui index based on density functional theory (DFT) calculation. In addition, the EC/PMS/Fe(III) system exhibited robust performance with the addition of co-existing ions. This work provides a novel strategy for efficient degradation of NAs for future remediation of petroleum wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • The E/Fe/sulfite system significantly improved sludge dewaterability. • Synergistic impact between electrochemical oxidation and thermal effect existed. • Releasing bound water was mainly ascribed to TB-EPS degradation and cell damage. • Degradation of proteins to hydrophobic amino acids promoted sludge dewaterability. Sulfate radical (SO 4 · -)-based advanced oxidation processes (SR-AOPs) are promising for sludge dewatering. In this work, an electrochemically driven Fe0-activated sulfite system (E/Fe/sulfite) was developed and demonstrated for sustainably releasing Fe2+ to activate sulfite for dewatering waste activated sludge. Under the optimal conditions (sulfite dosage = 40 mg/g dry solids, current density = 30 mA/cm2, pH = 6, and time = 60 min), the reduction of capillary suction time and water content of sludge cake were 87.9 ± 2.8 % and 73.1 ± 0.8 %, respectively. The improved dewatering performance was attributed to the degradation of tightly-bound extracellular polymeric substances, along with the decreased live/dead cell ratio and the increased permeability of sludge flocs. The thermal effect (∼21–59 °C) in the E/Fe/sulfite system accelerated the release of intracellular proteins, which could be effectively degraded by the strong oxidizing SO 4 · -. The results also suggested that electrochemical oxidation and thermal effect in the E/Fe/sulfite system had a synergistic impact on improving sludge dewaterability. According to the density functional theory calculation, the hydrophobic amino acids produced from protein degradation were favorable for forming the drainage channels and enhancing sludge dewaterability. This study provides new insights for understanding the SR-AOPs and their applications to sludge treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pyridine degradation fitted well with pseudo-first-order reaction kinetics. • pH- and Cl- concentration-dependent contributions of radicals were confirmed. • A strong correlation existed between pH/Cl- concentration and trichloromethane concentration. • Ring cleavage on the 6 N atom of pyridine is the main mechanism. • Toxicity increased due to the formed chlorinated by-products. To reduce the pressure of salt separation crystallization and contaminants removal, we systematically investigated the electrochemical oxidation of pyridine (Pyr) in low-salinity reverse osmosis concentrate (ROC) using a Ti/RuO 2 -IrO 2 anode with a high-performance chlorine evolution reaction. We mainly focused on the pH- and Cl- concentration-dependent reaction kinetics, degradation mechanisms, and toxicity assessment. Specifically, the Pyr degradation followed a pseudo-first-order kinetic model. A pH-dependent reaction kinetics study showed that reactive chlorine species (RCS) and ·OH were the dominant species that reacted with Pyr. Furthermore, the degradation efficiency of Pyr reached its maximum value at pH 2, owing to the formation of more RCS. Additionally, Pyr degradation depends on the contribution of RCS in the presence of Cl-. Under low and high Cl- concentrations, the secondary effects were free available chlorine (FAC) and ·OH, respectively. The concentration of trichloromethane (TCM) increased to 9.96 μM first and then decreased to 5.42 μM within 90 min. The variation trend in its concentration is consistent with that of the RCS contribution under different pH and Cl- concentration. The active sites of Pyr were calculated using frontier electron density (FED) and Laplacian bond order (LBO) calculations. The degradation performance and mechanisms of Pyr, wherein ring cleavage on the 6 N atom of Pyr was the main mechanism by electrochemical treatment, were explored through theoretical calculations and gas chromatography-mass spectrometry (GC–MS) analysis. The generation of transformation products (TPs) increased the toxicity of the Pyr water after electrochemical treatment. The overall findings provide new insights into the treatment of ROC, offering significant reference information for improving water utilization and near-zero liquid discharge (near-ZLD) of real wastewater. [ABSTRACT FROM AUTHOR]

This study focuses on the role of the anode material for the electrochemical degradation of the top-selling anti-inflammatory drug naproxen (NPX). Aqueous solutions containing 40 mg L −1 NPX sodium in 0.050 M NaClO 4 at pH 3.0 were comparatively treated by electrochemical advanced oxidation processes (EAOPs) like electro-oxidation with electrogenerated H 2 O 2 (EO-H 2 O 2 ), electro-Fenton (EF) and UVA photoelectro-Fenton (PEF). The experiments were performed in a 2.5 L flow plant equipped with an annular glass photoreactor coupled to a cell with a Pt, IrO 2 -based (DSA-O 2 ), RuO 2 -based (DSA-Cl 2 ) or boron-doped diamond (BDD) anode and an air-diffusion cathode to electrogenerate H 2 O 2 . In EF and PEF, 0.50 mM Fe 2+ was added as catalyst. At 50 mA cm −2 , the oxidation power of EAOPs rose in the order: EO-H 2 O 2 < EF < PEF, regardless of the anode used. The IrO 2 -based anode led to greater mineralization in EO-H 2 O 2 and EF. In contrast, the BDD anode allowed an almost total mineralization in PEF, being superior to 85% attained with the other three materials. DSA, a significantly cheap anode compared to Pt and BDD, can then be a suitable candidate for treating NPX solutions by EAOPs. For each process, the mineralization current efficiency and specific energy consumption were determined. The NPX concentration decay always followed a pseudo-first-order kinetics and, in PEF, it was enhanced in the sequence: RuO 2 -based < Pt < BDD < IrO 2 -based. GC–MS analysis of treated solutions allowed detecting six aromatic products, whereas maleic and oxalic acids were identified by ion-exclusion HPLC. A reaction sequence for the degradation of NPX by EAOPs is finally proposed. [ABSTRACT FROM AUTHOR]

We have studied electrochemical advanced oxidation of three single substrates (oxalic acid, maleic acid, and 2-naphthol) and real wastes (primary sewage, automotive wastewater, and composting leachate), at boron doped diamond, at which anode organic substrates undergo electrochemical mineralization by reactive hydroxyl species. Experimental data obtained under batch conditions at laboratory scale were fitted to three kinetic models under various conditions of current density and substrate concentration. The optimum kinetic regime of linear loss of substrate with time at constant current density can be achieved for almost all substrates to high conversion, except under extreme conditions of low substrate concentration and high current density. Proposals are made for optimizing this kinetic regime to the treatment of real wastes under flow conditions. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide removal is usually a necessary but costly step following the anaerobic digestion (AD) in order to upgrade biogas quality. Mitigating sulfide levels of biogas and digestate simultaneously in AD process will decrease the capital cost by eliminating standalone biogas upgrading facility. However, current in situ remediation methods, for instance, dosing of magnesium/sodium hydroxide, oxygen gas, iron salts, and nitrite or nitrate, potentially cause interference to biogas production and may intensively consume energy and chemicals. Here, an electrochemical remediation method was studied to use low-price electrode materials of carbon cloth and stainless steel AISI 304. These electrode materials at 3 V showed a complete removal of sulfide in 2 days in synthetic media of 10 mM sulfide solution. Operating conditions for carbon cloth and stainless steel electrodes as well as major intermediates of electrochemical reactions in bench-scale digester fed with dairy manure were examined to study the performances in sulfide removal and biomethane production. Based on the results, it was concluded that carbon cloth at 2 and 3 V, and stainless steel anodes at both 1 and 2 V have a potential of significantly removing hydrogen sulfide from biogas under continuous operation given sufficient electrode surface area. Intermittent 3 V voltage application (15 minutes per day) of stainless steel can remove most biogas hydrogen sulfide. The electrochemical sulfide oxidation and removal showed no/little negative effect on biomethane production, and therefore can be a promising technology for the AD industry to develop a cost-effective approach to producing sulfide free biogas. [ABSTRACT FROM AUTHOR]

A novel dual tubular membrane electrodes reactor was fabricated to degrade a refractory heterocyclic compound-tricyclazole using a tubular membrane Ti/IrO 2 –Ta 2 O 5 as anode and a carbon black-polytetrafluoroethylene (CB-PTFE) modified graphite membrane as cathode. Field emission scanning electron microscopy (FE-SEM), cyclic voltammetry (CV), Linear Sweep Voltammetry (LSV) and accelerated lifetime tests revealed that a porous tubular membrane Ti/IrO 2 –Ta 2 O 5 performed better electrocatalytic activity and high stability under acidic conditions. Meanwhile, the effects of aeration on electrogeneration of hydrogen peroxide (H 2 O 2 ) were assessed and the role of anode in dynamic system was elucidated by comparing with the static system. The influence of the operative parameters such as current density (2.5–12.5 A/m 2 ), membrane flux (52–178 L/m 2 ·h) and pH (3–11) were optimized and monitored. It is demonstrated that tubular membrane Ti/IrO 2 –Ta 2 O 5 anode provided enough oxygen to electrogenerate H 2 O 2 , up to 1586 mg/m 2 ·h, at 10 A/m 2 without aeration in acidic solution. Even if no circulation of the influent, the best removal rate of contaminants reached a stable value 79% at 20 min, which was 6.58-fold greater than the sum of the individual electrochemical oxidation. Synergism was observed during the dual tubular membrane E-Fenton system. [ABSTRACT FROM AUTHOR]

A novel molybdenum modified PbO 2 electrode was successfully prepared with the method of electrodeposition. The SEM and XRD were employed to study the surface morphology of electrodes, which indicated that the modified PbO 2 electrode had a larger effective area and more compact film. Electrochemical degradation of cinnamic acid (CA) in aqueous solution with Mo–PbO 2 electrode and PbO 2 electrode were investigated. The results showed that the Mo–PbO 2 electrode had a better effect of CA removal. The operational parameters influencing the electrochemical degradation of CA with Mo–PbO 2 electrode were optimized and the results revealed that the electrochemical degradation of CA followed the pseudo-first-order kinetics and the optimal removal of CA and COD were 85.51% and 25.79% after 120 min on condition of the electrolyte concentration, initial concentration of CA, current density and initial value of pH were 0.1 mol/L, 300 mg/L, 10 mA/cm 2 and 3.4, respectively. The degradation mechanism of CA in electrochemical oxidation with Mo–PbO 2 electrode was analyzed and the main degradation pathway of CA was proposed based on the intermediates identified by IC and GC–MS. [ABSTRACT FROM AUTHOR]

A novel anode Ti/TiO x H y /Sb−SnO 2 with excellent oxidation ability and long lifetime was successfully fabricated by introducing a TiO x H y interlayer through a simple way. The Ti substrate was modified through thermal oxidation followed by an electrochemical reduction process. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), accelerated lifetime test, scanning electron microscope (SEM) and X-ray diffraction (XRD) were adopted to characterize its morphology, crystal structure and electrochemical properties. These studies indicated that TiO x H y interlayer played a critical role in improving electrode stability. Besides, the electrochemical oxidation of aniline in the NaCl and Na 2 SO 4 were both investigated to test the application of this Ti/TiO x H y /Sb−SnO 2 electrode. Results showed that nearly 70% of aniline could be degraded within 2 h. After characterization of the intermediates and products, a possible electrochemical degradation mechanism of aniline was proposed. It was worth noting that due to electro-polymerization, some nonconductive oligo(aniline)s could accumulate on the anode surface and lower the oxidation ability of the anode. However, the anode could be recovered repeatedly (at least 5 times) by essential electrochemical activation process, which also relied on the high electrode stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel SnO 2 -Sb reactive membrane electrode (RME) was fabricated for disinfection. • The ceramic RME with tailored pores exhibited a high electrocatalytic activity. • The RME-based electrochemical system achieved 100% inactivation of E. coli and MS2. • Microscopic studies revealed serious destruction of pathogens in water by the RME. • Acidic interior flow with ·OH endows the RME's great disinfection efficiency. Exposure to waterborne pathogens is still a widespread threat to public health, and efficient and reliable disinfection technologies are urgently needed for decentralized applications. Herein, we developed a novel freestanding and flow-through SnO 2 -Sb reactive membrane electrode (RME) for electrochemical wastewater disinfection. When water was forced to flow through the porous RME, large amounts of reactive ·OH and H+ were generated within the interior pores of the anode, creating a strongly acidic local environment enriched with ·OH for the rapid inactivation of bacteria and viruses. At an applied voltage of 3.5 V, 100% removal of Escherichia coli (>6.3-log inactivation) was achieved by the flow-through RME at a high flux, which was significantly more effective than the system operated in the conventional flow-by mode (2.7-log inactivation). Using the bacteriophage MS2 strain as a model virus, a disinfection efficiency of 100% (>8.3-log inactivation) was achieved by the RME at 3.5 V. The transmission electron microscopy analysis revealed that E. coli and MS2 in the disinfected water suffered from serious destruction and disintegration, reflecting the strong electrocatalytic oxidation capacity of the charged RME. The SnO 2 -Sb RME-based electrochemical system performed very well in disinfecting complex municipal wastewater, demonstrating its potential for practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sonoelectrochemistry shows promise for removing organic pollutants from water. • This method can rapidly mineralise many persistent organic pollutants in water. • Highly oxidising radicals are the main agents performing mineralisation. • Fundamentals of sonoelectrochemical organic pollutant degradation are reviewed. • An in-depth analysis of recent examples in this field is provided. The combination of electrochemistry and ultrasonic irradiation (sonoelectrochemistry) has gained increasing attention in recent years as a method for removing dissolved pollutants from water. This interest stems from the potential for sonoelectrochemical approaches to completely mineralise dissolved pollutants, converting them into harmless mineral species such as water and carbon dioxide. In many cases, the electrochemical and ultrasonic inputs into a sonoelectrochemical pollutant degradation process are found to be synergistic, producing a faster rate of degradation than that produced by the sum of the purely electrochemical or purely sonochemical inputs on their own. This synergism has several causes, with enhanced production of powerfully oxidising radicals and improved mass transport to and from the electrode surface being the two most often cited. In this review, we first give an overview of the various factors that impact on sonoelectrochemical pollutant degradation studies (including reactor design, sonochemical and electrochemical parameters and reaction conditions), before then discussing in detail examples of sonoelectrochemical processes for the degradation of persistent organic pollutants in water from 2015 onwards. [ABSTRACT FROM AUTHOR]

In this work, the remediation of wastewater polluted with 2,4-D via conductive-diamond electrochemical oxidation using solar energy as a direct electrical power source has been investigated. The changes in operating conditions during the solar test are clearly related to the day–night cycle, with a maximum solar irradiation intensity of 450 W m −2 at noon and an average daily charge supplied of 22.5 A h m −2 d −1 . A solar irradiation intensity greater than 100 W m −2 is necessary to produce current, and values over 200 A m −2 are required for efficient solar-powered processes. Despite fluctuations in the intensity supplied to the electrochemical cell, electrolysis with diamond electrodes can attain complete depletion of 2,4-D and its mineralization, although the changing operating conditions applied during the electrolysis powered by solar energy favor the accumulation of many intermediates. In contrast, only very low concentrations of two intermediates were detected during electrolysis powered galvanostatically with a power supply at 3.0 A, indicating that the intensity highly influences the oxidation rate involved in the electrolysis. [ABSTRACT FROM AUTHOR]

This paper explores the applicability of electrochemical oxidation on two cytostatic drugs ifosfamide (IF) and cyclophosphamide (CF) by means of the BDD anode. The effect of the important electrochemical parameters: current density (4.8–16.0 mA cm −2 ), IF drug concentration (5–55 mg L −1 ), and initial pH (4.0–9.5) on the efficiency of the applied electrochemical process was evaluated. Both aforementioned drugs decomposed in accordance with a pseudo-first order kinetics. The obtained results indicate that the current density and initial drug concentration significantly influence the rate of electrochemical decomposition and the process efficiency for both drugs, while the pH effect is marginal. Additionally the effect of inorganic ions such as Cl − , PO 4 3− , NH 4 + , NO 3 − and HCO 3 − on the decomposition behavior of IF was also investigated. Among them Cl − and PO 4 3− ions significantly elevated the decomposition rate of the drug. To determine the degradation pathway of IF, the organic by-products, and the released inorganic ions, were identified and quantified over the entire time of electrolysis. Despite the fact that the values of coefficient rate k app of parent compounds are similar, the quality and the quantities of organic and inorganic intermediates determined during the electrolysis of IF and CF found during electrolysis was differed. The analysis of organic intermediates via LC–MS method resulted in the identification of a few products. [ABSTRACT FROM AUTHOR]

A significant challenge for large-scale use of electrochemical oxidation (EO) is high energy consumption, and for EO to become accepted as a standard technique, the amount of energy consumed in the process must be reduced. In this study, it was investigated how the energy consumption of EO could be lowered by combining the process with membrane filtration, in a setup where EO was applied to the membrane retentate stream. Use of two types of membranes, a nanofiltration (NF) and a reverse osmosis (RO) membrane, was investigated, and to provide realistic estimates on the energy consumption of the treatment, natural groundwater spiked with the pesticide residue 2,6-dichlorobenzamide (BAM) was used as matrix in the experiments. To understand the effect of the membranes on the energy consumption, their effect on the EO degradation efficiency was also determined. The results showed that membranes significantly reduced the energy consumption of the EO processes. Using the RO membrane with a recovery of 90%, the energy consumption of the combined EO and membrane setup used 95% less energy (0.96 kW h/m 3 ) compared to the stand-alone EO treatment (18.5 kW h/m 3 ). The reduction in energy consumption was found to be a result of primarily two factors; (1) a smaller volume of water was in need in the energy intensive EO treatment, and (2) the high rejection of chloride by the RO membrane increased the rate of degradation through mediated active chlorine oxidation in the membrane retentate. It was not possible to obtain the same positive benefits using the NF membrane, which was mainly due to a lower chloride rejection and a too low rejection of BAM. The investigation showed that combining RO filtration with EO of the contaminants in the concentrate provides a promising strategy for the dissemination of advanced oxidative treatment techniques in larger scale and actual use for protection of the environment. [ABSTRACT FROM AUTHOR]

The concern for the removal of contaminants, such as hydrogen sulfide (H 2 S), during crude oil processing has been intensified. Sulfur compounds, such as dissociated H 2 S, are detected in the effluents of process gas condensation and streams of acid water. The objective of this study is to apply electrochemical oxidation to neutralize H 2 S in industrial effluents. Tests were performed in a porous bed electrochemical reactor, which was composed of reticulated vitreous carbon. The oxidation process is direct and potentiostatically controlled, and the dissociated sulfide was oxidized to sulfate and/or thiosulfate, main product of the reaction. Figures of merit were constructed to evaluate the performance of electrochemical reactor under different hydrodynamic conditions, by varying the flow rate, and overpotential, by varying the distance between the electrodes in the reactor. The figures of merit indicated that the best condition for the formation of thiosulfate occurred at the lowest flow rate used, 1.05 L h −1 and at a greater distance between the electrodes, 60 mm. [ABSTRACT FROM AUTHOR]

The Electro-Fenton (EF) process has shown great potential in refractory wastewater treatment. However, its efficiency is highly pH-dependent and the high reagent costs for pH adjustment greatly limit its large-scale application. This study used a bench-scale EF reactor to study pH variation during the treatment of an acrylic fiber wastewater. The appearance of pH inflection points (pH IPs), i.e., sudden changes in pH, under different H 2 O 2 dosages, current densities, and ratios of [Fe 2+ Theo ]/[H 2 O 2 ] ( R Fe : H 2 O 2 ), were investigated. The pH IPs appeared on the time scale of 5–7.5 min, and were favored at decreased H 2 O 2 dosages (2.5–1.0 mM), increased current densities (3–4.5 mA/cm 2 ), and elevated R Fe : H 2 O 2 (0.1:1–0.2:1). The appearance of pH IPs was indicative of the exhaustion of H 2 O 2 and a significant decrease of COD degradation, as expressed by the pseudo-first order kinetic constant ( k ) of COD degradation. Besides this, the substitution of Fe(OH) 3 by Fe(OH) 2− and Fe(OH) 2 − occurred after pH IP appearance, and the dominant mechanism changed from electrochemical oxidation (EO) to electro-coagulation (EC) accordingly. In the presence of sufficient H 2 O 2 , the formation of Fe(OH) 3 barely affected pH variation. After H 2 O 2 exhaustion, i.e., the appearance of pH IPs, dissolved O 2 rapidly oxidized Fe 2+ to Fe 3+ , the hydrolysis of which contributed to immediate pH increase thereafter. The optimization of the EF process may be achieved by adjusting H 2 O 2 doses and the control of pH IP appearance. [ABSTRACT FROM AUTHOR]

[Display omitted] • DSA® and BDD were very efficient in removing VOCs from aqueous medium. • In methanol solutions, BDD promotes greater conversion of VOCs than DSA®. • Value-added products were produced in methanol medium. • The new concept of electro-refinery was explored. In the search for a method that can remove pollutants from gases or enhance the efficiency of the treatment of liquid wastes, electrolysis of water and methanol solutions containing benzene, toluene, and xylene were carried out in this work. Using a filter-press flow electrochemical cell, the efficiency of two different anodes (diamond coatings and mixed metal oxides) were evaluated against the electrochemical oxidation of contaminants in the different solvents mentioned. Results demonstrate that these pollutants can be removed from both types of matrixes and that the nature of the electrode influences greatly on the efficiency. In aqueous medium both electrodes perform similarly but diamond overcomes metal oxide anodes in methanol. In addition to a higher mineralization rate in that case, several highly value-added products are obtained during the process. For instance, anisole, methyl anisole and dimethyl anisole were produced from electrochemical oxidation of benzene, toluene and xylene, respectively, in methanol medium. These results pointing out that a change in the paradigm of the treatment must be made in the next years, going from the destruction of the pollutants to their conversion into highly valuable products at the frame of the circular economy premises. [ABSTRACT FROM AUTHOR]

[Display omitted] • Superior CIP removal was achieved in the E-PS using SnO 2 -Bi/Ti anode and FeCM cathode. • FeCM cathode outperforms various cathodes (Pt, Ti, graphite, and SS) in the E-PS. • 1O 2 was continuously generated and efficiently utilized for improved CIP removal. • E-FeCM-PS system shows superior reactivity and high stability. • E-FeCM-PS system exhibits high efficiency in remediating actual hospital effluent. In this work, electrochemical activation of persulfate (E-PS) for the energy efficient treatment of ciprofloxacin (CIP) was performed using a novel iron-decorated carbon membrane (FeCM) cathode and SnO 2 -Bi/Ti anode. Synergistic effect of electrochemical oxidation and PS activation resulted in superior CIP removal. The FeCM cathode outperforms various cathodes (Pt, Ti, graphite, and stainless steel), owing to the existence of C = O, Fe2+/Fe3+, and F on FeCM, which can facilitate 1O 2 generation and utilization in the E-PS system. Moreover, the continuous supply of negative charges endows rapid redox cycle of Fe2+/Fe3+ on FeCM cathode, which not only prevents iron leaching, but also reduces the consumption of active sites, and thus, enables FeCM with high stability over a wide pH range and improved cyclic performance. The potential of E-FeCM-PS for outdoor application were evaluated by removing various persistent organic pollutants, and treating actual hospital effluent. The CIP removal mechanism in the E-FeCM-PS process and the possible CIP degradation pathways were proposed. Overall, this work provides a plausible route for the continuous production of 1O 2 for effective abatement of organic contaminants via electro-activation of PS and gives an insight into the intrinsic role of iron-doped carbon membrane for persulfate cathodic activation. [ABSTRACT FROM AUTHOR]