Search

• A novel side-aerated reactor for in-situ H 2 O 2 electrosynthesis was designed. • Side-aerated reactor coupled with a composite cathode greatly improved H 2 O 2 production. • Different aeration system and cathodes were evaluated for comparison. • Key factors for in-situ H 2 O 2 electrosynthesis were determined. The active graphite felt (GF) catalytic layer was effectively synthesized through a wet ultrasonic impregnation-calcination method, modified with CB and PTFE, and implemented in a pioneering side-aeration electrochemical in-situ H 2 O 2 reactor. The optimal mass ratio (CB: PTFE 1:4) for the modified cathode catalytic layer was determined using a single-factor method. Operating under optimum conditions of initial pH 5, 0.5 L/min air flow, and a current density of 9 mA/cm2, the system achieved a remarkable maximum H 2 O 2 accumulation of 560 mg/L, with the H 2 O 2 production capacity consistently exceeding 95 % over 6 usage cycles. The refined mesoporous structure and improved three-phase interface notably amplified oxygen transfer, utilization, and H 2 O 2 yield. Side aeration led to an oxygen concentration near the cathode reaching 20 mg/L, representing a five-fold increase compared to the 3.95 mg/L achieved with conventional bottom aeration. In the final application, the reaction system exhibited efficacy in the degradation of landfill leachate concentrate. After a 60-minute reaction, complete removal of chroma was attained, and the TOC degradation rate surpassed 60 %, marking a sixfold improvement over the conventional system. These results underscore the substantial potential of the system in H 2 O 2 synthesis and environmental remediation. [ABSTRACT FROM AUTHOR]

• Electro-Fenton was integrated with membrane distillation for VOCs interception. • An oxidation barrier containing ·OH was constructed at the gas-liquid interface. • More than 90% phenol and other by-products were successfully intercepted. Membrane distillation (MD) is a promising alternative desalination technology, but the hydrophobic membrane cannot intercept volatile organic compounds (VOCs), resulting in aggravation in the quality of permeate. In term of this, electro-Fenton (EF) was coupled with sweeping gas membrane distillation (SGMD) in a more efficient way to construct an advanced oxidation barrier at the gas-liquid interface, so that the VOCs could be trapped in this layer to guarantee the water quality of the distillate. During the so-called EF-MD process, an interfacial interception barrier containing hydroxyl radical formed on the hydrophobic membrane surface. It contributed to the high phenol rejection of 90.2% with the permeate phenol concentration lower than 1.50 mg/L. Effective interceptions can be achieved in a wide temperature range, even though the permeate flux of phenol was also intensified. The EF-MD system was robust to high salinity and could electrochemically regenerate ferrous ions, which endowed the long-term stability of the system. This novel EF-MD configuration proposed a valuable strategy to intercept VOCs in MD and will broaden the application of MD in hypersaline wastewater treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, a new hybrid system composed of a photo-catalysis (UV/ZnO) process combined with an electro-Fenton (EF) process equipped with a micro porous graphite air diffusion cathode (MPGADC) was used to treat petroleum refinery wastewater (PRW). The hybrid system was operated in a batch recycle mode and its performance was investigated and optimized using a response surface methodology (RSM). Three operating parameters affecting on the removal efficiency (RE%) of chemical oxygen demand (COD) were investigated including current density (2–10 mA/cm2), ZnO dosage (0.05–0.35 g/L), and Fe2+concentration (0.05–0.15 mM). Results showed that the optimum operating conditions can be achieved using a current density of 6.44 mA/cm2, with ZnO dosage of 0.35 g/L, and concentration of Fe2+ ions at 0.05 mM in which RE% of 90.15% was obtained with requiring a total electrical energy consumption (EEC T) of 19.102KWh/m3. Furthermore, analysis of variance (ANOVA) exhibited a high value of determination coefficient (R2) close to 98.24% indicating a satisfactory fit between the obtained regression model and the experimental results. Moreover, ANOVA results revealed that current density has the most significant effect on RE% with a contribution of 52.41% followed by ZnO dosage and Fe 2 + concentration both of them with a contribution of 11.64%. The comparison between the individual photo-catalysis process and hybrid process showed that RE% increases from 77.83% to 90.15% making an enhancement by 15.83% in RE% while EEC T decreased from 27.171to 19.102KWh/m3 making a reduction by 29.7% in EEC T. Hence, combining EF with photo-catalysis process improves the efficiency and reduced the required energy in comparison with the individual photo-catalysis process. Therefore, the combined process could be considered as an alternative, sustainable, green and cost-effective method for treatment of refinery wastewaters. [Display omitted] • A novel photocatalysis-ElectroFenton system was applied successfully for treatment wastewater. • The optimum conditions were: current density of 6.44 mA/cm2, Fe2+concentration of 0.05 mM, Zn O 2 dosage of 0.35 g/l. • A maximum COD removal (RE% = 90.15% %) with a lower energy consumption (EEC T = 19.102kWh/m3) were achieved after operation of 40 min. • Reaction time was the most effective parameter followed by Z n O 2 dosage, Fe2+ concentration, and current density. • EF+UV/ZnO in comparison with UV/ZnO alone results in an enhancement of 15.83% in RE% and a reduction by 29.7% in EEC T. [ABSTRACT FROM AUTHOR]

In this work, hydrogen peroxide (H 2 O 2) is produced using an optimized electrochemical cell equipped with a gas diffusion electrode (GDE) as cathode, reaching efficiencies as high as 20.1%, when operating in a single compartment configuration, which increases up to the range 50–60, when a proton exchange membrane is used to separate the anodic and cathodic compartments, pointing out the great significance of the anodic oxidation of H 2 O 2 and the scavenging effects of the oxidants produced on the anode surface. As compared to previous materials tested, the GDE implemented in this cell underwent a more sustainable manufacturing procedure and exhibited an outstanding performance. The H 2 O 2 produced electrochemically is dosed to the real leachate of an industrial dump, strongly polluted with derivatives of lindane. This waste is associated to the operation of a large facility in the seventies and contains different isomers of hexachlorocyclohexane and other chlorinated hydrocarbons, produced during the ageing of the dump. Effects of the addition of iron (II) sulfate salts and irradiation of UVC were also evaluated. All electrochemically-assisted technologies evaluated (named as chemical (EACO), Fenton (EAFO), photolysis (EAPO) and photo-Fenton (EAPFO) oxidations) were able to successfully remove the pollutants, although with important differences in the efficiencies reached. Results demonstrate that EACO, that is, oxidation by molecular H 2 O 2 is the most effective treatment for the treatment of this type of wastes, pointing out that activation of H 2 O 2 to hydroxyl radicals, either by electrochemically assisted Fenton or photolysis is not positive for this waste. As well, among the different pollutants contained in the raw waste, removal of hexachlorocyclohexane (HCHs) and non-chlorinated volatile organic compounds (VOCs) stands out (both groups being the primary species contained in the wastes). These results are very important not only because of the outstanding productions of H 2 O 2 reached with the novel approach of electrochemical cell used, but also because of the implications of the mechanistic understanding of the attack of H 2 O 2 species in the design of a full-scale application to remediate this real important problem. [Display omitted] • Improved production of H 2 O 2 with a novel GDE and cell. • H 2 O 2 is produced with efficiencies over 20% in non-divided configurations. • Improved efficiency when using divided cells, with values as high as 50–60%. • Several electrochemical H 2 O 2 based technologies suitable for degradation wastes. • Unexpectedly H 2 O 2 more efficient that hydroxyl radicals in destroying CHCs. [ABSTRACT FROM AUTHOR]

The Electro-Fenton process is getting a rapid development recently as a novel advanced electro-oxidation technology for the removal of organic pollutants from water. In this work, a three-dimensional (3D) porous Fe 3 N/FeS composite electrode was created from a Fe 2 (SO 4) 3 -based composite ink by the direct-writing 3D printing technology combined with a high temperature heat treatment under ammonia atmosphere. Fe 3 N served as the conductive skeleton of the electrode, while FeS could provide Fe2+ to react with in-situ generated H 2 O 2 in the Electro-Fenton process to generate ·OH radicals. Thus, it could eliminate the need of external ferrous ion addition. The 3D porous Fe 3 N/FeS composite electrode had desired 3D interconnected macro-channels for efficient mass transport and rough rod surfaces to provide more active sites, which resulted in its superior degradation performance on organics than its traditional two-dimensional (2D) plate counterpart. A two-step H 2 O 2 production path was found on the 3D Fe 3 N/FeS composite electrode, which had been found to possess a faster reaction kinetics. It effectively degraded rhodamine B (RhB) within a wide pH range from ∼3 to ∼ 10, demonstrated stable performances in repeated uses, and had low iron ion leaching, all of which were beneficial for its potential applications. Furthermore, it also demonstrated effective degradation performances on antibiotics of amoxicillin (AMX) and tetracycline hydrochloride (TC-HCl) in both deionized (DI) water and tap water matrixes, indicating its potential to solve the emerging contaminant problem in real water treatment practices. [ABSTRACT FROM AUTHOR]

A low-cost micro porous graphite air diffusion cathode (MPGADC) has been utilized successfully for the in-situ hydrogen peroxide generation via O 2 reduction in 0.05 M Na 2 SO 4. Using a tubular electrochemical reactor with a novel design composed of MPGADC as a cathode and a hollow cylinder porous graphite as an anode, a maximum of 68 mg/ L of H 2 O 2 was produced at a current density of 25 mA/cm2, an air flow rate of 3 L/min, and a pH value of 3. Electro-Fenton (EF) process was adopted to remove the chemical oxygen demand (COD) from the wastewater of Al-Dora petroleum refinery in Iraq using this new style of tubular electrochemical reactor. Based on the response surface methodology (RSM) with Box-Behnken design (BBD), the effect of EF operating parameters on the COD removal was investigated. The optimal conditions for maximizing COD removal efficiency (RE%) with lowering specific energy consumption (SEC) using EF process were determined to be a current density of 6.66 mA/cm2, Fe2+ concentration of 0.80 mM, and an electrolysis duration of 60 min, in which RE% of 94% with SEC of 3.75 kWh/kg COD were achieved. In addition, the results demonstrated that the current density has the greatest influence on the COD removal, followed by electrolysis duration and then Fe2+ concentration. Furthermore, current density has the greatest impact on the specific energy consumption, followed by time, while Fe2+ concentration has a negligible effect. The high R2 value (98.33%) confirmed the goodness of fitting the model equation. These results established the viability of employing the new cathode design for the EF process in treatment of petroleum refinery wastewaters. [Display omitted] • Low-cost micro porous graphite air diffusion cathode was utilized for COD removal from wastewater using electro Fenton. • The effects of various operational parameters on COD removal(RE%) were evaluated and optimized by RSM. • The new cathode generated a maximum of 68 mg/ L of H 2 O 2 at current density of 25 mA/cm2 and air flow rate of 3L/min. • Current density has the greatest influence on the RE%, followed by electrolysis duration and Fe2+ concentration. • The optimal conditions were current density of 6.66 mA/cm2, Fe2+ concentration of 0.80 mM, and 60 min, in which RE% and SEC were 94% and 3.75 kWh/kg COD. [ABSTRACT FROM AUTHOR]

Spent caustic is a highly contaminated wastewater from critical industries with complicated chemistry and different environmental adverse effects. Conventional wastewater remediation approaches are not effective enough for the remediation of spent caustic. Hence in this study, Electro-Fenton (EF) technology as a subsection of Advanced Oxidation Processes (AOPs) was applied for the removal of chemical oxygen demand (COD) in spent caustic effluent. For statistical analysis and experimental design of each factor including H 2 O 2 /COD, current density, pH, and treatment time on the COD removal (response), the Box Behnken Design (BBD) was used. The optimal conditions for operating factors were as the following: H 2 O 2 /COD = 0.73, pH= 5.46, current density = 18.83 mA/cm2 and treatment time= 69.88 min. In these conditions, the actual and predicted COD removal was 93.0% and, 94.38%, respectively. Finally, it concludes that Electro-Fenton technology was reliable and outstandingly efficient for COD removal in spent caustic wastewater. The kinetic studies confirmed that the removal of COD tracked the first-order kinetic model and the constant reaction rate and half-life of COD removal kinetic were 0.0257 min−1 and 27 min, respectively. The operating costs analysis showed that the Electro-Fenton process had lower operating costs and it can be a good opportunity for the treatment of spent caustic wastewater on an industrial scale. The operational cost for this process was found to be 1.562$ M−3kg−1COD removal. [ABSTRACT FROM AUTHOR]

As an easily obtained organic waste, by-product acetic acid could be an appropriate co-substrate with blue algae wastes (increase C/N ratio of substrates) for co-fermentation of PHA production. However, there are still acrylic acid and other chemicals in by-product acetic acid, which could cause severe inhibition for fermenting microorganisms during PHA production process. The current study represented that alkali pretreatment (pH level of 12) is a more favorable method compared with thermal pretreatment (80 ℃ for 30 min) for breaking cell walls of blue algae. It seemed that there was no synergistic effect of the combination of thermal and alkali pretreatment methods (temperature of 80 ℃ and pH level of 12). Optimal parameters during electro-fenton process for removal of inhibitors in by-product acetic acid were under current of 0.5 A, pH level of 3 and reaction time of 120 min. Both the highest dry weight of PHA and PHA concentration were achieved by applying blue algae and by-product acetic acid (after pretreatment) as co-substrates (mixed ratio of 3:1, stirring speed of 200 r/min, 24 h), indicating that using by-product acetic acid (after pretreatment) as co-substrate could increase C/N ratio and promote PHA production successfully. The current study could offer new insights for improving PHA production by co-fermentation. [Display omitted] • Alkali pretreatment is a more favorable method compared with thermal pretreatment. • There was no synergistic effect of the combination of thermal and alkali pretreatment. • Optimal parameters for removal of inhibitors in by-product acetic acid were determined. • By-product acetic acid (after pretreatment) as co-substrate could promote PHA production. [ABSTRACT FROM AUTHOR]

Emerging contaminants (ECs) are concerned worldwide due to their ubiquitous, persistence, high toxicity and low treatment efficiency in conventional processes. Meanwhile, the electro-Fenton (EF) technique has gained significant attention owing to its high efficiency and environmental compatibility for the degradation of ECs. Nevertheless, the EF process has suffered low Faraday efficiency, high cost and poor mass transfer, mainly in the low efficiency of Fe3+/Fe2+ cycle, insufficient capacity of oxygen reduction and limitation of low pH. The ways to improve EF efficiency include adding catalysts, optimizing electrode materials, and coupling other technologies. Among them, cathode material is the key factor affecting EF efficiency. In recent years, researchers have carried out a large number of related studies, among which carbonaceous materials (CMs) have become one of the most promising EF cathode materials due to their excellent performance advantages. Many works on the preparation and modification of novel carbon materials have been paid attention to, but lacks a systematic review report summarizing carbon cathode in EF process. Aiming at this issue, this paper summarizes the modification of CMs to improve H 2 O 2 electrogeneration, strengthen Fe3+/Fe2+ cycle efficiency, and broaden pH window, respectively. Besides, the development of biochar materials is summarized, and the existing shortcomings and future development directions in the field of cathode EF are briefly discussed. [Display omitted] • Cathode material is a key factor affecting cathode electro-Fenton efficiency. • Various carbonaceous cathodes for emerging contaminants degradation are summarized. • Cathode modification for H 2 O 2 generation, Fe3+/Fe2+ cycle and pH window are reviewed. • The development of biochar materials as electro-Fenton cathode is introduced. • The shortcomings and future research directions for electro-Fenton are proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dual-functional electrocatalyst of defective cobalt-nitrogen-doped porous carbon was synthesized. • Carbon defects and graphitic nitrogen improved the selectivity and yield of H 2 O 2. • Co-doping of Co and pyridinic-N contribute to the decomposition of H 2 O 2 into ·OH. • Co 1 /Zn 1 -NPC has excellent stability and stable treatment performance in electro-Fenton. Tetracycline hydrochloride (TC) is one of the organic pollutants that can be consistently monitored in the aquatic environment and pose a great threat to the environment. The development of a bifunctional electro-Fenton (EF) catalyst capable of in situ H 2 O 2 production and decomposition to ·OH to degrade the pollutant is an efficient and green approach to deal with antibiotic pollution. The bifunctional catalysts Co, N double doped defective carbon materials were prepared by pyrolysis ball milling method using zeolite imidazolium ester skeleton structural materials (ZIFs) series materials as precursors, which showed more than 80% selectivity to H 2 O 2 and could basically remove TC within 120 min in EF system. Carbon defects and graphitic nitrogen can effectively improve the selectivity and yield of H 2 O 2 , while graphitization degree improves the charge transfer rate, the doping of Co and pyridinic-N contribute to the decomposition of H 2 O 2 into ·OH. The active species present in the Co 1 /Zn 1 -NPC/EF system is ·OH, and factors such as coexisting ions, humic acid and water quality have little effect on the efficiency of the degradation of TC in the Co 1 /Zn 1 -NPC/EF system, whereas Co 1 /Zn 1 -NPC electrocatalytic catalyst has excellent stability and stable treatment performance for a wide range of pollutants, as well as being an environmentally friendly green catalyst without metal leaching. Furthermore, the possible pathways and the toxicity hazard of TC degradation were proposed. The bifunctional electrocatalyst prepared in this research provides a novel strategy for the green and efficient treatment of pollutants in wastewater. [ABSTRACT FROM AUTHOR]

• A metal-free floating electrochemical advanced oxidation system was established. • The floating electrode can efficiently produce H 2 O 2 without aeration. • The oxygenated graphene aerogel catalyst promoted the activation H 2 O 2 to ·OH. • The primary activation sites were identified as the = O and –COOH groups. • The system exhibited wide pH application range and good practicality. Metal-free electro-Fenton (EF) are a promising technology for environmental remediation. This paper reports a novel EF modified with oxygenated graphene aerogel used as a floating electrode for efficient degradation of bisphenol A (BPA) through improved H 2 O 2 yield combined with activation of hydroxyl radical (·OH) production. Impressively, the floating configuration of the electrodes allowed oxygen from the air to diffuse naturally into the reaction interface, reducing additional aeration energy consumption. The current efficiency of the floating system for H 2 O 2 production was 40 times higher than the conventional vertical mode. The pollutant degradation trend exhibited a positive correlation with the ·OH production performance of the electrode. The modified catalyst system achieved the highest ·OH yield of 76.48 μM within 60 min, which was 2.72 times greater than that of the catalyst-free (28.10 μM) and 2.06 times higher than that of the unmodified catalyst (37.19 μM). Experiments and theoretical calculations indicated that the oxygen-containing functional groups introduced the graphene skeleton created new sites for in situ activation of electrogenerated H 2 O 2 , resulting in increased ·OH production. The primary activation sites were identified as the = O and –COOH groups, with the = O edges playing a particularly significant role. This system offers long-lasting stability and avoids secondary pollution, making it ideal for green environmental remediation compared to the traditional EF process. [ABSTRACT FROM AUTHOR]

Designing a membrane electrode with high activity and anti-scaling ability in a wide pH range is crucial to the development of flow-through electro-Fenton system. Herein, we reported a novel porous membrane composed of ultrafine FeMn bimetallic nanoparticles anchored in nitrogen-doped carbon nanofibers (FeMn/N-CNF) obtained through a facile electrospinning-carbonization process. The strong metal-support interaction (SMSI) phenomena including carbon encapsulation structure and electron transfer from metal to N-CNF, beneficial to the intrinsic activities, were successfully induced by the enhanced interfacial metal-nitrogen bonding in FeMn/N-CNF. Microstructural characterizations and leaching test revealed that the SMSI encapsulation structure could promote the formation of ultrafine FeMn nanoparticles in N-CNF during the high-temperature carbonization process and prevent leaching of active Fe/Mn metals into solution across a wide pH range. The constructed gravity-driven flow-through electro-Fenton system based on a FeMn/N-CNF cathode membrane exhibited superior performance to generate H 2 O 2 (36.23 mmol L−1 h−1) and subsequent activate H 2 O 2 decomposition to hydroxyl radicals (0.1024 min−1), achieving remarkable degradation efficiencies of 96.8%, 92.3%, and 90.3% within 60 min for Rhodamine B, Tetracycline, and Methyl Orange, respectively. Furthermore, the FeMn/N-CNF membrane filter demonstrated good pH adaptability, excellent cycle stability and anti-scaling ability during the degradation process. This work offers a viable avenue to enhance degradation performance and environmental robustness for practical water decontamination via achieving SMSI effect in carbon-supported electro-Fenton membranes. [Display omitted] • Ultrafine nanoparticles anchored in N-CNF porous membrane is simply prepared. • Strong metal-support interaction (SMSI) is existed in FeMn/N-CNF. • Gravity-driven flow-through electro-Fenton FeMn/N-CNF system is constructed. • Such system achieves efficiently degradation for various pollutants in wide pH range. • FeMn/N-CNF filter exhibits excellent anti-scaling ability and mechanical stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Solvothermal method followed by calcination treatment under different temperature was facilely utilized to synthesize Fe-NiCo 2 O 4 nanosheets with different crystallinity. • The resultant Fe-NiCo 2 O 4 show similar nanosheets with porous structure. • As catalysts for OER, the Fe-NiCo 2 O 4 nanosheets obtained as 300 ℃ exhibit superior electrical conductivity and catalytic activity to the other studied Fe-NiCo 2 O 4 and RuO 2. • Additionally, the outstanding stability was observed for the optimized Fe-NiCo 2 O 4 nanosheets. Recently, the electro-Fenton (EF) process by coupling cathodic two-electron oxygen reduction reaction (2e- ORR) with anodic oxygen evolution reaction (OER) has emerged as a potentially viable technology, while the sluggish OER is the main bottleneck. As promising OER catalysts, the amorphous and crystal phases of spinel oxides display high activities and electrical conductivity, respectively. Efforts to produce amorphous/crystal spinel oxides have progressed slowly, and how an amorphous/crystal structure benefits the catalytic performances remains elusive. Herein, Fe-doped NiCo 2 O 4 (Fe-NiCo 2 O 4) was used as a model catalyst to explore the effect mechanism of crystallinity controlled by annealing temperature on OER performance. The results display that the Fe-NiCo 2 O 4 obtained at 300 ℃ shows amorphous/crystal structure, which facilitates the active site exposure and the charge transfer, leading to superior OER activity and catalytic stability. Based on the crystallinity regulation of OER catalysts, we propose an anodic optimized strategy to upgrade the EF-related processes by effectively providing O 2 produced in the anode. [ABSTRACT FROM AUTHOR]

The presence of polyethylene terephthalate (PET) microplastics (MPs) in waters has posed considerable threats to the environment and humans. In this work, a heterogeneous electro-Fenton-activated persulfate oxidation system with the FeS 2 -modified carbon felt as the cathode (abbreviated as EF-SR) was proposed for the efficient degradation of PET MPs. The results showed that i) the EF-SR system removed 91.3 ± 0.9 % of 100 mg/L PET after 12 h at the expense of trace loss (< 0.07 %) of [Fe] and that ii) dissolved organics and nanoplastics were first formed and accumulated and then quickly consumed in the EF-SR system. In addition to the destruction of the surface morphology, considerable changes in the surface structure of PET were noted after EF-SR treatment. On top of the emergence of the O-H bond, the ratio of C-O/C=O to C-C increased from 0.25 to 0.35, proving the rupture of the backbone of PET and the formation of oxygen-containing groups on the PET surface. With the verified involvement and contributions of SO 4 •- and •OH, three possible paths were proposed to describe the degradation of PET towards complete mineralization through chain cleavage and oxidation in the EF-SR system. [Display omitted] • EF-SR achieved 91.3 ± 0.9 % removal of 100 mg/L PET after 12 h at trace loss of FeS 2. • Dissolved organics and nanoplastics were formed/accumulated and quickly consumed. • Considerable changes in surface morphology and structure of PET MPs were noted. • 3 possible paths were proposed to describe PET degradation/mineralization in EF-SR. [ABSTRACT FROM AUTHOR]

A hydrophobic Cu 2 O cathode (Cu x O-L) was designed to solve the challenge of low oxidation ability in electro-Fenton (EF) for treating emerging pollutants. This fabrication process involved forming Cu(OH) 2 nanorods by oxidizing copper foam (Cu-F) with (NH 4) 2 S 2 O 8 , followed by coating them with glucose via hydrothermal treatment. Finally, a self-assembled monolayer of 1-octadecanethiol was introduced to create a low-surface-energy, functionalized Cu x O-L cathode. Results exhibited an approximately 7.9-fold increase in hydroxyl radical (·OH) generation compared to the initial Cu-F. This enhancement was attributed to two key factors: (Ⅰ) the superior O 2 -capturing ability of Cu x O-L cathode, which led to high H 2 O 2 production due to a 2 nm thick hydrophobic gas layer facilitated O 2 -capturing; (Ⅱ) a relative high concentration of Cu+ at the Cu x O-L cathode promoted the activation of H 2 O 2 into·OH. In addition, the performance of EF with the Cu x O-L cathode using sulfathiazole (STZ) as a model pollutant was evaluated. This study offers valuable insights into the design of O 2 -capturing cathodes in EF processes, particularly for treating emerging organic pollutants. [Display omitted] • Bio-inspired hydrophobic Cu 2 O cathode (Cu x O-L) was designed； • ·OH concentration on Cu x O-L cathode increased approximately 7.9-fold; • A 2-3 nm gas film enhances the cathode's O 2 capturing; • Cu+ was active site for H 2 O 2 formation, favoring its activation into·OH. [ABSTRACT FROM AUTHOR]

[Display omitted] • Enhancing electro-Fenton performance by adjusting catalyst pore size was proposed. • Synchronized enhancement of H 2 O 2 production and Fe2+ reduction was achieved. • 0.1 mM Fe2+ was adequate to accomplish 20 mg/L sulfamethazine degradation at pH 3–7. • The energy consumption was 0.87 kWh per gram of removed total organic carbon. • Finite element simulation revealed the accelerated mass transfer on optimized pores. Electro-Fenton (EF) is efficient in decontaminating refractory pollutants but high consumption of Fe2+ as a hydrogen peroxide (H 2 O 2) activator increases its operation cost. Designing EF system with accelerated Fe2+/Fe3+ cycling is crucial for both hydroxyl radical generation and Fe2+ dosage reduction. Here, we employed pore structure tailoring engineering to optimize pore size of mesoporous hollow carbon spheres (MHCS), achieving an improved H 2 O 2 electro-synthesis and Fe2+ regeneration. MHCS with 8 nm surface pores yielded 81.33 mmol g catalyst −1h−1 H 2 O 2 and realized 51.2 % Fe2+ regeneration efficiency, enabling complete removal of sulfamethazine with a low energy consumption of just 0.87 kWh g−1 total organic carbon. Finite element simulation revealed that MHCS with 8 nm surface pores favored mass transfer, facilitating solute diffusion to the electrode's active layer for reaction. In addition, EF system maintained a degradation efficiency of 90 % after five cycles of operation and was effective in removing various types of pollutants, which implies its application potential. This work demonstrated a novel catalyst structure optimization strategy to both enhance Fe2+ regeneration and improve EF performance, offering an energy-efficient water purification solution. [ABSTRACT FROM AUTHOR]

Based on the principle of electro-Fenton (EF) reaction, this investigation was experimented to treat copper (Cu) and lead (Pb), which are lower mobile in dredged sediment in a self-made EF reactor, and simultaneously dewater it. The results of the study showed that when Fe2+ concentration was 1 mM, the initial current density was 10.4 mA/cm2, and the initial pH was neutral, after 24 h, the conversion of the stable form to the activated state of Cu and Pb were 24.77 % and 68.42 %, respectively. Further, the water content of the dredged sediment was significantly reduced from the initial 58–26 % after the EF. The mechanism experiment confirmed that ·OH and SO 4 ·- were the main factors for converting Cu and Pb forms, destroying the EPS structure in the dredged sediment and decomposing its main components, improving the dewatering property of the dredged sediment. In addition, EF treatment did not decrease microbial diversity in dredged sediments, and Flavobacterium and Bacillus , which are beneficial for agricultural production, became featured taxa after EF. This study provided a new perspective that transforms Cu and Pb into a more easily removable form with simultaneous efficient dewatering, which is more conducive to subsequent conventional treatment of the dredged sediment. • Using a novel EF reactor to treat HMs in dredged sediment and simultaneous dewatering. • Cu and Pb from oxidizable and residual states to available fraction after EF. • OH and SO 4 ·− were responsible for the transformation of Cu and Pb forms. • Reduction in water content of dredged sediment from 58.4 % to 26.3 % after EF. • Firmicutes and Actinobacteria were feature taxa after EF. [ABSTRACT FROM AUTHOR]

Electrochemical advanced oxidation processes (EAOPs) are particularly notable for their environmental friendliness, efficiency, and lack of secondary contamination. These approaches are primarily founded on the electrochemical production of powerful oxidants, exemplified by ·OH, ·O 2 -, 1O 2 and SO 4 ·−. The article commences with a thorough review of the process mechanisms of EAOPs, followed by a detailed summary of the common free radical detection methods utilized in EAOPs. Subsequently, we examine the prevalent non-active anode materials in EAOPs (BDD, SnO 2 , PbO 2), as well as the particle electrodes in solution, encompassing their preparation methods and respective performances. In addition, the application of EAOPs in the removal of organic and inorganic pollutants, desulfurization of coal and minerals, and sludge treatment was also summarized. Finally, certain limitations of EAOPs research are presented, along with some recommendations for future development. [Display omitted] • Detailed summarize the detection of free radicals in EAOPs. • Three non-active electrodes used in EAOPs were completely introduced. • EAOPs used in pollutant removal, desulfurization and sludge treatment were presented. [ABSTRACT FROM AUTHOR]

The electro-Fenton oxidation process for the degradation of organic pollutants in recalcitrant wastewater has garnered significant attention and research efforts in the field of advanced water treatment. This is primarily due to its highly effective degradation capabilities and the advantages it offers, including the avoidance of unsafe transportation and storage of hydrogen peroxide (H 2 O 2). However, challenges such as relatively high energy consumption, complex operational requirements, and limited operational stability continue to pose significant economic constraints on the widespread application of electro-Fenton technology in water purification. In this study, we employed a secondary hydrothermal method to construct a multi-layered CNT/MoS 2 /Fe 3 O 4 composite heterostructure in situ. Leveraging the synergistic effects of the introduced variable valence elements, Fe and Mo, and the interconnected multi-layered membrane structure, the CNT/MoS 2 /Fe 3 O 4 electro-Fenton membrane holds promise in a permeable filtration system. Under the conditions of a current density of 1.50 mA/cm² and an electrolyte concentration of 0.50 mol/L, the CNT/MoS 2 /Fe 3 O 4 composite membrane exhibited a degradation efficiency of over 90.00 % for 100.00 mg/L RhB within 10 minutes, and the degradation rate approached nearly 99.00 % at 60 minutes. Furthermore, the degradation efficiency for various recalcitrant organic dye wastewaters, including phenol, methyl orange, and methylene blue, could be maintained at levels ranging from 80.00 % to 97.00 %. Particularly, under optimized operating conditions, the specific energy consumption (EC) for the CNT/MoS 2 /Fe 3 O 4 membrane process was measured at 0.60±0.01 kWh/m³, showcasing exceptionally low energy consumption characteristics. In conclusion, it is expected to contribute to the reduction of the overall consumption of heterogeneous electro-Fenton oxidation systems and enhance their operational efficiency. This innovative approach represents a significant advancement in the field, offering the potential to address the economic limitations associated with electro-Fenton technology in water quality purification. [Display omitted] • In-situ interconnected CNT/MoS 2 /Fe 3 O 4 heterostructures were constructed via secondary hydrothermal method. • The CNT/MoS 2 /Fe 3 O 4 composite membrane achieved a RhB degradation rate of nearly 99.00 %. • The degradation efficiency for dyes like phenol, methyl orange and methylene blue was 80.00–97.00 %. • Optimized CNT/MoS 2 /Fe 3 O 4 membrane process had low energy consumption of only 0.60±0.01kWh/m³. [ABSTRACT FROM AUTHOR]

The removal of the bisphenol A (BPA) from sulphate-rich wastewater has been investigated using an electro-Fenton oxidation system with metal-oxide carbon nanostructured anode. The process produces highly oxidizing species, including hydroxyl radicals on the anode surface and bulk solution via an electrochemically monitored Fenton reaction. The focus of this research is the detection of BPA intermediates and the prediction of the BPA degradation mechanism during the electro-Fenton process using the SnO 2 -MWCNT nanostructured anode. In accordance to detected reactive oxygen species, BPA intermediates, and their respective peak area profiles, two primary degradation pathways can be defined. Whether direct cleavage of BPA precedes hydroxylation, oxidation, and dealkylation, or vice versa, the resulting products consist of catechols, dicatechols, quinones, aldehydes, carboxylic acids, and ultimately carbon dioxide and water. To ensure a comprehensive understanding, the impact of applied current, catalyst concentration, and treatment duration on degradation and mineralization efficiency, as well as degradation kinetics, was investigated. The degradation of BPA was found to follow pseudo-first-order reaction kinetics. The results showed that the degradation of BPA was attributed to the co-action of electro-Fenton oxidation and electrochemical oxidation. This study confirms the eco-friendly nature of the electro-Fenton process by demonstrating the toxicity of intermediaries formed during BPA treatment. • BPA degradation was studied via electro-Fenton using SnO 2 -MWCNT nanostructured anode. • BPA intermediates have been identified and two reaction pathways have been proposed. • Toxicity predictions have confirmed the formation of non-toxic intermediates. • BPA oxidation by OH∙ follows pseudo-first-order kinetics. [ABSTRACT FROM AUTHOR]

[Display omitted] • The release of Li+ were mainly triggered by the rapid attack of a large amount of OH. • Electrochemical leaching was a chemical reaction control model. • Dissolution of each metal ion was feasible in this leaching environment. In recent years, lithium-ion batteries have been increasingly used in electric and hybrid vehicles. It is anticipated that the first lithium-ion batteries will be discarded at the height of their useful lives in 2025, so developing an effective and ecologically friendly recycling process is essential. In this study, an electrochemical cathode synergism is proposed for the electro-catalyzed oxidation of lithium nickel cobalt manganese oxide powder and lithium iron phosphate powder to extract metal. The oxidation of Fe2+ and the release of Li+ (98 %) in LiFePO 4 and the leaching of Ni (92 %), Co (91 %), Mn (94 %) and Li (97 %) from its NCM523 were mainly triggered by the rapid attack of a large amount of OH during advanced oxidation. The leaching kinetic analysis showed that the leaching system for electrochemical leaching of binary and ternary cathode materials was a chemical reaction control model, and the leaching thermodynamic analysis showed that the dissolution of each metal ion was feasible in this leaching environment. The suggested recycling technique utilizes fewer chemicals and generates less waste when compared to previous recycling techniques. The method offers a fresh approach to environmentally friendly recycling for spent lithium-ion battery leaching and recycling. [ABSTRACT FROM AUTHOR]

[Display omitted] • Macroscopic ordered 3D-FeO/C electrode was constructed by 3D printing technology. • 3D-FeO/C can efficiently degrade antibiotic drug and pharmaceutical wastewater. • Confinement effect and enhanced mass transfer synergistically act on EF reaction. • Degradation mechanism of ornidazole and pharmaceutical wastewater was revealed. In this study, researchers constructed a monolithic 3D-FeO/C electrode with a macro-ordered pore structure using direct-write 3D printing technology. Experimental results showed that the 3D-FeO/C electrode possessed excellent degradation performance for ornidazole (ONZ) (complete degradation within 120 min) and pharmaceutical wastewater (51.13 % in TOC and 63.72 % in COD removal within 420 min). The detailed reaction mechanism of the EF system was revealed through characterization analysis, mass transfer simulation, and experimental results, in which the excellent EF performance is mainly due to the confinement effect of FeO active sites encapsulated in the carbon layer, as well as the enhancement of mass transfer induced by 3D printing macro-ordered structure network. In addition, the degradation pathway of ONZ, the toxicity of its degradation intermediates, and the degradation pathway of actual pharmaceutical wastewater were revealed in detail. This study proposes a new 3D printing method to enhance the mass transfer of electrode materials in EF systems, which has good potential for application to real wastewater. [ABSTRACT FROM AUTHOR]

Electrochemical oxidation (EO), electro-Fenton (EF), and photoelectro-Fenton (PEF) with a BDD anode have been comparatively assessed to remediate solutions of Red CL and/or Red WB azo dyes from real raw water. For the EO process in 50 mM Na 2 SO 4 at pH 3.0, the main oxidant was the heterogeneous •OH generated at the anode, whereas in EF and PEF, the cathodic production of H 2 O 2 and the addition of 0.50 mM Fe2+ catalyst additionally originated homogeneous •OH that enhanced the oxidation of organics. In PEF, the solution was illuminated with a 6 W UVA light. An almost total discoloration was always found operating with a 1:1 mixture of 200 mg L−1 of both dyes in 60 min, whose efficiency increased in the order of EO < EF < PEF. The HPLC analysis of the dye mixture treated by PEF disclosed that its degradation process agreed with its discoloration. A high 74% of COD was reduced due to the oxidative action of hydroxyl radicals and the photolysis of final Fe(III)-carboxylate species with UVA irradiation. The process was accompanied by an energy consumption of 0.76 kWh (g COD)−1, a value similar to the energy consumed by the applied UVA light. [Display omitted] • Remediate concentrated solutions of Red CL and/or Red WB azo dyes used in the tannery industry from real raw water. • In all these treatments, the loss of color was increased by raising the current density (j) and the dye content. • An almost total discoloration was always found operating with a 1:1 mixture of 200 mg L−1 of both dyes in 60 min. • The HPLC analysis of the dye mixture treated by PEF disclosed that its degradation process. [ABSTRACT FROM AUTHOR]

[Display omitted] • The BWBC*@Ni-F exhibited excellent H 2 O 2 accumulation of 303 mg L-1. • The DCEF system efficiently degraded contaminants in a wide pH range of 3–11. • The DCEF system displayed high TOC removal efficiency and low energy consumption. • The BCO 2 and C=O groups played a pivotal role in the activation of H 2 O 2. Electro-Fenton (EF) process stands out as an energy-efficient and highly promising advanced oxidation technology for organic contaminants degradation. However, achieving optimal heterogeneous catalytic conditions for simultaneous H 2 O 2 generation and spontaneous Fe2+ regeneration poses difficulties in conventional EF. This is due to the electric potential difference between H 2 O 2 generation and Fe2+ regeneration at a single cathode. Therefore, the boron doped biochar modified dual-cathode EF (DCEF) system was designed in this work to overcome the defect of conventional EF system, which not only demonstrated outstanding accumulation of H 2 O 2 (>300 mg L-1) but also exhibited a remarkable capability of degradation (>90 %). Furthermore, the system could also adapt to a broad pH range of 3–11. The superior doxycycline (DOX) degradation efficiency of DCEF system could be attributed to the dominant role played by C=O and BCO 2 groups in the activation of H 2 O 2 and subsequently generating reactive oxygen species (ROSs), as revealed by XPS analysis and DFT calculation. In addition, the DCEF system achieved an impressive TOC removal efficiency of 70.5 % and a minimal energy consumption (EC) of 0.32 kWh (g TOC)-1. Therefore, this work introduced a DCEF system to address the challenges of conventional EF system, which shed light on the design of wastewater treatment technology and lied the groundwork for a strategy of resource utilization. [ABSTRACT FROM AUTHOR]

• A new photovoltaic electric Fenton (PVEF) system was developed with a low energy consumption of 5.5 kWh/kg. • The performance of PVEF systems in different types of wastewater were evaluated. • The PVEF can replace the deep treatment process in wastewater treatment plants, reducing energy consumption by 803 kWh and carbon emissions by 305 t. In the current mainstream wastewater treatment technologies, electro-Fenton (EF) has been widely used as an advanced oxidation process for achieving deep degradation of organic pollutants without secondary pollution. However, the high energy consumption of EF has hindered its development to a certain extent. In this study, a photovoltaic(PV)-driven EF system is developed to incorporate photovoltaic energy into the EF system to efficiently degrade organic matter in sewage and reduce energy consumption and operating costs of sewage treatment. To fully evaluate the performance of the photovoltaic drive electro-Fenton degradation sewage (PVEF) system, we investigated the effects of system configuration, current density, and stirring speed on the degradation of methyl orange (AO7) by the PVEF system. After determining the optimal experimental conditions, we explored the treatment efficiency and feasibility of the system for three different types of pollutants. Laboratory scale experiments also confirmed the critical effects of current density and stirring speed on the energy consumption of degradation. Finally, PVEF technology replaces the advanced treatment process in the sewage treatment plant, and the energy consumption model is established based on the local dye sewage plant in Chengdu to evaluate its applicability in different regions. The experimental results show that the dual-cathode system reduced energy consumption by 24.9 % and increased degradation efficiency by 30 % compared to the conventional EF system·H 2 O 2 generated under the optimal conditions is fully utilized, resulting in a removal rate of more than 95 % in 20 min for AO7. The optimal energy efficiency condition is determined when the current density is 3 mA/cm2 and the stirring speed is 1000 rpm, which reduces the system's energy consumption. The degradation test results of different pollutants show that the system can realize the degradation of various pollutants. The simulation results of the sewage plant scale show that the PVEF system can reduce carbon emission by 305 t instead of the traditional advanced treatment process. [ABSTRACT FROM AUTHOR]

Electrochemical advanced oxidation processes (EAOPs) based on natural air diffusion electrode (NADE) promise efficient and affordable advanced oxidation water purification, but the sustainable operation of such reaction systems remains challenging due to severe cathode electrowetting. Herein, a novel floating cathode (FC) composed of a stable hydrophobic three-phase interface was established by designing a flexible catalytic layer of FC. This innovative electrode configuration could effectively prolong the service life of the cathode by mitigating the interference of H 2 bubbles from the hydrogen evolution reaction (HER), and the H 2 O 2 production rate reached 37.59 mg h−1·cm−2 and realize a long-term stable operation for 10 h. Additionally, an FC/carbon felt (CF) dual-cathode electro-Fenton system was constructed for in situ sulfamethoxazole (SMX) degradation. Efficient H 2 O 2 production on FC and Fe(III) reduction on CF were synchronously achieved, attaining excellent degradation efficiency for both SMX (ca. 100%) with 2.5 mg L−1 of Fe(Ⅱ) injection. For real wastewater, the COD removal of the FC/CF dual-cathode electro-Fenton system was stabilized at exceeding 75%. The practical application potential of the FC/CF dual-cathode electro-Fenton system was also demonstrated for the treatment of actual landfill leachate in continuous flow mode. This work provides a valuable path for constructing a sustainable dual-cathode electro-Fenton system for actual wastewater treatment. [Display omitted] • Floating cathodes facilitate sustainable electrochemical production of H 2 O 2. • The moderate loading of PTFE reinforced the anti-wettability of FC cathode. • The stable operation of FC attributed to its resistance to H 2 bubbles from HER. • Effective SMX removal was achieved in the FC/CF dual-cathode electro-Fenton system. [ABSTRACT FROM AUTHOR]

Electro-Fenton (EF) can in-situ produce H 2 O 2 and effectively activate H 2 O 2 to generate powerful reactive species for the destruction of contaminants under acidic conditions, however, the production of iron-containing sludge and requirement of low working pH significantly hinder its practical application. Herein, a novel Cu, N co-doped carbon (Cu–N@C) with metal organic framework (MOF) as a precursor was constructed and adopted for the elimination of pefloxacin (PEF) in the heterogeneous electro-Fenton (HEF) process. PEF could be almost completely removed within 1 h and total organic carbon (TOC) removal efficiency was 48.57% within 6 h. Meanwhile, Cu–N@C had good repeatability and environmental adaptability, it can still maintain excellent catalytic performance after 10 cycles, and it exhibited satisfactory remediation performance in simulated water matrix. In addition, the HEF process catalyzed by Cu–N@C also showed satisfactory degradation effect on other organic pollutants including atrazine, methylene blue, and chlorotetracycline. Under the action of impressed current, the HEF system could generate H 2 O 2 in-situ, and the active species could be generated in the redox cycle of Cu0/Cu1+/Cu2+. Electron paramagnetic resonance and quenching experiments confirmed that •OH was the dominant active species in the degradation of organic compounds. The degradation process of PEF was studied by mass spectrometry analysis of intermediate products. This study provided a simple method to prepare MOF-based electrocatalyst, which exhibits promising application potential for treatment wastewater. [Display omitted] • Cu–N@C-700 showed satisfactory reactivity to remove PEF in the HEF process. • •OH was the dominant active species in the degradation of organic pollutants. • Redox cycle of Cu0/Cu1+/Cu2+ is favorable to catalyze H 2 O 2 for •OH formation. • Cu–N@C-700 exhibited excellent applicability and stability. [ABSTRACT FROM AUTHOR]

Rational reuse of municipal sludge to produce electro-Fenton electrode can not only save resources, but also produce superior peroxide and degradation pollutants simultaneously. Herein, a novel electro-Fenton electrode derived from sludge biochar loaded on Ni foam (SBC@Ni) was constructed via high temperature pyrolysis and chemical coating for efficient H 2 O 2 evolution and pollutant degradation. Systematic experiments and density functional theory calculations (DFT calculation) explained that the production of graphite C and graphite N during high-temperature pyrolysis of municipal sludge can greatly enhance the oxygen reduction reaction of SBC@Ni electrode and promote the evolution of H 2 O 2. And the hybrid heterojunctions, such as FeP, also played a key role in electrocatalytic processes. Notably, the electrode still exhibited excellent performance after 1000 linear scans and 12 h of continuous current stimulation, which demonstrated the excellent stability of the electrode. Moreover, SBC@Ni electrode can not only effectively oxidize 4-chlorophenol through the electro-Fenton effect, but also fully mineralize organic matter, indicating promising environmental application. The free radical quenching experiment also revealed that the ·OH is the main active species for 4-CP degradation in SBC@Ni electro-Fenton system. [Display omitted] • The Ni biochar electrode effectively promoted the electro-Fenton reaction. • High-temperature pyrolysis contributed to the formation of Graphite-C/N. • DFT proved that Graphite-C/N can accelerate the 2e– ORR reaction. • Sludge biochar electrodes can efficiently and stably degrade and mineralize 4-CP. [ABSTRACT FROM AUTHOR]

• A novel sustainable electro-Fenton system is successfully constructed. • NPC-D/MoS 2 NA can simultaneously remove Cr (VI) and contaminants. • Dual-site NPC-D cathode has high selectivity of 2e− ORR for H 2 O 2 production. • Electric field-driven MoVI/MoIV conversion rapidly promotes the redox processes. • The synergistic redox mechanism of electron-Fenton system is deeply unveiled. Simultaneous removal of heavy metals and organic contaminants remains a substantial challenge in the electro-Fenton (EF) system. Herein, we propose a facile and sustainable "iron-free" EF system capable of simultaneously removing hexavalent chromium (Cr (VI)) and para-chlorophenol (4-CP). The system comprises a nitrogen-doped and carbon-deficient porous carbon (dual-site NPC-D) cathode coupled with a MoS 2 nanoarray promoter (MoS 2 NA). The NPC-D/MoS 2 NA system exhibits exceptional synergistic electrocatalytic activity, with removal rates for Cr (VI) and 4-CP that are 20.3 and 4.4 times faster, respectively, compared to the NPC-D system. Mechanistic studies show that the dual-site structure of NPC-D cathode favors the two-electron oxygen reduction pathway with a selectivity of 81 %. Furthermore, an electric field-driven uncoordinated Mo valence state conversion of MoS 2 NA enchances the generation of dynamic singlet oxygen and hydroxyl radicals. Notably, this system shows outstanding recyclability, resilience in real wastewater, and sustainability during a 3 L scale-up operation, while effectively mitigating toxicity. Overall, this study presents an effective approach for treating multiple-component wastewater and highlights the importance of structure-activity correlation in synergistic electrocatalysis. [Display omitted] [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H 2 O 2) synthesis by electrochemical two-electron oxygen reduction has garnered increasing interest as a wide range of potential applications. Gas diffusion electrodes (GDEs) can effectively promote the H 2 O 2 production efficiency by overcoming the oxygen mass transfer limitations but strongly influenced by the electrowetting process along the long-term operation. In this study, the effect of trans -electrode pressure (TEP) of GDE cathode on the electrowetting process was further elucidated. We controlled the TEP values of four types of GDEs: two Ni-based GDEs and two carbon cloth GDEs prepared by hot-pressing or brushing carbon black. SBA-15 was further used to regulate the microstructure of one Ni-based GDE. It was found that an optimal range of TEP occurred for all tested GDEs in terms of the max. concentration, the yield efficiency, the energy consumption, and the stability because TEP may change the triple-phase interface and influence the anti-electrowetting effect. The porosity of hot-pressed Ni GDE can maintain the TEP window and thus enhance the production of H 2 O 2 , likely via creating oxygen-containing functional groups and a bimodal pore structure on the electrode, revealed with several characterization techniques including SEM, CA, XPS, Raman spectra, CV and EIS. The porous Ni GDE presented an efficient and stable production of H 2 O 2 for 10 cycles: yielding H 2 O 2 at 4393.2–4602.2 mmol m−2 h−1 with current efficiencies of 94.2–98.7%. The best accumulated H 2 O 2 concentration can reach up to 3.58 ωt% H 2 O 2 at 10 h. The results provide an important reference for the industrial scaleup of electro-production of H 2 O 2 with GDEs. [Display omitted] • A comparison on working pressure windows of Ni and carbon-cloth based electrodes. • Effect of working pressure on flooding performance and H 2 O 2 production also were explored. • The trend of cell voltage, energy consumption and their cost were evaluated. • Deep in-sighting of Ni-based hot-pressing GDE electrode by XPS, Raman, CV and EIS. • Optimal H 2 O 2 production reached up to 13 g/L at 2 h and current efficiency was stable at about 98.7%. [ABSTRACT FROM AUTHOR]

Carbamazepine (CBZ) is one of the most stable pharmaceutical compounds that is commonly found in the effluents of wastewater treatment plants (WWTP). In this context, this contribution presents a comprehensive analysis of the different operating parameters of a flow-through and pilot-scale cylindrical reactor for hydrogen peroxide (H 2 O 2) generation, in which the degradation of CBZ takes place. The electrochemical system was evaluated using 8 L of electrolytes prepared with tap water in the presence of methanol as dissolved organic matter or spiked tertiary WWTP effluent, at a volumetric flow of 7 L min−1. This reactor (i) improves the mass transport due to its flow-through configuration using fibrous quasi-three-dimensional carbon felt electrodes, (ii) operates without an external oxygen supply to promote the H 2 O 2 electrosynthesis because it is incorporated by a jet aerator (iii) achieves the Fenton reaction at circumneutral pH due to Fe(II) disposition from a cation exchange resin. At first, the carbonaceous materials were electrochemically characterized by cyclic voltammetry measurements. Different operating parameters were evaluated by factorial design methodologies for H 2 O 2 generation, energetic consumption and CBZ removal. The application of a current density of 1.4 mA cm−2, in a cathode-anode-cathode arrangement immersed in a 120 mM ionic strength solution, allowed to obtain up to 6.4 mg H 2 O 2 L−1 after 40 min, consuming 0.44 kWh m−3. Later, the Fenton reaction was validated by a florescence study, and by the incorporation of 0.75 g of granular activated carbon and 5 g of Fe(II) loaded resin, CBZ abatement yields of 68 % and 32 % were obtained using a synthetic solution and a spiked tertiary WWTP effluent, respectively, and up to 28 % of the dissolved total organic carbon was removed. Finally, an analysis of the stability of the carbon felt electrodes was tackled using scanning electron microscopy and energy-dispersive X-ray spectroscopy. [Display omitted] • Electrochemical H 2 O 2 generation and CBZ degradation for real aqueous solutions. • Flow-through electrochemical reactor equipped with affordable carbon felt electrodes at pilot-scale. • Higher CBZ removal in tap water compared with CBZ spiked tertiary effluent. • The study contributes to bridge the gap between laboratory scale assays and real working conditions. [ABSTRACT FROM AUTHOR]

This presents the efficacy of a 3D-ElectroFenton (3D-EF) reactor with active perovskite/carbon black/PTFE microelectrodes for the removal of carbamazepine (CZP) present in wastewater. Incorporating particle microelectrodes in the reactor enhanced the electron transfer and improved the electrocatalytic efficiency, leading to a more effective CZP removal. The optimal operational conditions were meticulously determined, including current intensity (0.05 – 0.3 A) and particle loading (0 – 1.5 g), to optimize the process and minimize energy consumption. The findings reveal that a current intensity of 0.2 A was the most effective, achieving 90% of CZP removal in 60 min and 3.86 kWh/mg of CZP. A higher current intensity of 0.3 A significantly increased the energy consumption (6.02 kWh/mg of CZP) for a total and faster CZP removal. The 3D-EF reactor was also operated continuously with ultrapure water and real urban wastewater fortified with CZP. A remarkable 62% CZP removal after 96 h on continuous operation was achieved with urban wastewater. Physicochemical and electrochemical characterization of microelectrodes demonstrated their high mechanical integrity and chemical stability. Our study underscores the potential of a 3D-EF system as a promising advanced oxidation process to address the continuous removal of antidepressant carbamazepine as one of the more resistant micropollutants of emerging concern in wastewater treatment, offering hope for a more efficient and sustainable future. • An innovative configuration of a continuous 3D electro-Fenton (EF) reactor has been proposed. • Perovskite/Carbon Black microelectrodes enhanced the efficiency of an EF reactor. • Complete carbamazepine removal by 3D-EF process under neutral pH. • 65% carbamazepine removal in a real wastewater for 96 hours of treatment. [ABSTRACT FROM AUTHOR]

Electro-Fenton (EF) technology has been recognized as a highly promising electrochemical advanced oxidation process. Promoting effective contact between active species and contaminant is crucial in electrocatalysis. Herein, we had innovatively designed a unique nanozymes in the form of hemp-ball-like structures, consist of the uniform growth of Fe 3 O 4 nanoparticles on nitrogen-doped nano hollow carbon spheres (NHCS). This catalyst was employed in a flow-through EF system with carbon felt (CF) filters serving as the work electrode. The active sites were fully exposed through the ultradispersed Fe 3 O 4 nanoparticles, and the NHCS facilitated efficient cycling of Fe3+/Fe2+. The results showed that the generation capacity of hydroxyl radicals (·OH) was enhanced, and the oxidation flux reached 370.080 mg h−1m−2 with low energy consumption. The superiority of the hollow carrier was proved by the degradation results and COMSOL calculation for various carbon carriers. Moreover, the active catalyst exhibited adaptability in complex water matrices. This study offers a new perspective to synergize nanomaterials, EF reactions and flow-type systems. • A hemp-ball-like catalyst was fabricated with Fe 3 O 4 nanoparticle and nanoscale NHCS. • The different carbon supports was used to reveal the influence of structure. • COMSOL was used to reveal the mass transfer of the membrane interior. • NHCS-Fe 3 O 4 membrane exhibited exceptional performance and durability. • NHCS-Fe 3 O 4 membrane was high environmental adaption in the actual water. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA) is an endocrine disrupting chemical with high detection frequency and content, which seriously harms the ecology and human health. Spirit-based distillers' grains (DG) are solid residues produced during the brewing process, and their treatment has gotten the concern. It is an attractive effort to combine the comprehensive utilization of DG with the removal of BPA. Herein, O-doped porous biochar (OPB) was fabricated using DG as the precursor and used in an electro-Fenton (EF) system to degrade BPA. OPB exhibited a large surface area (i.e., 1432 m2/g) and doping of oxygen, which can facilitate dissolved O 2 diffusion and enhance the yield of H 2 O 2 (i.e., 3.0–15.5 mmol/L), and 20 mg/L BPA was rapidly removed by the EF system at the optimum condition (i.e., −0.5 V, pH 4, and 0.3 mM Fe2+) during 30 min with the apparent kinetic constant of 0.267/min. In addition, OPB demonstrated efficient stability in removing BPA after four cycles in the EF system. According to the results of density functional theory calculation and ultra-performance liquid chromatography–tandem mass spectrometry analysis, the three pathways were inferred to be hydroxylation, ketoneation, oxidation, and benzene ring cleavage, and then further decomposed into CO 2 and H 2 O, and the toxicity to the environment gradually decreased with the occurrence of the reaction. This study provides a new idea for resource recovery from waste biomass to solve the problem of water pollution. [Display omitted] • O-doped porous biochar (OPB) was prepared using spirit-based distiller's grains. • BPA was completely removed by the OPB-modified electro-Fenton system in 30 min. • The degradation mechanism of Bisphenol A was explored by DFT and LC-MS/MS. [ABSTRACT FROM AUTHOR]

In order to achieve considerable generation of free radicals during electro-coagulation (EC) process, EC with air breathing cathode (EC-ABC) was designed to allow for the coexistence of electro-Fenton (EF) and EC functions. This EC-EF-ABC synergetic system allows for both in-situ free radicals and adsorptive flocs generation in an undivided electrolytic cell. The yield of hydroxyl radicals and adsorptive flocs were quantified for accurate mechanism analysis. The control mechanism of the transition from EF to EC function during EC-ABC system was investigated. The air cathode material was studied and optimized to obtain high hydroxyl radical generation. The influences of both dissolved oxygen (DO) and pH condition on hydroxyl radical and flocs generation were studied. Whiles the latter was found to dominate the successive EF and EC functions, and further controls the hydroxyl radicals and flocs yield, the former only has a dominant effect on the hydroxyl radical yield. The adsorptive iron (oxy)hydroxide flocs' structure was also found to be fully depend on the DO condition. The control mechanism of initial pH and DO condition on radical and flocs generation was simplified as a 'Sudoku-like' relationship. The optimized initial pH and DO condition was studied to maximize the generation of hydroxyl radicals and adsorptive flocs. The design of EC-ABC process could have both advanced oxidation and adsorption abilities for wastewater pollutant removal. [Display omitted] [ABSTRACT FROM AUTHOR]

Landfill leachate is a complex effluent and it is difficult to deal with. Electrochemical methods have been considered as a promising alternative technology for treatment of landfill leachate with refractory organic contaminants and heavy metals. Peroxi-coagulation (PC) process with iron anode and modified graphite felt cathode was developed for efficient landfill leachate concentrate treatment. Compared to electro-Fenton (EF) and electrocoagulation (EC) processes, the PC process was more cost-effective due to the combined action of •OH oxidation and iron hydroxides coagulation. A maximal TOC removal of 77.2% ± 1.4% was obtained after 360 min at initial pH = 5.0 and current density of 10 mA/cm2. After the PC process, concentrations of all seven heavy metals in the final effluents were below the allowable emission limits given by the present regulatory standards. The method preference for heavy metal removal was PC > EC > EF. Based on the three-dimensional fluorescence spectroscopy coupled with regional integration analysis during the PC treatment, the florescence peaks of both humic acids and fulvic acids disappeared after treatment for 360 min. Decreasing trends were observed in the fluorescent regional standard volumes for aromatic protein I (31.4%), aromatic protein II (63.7%), fulvic acid-like (69.5%), soluble microbial by-product-like (75%) and humic acid-like regions (76.3%). The results indicate that comparing to the EF and EC process, the PC process provide a promising and more cost-effective alternative for the treatment of landfill leachate concentrate. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, carbamazepine (CBZ) decay in solution has been studied by coupling electrocoagulation with electro-Fenton (EC-EF) with a novel P-rGO/carbon felt (CF) cathode, aiming to accelerate the in-situ generation of •OH, instead of adding Fe2+ and H 2 O 2. Firstly, the fabricated P-rGO and its derived cathode were characterized by XRD, SEM, AFM, XPS and electrochemical test (EIS, CV and LSV). Secondly, it was confirmed that the performance in removal efficiency and electric energy consumption (EEC) by EC-EF (k obs =0.124 min−1, EEC=43.98 kWh/kg CBZ) was better than EF (k obs =0.069 min−1, EEC=61.04 kWh/kg CBZ). Then, P-rGO/CF (k obs =0.248 min−1, EEC=29.47 kWh/kg CBZ, CE=61.04%) showed the best performance in EC-EF, among all studied heteroatom-doped graphene/CF. This superior performance may be associated with its largest layer spacing and richest C=C, which can promote the electron transfer rate and conductivity of the cathode. Thus, more H 2 O 2 and •OH could be produced to degrade CBZ, and almost 100% CBZ was removed with k obs being 0.337 min−1 and the EEC was only 24.18 kWh/kg CBZ, under the optimal conditions (P-rGO loading was 6.0 mg/cm2, the current density was 10.0 mA/cm2, the gap between electrode was 2.0 cm). Additionally, no matter the influent is acidic, neutral or alkaline, no additional pH adjustment is required for the effluent of EC-EF. At last, an inconsecutive empirical kinetic model was firstly established to predict the effect of operating parameters on CBZ removal. [Display omitted] [ABSTRACT FROM AUTHOR]

Heterogeneous electro-Fenton (hetero-EF) technology represents a promising and safe approach to water treatment. However, conventional hetero-EF catalysts still face the challenges of removing contaminants selectively and operating efficient in complex water quality. We proposed a novel system utilizing amorphous CoS x (A-CoS x) that overcame these limitations. This material generated only singlet oxygen (1O 2), a highly specific oxidant, for contaminants degradation. Unlike traditional crystalline catalysts, A-CoS x efficiently utilized hydrogen peroxide (H 2 O 2) to directly produce 1O 2 , exhibiting high catalytic activity across a wide pH range (3.0–11.0). The formation mechanism of 1O 2 was confirmed through experimental investigations, density functional theory (DFT) calculations, and advanced characterization techniques. This system effectively degraded contaminants even in complex water with interferences and enabled selective targeting of pollutants with electron-donating groups. This innovative approach using amorphous materials offers a promising strategy for the regulation of ROS and enabling selective contaminant removal in water treatment. [Display omitted] • The role of amorphous CoS x catalyst for 1O 2 generation in hetero-EF system was revealed. • A-CoS x achieved nearly 100 % H 2 O 2 utilization efficiency and 1O 2 conversion in the hetero-EF system. • The A-CoS x /hetero-EF system demonstrated exceptional efficiency and selectivity in water decontamination. [ABSTRACT FROM AUTHOR]

Currently, most magnetorheological polishing methods use point or linear scanning. When these methods are applied to large-size semiconductor polishing, they are often limited by efficiency, making it difficult to simultaneously consider the surface quality and processing efficiency. In addition, because the mechanism of magnetorheological polishing is not yet clear, it is difficult to achieve the effect of synergistic enhancement of polishing efficiency and surface quality by simply increasing the magnetic field strength or introducing chemical reactions. In this paper, we propose a new method of combining the flexible force of magnetorheological action with the controllable electro-Fenton chemical action, and experimentally confirm the mechanism of the new skin corrosion effect that occurs under the flexible force applied to the magnetorheological micro-abrasive head, which provides a favorable theoretical research basis for improving the quality and efficiency of magnetorheological polishing. We also simulated the process using a magnetorheological electro-Fenton friction wear device and analyzed the influence of various parameters on the formation of the new skin corrosion effect. The results show that in the case of conventional friction and wear methods failing to form significant material removal corrosion trajectories, the composite friction method of magnetorheological electro-Fenton was able to form a corrosion layer of significant thickness over the entire range of action after the use of magnetorheological electro-Fenton composite friction method. Different third-generation semiconductor materials and crystal directions are presented with very significant corrosion effects. In particular, the best results were obtained when H 2 O 2 was continuously added at a rate of 0.30 g/min, a current parameter of 20 mA, a concentration of 3 wt% diamond particles, and a load of 0.418 N was applied, resulting in a cracked corrosion layer. [Display omitted] [ABSTRACT FROM AUTHOR]

Inspired by the growing development of dual single-atom catalysts (SACs), a bimetallic single-atom alloy (SAA) based macro-assembled graphene aerogel (MAGA) was synthesized in this study. The single-atom NiCo alloy-based graphene aerogel (i.e., NiCo/GO aerogel) with pinning effect was used as a sustainable cathode material in an in-situ H 2 O 2 generation system (i.e., electro-Fenton (EF) process). The atomic structure of NiCo/GO aerogel was identified by the combined microscopic and spectroscopic techniques. The SAA cathode exhibited a remarkable catalytic activity towards the two-electron-dominated oxygen reduction reaction (ORR) with the EF process for wastewater treatment. The energy consumption was calculated to be around 0.660 kW·h/t for treatment of water containing 2 mg L−1 ibuprofen (IBU). Density functional theory (DFT) analysis revealed the specific roles of the dual-functional NiCo SAA in the GO aerogel cathode, i.e., the Co sites more preferentially adsorb O 2 molecules for H 2 O 2 generation while the Ni sites function as the active sites for H 2 O 2 dissociation and activation. The research findings shed light on the controlled synthesis of SAAs for advanced catalysis and its potential application in the treatment of emerging organic contaminants for water safety and pollution control. [Display omitted] • Single-atom NiCo/GO aerogel with pinning effect was used as a sustainable cathode material in an EF system. • The energy consumption was calculated to be around 0.660 kW·h/t for treatment of water containing 2 mg L−1 IBU. • DFT revealed that Co sites were for H 2 O 2 generation, while the Ni sites function as active centers for H 2 O 2 activation. • A flow-through system was established as well. [ABSTRACT FROM AUTHOR]

[Display omitted] • N-doped porous carbon materials (WNPC) were derived by ZIF-8 modified balsa wood. • WNPC showed excellent H 2 O 2 generation capability in electro-Fenton system. • WNPC has a good selectivity for two electron oxygen reduction reaction. • Hydroxyl radicals were the main active substances for efficient TC degradation. Efficient electrochemical advanced oxidation processes (EAOPs) based on carbon catalysts are highly promising candidates for green environmental remediation technologies. Wood derived N-doped porous carbon (WNPC) was prepared the balsa wood with in-situ growth of zeolitic imidazolate framework-8 (ZIF-8) was used as precursor. WNPC acted as self-supporting electric Fenton cathode with high yield and selectivity (96 %) of in-situ H 2 O 2 generation, which effectively avoided the use binder for powder material. Owing to abundant N-doping and oxygen functional groups, the H 2 O 2 yield of WNPC was three times that of balsa wood derived carbon (WC) in electro-Fenton system. The graphite-N promoted the electron transfer, while the pyridinic-N could enhance the selectivity of the 2e-ORR for H 2 O 2 generation. Furthermore, the specific surface area of WNPC was 10 times of WC, with improved hydrophilicity and accelerated electron transfer. The removal efficiency of tetracycline hydrochloride (TC) achieved 91 % within 120 min in electro-Fenton system with WNPC and Fe2+, which was much higher than that with WC (63 %). Free radical scavenging and electron paramagnetic resonance experiments confirmed that ·OH and O 2 –· were the main active substances for TC degradation in electro-Fenton system. In addition, WNPC has good stability, reusability, and comparable degradation performance of various organic pollutants, and also had efficient degradation performance with actual water. This research proposed a novel strategy to construct efficient electro-Fenton catalyst with wood as precursor, which provides an advancing electrocatalytic methods to achieve efficient and environmentally conscious water purification. [ABSTRACT FROM AUTHOR]

Low H 2 O 2 production, narrow adaptive pH range and slow Fe(II) regeneration on the cathode still limit efficiency of electro-Fenton (EF) and its application. Herein, we designed a bifunctional catalyst with FeS and Fe 3 O 4 nanoparticles dispersed on porous carbon (CFeS@C) using template of sodium alginate (SA)/FeSO 4 hydrogel mixed with carbon black (CB), which presented high H 2 O 2 generation efficiency and outstanding tetracycline degradation efficiency under wide pH ranges (3-8) with a low energy consumption of 19.6 kWh/kg total organic carbon (TOC). The introduction of CB created abundant oxygen vacancies in CFeS@C, promoting the oxygen adsorption and the electrochemical generation of H 2 O 2 , which further boosted the formation of •OH due to the interaction with Fe2+ on the cathode surface. Simultaneously, the reaction between the outer layer of FeS and Fe3+ not only accelerated iron cycling but also reduced the solution pH. It was verified that •OH and 1O 2 played a dominant role in organics degradation. The system maintained stability after 10 cycles and effectiveness in the treatment of pharmaceutical wastewater. This study would offer a new strategy to develop an efficient and durable bifunctional catalyst for heterogeneous EF system working in wide pH conditions for wastewater treatment. [Display omitted] • H 2 O 2 generation and multiple reactive species was achieved on FeS/Fe 3 O 4 @C as cathode. • The multi-layered reaction centers of O V , FeS and Fe 3 O 4 promoted pollutants removal. • Radical and non-radical oxidants were produced simultaneously on the cathode. • This system exhibited efficient degradation behavior in wider application pH. • It was promising and stable for removing various pollutants in water/wastewater. [ABSTRACT FROM AUTHOR]

In-situ hydrogen peroxide (H 2 O 2) production is pivotal for the effective implementation of the electro-Fenton reaction. However, challenges such as low H 2 O 2 yields and a short electrode lifespan have hindered its application. This study introduced a novel gas diffusion electrode (GDE), the CB (E) -Ni foam (GDE) , fabricated through a combination of carbon black (CB) electrodeposition and polytetrafluoroethylene (PTFE) impregnation techniques. Comprehensive physicochemical characterizations and electrochemical evaluations indicated that CB was more uniformly dispersed across the Ni foam, enhancing its electrochemical activity. When employed as a cathode, the CB (E) -Ni foam (GDE) demonstrated superior two-electron oxygen reduction reaction (2e− ORR) capabilities, marked by increased oxygen utilization and reduced energy demands, achieving a remarkable H 2 O 2 concentration of 897.73 mg/L after 120 min. This performance significantly outpaces that of traditional GDEs. The unique structure of the CB (E) -Ni foam (GDE) not only prolonged electrode life by preventing rapid deactivation but also boosted H 2 O 2 production and oxygen efficiency by 31.78% and 31.79%, respectively, when compared to a standard non-GDE configuration. In practical applications, the CB (E) -Ni foam (GDE) demonstrated utility by facilitating an 84.1% degradation rate of fulvic acid over 120 min within a homogeneous electro-Fenton system, highlighting its potential for environmental remediation. [Display omitted] • CB (E) -Ni foam (GDE) electrode was prepared by electrodeposition and impregnation methods to enhance the 2e− ORR activity. • The CB (E) -Ni foam (GDE) electrode showed a significant enhancement in H 2 O 2 yield to a notable concentration of 897.73 mg/L. • The lifespan of CB (E) -Ni foam (GDE) was greatly increased by impregnating PTFE on the cathode's side facing side-aeration. [ABSTRACT FROM AUTHOR]

The present study demonstrates, for the first time, the feasibility of a two-step process consisting of Electro-Fenton (EF) followed by microalgae to treat highly loaded real food processing wastewater along with resource recovery. In the first step, EF with a carbon felt cathode and Ti/RuO 2 –IrO 2 anode was applied at different current densities (3.16 mA cm−2, 4.74 mA cm−2 and 6.32 mA cm−2) to decrease the amount of organic matter and turbidity and enhance biodegradability. In the second step, the EF effluents were submitted to microalgal treatment for 15 days using a mixed culture dominated by Scenedesmus sp., Chlorosarcinopsis sp., and Coelastrum sp. Results showed that current density impacted the amount of COD removed by EF, achieving the highest COD removal of 77.5% at 6.32 mA cm−2 with >95% and 74.3% of TSS and PO 4 3− removal, respectively. With respect to microalgae, the highest COD removal of 85% was obtained by the culture in the EF effluent treated at 6.32 mA cm−2. Remarkably, not only 85% of the remaining organic matter was removed by microalgae, but also the totality of inorganic N and P compounds, as well as 65% of the Fe catalyst that was left after EF. The removal of inorganic species also demonstrates the high complementarity of both processes, since EF does not have the capacity to remove such compounds, while microalgae do not grow in the raw wastewater. Furthermore, a maximum of 0.8 g L−1 of biomass was produced after cultivation, with an accumulation of 32.2% of carbohydrates and 25.9% of lipids. The implementation of the two processes represents a promising sustainable approach for the management of industrial effluents, incorporating EF in a water and nutrient recycling system to produce biomass that could be valorized into clean fuels. [Display omitted] • A novel two-step electro-Fenton (EF)-microalgae process was proposed. • EF reduced organic load and suspended solids from a raw real industrial effluent. • After EF, microalgae removed remaining N and P compounds as well as Fe catalyst. • Microalgae accumulated carbohydrates and lipids with potential for biofuel production. • EF-microalgae is a sustainable option for wastewater treatment with resources recovery. [ABSTRACT FROM AUTHOR]

PAHs is the group of emerging micro-pollutants present in most environmental matrices that has the tendency to bioaccumulate and cause carcinogenic effects to human health. The present research involved the quantification and treatment of leachate produced from secured landfill, to eliminate the PAHS. Electro-Fenton process, a class of advanced oxidation process, is adopted to degrade the PAHs using titanium electrodes as both anode and cathode. Artificial intelligence based statistical tool "Central Composite Design" a module of JMP -19 software was used to design the experiments and optimize the critical parameters involved in the research. It was observed that the value of P is significant (P < 0.05) for all the independent variables evidencing the significant correlation between experimental values and predicted values of the software. The value of R2 obtained was 0.96 and 0.97 for COD and PAHs respectively. The maximum removal efficiency of COD and PAH was found to be 84.24% and 90.78% respectively. The optimized conditions obtained from the central composite design were: pH = 5; Fe2+ = 0.1 g/L; H 2 O 2 = 2 g/L; reaction time = 60 min; and electric intensity = 0.2 A. Additionally, optimized experimental conditions were used to study the removal efficiencies of individual 16 PAHs and are also reported. From the close proximity of experimental and predicted results of the software it can be proved that central composite design is efficient enough to be used as a statistical tool in design and analysis for treatment of landfill leachate. [Display omitted] • Electro Fenton method was used to remove PAHs. • Artificial intelligence based optimization is applied for leachate treatment. • The removal efficiency of COD and PAH were found to be 84.24% and 86.05%. • Removal efficiency of 16 individual PAHs are determined. [ABSTRACT FROM AUTHOR]