High-performance, stable CoNi LDH@Ni foam composite membrane with innovative peroxymonosulfate activation for 2,4-dichlorophenol destruction

In this study, the cobalt-nickel layered double hydroxides (CoNi LDH) were synthesized with a variety of Co/Ni mass ratio, as CoxNiy LDHs. In comparison, Co1Ni3 LDH presented the best peroxymonosulfate (PMS) activation efficiency for 2,4-dichlorophenol removal. Meanwhile, CoNi LDH@Nickel foam (CoNi LDH@NF) composite membrane was constructed for enhancing the stability of catalytic performance. Herein, CoNi LDH@NF-PMS system exerted high degradation efficiency of 99.22% within 90 min for 2,4-DCP when [PMS]0 = 0.4 g/L, Co1Ni3 LDH@NF = 2 cm × 2 cm (0.2 g/L), reaction temperature = 298 K. For the surface morphology and structure of the catalyst, it was demonstrated that the CoNi LDH@NF composite membrane possessed abundant cavity structure, good specific surface area and sufficient active sites. Importantly, ·OH, SO4·- and 1O2 played the primary role in the CoNi LDH@NF-PMS system for 2,4-DCP decomposition, which revealed the PMS activation mechanism in CoNi LDH@NF-PMS system. Hence, this study eliminated the stability and adaptability of CoNi LDH@NF composite membrane, proposing a new theoretical basis of PMS heterogeneous catalysts selection.

Structural dependence of PFAS oxidation in a boron doped diamond-electrochemical system

Driven by long-term persistence and adverse health impacts of legacy perfluorooctanoic acid (PFOA), production has shifted towards shorter chain analogs (C4, perfluorobutanoic acid (PFBA)) or fluorinated alternatives such as hexafluoropropylene oxide dimer acid (HFPO-DA, known as GenX) and 6:2 fluorotelomer carboxylic acid (6:2 FTCA). Yet, a thorough understanding of treatment processes for these alternatives is limited. Herein, we conducted a comprehensive study using an electrochemical approach with a boron doped diamond anode in Na2SO4 electrolyte for the remediation of PFOA common alternatives, i.e., PFBA, GenX, and 6:2 FTCA. The degradability, fluorine recovery, transformation pathway, and contributions from electro-synthesized radicals were investigated. The results indicated the significance of chain length and structure, with shorter chains being harder to break down (PFBA (65.6 ± 5.0%) < GenX (84.9 ± 3.3%) < PFOA (97.9 ± 0.1%) < 6:2 FTCA (99.4 ± 0.0%) within 120 min of electrolysis). The same by-products were observed during the oxidation of both low and high concentrations of parent PFAS (2 and 20 mg L-1), indicating that the fundamental mechanism of PFAS degradation remained consistent. Nevertheless, the ratio of these by-products to the parent PFAS concentration varied which primarily arises from the more rapid PFAS decomposition at lower dosages. For all experiments, the main mechanism of PFAS oxidation was initiated by direct electron transfer at the anode surface. Sulfate radical (SO4•-) also contributed to the oxidation of all PFAS, while hydroxyl radical (•OH) only played a role in the decomposition of 6:2 FTCA. Total fluorine recovery of PFBA, GenX, and 6:2 FTCA were 96.5%, 94.0%, and 76.4% within 240 min. The more complex transformation pathway of 6:2 FTCA could explain its lower fluorine recovery. Detailed decomposition pathways for each PFAS were also proposed through identifying the generated intermediates and fluorine recovery. The proposed pathways were also assessed using 19F Nuclear Magnetic Resonance (NMR) spectroscopy.

Photo-thermal activation of persulfate for the efficient degradation of synthetic and real industrial wastewaters: System optimization and cost estimation

The photo-thermal activation of persulfate (PS) was carried out to degrade various pollutants such as reactive blue-222 (RB-222) dye, sulfamethazine, and atrazine. Optimizing the operating parameters showed that using 0.90 g/L of PS at pH 7, temperature of 90 °C, initial dye concentration of 21.60 mg/L, and reaction time of 120 min could attain a removal efficiency of 99.30%. The degradation mechanism was explored indicating that hydroxyl and sulfate radicals were the prevailing reactive species. The degradation percentages of 10 mg/L of sulfamethazine and atrazine were 83.30% and 70.60%, respectively, whereas the mineralization ratio was 63.50% in the case of real textile wastewater under the optimal conditions at a reaction time of 120 min. The treatment cost per 1 m3 of real wastewater was appraised to be 1.13 $/m3 which assured the inexpensiveness of the proposed treatment system. This study presents an effective and low-cost treatment system that can be implemented on an industrial scale.

Current trends on dry photocatalytic oxidation technology for BTX removal: Viable light sources and highly efficient photocatalysts

One of the main gaseous pollutants released by chemical production industries are benzene, toluene and xylene (BTX). These dangerous gases require immediate technology to combat them, as they put the health of living organisms at risk. The development of heterogeneous photocatalytic oxidation technology offers several viewpoints, particularly in gaseous-phase decontamination without an additional supply of oxidants in air at atmospheric pressure. However, difficulties such as low quantum efficiency, ability to absorb visible light, affinity towards CO2 and H2O synthesis, and low stability continue to limit its practical use. This review presents recent advances in dry-phase heterogeneous photodegradation as an advanced technology for the practical removal of BTX molecules. This review also examines the impact of low-cost light sources, the roles of the active sites of photocatalysts, and the feasible concentration range of BTX molecules. Numerous studies have demonstrated a significant improvement in the efficiency of the photodegradation of volatile organic compounds by enhancing the photocatalytic reactor system and other factors, such as humidity, temperature, and flow rate. The mechanism for BTX photodegradation based on density functional theory (DFT), electron paramagnetic resonance (EPR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) investigations is also discussed. Finally, the present research complications and anticipated future developments in the field of heterogeneous photocatalytic oxidation technology are discussed.

Photodegradation of polyethylene debris in water by sulfur-doped TiO2: system optimization, degradation mechanism, and reusability

Given the immense threats of microplastics, we herein investigate photodegrading the debris of polyethylene bags (PBs) by sulfur-doped titanium dioxide. The optimization of operating parameters showed that controlling the water pH at 3 and introducing PBs by 0.10 g/L under a catalyst dose of 1.25 g/L reduced the polyethylene mass by 3.10% in 7 h, whereas raising the catalyst dose to 3 g/L improved the mass reduction to 4.72%. The extension of degradation time to 100 h at pH 3, catalyst dosage of 3 g/L, and PBs concentration of 0.10 g/L increased the mass loss ratio to 21.74%. Scanning electron microscopy of PBs after 100 h of photodegradation showed cracks on the surface accompanied by the increase of carbonyl index from 0.52 to 1.41 confirming the breakdown of the polymeric chain. Total organic carbon increased from 0.80 to 7.76 mg/L in the first 10 h of photodegradation, then decreased to 1 mg/L after extending the reaction time to 100 h due to the mineralization of organic intermediates generated from the photodegradation of PBs. Trapping tests exhibited the major role of hydroxyl radicals in the degradation system, and the catalyst showed high stability under five repetitive runs. This study proposes an efficient treatment system that can be implemented on a wider scale utilizing the synthesized catalyst to degrade plastics efficiently before their release to water streams.

Natural siderite derivatives activated peroxydisulfate toward oxidation of organic contaminant: A green soil remediation strategy

Natural siderite (FeCO₃), simulated synthetic siderite and nZVI/FeCO₃ composite were used as green and easily available iron-based catalysts in peroxydisulfate activation for remediating 2-chlorophenol as the target contaminant and this technique can effectively degrade organic pollutants in the soil. The key reaction parameters such as catalysts dosage, oxidant concentration and pH, were investigated to evaluate the catalytic performance of different materials in catalytic systems. The buffering property of natural soil conduced satisfactory degradation performance in a wide pH range (3-10). Both the main non-radical of ¹O₂ and free radicals of SO₄^·- and OH^· were evidenced by quenching experiment and electron paramagnetic resonance. The reduction of nZVI on FFC surface not only has the advantage for electronic transfer to promote the circulation of Fe(III) to Fe(II), but also can directly dechlorinate. Furthermore, the intermediates were comprehensively analyzed by GC-MS and a potential removal mechanism of three oxidant system for 2-CP soil degradation was obtained. Briefly, this research provides a new perspective for organic contaminate soil treatment using natural siderite or simulated synthetic siderite as efficient and environmental catalytic material.

Dark transformation from 17β-estradiol to estrone initiated by hydroxyl radical in dissolved organic matter

The occurrence and fate of 17β-estradiol (E₂) in natural water have gained extensive attention owing to its high ecotoxic risk to wildlife. Dissolved organic matter (DOM) is a ubiquitous water constituent and contributes significantly to E₂ removal, although the reaction mechanism is rarely clarified. The present study aims to investigate E₂ transformation in water containing fresh or aged DOM surrogates at environmentally relevant concentrations in the dark. Experiments along with radical probes of benzene and furfuryl alcohol reveal that reactive radicals, particularly hydroxyl radical (·OH), formed non-photochemically at higher concentrations in aged DOM than in fresh DOM. The contribution of ·OH in E₂ removal is indicated by the decreases in the removal of radical probes in the presence of E₂; moreover, E₂ removal is inhibited in the presence of radical scavengers. The dose-dependent inhibitive effect of substrate concentrations, including E₂ and coexistent propylparaben, shows that the radical concentration is a limiting factor for E₂ removal, which could be enhanced by increasing DOM concentration, dissolved oxygen, and light supply. As the main byproduct, estrone (E₁) is persistent in the current DOM water in the dark, but it can be easily photodegraded when exposed to light. Theoretical analysis reveals that the initial step is ·OH-initiated H- abstraction on the hydroxyl group in the cyclopentane ring of E₂. The formed singlet excited state of E₂ undergoes further intramolecular rearrangement and oxidative dehydrogenation to generate E₁ and the hydroperoxy radical (·HO₂). Considering the universal occurrence of E₂ in DOM-rich aquatic matrices, the present findings have special implications for the biogeochemical cycle and risk assessment of this pollutant in natural aquatic environments, particularly those beyond the photic zone.

Degradation of lomefloxacin by MoS(2)/MIL-53(Fe, Cu) catalyst in heterogeneous electro-Fenton process

A novel heterogeneous catalyst named MoS₂/MIL-53(Fe, Cu) (MMFC) was prepared by hydrothermal method and applied in a heterogeneous electro-Fenton (hetero-EF) system for lomefloxacin (LOM) degradation in this work. Under the optimal conditions of current density 3 mA/cm², catalyst dosage 0.100 g/L, and initial pH 6, 93.5% LOM (2 mg/L) removal efficiency was achieved in the MMFC hetero-EF system within 60 min, indicating an obvious improvement compared with the MIL-53(Fe, Cu) hetero-EF system. The good catalytic activity was attributed to more effective active sites of the catalyst and the conversion of Fe(II)/Fe(III) and Cu(I)/Cu(II) promoted by Mo(IV) in MoS₂, which could be inferred by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) characterizations. The reusability and stability of MMFC were explored based on five cyclic experiments, and the average degradation efficiency reached 73.9%. Furthermore, the hetero-EF system could achieve the total removal of moxifloxacin and tetracycline within 6 min and 40 min, respectively. Quenching experiments revealed that the hydroxyl radicals (·OH) were the main reactive radicals while superoxide radicals (·O₂^-) and singlet oxygen (¹O₂) played a certain part in LOM degradation. Finally, the possible mechanism of the hetero-EF process and LOM degradation pathways were proposed, including substitution, elimination, and cleavage of ring structures. Accounting for good catalytic performance, low preparation cost, and satisfactory versatility, the MMFC exhibited good potential to work as a hetero-EF catalyst for wastewater treatment.

Performance and mechanism of sodium percarbonate (SPC) enhancing short-chain fatty acids production from anaerobic waste activated sludge fermentation

A novel pretreatment technique (i.e., using Sodium percarbonate, SPC) to improve the short-chain fatty acids (SCFA) production waste activated sludge (WAS) was proposed in this study. Results indicated that the maximum SCFA production of 1605.7 mg COD/L and acetic acid of 52.9% were attained at 0.2 g SPC/g TSS, being 8.4 and 2.8 times of the control (191.3 mg COD/L and 19%), respectively. Meanwhile, the optimal time for SCFA accumulation was decreased from 6d (control) to 4d (0.2 g/g TSS). Mechanism explorations unraveled that SPC largely accelerated WAS solubilization and enhanced the bioavailability of organics released from WAS. It improved enzymatic activities related to hydrolysis and acidogenesis, while suppressed the Coenzyme F₄₂₀ responsible for SCFA consumption. Illumina MiSeq sequencing analysis showed that SPC substantially enhanced the relative abundances of hydrolytic and/or acid-forming microbes. Furthermore, CO₃^- and O₂^- were the key factors to production enhancement in SPC-involved sludge fermentation.

Motivation of reactive oxygen and nitrogen species by a novel non-thermal plasma coupled with calcium peroxide system for synergistic removal of sulfamethoxazole in waste activated sludge

Large amounts of antibiotics are concentrated in waste activated sludge (WAS) and released into the environment. It is thus critical to develop advanced sludge treatment technology to remove these antibiotics. Dielectric barrier discharge (DBD) combined with calcium peroxide (CaO₂), as an innovative technology to attenuate sulfamethoxazole (SMX) in sludge, was investigated. Evident synergistic effects between DBD and CaO₂ were observed on the SMX degradation with a synergistic factor of 2.02. Moreover, the energy consumption of DBD/CaO₂ was significantly lower than that of DBD alone. At a typical CaO₂ dosage of 0.1 g/g TS and discharge power of 64.5 W, the highest SMX removal of 96% was achieved within 50 min. The synergistic effects of DBD/CaO₂ could be associated with the base catalysis of H₂O₂ and O₃, UV-base-photolysis, peroxone oxidation, and photocatalytic H₂O₂. DBD/CaO₂ generated various reactive oxygen species (ROS) and nitrogen species (RNS) that participated in SMX removal. The contributions of these reactive species followed the sequence of e^- > •OH > •O₂^- > ¹O₂ > ONOO^-. Based on the detected transformation by-products and their variations during treatment, a plausible SMX degradation pathway in sludge was proposed. Besides, DBD/CaO₂ also promoted sludge disintegration, dewatering, heavy metal removal, sludge reduction, sludge solubilization, and acetate-enriched volatile fatty acid (VFA) production. Therefore, DBD/CaO₂ exhibited great potential for controlling antibiotic, as well as promoting sludge reduction, decontamination, and resourcization.

Enhanced PAHs-contaminated site soils remediation by mixed persulfate and calcium peroxide

Polycyclic aromatic hydrocarbons (PAHs) remain in the site soils after relocated coking plants and oil refineries pose huge constraints to the subsequent land utilization. However, single persulfate (PS) or calcium peroxide (CP) remediation strategies can only inefficiently oxidize some PAHs in soil. This work sought to optimize PS/CP oxidation remediation strategy and verify its practical application effect in soil samples spiked with PAHs. The results showed that the mixed PS/CP oxidation remediation was better than the single oxidants strategies; it had high remediation performance in different particles and pollution loads of PAHs-contaminated soils. Simultaneously, reactive radicals (SO₄·^- and ·OH) were detected, and one side-product (CaSO₄) was characterized. This work optimized the mixed PS/CP system (0.3 mol/L PS, and 8 g/kg CP, together with 0.18 mol/L Fe²⁺ and 0.11 mol/L C₂O₄^2-), and the corresponding Total-PAHs removal rate was 85.41%. Compared to the cost based on benzopyrene (BaP) removal, the study provided a cost-effective mixed PS/CP oxidation remediation technique (1.22 $/ton), widely applicable in soils polluted with various organic contaminants represented such as PAHs.

Enhanced formation of trichloronitromethane precursors during UV/monochloramine treatment

This study systematically investigates the formation of trichloronitromethane (TCNM) from 2 natural waters, 6 humic substances and 16 phenolic compounds during UV/monochloramine (UV/NH₂Cl) followed by post-chloramination. Using ¹⁵N-NH₂Cl as an isotope tracer, we found that ¹⁵N-TCNM accounted for 70.7-76.5% of total TCNM during UV/NH₂Cl treated 2 natural waters, which was significantly higher than the proportion of ¹⁵N-TCNM in chloramination (NH₂Cl alone). This is a direct evidence that NH₂Cl, rather than the nitrogenous matters in waters, was the predominant nitrogen source of TCNM during UV/NH₂Cl treatment. Phenol derivatives with meta-substituents and with electron-withdrawing groups facilitated the formation of TCNM precursors during UV/NH₂Cl treatment. Significant correlations were found between Hammett constants (σ) of substituents and TCNM formation potentials. The formation mechanisms of TCNM were revealed using resorcinol as a representative phenolic compound. During UV/NH₂Cl treatment, HO^•, reactive chlorine species and reactive nitrogen species contributed to 28.1%, 29.0% and 19.4% of resorcinol degradation. Five nitro(so)-intermediates were identified as the main TCNM precursors. The formation pathways of TCNM were proposed. Alkaline pH was recommended to reduce the formation of TCNM precursors during UV/NH₂Cl treatment.

New insights into the mechanisms of tartaric acid enhancing homogeneous and heterogeneous copper-catalyzed Fenton-like systems

The specific roles of tartaric acid (TA), as an eco-friendly ligand, in homogeneous and heterogeneous copper-catalyzed systems were systematically revealed and new mechanisms of TA enhancing the three Fenton-like processes were proposed to provide a theoretical significance in overcoming the deficiency of conventional Fenton processes. The results identified hydroxyl radical (•OH) as the main species responsible for the simultaneous decomposition of TA and metronidazole (MNZ) according to TOC removal. The ESR technique was used to detect superoxide radicals (•O₂^-), carbon-centered radical (•R) and hydrogen radical (•H) in the Cu²⁺/TA/H₂O₂ system, which contributed to the acceleration of the Cu²⁺/Cu⁺ redox cycle. The enhancing effect of TA on the homogeneous process was ascribed to the formation of a soluble complex with Cu²⁺, which favored the pH range extension, Cu⁺ oxidation, and radical generation. Moreover, the adsorption of TA on the catalysts surface promoted the consumption of H₂O₂, inducing •OH generation. The formed surface complex (≡Cu²⁺-TA) also accelerated the regeneration of ≡Cu⁺, which was confirmed by density functional theory (DFT) calculation and surface characterization analysis (SEM, XRD, and XPS). The possible degradation pathways of MNZ in TA-modified Fenton-like system were also clarified.

Heterogeneous degradation of organic contaminant by peroxydisulfate catalyzed by activated carbon cloth

An eco-friendly material, activated carbon cloth (ACC) was used as the heterogeneous catalyst in activation of peroxydisulfate (PDS) for the efficient degradation of organic pollutant in water. Besides, the effects of several parameters in the ACC/PDS process including initial pH, PDS concentration, reaction temperature, stirring speed and co-existing anions were investigated. Under optimum conditions, almost complete removal (98.6%) of AO7 in 60 min and 67.4% of total organic carbon (TOC) removal within 180 min were obtained, accompanied by the remarkable destruction of azo band and naphthalene ring on AO7. The electron paramagnetic resonance and radical quenching experiments were carried out to identify the reactive radicals in the ACC/PDS process. Surface characteristic techniques such as XRD, BET, SEM, FTIR, XPS were applied to analysis the change of crystal structure, surface area, surface morphology, functional groups on the surface of fresh and spent ACC samples. Hydroxyl groups (C‒OH) and π-π transitions significantly affected the catalytic activity of ACC. The intermediate products of AO7 oxidation were identified by LC-MS and the corresponding degradation pathway was proposed.

Attenuation of pharmaceutically active compounds in aqueous solution by UV/CaO2 process: Influencing factors, degradation mechanism and pathways

As freshwater sources continue to be influenced by wastewater effluents, there is a dire need to develop advanced water treatment processes capable of treating the wastewater-derived contaminants, especially for pharmaceutically active compounds (PhACs). Ultraviolet light (UV) combined with calcium peroxide (CaO₂) as an advanced oxidation process (AOP) to attenuate five widespread PhACs (carbamazepine (CBZ), primidone (PMD), phenobarbital (PBB), thiamphenicol (TAP) and florfenicol (FF)) was investigated in this paper. The degradation of these compounds followed pseudo-first-order kinetics (R² > 0.96). The optimum CaO₂ dosage was 0.1 g L^-1 and lower initial contaminants concentration was beneficial to their degradation. The UV/CaO₂ treatment of test PhACs was attributed to the combination of UV/H₂O₂ and UV-base-photolysis (UV/Ca(OH)₂), and the degradation mechanism was recognized as both UV direct photolysis and indirect photolysis caused by reactive radicals (•OH, triplet states of dissolved organic matter (³DOM*), and ¹O₂). Furthermore, the tentative transformation pathways of the five PhACs were proposed based on the detected intermediates and the degradation mechanisms. The final products of inorganic carbon and nitrogen indicate UV/CaO₂ treatment can significantly mineralize test PhACs. Also, the CaO₂ addition significantly reduced the energy consumption of UV irradiation according to electrical energy per order. The effective removal of CBZ and PMD in a secondary wastewater effluent by UV/CaO₂ treatment demonstrates the potential use of this AOP technology in advanced treatment of wastewater-derived PhACs.

Effects of water matrices on the degradation of naproxen by reactive radicals in the UV/peracetic acid process

The UV/peracetic acid (UV/PAA) process as a novel advanced oxidation process has been reported to produce carbon-centered radicals (RC•) for Naproxen (NAP) degradation, which is a representative of naphthyl structure substances. Real water matrices, such as carbonate and bicarbonate ions (CO₃^2-/HCO₃^-), humic acid (HA), and chloride ion (Cl^-), may react with these reactive radicals and change their contributions to NAP degradation. The results showed that RC• contributed 60.8% and •OH contributed 39.2% to NAP degradation in pure water by a competition method. CO₃^2-/HCO₃^- (0-20 mM) showed minimal effect on NAP degradation in the UV/PAA process, meanwhile, it has observable inhibition effect on NAP degradation in the UV/H₂O₂ process (mainly of •OH) and minimal effect in the UV/PAA process with tert-butanol (TBA) (mainly of RC•). Results suggested that CO₃^2-/HCO₃^- could react with •OH yielding CO₃•^- with low reactivity to NAP, CO₃•^- could further react with PAA to produce RC•. This speculation was confirmed by the increased contribution of RC• to NAP degradation with the increase of CO₃^2-/HCO₃^- concentration through the competition method. HA (0-5 mg/L) had a higher scavenging capacity for RC• than •OH because HA with naphthyl structure was likely to be attacked by RC•. Cl^- (0-200 mM) had little effect on NAP degradation in the UV/PAA and UV/H₂O₂ processes, while exerted an observable inhibition on NAP degradation in the UV/PAA process with TBA. This finding suggested that Cl^- could react with RC• to produce Cl•, which could further convert into HOCl•^-, and then excess •OH was formed. The new knowledge on the conversion of reactive radicals obtained in this study provides an important basis for facilitating further research on the UV/PAA advanced oxidation.

Thermo-activated peroxydisulfate oxidation of indomethacin: Kinetics study and influences of co-existing substances

The widespread occurrence of non-steroidal anti-inflammatory drugs (NSAIDs) (e.g., Indomethacin) in the ambient environment has attracted growing concerns due to their potential threats to ecosystems and human health. Herein, we investigated the degradation of indomethacin (IM) by thermo-activated peroxydisulfate (PDS). The pseudo first-order rate constant (k_obs) of degradation of IM was increased significantly with higher temperatures and PDS doses. Moreover, when the initial pH value was raised from 5 to 9 the IM degradation was initially decreased and then increased. Basic conditions were favorable for the removal of IM in the thermo-activated peroxydisulfate system. A response surface methodology based on the Box-Behnken design (BBD) was successfully employed for the optimization of the thermo-activated peroxydisulfate (PDS) system. The presence of chlorine ions manifested a dual effect on the degradation of IM, while bicarbonate and SRFA (as a NOM model) reduced it. Radical scavenging tests and electron spin resonance (ESR) revealed that the dominant oxidizing species were SO₄^- and OH at pH 9. Furthermore, the TOC removal efficiency attained 28.8% and the release of Cl^-was 38.5% at 60 °C within 24min, while the mineralization rate of IM were 85.5% with the PDS concentration up to 20  mM at 2 h oxidation. To summarize, thermo-activated PDS oxidation is a promising technique for the remediation of IM-contaminated water.

The mechanism and efficiency of MnO2 activated persulfate process coupled with electrolysis

Pure three-dimensional manganese oxides (MnO₂) were successfully synthesized by a simple one-step hydrothermal process. The obtained particles were characterized via XRD, BET, SEM, XPS and FTIR techniques. To enhance the efficiency of heterogeneous catalytic process, a facile and effective electrochemical method was introduced. The degradation of C. I. Acid Orange 7 (AO7) as the target pollutant in aqueous solution by an oxidation system involving MnO₂ activated peroxydisulfate (PDS) coupled with electrochemical method is reported herein. Influences of some key reaction parameters such as initial pH (pH₀), current density, initial AO7 concentration, dosage of MnO₂ and anions (Cl^-, NO₃^-, HCO₃^- and H₂PO₄^-) were investigated. The cyclic voltammetry (CV) was performed to investigate the charge transfer process occurred at the surface of catalyst. LC-MS/MS analysis was applied to identify degradation intermediates and a plausible degradation mechanism is proposed accordingly. Activated sludge inhibition tests were carried out to evaluate the change of toxicity of the dye solution in the oxidation process. The inorganic by-products such as NO₂^-, NO₃^-, and NH₄⁺ along with AO7 degradation were also identified. The stability of MnO₂ catalyst was evaluated by recycling experiments and the electrical energy consumption was also investigated. Radical quenching tests with several scavengers (methanol, tert-butyl alcohol, 1,4-benzoquinone and phenol) were performed to clarify the dominating reactive species participating in this oxidation process and the underlying mechanisms involving the generation of radical from the proposed electro-assisted heterogeneous activated PDS system were identified.