Formation of active chlorine species involving the higher oxide MOx+1 on active Ti/RuO2-IrO2 anodes: A DEMS analysis

Exploring the viability of peracetic acid-mediated antibiotic degradation in wastewater through activation with electrogenerated HClO

Electrochemical advanced oxidation processes (EAOPs) face challenging conditions in chloride media, owing to the co-generation of undesirable Cl-disinfection byproducts (Cl-DBPs). Herein, the synergistic activation between in-situ electrogenerated HClO and peracetic acid (PAA)-based reactive species in actual wastewater is discussed. A metal-free graphene-modified graphite felt (graphene/GF) cathode is used for the first time to achieve the electrochemically-mediated activation of PAA. The PAA/Cl- system allowed a near-complete sulfamethoxazole (SMX) degradation (kobs =0.49 min-1) in only 5 min in a model solution, inducing 32.7- and 8.2-fold rise in kobs as compared to single PAA and Cl- systems, respectively. Such enhancement is attributed to the occurrence of 1O2 (25.5 μmol L-1 after 5 min of electrolysis) from the thermodynamically favored reaction between HClO and PAA-based reactive species. The antibiotic degradation in a complex water matrix was further considered. The SMX removal is slightly susceptible to the coexisting natural organic matter, with both the acute cytotoxicity (ACT) and the yield of 12 DBPs decreasing by 29.4 % and 37.3 %, respectively. According to calculations, HClO accumulation and organic Cl-addition reactions are thermodynamically unfavored. This study provides a scenario-oriented paradigm for PAA-based electrochemical treatment technology, being particularly appealing for treating wastewater rich in Cl- ion, which may derive in toxic Cl-DBPs.

Mn-Co-Ce/biochar based particles electrodes for removal of COD from coking wastewater by 3D/HEFL system: Characteristics, optimization, and mechanism

In this work, the Mn, Co, Ce co-doped corn cob biochar (MCCBC) as catalytic particle electrodes in a three-dimensional heterogeneous electro-Fenton-like (3D-HEFL) system for the efficient degradation of coking wastewater was investigated. Various characterization methods such as SEM, EDS, XRD, XPS and electrochemical analysis were employed for the prepared materials. The results showed that the MCCBC particle electrodes had excellent electrochemical degradation performances of COD in coking wastewater, and the COD removal and degradation rates of the 3D/HEFL system were 85.35% and 0.0563 min-1 respectively. RSM optimized conditions revealed higher COD removal rate at 89.23% after 31.6 min of electrolysis. The efficient degradability and wide adaptability of the 3D/HEFL system were due to its beneficial coupling mechanism, including the synergistic effect between the system factors (3D and HEFL) as well as the synergistic interactions between the ROS (dominated by •OH and supplemented by O2•-) in the system. Moreover, the COD removal rate of MCCBC could still remain at 81.41% after 5 cycles with a lower ion leaching and a specific energy consumption of 11.28 kWh kg-1 COD. The superior performance of MCCBC, as catalytic particle electrodes showed a great potential for engineering applications for the advanced treatment of coking wastewater.

Development of an environmentally sustainable technique to minimize the sludge production in the textile effluent sector through an electrokinetic (EK) coupled with electrooxidation (EO) approach

This study presents an environmentally sustainable method for minimizing sludge production in the textile effluent sector through the combined application of electrokinetic (EK) and electrooxidation (EO) processes. AAS and XRF analyses reveal that utilizing acidic electrolytes in the EK method successfully eliminates heavy metals (Cu, Mn, Zn, and Cr) from sludge, demonstrating superior efficiency compared to alkaline conditions. In addition, the total removal efficiency of COD contents was calculated following the order of EK-3 (60%), EK-1 (51%) and EK-2 (34%). Notably, EK-3, leveraging pH gradient fluctuations induced by anolyte in the catholyte reservoir, outperforms other EK systems in removing COD from sludge. The EK process is complemented by the EO process, leading to further degradation of dye and other organic components through the electrochemical generation of hypochlorite (940 ppm). At an alkaline pH of 10.0, the color and COD removal were effectively achieved at 98 and 70% in EO treatment, compared to other mediums. In addition, GC-MS identified N-derivative residues at the end of the EO. This study demonstrates an integrated approach that effectively eliminates heavy metals and COD from textile sludge, combining EK with EO techniques.

Approaching easy water disinfection for all: Can in situ electrochlorination outperform conventional chlorination under realistic conditions?

Electrochlorination has gained research interest for its potential application as decentralized water treatment. A number of studies have displayed promising efficiency for water disinfection. However, a comprehensive comparison of in situ electrodisinfection to existing disinfection techniques, particularly under realistic water composition and flow rates, still needs additional research efforts. The aim of this study is to evaluate in situ electrochlorination while comparing the treatment with conventional chemical chlorination for point-of-entry decentralized disinfection at the household level. An electrochemical flow cell reactor was operated in a single pass mode considering water flow and water consumption for a household of four family members. Disinfection efficiency assessment of both electrochemical and chemical chlorination was conducted using bacterial and viral surrogates, E. coli and MS2 bacteriophage. Furthermore, a techno-economic analysis was conducted, using the levelized cost of water, to compare two electrochemical chlorination scenarios (i.e., electrical grid energy use, and solar panel powered system) and benchmarked against the baseline treatment of chemical chlorination. The findings revealed increased inactivation efficiency of in situ electrochlorination over conventional chlorination (p-value < 0.05). The synergetic impact of radicals and chlorine, and/or contribution of high chlorine concentration at acidic pH near anode surface were identified as key factors that could enhance disinfection performance of in situ electrochlorination. The techno-economic analysis demonstrated that electrochemical treatment, when operated using renewable energy sources, is not only a more environmentally sustainable approach, but also emerges as a more economically feasible solution for decentralized water treatment application. The results highlight that in situ electrochlorination is a more advanced alternative to decentralized water chlorination. However, further fundamental research on products and by-products formation under various water matrices is required.

Effect of Long-Term Sodium Hypochlorite Cleaning on Silicon Carbide Ultrafiltration Membranes Prepared via Low-Pressure Chemical Vapor Deposition

Sodium hypochlorite (NaClO) is widely used for the chemical cleaning of fouled ultrafiltration (UF) membranes. Various studies performed on polymeric membranes demonstrate that long-term (>100 h) exposure to NaClO deteriorates the physicochemical properties of the membranes, leading to reduced performance and service life. However, the effect of NaClO cleaning on ceramic membranes, particularly the number of cleaning cycles they can undergo to alleviate irreversible fouling, remains poorly understood. Silicon carbide (SiC) membranes have garnered widespread attention for water and wastewater treatment, but their chemical stability in NaClO has not been studied. Low-pressure chemical vapor deposition (LP-CVD) provides a simple and economical route to prepare/modify ceramic membranes. As such, LP-CVD facilitates the preparation of SiC membranes: (a) in a single step; and (b) at much lower temperatures (700-900 °C) in comparison with sol-gel methods (ca. 2000 °C). In this work, SiC ultrafiltration (UF) membranes were prepared via LP-CVD at two different deposition temperatures and pressures. Subsequently, their chemical stability in NaClO was investigated over 200 h of aging. Afterward, the properties and performance of as-prepared SiC UF membranes were evaluated before and after aging to determine the optimal deposition conditions. Our results indicate that the SiC UF membrane prepared via LP-CVD at 860 °C and 100 mTorr exhibited excellent resistance to NaClO aging, while the membrane prepared at 750 °C and 600 mTorr significantly deteriorated. These findings not only highlight a novel preparation route for SiC membranes in a single step via LP-CVD, but also provide new insights about the careful selection of LP-CVD conditions for SiC membranes to ensure their long-term performance and robustness under harsh chemical cleaning conditions.

Benign electrolytic modifications of starch: effects on functional groups and physical properties

Herein, a low-cost electrolytic technology for starch modification has been developed using abundant chloride salt as a redox mediator. The effects of electrolysis conditions on the in situ starch modification are investigated in detail, including chloride concentrations, applied voltages, and electrolysis durations. The modification mechanisms are determined by the type of chlorine species (Cl2, HClO, ClO-, and HCl) generated during the process. Following electrolysis, carbonyl and carboxyl groups ranging from 0.056 to 1.3 g/100 g of starch and 0.006 to 0.5 g/100 g of starch, respectively, were observed. Starch granule median size can be reduced from 15.3 μm to 13.5 μm. In addition to the pronounced changes in granule size, shape, and functional groups, electrolysis leads to increased moisture resistance, higher crystallinity, and substantial alterations in the pasting properties.

Dipropyl ammonium ionic liquids to prepare Ti/RuO2-Sb2O4 anodes at different calcination temperatures

The development of technologies capable of producing efficient and economically viable anodes is essential for the electrochemical treatment of water contaminated with complex organic pollutants. In this context, the use of ionic liquids as solvents to prepare mixed metal oxide (MMO) anodes has proven to be an up-and-coming alternative. Here, we analyze the influence of the temperature of calcination (300, 350, and 400 ºC) on the production of Ti(RuO2)0.8-(Sb2O4)0.2 anodes made using the thermal decomposition method using three ionic liquids (IL) as solvents: dipropyl ammonium acetate (DPA-Ac), dipropyl ammonium propionate (DPA-Pr), and dipropyl ammonium butyrate (DPA-Bu). The decomposition temperature for all IL, accessed by thermogravimetry, is below 200 ºC. Physical and electrochemical analyses demonstrate that the calcination temperature of the anodes is decisive for their durability and electrochemical properties. Anodes prepared with DPA-Bu at 350 ºC show higher stability (around 35 h) than those made with other ILs at temperatures of 300 and 400 ºC and improved results in terms of 4-NP mineralization, where 97% of TOC removal was achieved in 120 min. It could be verified that the calcination temperature and IL employed had a decisive influence on the characteristics of the presented anodes. Therefore, the anode prepared with DPA-Bu at 350 ºC is promising for application in the degradation of organic compounds.

Self-adaptive amorphous CoOxCly electrocatalyst for sustainable chlorine evolution in acidic brine

Electrochemical chlorine evolution reaction is of central importance in the chlor-alkali industry, but the chlorine evolution anode is largely limited by water oxidation side reaction and corrosion-induced performance decay in strong acids. Here we present an amorphous CoOxCly catalyst that has been deposited in situ in an acidic saline electrolyte containing Co2+ and Cl- ions to adapt to the given electrochemical condition and exhibits ~100% chlorine evolution selectivity with an overpotential of ~0.1 V at 10 mA cm-2 and high stability over 500 h. In situ spectroscopic studies and theoretical calculations reveal that the electrochemical introduction of Cl- prevents the Co sites from charging to a higher oxidation state thus suppressing the O-O bond formation for oxygen evolution. Consequently, the chlorine evolution selectivity has been enhanced on the Cl-constrained Co-O* sites via the Volmer-Heyrovsky pathway. This study provides fundamental insights into how the reactant Cl- itself can work as a promoter toward enhancing chlorine evolution in acidic brine.

Synergistic degradation of trimethoprim and its phytotoxicity via the UV/chlorine process: Influencing factors on removal and kinetic

Occurrence of trimethoprim (TMP), recalcitrant antibiotic, and its adverse effect on ecosystem have been reported in several countries. The study aims to remove the TMP and its phytotoxicity via a UV/chlorine process, compared with chlorination and UV irradiation alone. Various treatment conditions including chlorine doses, pHs, and TMP concentrations was conducted with synthetic waters and effluent waters. The UV/chlorine process exhibited a synergistic effect on the TMP removal, compared with chlorination and UV irradiation alone. The UV/chlorine process was the most effective in removing TMP, followed by chlorination. The UV irradiation slightly affected the TMP removal (less than 5%). The UV/chlorine process completely removed TMP by 15 min contact time, while chlorination for 60 min could achieve 71% of TMP removal. The TMP removal fitted well with the pseudo first-order kinetics, and the rate constant (k') increased with higher chlorine doses, lower TMP concentrations and low pH. HO• was the major oxidant affecting the TMP removal and its degradation rate, compared with other reactive chlorine species (e.g., Cl•, OCl•). The TMP exposure increased the phytotoxicity by decreasing a germination rate of Lactuca sativa and Vigna radiata seeds. The use of UV/chlorine process could effectively detoxify the TMP, resulting in the phytotoxicity level of treated waters equivalent or lower than those of TMP-free effluent water. The detoxification level depended on the TMP removal, and it was about 0.43-0.56 times of TMP removal. The findings indicated the potential use of UV/chlorine process in removing TMP residual and its phytotoxicity.

Evaluation of pathogen disinfection efficiency of electrochemical advanced oxidation to become a sustainable technology for water reuse

Water treatment and reuse is gaining acceptance as a strategy to fight against water contamination and scarcity, but it usually requires complex treatments to ensure safety. Consequently, the electrochemical advanced processes have emerged as an effective alternative for water remediation. The main objective here is to perform a systematic study that quantifies the efficiency of a laboratory-scale electrochemical system to inactivate bacteria, bacterial spores, protozoa, bacteriophages and viruses in synthetic water, as well as in urban wastewater once treated in a wetland for reuse in irrigation. A Ti|RuO₂-based plate and Si|BDD thin-film were comparatively employed as the anode, which was combined with a stainless-steel cathode in an undivided cell operating at 12 V. Despite the low resulting current density (<15 mA/cm²), both anodes demonstrated the production of oxidants in wetland effluent water. The disinfection efficiency was high for the bacteriophage MS2 (T99 in less than 7.1 min) and bacteria (T99 in about 30 min as maximum), but limited for CBV5 and TuV, spores and amoebas (T99 in more than 300 min). MS2 presented a rapid exponential inactivation regardless of the anode and bacteria showed similar sigmoidal curves, whereas human viruses, spores and amoebas resulted in linear profiles. Due the different sensitivity of microorganisms, different models must be considered to predict their inactivation kinetics. On this basis, it can be concluded that evaluating the viral inactivation from inactivation profiles determined for bacteria or some bacteriophages may be misleading. Therefore, neither bacteria nor bacteriophages are suitable models for the disinfection of water containing enteric viruses. The electrochemical treatment added as a final disinfection step enhances the inactivation of microorganisms, which could contribute to safe water reuse for irrigation. Considering the calculated low energy consumption, decentralized water treatment units powered by photovoltaic modules might be a near reality.

Singlet oxygen generation for selective oxidation of emerging pollutants in a flow-by electrochemical system based on natural air diffusion cathode

The decay of free radicals involved in side reactions is one of the challenges faced by electrochemical degradation of organic pollutants. To this end, a non-radical oxidation system was constructed by a natural air diffusion cathode (ADC) and a Ti-based dimensional stable anode coated by RuO₂ (RuO₂-Ti anode) for cathodic hydrogen peroxide activation by anodic chlorine evolution. The ADC fabricated by the carbon black of BP2000 produced a stable concentration of hydrogen peroxide of 339.94 mg L^-1 (current efficiency of 73.4%) without aeration, which was superior to the cathode made by the XC72 carbon black. The flow-by ADC-RuO₂ system consisted of an ADC and a RuO₂-Ti anode showed high selectivity to aniline (AN) compared to benzoate (BA) in a NaCl electrolyte, whose degradation efficiencies were 97.72% and 1.3%, respectively. Rapid degradations of a mixture of emerging pollutants and AN were also observed in the ADC-RuO₂ system, with pseudo-first-order kinetic constants of 0.51, 1.29, 0.89, and 0.99 min^-1 for Bisphenol A (BPA), tetracycline (TC), sulfamethoxazole (SMX) and AN, respectively. Quenching experiments revealed the main reactive oxygen species for the pollutant degradation was singlet oxygen (¹O₂), which was also identified by the electron spin resonance (ESR) analysis. Finally, the steady-stable content of ¹O₂ was quantitatively determined to be 6.25 × 10^-11 M by the method of furfuryl alcohol (FFA) probe. Our findings provide a fast, low energy consumption and well controlled electrochemical oxidation method for selective degradation of organic pollutants. H₂O₂ generated on an air diffusion cathode by naturally diffused O₂, reacts with ClO^- produced from chloride oxidation on the RuO₂-Ti anode to form singlet oxygen (¹O₂). The electrochemical system shows an efficient oxidation to electron-rich emerging pollutants including bisphenol A, tetracycline, sulfamethoxazole and aniline, but a poor performance on the electron-deficient compounds (e.g., benzoate).

Investigation on the adverse impacts of electrochemically produced ClOx- on assessing the treatment performance of dimensionally stable anode (DSA) for Cl--containing wastewater

The presence of chloride ions can facilitate the COD removal efficiency due to the involvement of active chlorine species in the electro-oxidation process, but few attentions have been paid to the negative effect of the electro-generated oxychlorides on electro-oxidation performance. In this study, the effects of oxychlorides were investigated as functions of current density and phenol concentration using DSA anodes in terms of the evaluation of the COD removal performance and the biological toxicity. The results show that oxychlorides formed in the electro-oxidation system could result in the over-evaluation of the COD removal performance. Increasing current density (15-50 mA cm^-2) aggravated the over-evaluation of COD removal (4%-18%), owing to the enhancement in the electrochemical generation of oxychlorides. The increase of phenol concentration inhibited the production of oxychlorides, but the effect of oxychlorides on COD values at phenol concentration of 200 mg L^-1 (82 mg L^-1) was higher than that at 100 mg L^-1 (51 mg L^-1). The ClO₃^- was predominantly responsible for over-evaluation of the COD removal. In addition, bioassays with chlorella indicated that the electro-generated oxychlorides significantly increased the biological toxicity of the treated Cl^--containing wastewater. This work provides new guidance for the correct evaluation of COD treatment performance and highlight the importance of minimizing toxic inorganic chlorinated byproducts during electro-oxidation of Cl^--containing wastewater.

Preparation of Fe-loaded needle coke particle electrodes and utilisation in three-dimensional electro-Fenton oxidation of coking wastewater

Novel iron-loaded needle coke spherical electrodes were fabricated for the first time using the sintering method. With DSA as the anode, nickel foam as the cathode and the spherical electrodes as the particle electrodes, a three-dimensional (3D) electro-Fenton system was constructed to treat coking wastewater. Using the chemical oxygen demand (COD) removal efficiency of coking wastewater as an indicator of electrode performance, the optimal conditions for particle electrode preparation were determined by single-factor experiments as consisting of a 4:1 catalyst-to-binder ratio, Fe²⁺ loading for the preparation of the particle electrodes of 2.5%, a particle size of 5.5 ± 0.5 mm, and a sintering temperature of 400 °C. Response surface methodology was applied to model and optimise the 3D electro-Fenton process for treating coking wastewater. Under the optimal conditions of an electrode spacing of 5 cm, applied voltage of 11.15 V, initial pH of 2.62, and particle electrode dosing of 12.23 g L^-1, the removal rates of COD, NH₃-N, NO₃^--N, total nitrogen, colour, and UV₂₅₄ were 87.5%, 100%, 72.2%, 84.8%, 95%, and 72.4%, respectively. Spectral analysis revealed that the 3D electro-Fenton system strongly degraded coking wastewater, causing decomposition of large molecules of organic compounds and residuals primarily consisting of olefins and alkanes. Because the prepared particle electrodes exhibited stable physical and chemical structure, they have great potential for engineering applications due to their resistance to water flow erosion, stable catalytic reaction activity, and reusability.

Coupling with in-situ electrochemical reactive chlorine species generation and two-phase partitioning method for enhanced microalgal biodiesel production

Microalgal-based biofuel production is of great significance in alleviating energy crisis and achieving carbon neutrality. However, the excessive costs and high solvent consumption in lipids extraction from microalgal obstruct the widespread application of biodiesel in practice. Reported herein is the construction of facile strategy for lipids extraction via electrocatalytic pretreatment and a subsequent two-phase partitioning method. Electrocatalytic pretreatment method adopts the solar as power source and avoids the drying of microalgal biomass, in favor of carbon neutrality requirement. During this process, eco-friendly electrode with high specific surface area could contribute to the sufficient generation of reactive chlorine species (RCS), facilitating the outflows of intracellular lipid. As a result, assisted with two-phase partitioning method, a satisfied performance of lipid recovery (86.72 %) was obtained. Notably, compared with traditional solvent method, two-phase partitioning method greatly reduced the dosage of organic solvent, which is an economical or environmental technique.

A New Method Based on a Zero Gap Electrolysis Cell for Producing Bleach: Concept Validation

Commercial bleach (3.6 wt% active chlorine) is prepared by diluting highly concentrated industrial solutions of sodium hypochlorite (about 13 wt% active chlorine) obtained mainly by bubbling chlorine gas into dilute caustic soda. The chlorine and soda used are often obtained by electrolyzing a sodium chloride solution in two-compartment cells (chlorine-soda processes). On a smaller scale, small units used for swimming pool water treatment, for example, allow the production of low-concentration bleach (0.3 to 1 wt% active chlorine) by use of a direct electrolysis of sodium chloride brine. The oxidation and degradation reaction of hypochlorite ion (ClO⁻) at the anode is the major limiting element of this two-compartment process. In this study, we have developed a new process to obtain higher levels of active chlorine up to 3.6%, or 12° chlorometric degree. For this purpose, we tested a device consisting of a zero-gap electrolysis cell, with three compartments separated by a pair of membranes that can be porous or ion-exchange. The idea is to generate in the anode compartment hypochlorous acid (HClO) at high levels by continuously adjusting its pH to a value between 4.5 and 5.5. In the cathodic compartment, caustic soda is obtained, while the central compartment is supplied with brine. The hypochlorous acid solution is then neutralized with a concentrated solution of NaOH to obtain bleach. In this work, we studied several membrane couples that allowed us to optimize the operating conditions and to obtain bleach with contents close to 1.8 wt% of active chlorine. The results obtained according to the properties of the membranes, their durability, and the imposed electrochemical conditions were discussed.

Electrochemical Degradation of Crystal Violet Using Ti/Pt/SnO2 Electrode

Today, organic wastes (paints, pigments, etc.) are considered to be a major concern for the pollution of aqueous environments. Therefore, it is essential to find new methods to solve this problem. This research was conducted to study the use of electrochemical processes to remove organic pollutants (e.g., crystal violet (CV)) from aqueous solutions. The galvanostatic electrolysis of CV by the use of Ti/Pt/SnO2 anode, were conducted in an electrochemical cell with 100 mL of solution using Na2SO4 and NaCl as supporting electrolyte, the effect of the important electrochemical parameters: current density (20–60 mA cm−2), CV concentration (10–50 mg L−1), sodium chloride concentration (0.01–0.1 g L−1) and initial pH (2 to 10) on the efficiency of the electrochemical process was evaluated and optimized. The electrochemical treatment process of CV was monitored by the UV-visible spectrometry and the chemical oxygen demand (COD). After only 120 min, in a 0.01 mol L−1 NaCl solution with a current density of 50 mA cm−2 and a pH value of 7 containing 10 mg L−1 CV, the CV removal efficiency can reach 100%, the COD removal efficiency is up to 80%. The process can therefore be considered as a suitable process for removing CV from coloured wastewater in the textile industries.

Electrochemical mineralization of iron-tannate stain on HAp and bovine enamel-A non-peroxide approach

Prolonged treatments for the destaining of teeth using high concentrations of hydrogen peroxide may cause secondary unwanted effects such as tooth hypersensitivity and gingival irritation. Hence, it is aimed to develop a non-peroxide-based method to oxidize iron-tannate (Fe-TA) stained hydroxyapatite (HAp) and bovine enamel (BE) samples. Constant current electrolysis (CCE) experiments were carried out on Pt working electrode in aqueous NaCl, KCl and KI solutions at discrete concentrations under continuous experiment and a non-continuous experiment. CCE shows that in the presence of iron tannate (Fe-TA) stained HAP, approximately 30 ppm of iodine was generated using 0.1M KI and nearly 40 ppm was produced with 0.2 M KI. By using a non-continuous CCE process, the lowest amount of chlorine was generated from NaCl solution, which was well within the safety limits for oral applications. Depending on the experimental conditions used, between 13 ppm and 124 ppm of chlorine was generated. CCE of Fe-TA stained on HAp using KCl reveals that at the lowest current density of 10 mA/cm², the amount of hypochlorite generated was 20 ppm on Pt electrode having a surface area of 6 cm². Ion chromatographic (IC) analysis revealed that non-continuous CCE of Fe-TA-BE in NaCl generated a low concentration of sodium perchlorate (0.8 ppm), whereas the continuous process generated no perchlorate, but a considerable higher quantity of chlorate for Fe-TA-BE (37 ppm) and Fe-TA-HAp (140 ppm) samples.

Mechanism of N,N-dimethylformamide electrochemical oxidation using a Ti/RuO2-IrO2 electrode

The compound N,N-dimethylformamide (DMF) is a widely used industrial chemical and a common environmental contaminant that has been found to be harmful to human health. In this study, electrochemical oxidation was adopted for the degradation of DMF. The effects of four kinds of electrodes on the removal rates of DMF and total organic carbon were compared, and based on the result, the Ti/RuO₂–IrO₂ electrode was selected as the operating electrode. The effects of three independent factors (current density, pH, and NaCl proportion) on the DMF degradation were investigated through single-factor experiments, and the experimental results were optimized by response surface methodology. The optimal experimental conditions were obtained as follows: current density = 47 mA cm⁻², pH = 5.5, and NaCl proportion = 15%. The electrochemical oxidation of 50 mg L⁻¹ DMF was performed under the optimal conditions; the degradation rate was 97.2% after 7 h, and the reaction followed the pseudo-first-order kinetic model. The degradation products under optimal conditions and chlorine-free conditions were analyzed, and four degradation pathways were proposed. The DMF degradation was more thorough under optimal conditions.

DEMS as an emerging technology was used to investigate the degradation mechanism of DMF.