{"doi":"10.17760/d20429230","title":"Electrogeneration of hydrogen peroxide for electro-Fenton process in the flow-through system","abstract":"Groundwater contamination is a major environmental challenge, especially in areas that rely on groundwater as a drinking water source. Remediation is important to protect and clean contaminated groundwater. Electrochemical advanced oxidation processes (EAOPs) utilize electrochemical systems for the oxidation of aqueous organic contaminants in groundwater. EAOP by electro-Fenton reaction generates hydrogen peroxide H2O2 and eventually hydroxyl radical (OH∙), a powerful oxidizing agent, to degrade contaminants. Two methods are identified for electrogeneration of H2O2: direct synthesis of H2O2 in the presence of a catalyst and cathode reduction of the dissolved O2 through the 2-electron oxidation reduction reaction (2e-ORR). The application of electro-Fenton reaction in a flow-through system can maximize the performance of the process. However, the efficiency and performance are impacted by flow conditions and flow rates, which can limit the success of the process. A four-stage experimental program is conducted in this study to (1) select the most efficient H2O2 electrogeneration method for a flow-through system; (2) optimize the performance of the modified graphite felt cathode on H2O2 production; (3) enhance the stability of the modified cathode; (4) compare two iron sources (cast iron anode and FeSO4 salt) on the performance of electro-Fenton process on removing ibuprofen, as a model contaminant, in a flow-through reactor. In the first stage, electrogeneration of H2O2 through direct synthesis in the presence of palladium (Pd) as a catalyst was evaluated under varying currents (60, 120, 200, and 250 mA) and flow conditions (3, 10, 20, and 50 mL/min). Experiments were then conducted without Pd to assess H2O2 production through 2e-ORR on a titanium mixed metal oxide (Ti/MMO) cathode by the process. In the second stage, a flow-through reactor with the polytetrafluoroethylene coated graphite felt (GF-PTFE) cathode was designed for in-situ H2O2 production. PTFE content, current, flow rate, and pH were evaluated to optimize H2O2 production. The third stage included experiments with a polydimethylsiloxane (PDMS) dampproof coating layer at the GF-PTFE electrode (GF-PDMS) to enhance the longevity of the cathode. The effect of current, flow rate, and pH were evaluated to identify optimum operating conditions. In the fourth stage, the electro-Fenton system is optimized to degrade ibuprofen (IBP), which is used as a model contaminant, under flow conditions. Two iron sources (cast iron anode and FeSO4) were investigated for enhancing ibuprofen removal rate. Variables tested include the location of cast iron anode, the concentration of FeSO4, current level, flow rate, and pH. Results show that 2e-ORR was less impacted by increasing flow rate, and therefore more effective for generating H2O2 in a flow-through system. Increasing retention time of anodic oxygen by a non-reactive porous media (glass-beads) increased production under high flow rates. The PTFE modified cathode increased concentration of H2O2 by 16 times compared to the unmodified cathode, but the concentration of H2O2 was not stable. PDMS dampproof coating enhanced the longevity of the cathode. H2O2 concentration decrease is limited to 2% after 24 hours testing using cathodes coated with 500 mg of PDMS. GF-PTFE and GF-PDMS produce maximum H2O2 concentrations at 120 mA and 250 mA, respectively. Increasing the current will increase production to some extent, but beyond an optimum current value, the efficiency decreases. Increasing flow rate diluted the accumulated H2O2 under the same current, leading to a decrease in the concentration. Both modified cathodes result in improved H2O2 generation under neutral and alkaline conditions than under acidic conditions. In the electro-Fenton experiment, location of the iron anode affects the concentration of dissolved iron near the cathode because of pH variation across the reactor. Iron anode at the bottom of the reactor had the best removal ","journal":null,"year":2021,"id":222608,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":1,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9552,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":823876,"name":"Yuwei Zhao","orcid":null,"position":0,"is_corresponding":true}],"reference_count":199,"raw_metadata":null,"created_at":"2026-07-18T23:54:03.549854Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}