Combined electrochemical in-situ activated chlorine production and photocatalytic for degradation of dimethyl phthalate using membrane filtration recycle TiO2

Abstract

The ultraviolet (UV)/chlorine advanced oxidation process (AOP), involving addition of activated chlorine to the UV irradiation system to generate hydroxyl radicals (HO·) and chlorine radicals (Cl·), is promising in addressing refractory organic matters. Herein, activated chlorine was electrochemically in-situ generated under low concentrations of chloride ions (Cl − ), serving as the chlorine source. A UV/electrochemistry/titanium dioxide (UV/E/TiO 2 ) system was established by coupled membrane filtration. TiO 2 was separated and circulated to remove dimethyl phthalate (DMP). Impacts of catalyst (TiO 2 ), Cl − concentrations, and initial pH on DMP degradation were investigated under different conditions. The results revealed that compared with E and UV/TiO 2 systems, the UV/E/TiO 2 system substantially enhanced the DMP degradation (from 5.11% and 22.54% to 78.33%), with a synergistic factor of 1.16. Radical quenching experiments confirmed that HO· and Cl· were the primary reactive substances for DMP degradation in the UV/E/TiO 2 system. Fluorescence probe experiments, coupled with HPLC and LC–MS analysis, revealed a continuous decrease in Cl − in the UV/E/TiO 2 system due to ongoing photolysis, generating more HO· for DMP degradation in contrast to the E/TiO 2 system. In conclusion, the coupled UV/E/TiO 2 system can promote the degradation of refractory organic pollutants in water environments, showcasing significant potential. • A novel process of coupled electrocatalysis and membrane filtration was developed • Electronic oxidation of NaCl was used as the source of active chlorine • The Cl − dosage used was lower than in actual wastewater with superior performance • The process shows a strong synergistic effect between electrocatalysis and membrane filtration • The problem of separation difficulty and reuse of catalyst was effectively solved