Using niobium/BDD anode-based multi-cell flow reactor for the electrochemical oxidation of methyl paraben in the presence of surfactants

This study reports the electrochemical oxidation of methyl paraben (MeP) in synthetic wastes in the presence of surfactants using boron-doped diamond (BDD) anode and the interfering effect of the surfactants in MeP removal. The selected surfactants (cationic, anionic, and neutral) were used at critical micellar concentrations (CMC) and below with measurements performed to evaluate the removal rates of MeP and total organic carbon (TOC). The effects of current density (15, 30, and 45 mA cm(-2)), surfactant concentration, and initial pH on the efficiency of the electrochemical oxidation process were analyzed. At low concentrations, the interfering effect of the anionic surfactant (sodium dodecyl sulfate -SDS) was greater than that of the cationic surfactant (hexadecyltrimethylammonium bromide -CTAB). The complete mineralization of MeP + SDS was achieved at 45 mA cm(-2) in 2 h; this was attributed to the generation of persulfate radicals at current densities higher than 15 mA cm(-2). Genapol C-100 (Genapol) exerted less interference during the mineralization of MeP + Genapol compared to the systems containing other surfactants at CMC. MeP removal was favored by the use of a basic medium. The increase in surfactant concentration decreased the efficiency of MeP and TOC removal due to the formation of micelles and the intensity of MeP-surfactant interactions, apart from the increase in organic load in the system. CTAB interacted more with the ionic form of MeP in the basic medium compared to the other surfactants. All these factors influenced the mineralization of organic compounds in the systems.