Study on the Mechanism of Sodium Dodecylbenzene Sulfonate Oxidation by Electro-Fenton System

Anionic surfactant wastewater has an irreversible effect on aquatic animals and plants. In this paper, the oxidation of sodium dodecylbenzene sulfonate (SDBS) by electro-Fenton system was researched. The results demonstrated that HO 2 · had a weak ability to oxidize SDBS; ·OH was the primary active substance for oxidizing SDBS. The broken bond sites of SDBS molecules oxidized by the active substances were analyzed by using the concept density functional theory. The calculation results indicated that ·OH initially attacked the C3-C11 bond in the SDBS molecule, and then ·OH underwent addition reactions, forming two typical structures: aromatic sodium p-hydroxybenzene sulfonate and aliphatic linear alkanes. Phenol and sodium dodecyl sulfate (SDS) were selected to study their oxidation behaviors in the electro-Fenton system. It can reflect the oxidation process of the products after the SDBS molecule was broken. The main active substance for oxidizing phenol in the electro-Fenton cathode chamber was ·OH, but the main active substance for oxidizing SDS was HO 2 ·. Unlike the ·OH produced by the cathode, the Pt(·OH) produced by the anode had no effect on the removal of SDBS. Nevertheless, Pt(·OH) exhibited an excellent oxidation effect on SDBS bond-breaking products. The research results clarified the mechanisms of SDBS oxidation in electro-Fenton system and the direction of regulation for the reaction path. It is believed that promoting the ·OH generated at the cathode makes SDBS bond breakage a key step in the electro-Fenton oxidation of SDBS. It provided a theoretical basis for enhancing the current efficiency of the system.