Efficient H2O2 generation and bisphenol A degradation in electro-Fenton of O-doped porous biochar cathode derived from spirit-based Distiller’s grains

Bisphenol A (BPA) is an endocrine disrupting chemical with high detection frequency and content, which seriously harms the ecology and human health. Spirit-based distillers’ grains (DG) are solid residues produced during the brewing process, and their treatment has gotten the concern. It is an attractive effort to combine the comprehensive utilization of DG with the removal of BPA. Herein, O-doped porous biochar (OPB) was fabricated using DG as the precursor and used in an electro-Fenton (EF) system to degrade BPA. OPB exhibited a large surface area (i.e., 1432 m2/g) and doping of oxygen, which can facilitate dissolved O2 diffusion and enhance the yield of H2O2 (i.e., 3.0–15.5 mmol/L), and 20 mg/L BPA was rapidly removed by the EF system at the optimum condition (i.e., −0.5 V, pH 4, and 0.3 mM Fe2+) during 30 min with the apparent kinetic constant of 0.267/min. In addition, OPB demonstrated efficient stability in removing BPA after four cycles in the EF system. According to the results of density functional theory calculation and ultra-performance liquid chromatography–tandem mass spectrometry analysis, the three pathways were inferred to be hydroxylation, ketoneation, oxidation, and benzene ring cleavage, and then further decomposed into CO2 and H2O, and the toxicity to the environment gradually decreased with the occurrence of the reaction. This study provides a new idea for resource recovery from waste biomass to solve the problem of water pollution.