Enhanced mineralization of antibiotic berberine by the photoelectrochemical process in presence of chlorides and its optimization by response surface methodology

As a broad-spectrum antibiotic, berberine is chemically produced mostly in Liao River Basin of China. In this paper, photoelectrochemical process in presence of chlorides was applied to the degradation of berberine with Pt/Ti electrodes. It was worth noting that TOC removal efficiency was by far higher than the sum of photo-irradiation and electrochemical processes because of the in situ generated active chlorine and radicals. And thus, a significantly synergistic effect was confirmed to verify that it was suitable extraordinarily for the mineralization of berberine. The effects of bias potential, initial pH and chloride concentration were investigated in details. And response surface methodology was further used to optimize the control parameters: bias potential 2.5 V, Cl- 98.6 mM, initial pH 3.1 and reaction time 3.6 h. Under the conditions, 88.1 % of TOC removal was obtained, which was only 2.0 % different from the predicted value by the established second-order polynomial model. Finally, excitation-emission matrix (EEM) and GC/MS analysis were also carried out to observe that berberine could be rapidly degraded during the process and most of the intermediate products with simple aromatic structures were mineralized.