Influencing factors of lignin degradation by combination of electrochemical oxidation and biodegradation

Lignin degradation by combining electrochemical oxidation (EO) with biodegradation (BD) was studied. The effects of four factors such as current density, electronic quantity, pH value, and concentration of the supporting electrolyte on lignin degradation were analyzed. The results showed that current density and electronic quantity had much more important impacts on lignin degradation than the pH value and concentration of the supporting electrolyte. Through comparison, the optimum conditions for ligning degradation were confirmed ascurrent intensity of 5.0 mA/cm², electric quantity of 20 kC, pH of 7, and concentration of supporting electrolyte of 0.1 mol/L. For kraft lignin and lignosulfonate degradation, COD removal rates of 65.97% and 59.31%, UV₂₈₀ reduction of 65.97% and 59.77%, and color removal efficiencies of 74.15% and 58.32% were obtained. It was confirmed that EO could destroy the recalcitrant bonding structure of lignin to produce biodegradable intermediates that could be removed easily by further bioprocesses.