Degradation of High Concentration Methanol in Aqueous Solution by Dielectric Barrier Discharge

Degradation of high concentration methanol in aqueous solution is carried out in a dielectric barrier discharge (DBD) reactor. The degradation pathway of methanol is investigated by detecting the degradation products by gas chromatography and ion chromatography. The results demonstrate that formaldehyde as an intermediate product is accumulated easily at the early stage of the degradation process. An increase in the initial concentration (100 to 20000 mg · L^-1) of methanol has a much greater effect on methanol mineralization than on methanol degradation. It is found that methanol degradation and mineralization could be enhanced by increasing either the acidity or basicity of the solution. The methanol degradation rate increases dramatically with the addition of Fe²⁺ (10-80 mg · L^-1), whereas the influence of Cl^- concentration (3000-24000 mg · L^-1) on methanol degradation and mineralization is not as significant. The increase in liquid conductivity increase and decrease in pH value are mainly attributable to the NO₃^- formation due to the DBD treatment. Moreover, the methanol degradation mainly occurs in the liquid film on the liquid interface that is in direct contact with DBD, and the amount of methanol diffusing into the liquid film (main reaction zone) determines the degradation efficiency.