Optimization of MnO_x/Ti composite membrane anode in the electrocatalytic membrane reactor by acidification for phenolic wastewater treatment

摘要

A novel electrocatalytic membrane reactor (ECMR), assembled by MnO_x/Ti (MT) composite membrane as an anode, was used to degrade phenolic wastewater. The MT composite membrane, MnO_x layer with the various crystal forms coated on porous tubular Ti support, was prepared by sol-gel method and then activated further by acidification to obtain acidified MnO_x/Ti (AMT) composite membrane. The XRD results showed that the crystallite size of MnO_x layer distinctly decreased after acidification. This is because of the Ti support had a great effect on the crystal form and crystallite size of MnO_x, especially after acidification. The results of XPS analysis showed that the interaction between Ti support and MnO_x layer had great influence on the Mn-O, Ti-O binding energies and active oxygen species of MT and AMT. Treated by ECMR with AMT, the phenol, COD and TOC removal rates of the synthetic phenolic wastewater were 96.45%, 84.97% and 71.26%, which were obviously higher than that of MT, 62.87%, 50.34% and 41.25%, respectively. It was revealed that acidified MnO_x as the catalysts in AMT composite membrane, with the specific crystal form, refined crystallite size and active oxygen species, exhibited a great potential in the electrocatalytic oxidative degradation of the phenolic wastewater.