Hydroxyl multi-walled carbon nanotube-modified nanocrystalline PbO anode for removal of pyridine from wastewater.

We prepared a hydroxyl multi-wall carbon nanotube-modified nanocrystalline PbO anode (MWCNTs-OH-PbO) featuring high oxygen evolution potential, large effective area, and excellent electrocatalytic performance. The oxygen evolution potential and effective area of the MWCNTs-OH-PbO electrode were 1.5 and 3.7-fold higher than the traditional PbO electrode. Electrochemical degradation of pyridine in aqueous solution was investigated by using the MWCNTs-OH-PbO anode. Based on pyridine decay rate (93.8%), total organic carbon reduction (84.6%), and energy consumption (78.8WhLorder) under the optimal conditions, the MWCNTs-OH-PbO electrode modified with MWCNTs-OH concentration of 1.0gL exhibited higher electrochemical oxidation ability than the traditional PbO electrode. The intermediate, hydroxypyridine, was found at the first stage of electrolysis. The primary mineralization product, NO, was detected in aqueous solution after electrolysis. A possible electrochemical mineralization mechanism including two potential routes, i.e., via formation of small organic molecules by ring cleavage reaction and direct mineralization to CO and NO, was proposed. The results demonstrated that the MWCNTs-OH-PbO electrode exhibited high efficiency for pyridine mineralization in aqueous solution under mild conditions.