High Performance and Drawback of Pbo2 Anodes in Wastewater Treatment

High Performance and Drawback of Pbo2 Anodes in Wastewater Treatment

The development of PbO2 anodes for the oxidation of organics has gained great interest in recent years because of their good conductivity and large overpotential for oxygen evolution in acidic media, which enable the production of hydroxyl radicals during water discharge.

PbO2 as itself has been used in the electrochemical treatment of wastewater and also in its doped form. On adding suitable dopant, PbO 2 exhibits exceptional electrochemical properties. Ni, Bi, Co, Er, and Ce are the most commonly used dopants. Niobium-doped PbO 2 has shown excellent hydrophilicity and conductivity due to the improvement in its microcrystal structure. It has also been reported that doping roughened the thin film surface and increased the effective surface area for the generation of hydroxyl radicals.

Ti/Bi-PbO2 showed the highest electrocatalytic activity for the generation of • OH. Obviously, the COD removal was maximum in the case of Ti/Bi-PbO 2. Though Ti/Bi-Co-PbO 2 exhibited the smallest removal rates, its current efficiency was higher than Ti/β-PbO 2 and Ti/Co-PbO 2. Thus, Bi doping into the PbO 2 matrix dramatically improves its characteristics, but Co doping does not make any such differences. It improved the electrocatalytic activity and produced compact coating with decreased crystallite size.

Even if the PbO2 anode showed good performance for removing color and COD from the solution, this electrode cost more on energy consumption. The practical applications in the oxidation of organics with this type of electrode have been limited due to its relatively shorter electrode service life, as well as concerns over the possible release of Pb4+ ions into the water.