Modified lead dioxide for organic wastewater treatment: Physicochemical properties and electrocatalytic activity

An investigation is reported on lead dioxide electrodeposition from methanesulfonate electrolytes additionally containing Ni2+ ions. It is shown that lead dioxide electrodes micromodified by nickel have different physico-chemical properties vs. nonmodified PbO2-anodes that are formed during the deposition. Electrocatalytical reactivity of electrodes involved in comparison to both the oxygen evolution, as well as to the electrooxidation of 2,4- dichlorophenoxyacetic (2,4-D) acid is investigated. Processes of electrochemical oxidation of 2,4-D on various materials occur qualitatively with the same mechanism and differ only in the rate. It is shown that the Ni-PbO2-anode possesses the highest electrocatalytic activity: the destruction rate of 2,4-D on it increases in 1.5 times in comparison with nonmodified lead dioxide. The COD of a 0.4 mM solution of 2,4-D, determined by the dichromate method, is 90.0 mg dm-3 which is 94 % of the theoretical value.