Electroadsorptive Removal of Impurities from Perchloric, Sulfuric, and Phosphoric Acids, and Sodium Hydroxide

A method for the purification of acids and alkali based upon adsorptive and electroactive properties of a column of platinum sponge held at a fixed potential has been developed. This column rapidly removes various cationic and anionic impurities. This flow-through nature of the electrode minimizes the diffusion path of impurities to the electrode surface and shortens preelectrolysis time considerably. The results of purity tests performed with a rotating platinum disk electrode (RPDE) on different supporting electrolytes before and after passing them through the platinum sponge purification column are discussed. The efficiency of the method is illustrated by comparing RPDE data obtained during hydrogen adsorption, oxygen reduction, isopotential point experiments, and experiments involving the formation and/or reduction of oxidized platinum.