Application of Double Potential-Step Chronocoulometry to the Study of the Cathodic Reduction of Oxalic Acid

摘要

A double potential-step chronocoulometric method is an significant method for the study of adsorption. It is known that the product glyoxylic acid(R) adsorbed on the fresh electrode surface. While with the galvanostatic electrolysis the reactant oxalic acid(O) adsorbing gradually on the electrode surface is proved. At this time a large of lead oxalate crystal can be found on the electrode surface by scan electronic microscope(SEM). Adding the additive tetrapropylammoniumhydroxide (TPAH) into the catholyte the fresh electrode surface is adsorbed by O. And at the first two hour the current efficiency is 95.60%.With the galvanostatic electrolysis the potential become more and more negative, which result in the additive deadsorbed. It is confirmed that the surface is presented that both O and R(glyoxylic acid) are adsorbable when t=4～10h, and the current efficiency is decreased correspondingly from 76.66% to 47.10%.