Rapid Reduction of U(VI) on Activated Platinum Wire Gauze Electrode for the Primary Coulometric Determination of Uranium

Abstract

A large enhancement in the active area of a hollow cylindrical platinum wire gauze electrode was achieved by repetitive multilayer growth of oxide followed by its reduction. Growth of oxide was obtained by a combination of chemical and electrochemical treatments. Enhancement in the active area of the electrode was checked by determining the time taken for the quantitative reduction of U(VI) to U(IV) at a controlled potential of −0.150 V vs SCE in 1 M H2SO4. A six-fold decrease in the reduction time was observed, indicating a corresponding six-fold increase in the active area of the electrode. The enhanced activity of the electrode was found to decay on ageing. Determination of uranium was carried out by a successive addition technique using the activated platinum wire gauze electrode and carrying out the reduction U(VI) to U(IV) at a controlled potential of −0.150 V vs SCE. Precision and accuracy of better than ±0.2% were obtained at 5 to 10 mg levels of uranium. This demonstrates the applicability of a platinum electrode, instead of the conventionally used Hg electrode, for determination of uranium by primary coulometry.