Accelerated denitration by formic acid accompanied with residual acid-electrolytic trimming

Abstract

In the literature the acidity of nitric acid in the partitioning process for transmutation is usually controlled by denitration with formic acid. In this process, the final acidity is limited and it takes a long time to reach a required level, which keeps the conventional denitration away from a continuous operation in the partitioning process. In this work, a new process consisting of an accelerated denitration with formic acid and an electrolytic trimming of the residual acidity is suggested. In this method, the mole ratio of formic to nitric acid of around 2.0 is used to destruct 2.0M nitric acid to below 0.5M within one hour, and then an electrolytic treatment of the residual solution by using 2-3 cells with a catalytic oxide electrode at 80-100 mA/cm² current density is used. It results in reducing 2.0M nitric acid of the feeding solution to 0.3-0.4M on the basis of the total acidity in the final effluent. It was confirmed as well that the denitration with formic acid can be performed in a continuous operation.