Study on the separation of nitric acid and acetic acid using multi-stage electrodialysis

In recent years, acetohydroxamic acid (AHA) has gained significant attention as a novel organic salt-free reagent in the reprocessing of the spent nuclear fuel. However, the primary byproduct of the AHA in the process, acetic acid (HAC), is difficult to destroy during the heating. It tends to evaporate along with nitric acid, which can contaminate the recovered nitric acid and affect its reuse. This study utilizes a multi-stage electrodialysis process to separate nitric acid from acetic acid, exploiting differences in their ionization degrees and ion migration speeds under an external electric field. The effects of current, type of reflux solution, reflux flow rate, and the number of reflux stages on the purity and recovery of nitric acid were examined. Results indicated that under the same reflux condition, increasing the current, raising the reflux flow rate or the concentration of solution could enhance the recovery rate of nitric acid. The purity of nitric acid products could reach 99.88 % at the two-stage reflux using nitric acid as a reflux solution. And a high recovery rate on the nitric acid of 97.48 % also could achieve, which meets the criteria for nitric acid reuse in the reprocessing of the spent nuclear fuel.