Reduction–Oxidation of Chromium Ions in Aqueous Solution by Treatment with Atmospheric-Pressure Direct-Current Discharge in Argon
Kinetic features of the oxidation–reduction processes of chromium ions in a potassium dichromate aqueous solution subjected to treatment in argon atmospheric-pressure dc discharge have been investigated in the discharge current range of 20–80 mA and the dichromate concentration range of 0.1–0.5 mmol/L. The solution served as the discharge cathode. It has been revealed that the discharge treatment stimulates the reduction reactions of Cr6+ to Cr3+ ions and the reverse reactions of oxidation of Cr3+ to Cr6+ ions; i.e., the oxidation–reduction reactions are reversible. The limiting degree of reduction of Cr6+ ions has been found to depend on the discharge current and the initial concentration of the solution. The apparent rate constants of oxidation and reduction have been determined, and the energy efficiency of the process has been evaluated. The data are compared with the results obtained earlier for a discharge in air.
Keywordsoxidation reduction chromium ions direct-current discharge solution
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