Continuous electrolytic decarbonation and recovery of a carbonate salt solution from a metal-contaminated carbonate solution

This work studied the characteristic changes of a continuous electrolytic decarbonation and recovery of a carbonate salt solution from a metal-contaminated carbonate solution with changes of operational variables in an electrolytic system which consisted of a cell-stacked electrolyzer equipped with a cation exchange membrane and a gas absorber. The system could completely recover the carbonate salt solution from a uranyl carbonato complex solution in a continuous operation. The cathodic feed rate could control the carbonate concentration of the recovered solution and it affected the most transient pH drop phenomenon of a well type within the gas absorber before a steady state was reached. which caused the possibility of a CO2 gas slip from the gas absorber. The pH drop problem could be overcome by temporarily increasing the OH- concentration of the cathodic solution flowing down within the gas absorber only during the time required fora steady state to be obtained in the case without the addition of outside NaOH. An overshooting peak of the carbonate concentration in the recovered solution before a steady state was observed, which was ascribed to the decarbonation of the initial solution filled within the stacked cells by a redundant current leftover from the complete decarbonation of the feeding carbonate solution. (C) 2009 Elsevier B.V. All rights reserved.