Ion fixation kinetics and column performance of nickel and zinc hexacyanoferrates(II)

Abstract

The fixation kinetics of caesium, silver, palladium ions and protons from aqueous solutions were studied on several types of zinc and nickel hexacyanoferrates(II) in order to gain a better understanding of the fixation mechanisms and to determine the optimum recovery conditions on columns. The studied products were prepared by direct precipitation or by slow growth on alkaline hexacyanoferrate(II) salts. In order for a column to exhibit good retention properties rapid kinetics are required. It was possible to select the best products as a function of the element to be fixed. For silver recovery, any nickel hexacyanoferrate(II) can be used. Caesium in appreciable amounts is best fixed on mixed zinc hexacyanoferrate(II) salts. Hexacyanoferrate(II) salts based on nickel have a greater affinity for palladium than those based on zinc. Owing to the occurrence of a rapid kinetic step, all these products could be used for trace recovery from liquid radioactive wastes.