Improved Durability of Solvent Impregnated Resin Using Acidic Organophosphorus Extractant

Solvent impregnated resins (SIRs) are an effective means for the separation of metal ions from their mixtures. However, their durability is limited due to dissolution of the extractant from the resin. Our previous studies on the repeated column test using PC88A-SIR in order to remove zinc from the model electroless nickel plating bath showed that zinc adsorption capacity gradually decreased over a few cycles. In this paper, the distribution of PC88A and Cyanex 272 between the aqueous solution and SIR or blank resin was measured batchwise. Then the column experiment was carried out, and the following two methods have been found to be effective: (i) Post-column process in which the feed solution is passed through the PC88A-SIR and then the equal weight of the blank resin (Amberlite XAD7HP) and (ii) replacement of the extractant by weaker acid, Cyanex 272. In the latter, the zinc adsorption ability of the SIR was constant for at least 37 cycles. It is suggested that the combination of these two methods significantly improves the SIR durability.