Separation of 133Ba and 137Cs from Mixtures of 133Ba and 137Cs by Environmentally Benign PEG-Based Aqueous Biphasic System

An aqueous biphasic technique has been developed for enrichment of long-lived Ba-133 from mixture of Ba-133-Cs-137. The differential behavior of PEG-4000 and PEG-6000 towards 133Ba and 137Cs have been demonstrated wherein the radionuclides were kept in 2 mol.L-1 solutions of various salts like Na-citrate, Na-malonate, Na-tartrate, Na2SO4, Na2S2O3, Na2SO3, (NH4)(2)SO4, Na2CO3, NaHSO3, K2HPO4, K3PO4 and 6 mol.L-1 KOH. A separation factor similar to 11,250 was achieved at the separating condition of 4 mL 2 mol.L-1 NaHSO3: 3 mL PEG 6000, wherein Ba-133 was completely extracted in the PEG rich phase. The influence of pH of salt-rich phases like (NH4)(2)SO4, Na-tartrate, K3PO4 and Na2CO3 on the extraction behavior of Ba-133 and Cs-137 was investigated.