Preconcentration and separation of silver from neutron poisons and rare earths using diphenyl-2-pyridylmethane as an extractant

The extraction of Ag from aqueous thiocyanate--perchlorate solutions using diphenyl-2-pyridylmethane (DPPM) in benzene has been investigated. The variables such as concentrations of perchloric acid, thiocyanate and DPPM influencing the extraction have been optimized. Maximum extraction has been achieved from 0.01M perchloric acid solution containing 0.01M potassium thiocyanate in 0.075M DPPM in benzene. The extraction was found to be independent of silver concentation in the range from 10 exp --4 -10 exp --6 M . The influence of several anions on the extraction was examined; only thiosulphate interfered seriously and reduced the extraction < 1%. Thus, 0.1M potassium thiosulphate was found to back-extract Ag quantitatively in one step. Under selected optimal conditions, very small extraction ( < 1% was observed for trivalent Gd, Dy, Ho,Tm, Yb, Lu; Cs(I) and Cd(II) and separation factors for these elements were better than 10 exp 3 . Only Sn(IV) exhibited quantitative extraction ( > 99%). This extraction procedure can be used for the preconcentration of Ag and Sn or their separation from rare earths mentioned above. Graphs. 9 ref.--AA