Sorption behavior of Am3+ on suspended pyrite

Sorption behavior of 241 Am (*10 -9 M) on naturally occurring mineral pyrite (particle size: B70 lm) has been studied under varying conditions of pH (2-11), and ionic strength (0.01-1.0 M (NaClO4)). The effects of humic acid (2 mg/L), other complexing anions (1 9 10 -4 M CO3 2- ,S O 4 2- ,C 2O4 2- and PO4 3- ), di- and trivalent metal ions (1 9 10 -3 MM g 2? ,C a 2? and Nd 3? ) on sorption behavior of Am 3? at a fixed ionic strength (I = 0.10 M (NaClO4)) have been studied. The sorption of 241 Am on pyrite increased with pH from 2.8 (84%) to 8.1 (97%). The sorption of 241 Am decreased with ionic strength at low pH values (2 B pH B 4), but was insensitive in the pH range of 4-10, suggesting the formation of outer-sphere complexes on pyrite surface at lower pH, and inner-sphere complexes at higher pH values. The sorption of 241 Am increased in the presence of (i) humic acid (5 \ pH \ 7.5), and (ii) C2O4 2- (2 \ pH \ 3). By contrast, other complexing anions such as (carbonate, phosphate, and sulphate) showed negligible influence on 241 Am sorption. The presence of Mg 2? ,C a 2? ions showed marginal effect on the sorption profile of 241 Am; while the presence of Nd 3? ion suppressed its sorption sig- nificantly under the conditions of present study. The sorption of 241 Am on pyrite decreased with increased temperature