Sorption of Eu(III) and Am(III) on attapulgite: effect of pH, ionic strength and fulvic acid

Abstract

Sorption of Eu(III) and Am(III) on attapulgite were studied as a function of pH, ionic strength, the liquid-to-solid ratio (V/m), and Eu(III) and Am(III) concentrations under ambient conditions using batch technique. The sorption of Eu(III) and Am(III) was quickly and ∼4 hours were enough to achieve the sorption equilibrium. The K′ values were 6.57×106 g mg-1 h-1 for Eu(III) and 6.67×106 g mg-1 h-1 for Am(III), respectively; and qe values were 4.46×10-7 mg/g for Eu(III) and 1.0×10-6 mg/g for Am(III), respectively. Sorption of Eu(III) and Am(III) on attapulgite were strongly affected by pH values, and weakly dependent on ionic strength. Sorption of Eu(III) and Am(III) were mainly dominated by surface complexation, although ion exchange also contributed to Eu(III) and Am(III) sorption. In the presence of fulvic acid (FA), the sorption edge of Eu(III) and Am(III) was obviously shifted to lower pH. The results showed that the sorption of Eu(III) and Am(III) to attapulgite was enhanced significantly in the range of pH 0.5 to 6.