Effects of phosphate and fulvic acid on the sorption and transport of uranium(VI) on silica column

Abstract

Column experiments were performed, breakthrough curves (BTCs) and displacement curves (DPCs) were obtained of uranium(VI) in the absence and presence of phosphate or fulvic acid individually and simultaneously which demonstrated the effects of phosphate and fulvic acid on the sorption and transport of U(VI) in a silica column at pH 3.7 and U(VI) concentration of 5·10⁻⁶ mol/L. It was found that in the presence of phosphate or fulvic acid sorbed preliminarily on the silica column, the amount of U(VI) sorbed increased significantly and the transport of U(VI) delayed significantly relative to that in the absence of phosphate or fulvic acid. Moreover, in the presence of phosphate and fulvic acids sorbed preliminarily and simultaneously on the silica column, the amount of U(VI) sorbed on the silica column is significantly increased again relative to that in the presence of phosphate or fulvic acid individually. Transport studies of U(VI) are important, since all uranium isotopes are radioactive, and uranium contamination of soils and groundwaters occurs at mining and mill sites. A fundamental understanding of the transport behavior of U(VI) in the water-mineral systems is necessary for accurate risk assessments.