Sorption of Trace Constituents from Aqueous Solutions onto Secondary Minerals

-Well-characterized American Petroleum Institute clay standards, source clays from The Clay Minerals Society, and other secondary minerals were used to determine the effects of U concentration, temperature, and solution composition on U-sorption properties. Uranium concentrations ranged from about 1.00 x 10 -4 M to 4.00 x 10 7 M, temperatures from 5 ~ to 65~ and solution compositions containing 0.01 M NaCl and 0.01 M NaHCO3. Silica gel efficiently sorbed uranyl carbonate anion complexes. The higher cation-exchange capacity materials most readily sorbed uranyl ions from the 0.01 M NaCl solution. Temperature increases tended to affect uranyl ion sorption adversely except when the U was present as carbonate complexes. Noncrystalline ferric oxyhydroxides sorbed uranyl ions much more efficiently than any of the secondary crystalline minerals studied. A method for accurately extrapolating U-sorption efficiencies between experimental points based on the Freundlich equation is presented. Key Words--Cation exchange, Clinoptilolite, Freundlich isotherm, Glauconite, lllite, Montmorillonite, Opal, Sorption, Uranium.