title: Sorption-desorption of Th(IV) on attapulgite: effects of pH, ionic strength and temperature.
abstract: The sorption of Th(IV) on attapulgite was studied as a function of pH, ionic strength, temperature, attapulgite contents and Th(IV) concentrations under ambient conditions using a batch technique. The results indicated that sorption of Th(IV) on attapulgite was strongly affected by pH values, and weakly dependent on ionic strength. Sorption of Th(IV) was dominated by surface complexation, although ion exchange also contributed to this sorption. Sorption of Th(IV) increased with increasing temperature of the system. Enthalpy (DeltaH(0)), entropy (DeltaS(0)) and Gibbs free energy (DeltaG(0)) were calculated from the temperature-dependent sorption data; the results indicated that the sorption of Th(IV) on attapulgite was a spontaneous process. Sorption-desorption hysteresis indicated that the sorption of Th(IV) was irreversible, and that the Th(VI) adsorbed on attapulgite was difficult to be desorbed from solid to liquid phases.
authors.affiliation: Radiochemistry Laboratory, Lanzhou University, Lanzhou, 730000 Gansu, PR China.
authors.forename: Wangsuo
authors.initials: W
authors.lastname: Wu
authors.forename: Qiaohui
authors.initials: Q
authors.lastname: Fan
authors.forename: Junzheng
authors.initials: J
authors.lastname: Xu
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Niu
authors.forename: Songsheng
authors.initials: S
authors.lastname: Lu
mesh_terms: D000327:Adsorption; D006863:Hydrogen-Ion Concentration; D017616:Magnesium Compounds / Q000737:chemistry*; D017655:Silicon Compounds / Q000737:chemistry*; D013696:Temperature; D013910:Thorium / Q000737:chemistry*
chemical_list: D017616:Magnesium Compounds; D017655:Silicon Compounds; D013910:Thorium; C026325:attapulgite