Sorption properties of Th(IV) on the raw diatomite--effects of contact time, pH, ionic strength and temperature.
Diatomite has a number of unique physicochemical properties and has diversified industrial uses. Natural diatomite has been tested as a potential sorbent for the removal of Th(IV) from aqueous solutions. The results indicate that sorption of Th(IV) is strongly dependent on ionic strength at pH<3, and is independent of ionic strength at pH>3. Outer-sphere complexation or ion exchange may be the main sorption mechanism of Th(IV) to diatomite at low pH values, whereas the sorption of Th(IV) at pH>3 is mainly dominated by inner-sphere complexation or precipitation. The competition for Th(IV) between aqueous or surface adsorbed anions (e.g., herein ClO(4)(-), NO(3)(-) and Cl(-)) and surface functional groups of diatomite is important for Th(IV) sorption. The thermodynamic data (DeltaH(0), DeltaS(0), DeltaG(0)) are calculated from the temperature-dependent sorption isotherms. The results suggest that sorption process of Th(IV) on diatomite is spontaneous and endothermic.
Sheng
Guodong
G
Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031, PR China.
Hu
Jun
J
Wang
Xiangke
X
D000042:Absorption; D003198:Computer Simulation; D007692:Diatomaceous Earth / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D013696:Temperature; D013910:Thorium / Q000737:chemistry*
D013910:Thorium; D007692:Diatomaceous Earth; C033787:diatomite