title: Effect of soil humic and fulvic acids, pH and ionic strength on Th(IV) sorption to TiO2 nanoparticles.
abstract: Thorium is considered as a chemical analog of other tetravalent actinides. Herein, the sorption of Th(IV) on TiO(2) in the presence or absence of soil fulvic acid (FA)/humic acid (HA) as a function of pH, ionic strength and FA/HA concentration has been studied by a batch method. The morphology was characterized by scanning electron microscopy (SEM). The results indicate that sorption of Th(IV) on TiO(2) increases from 0% to approximately 94% at pH 1 approximately 4, and then maintains level with increasing pH values. Both FA and HA have a positive effect on Th(IV) sorption at low pH values and the contribution of FA on Th(IV) sorption is rather higher than that of HA at pH<4. The sorption is weakly dependent on the concentration of KNO(3) in solution, but the cations K(+), Na(+) and Li(+) influence Th(IV) sorption more obviously. The batch results indicate that the inner sphere complex formation is formed at bare surfaces or FA/HA-bound TiO(2) particle surfaces. Results of SEM analysis show that the particle sizes of TiO(2), Th-TiO(2) and Th-HA-TiO(2) colloids are quite different. Surface complexation may be considered as the main sorption mechanism.
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, 230031 Hefei, P.R. China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Tan
authors.forename: Xiangke
authors.initials: X
authors.lastname: Wang
authors.forename: Changlun
authors.initials: C
authors.lastname: Chen
authors.forename: Aihua
authors.initials: A
authors.lastname: Sun
mesh_terms: D000327:Adsorption / Q000187:drug effects; D001578:Benzopyrans / Q000737:chemistry*; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D008094:Lithium / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry; D009566:Nitrates / Q000737:chemistry; D009994:Osmolar Concentration; D017680:Potassium Compounds / Q000737:chemistry; D012987:Soil / Q000032:analysis*; D013910:Thorium / Q000302:isolation & purification*; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D001578:Benzopyrans; D006812:Humic Substances; D009566:Nitrates; D017680:Potassium Compounds; D012987:Soil; C009495:titanium dioxide; D013910:Thorium; C031618:sodium nitrate; D008094:Lithium; D014025:Titanium; C023844:potassium nitrate; C005023:fulvic acid