RES³T - Rossendorf Expert System for Surface and Sorption Thermodynamics

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Surface Complex Formation Data:

Mineral: Quartz
Reference: DK01
SCM Type: NE - Non-electrostatic
Ligand: UO2<2+> - uranyl(VI)
Site Type: »Si(w)-OH
Equation: »Si(w)-OH + UO2<2+> + CO3<2->  ⇔  »Si(w)-O-UO2CO3<1-> + H<1+>
LogK: 10.183        LogK°I=0 (Conversion to I = 0):   10.18         LogK2.31 nm−2 (SSD-normalized):   16.74
Experiment: Batch Sorption Experiments
Ionic Strength: 0.0 mol/L NaNO3
pH Range: 7.5-9
Fit Method: FITEQL
Comment: apparent stability constant for I=0, for conversion to other ionic strengths, activity constants of all surface species are assumed equal to one; no electrical double layer correction to the mass laws for charged surface species; fit with U(VI) adsorption data over the entire pH range and the thermodynamic set in table 2-1 of [DKP01]; ternary surface complex involving uranyl cation, carbonate anion, and strong-site surface functional group; because only data available for pH 7.5-9 were for the system with 1µM U(VI), only a weak site ternary complex was considered; raw data of [KD01] cited in [K02b]; original reaction equation in the study: »Si(w)-OH + UO2<2+> + H2CO3 = »Si(w)-O-UO2CO3<1-> + 3 H<1+> with logK = -6.5, formation constant in aqueous solution: H2CO3 = CO3<2-> + 2H<1+> logK = -16.683 [Grenthe et al. 1992]
 
1 data sets were retrieved