RES³T - Rossendorf Expert System for Surface and Sorption Thermodynamics

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Surface Complex Formation Data:

Mineral: Goethite
Reference: SPH08
SCM Type: 1pK-BS - 1pK-Basic Stern
Ligand: CO3<2-> - carbonate
Site Type: »Fe-singly
Equation: 2 »Fe-OH<0.5-> + CO3<2-> + 2 H<1+>  ⇔  (»Fe-O)2-CO<1-> + 2 H2O
LogK: 22.625        LogK°I=0 (Conversion to I = 0):   23.27         LogK2.31 nm−2 (SSD-normalized):   22.77
Experiment: Potentiometric Titration
Ionic Strength: 0.1 mol/L NaNO3
Temperature: 298.15 K
pH Range: 3-9
Fit Method: EQLFOR
Comment: carbonate sorption data of [VL00] (open system p(CO2) in 0.1 M NaNO3) fitted to the surface complexation equilibria; original reaction equation in the article is given as 2 »Fe-OH<0.5-> + H2CO3 = (»Fe-O)2-CO<1-> + 2 H2Owith logK = 5.93; thermodynamic data: logK1 = -6.366 for the reaction H2CO3 = H<1+> + HCO3<1->[FNK96], logK2 = -10.329 for HCO3<1-> = H<1+> + CO3<2-> [GFFGN03] --> so for H2CO3 = 2H<1+> + CO3<2-> the logK = -16.695
 
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