RES³T - Rossendorf Expert System for Surface and Sorption Thermodynamics

Show Detailed Complexation Query Results


Surface Complex Formation Data:

Mineral: Ferrihydrite
Reference: CZR91
SCM Type: TL - Triple Layer
Ligand: Ca<2+> - calcium
Site Type: »Fe-OH
Equation: »Fe-OH + Ca<2+>  ⇔  »Fe-O-Ca<1+> + H<1+>
LogK: -4.87 ± 0.22         LogK2.31 nm−2 (SSD-normalized):   -3.93
Experiment: Batch Sorption Experiments
Ionic Strength: NaNO3
Temperature: 298.15 K
pH Range: 4.5-10.5
Ligand Concentration Range: 1E-4 mol/L
Fit Method: FITEQL
Comment: data were modeled assuming the formation of only outer-sphere complexes (=FeO-Ca<+> and =FeO-CaOH); log K depends on initial Ca sorption and ionic strength! -> reflects the heterogeneity of the surface?; given value for 1E-4M Ca and I = 0.5, 0.1 and 0.005 M; fit not so good as with complexes =FeO-CaOH and (=FeO)2-Ca; Fe 0.77-0.87mM = 0.13-0.15 g/L Fe2O3*H2O
 
1 data sets were retrieved