RES³T - Rossendorf Expert System for Surface and Sorption Thermodynamics

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Surface Complex Formation Data:

Mineral: Goethite
Reference: S79
SCM Type: CC - Constant Capacitance
Ligand: PO4<3-> - phosphate
Site Type: »Fe-OH
Equation: »Fe-OH + PO4<3-> + 2 H<1+>  ⇔  »Fe-HPO4<1-> + H2O
LogK: 28.902        LogK°I=0 (Conversion to I = 0):   29.27         LogK2.31 nm−2 (SSD-normalized):   34.17
Experiment: Potentiometric Titration
Ionic Strength: 0.0053 mol/L lake water
Solid/Liquid Ratio: 0.005 g/L
pH Range: 7.5
Ligand Concentration Range: 1E-6 mol/L
Fit Method:
Comment: natural lake water: 3.2E-8 M H+, 4.9E-7 M OH-, 1E-4 M SO42-, 1E-6 M H2PO4-, 5E-4 M H4SiO4 (in [SS80] and [SKS80] 5E-5 M), 5E-3 M HCO3-, 2E-4 M Mg2+, 1E-3 M Ca2+, 1E-8 M Pb2+; SCM \"ligand exchange model\", cited in [SKS80] and [SS80]; original reaction equation in the study: »Fe-OH + H3PO4 = »Fe-HPO4<1-> + H<1+> + H2O with logK = 7.2, formation constant in aqueous solution: PO4<3-> + 3H<1+> = H3PO4 logK = 21.702 [GFFGN03]
 
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