RES³T - Rossendorf Expert System for Surface and Sorption Thermodynamics

Show Detailed Complexation Query Results


Surface Complex Formation Data:

Mineral: Ferrihydrite
Reference: DCE02
SCM Type: DDL - Diffuse Double Layer
Ligand: Si(OH)4<0> - Silicic acid
Site Type: »Fe-OH
Equation: »Fe-OH + 2 Si(OH)4<0> + H<1+>  ⇔  »FeSi2O2(OH)5 + 2 H2O
LogK: 6.978        LogK°I=0 (Conversion to I = 0):   6.99         LogK2.31 nm−2 (SSD-normalized):   7.93
Experiment: Batch Sorption Experiments
Ionic Strength: 0.001 mol/L NaNO3
Temperature: 298.15 K
Solid/Liquid Ratio: 0.478 g/L
pH Range: 5-9.5
Ligand Concentration Range: 0-0.0033 mol/L
Fit Method: MS Excel
Comment:

Original equation:
≡FeOH + Si2O2(OH)5− + H+ → ≡FeSi2O2(OH)5 + H2O   Ka = 9.50E+11
2Si(OH)4 → Si2O2(OH)5− + H+ + H2Onbsp;  Ka = 1.00E−5

SLR = 250 mg/L as Fe

Silica concentrations ranging from 0 to 200 mg/L as SiO2.

Ka ≤1.90E+01

At pH > 7.25, bottles were covered with HDPE lids or poly(vinyl chloride) plastic wrap to minimize CO2 dissolution, but these steps did not completely eliminate it. Titration of control samples held at constant pHs indicated less than 5 × 10−5 M CO2 was dissolving into samples each hour, even at the highest pHs.

 
1 data sets were retrieved