Abstract
The constant capacitance model and the Elovich equation were combined in the following mathematical expression enabling calculation of the amount of silicic acid adsorbed by iron oxides as a function of the Si concentration, pH, soil:solution ratio, and reaction time: [GRAPHICS] K(a1) is the protolytic surface constant and K(Si) is the stability constant for the Fe oxide-silicate surface complex; -logK(a1) = 6.40-0.54(8-pH) and logK(Si) = 3.85 for ferrihydrite and goethite. Good agreement was found between calculated Si adsorption and the amount actually found to be adsorbed by synthetic ferrihydrite and goethite at different pH (3-6), Si concentration (1-600 muM), solid:solution ratio (1:300, 1:1200) and reaction time (1-480h).
| Original language | English |
|---|---|
| Journal | Soil Science |
| Volume | 158 |
| Issue number | 1 |
| Pages (from-to) | 40-46 |
| Number of pages | 7 |
| ISSN | 0038-075X |
| Publication status | Published - 1994 |