Kinetics of Arsenite Sorption in Soils

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Abstract
The sorption of As(III) by 10 surface and subsurface horizons was investigated. An Elovich type equation and a modified Freundlich equation were used to describe the kinetics of the As(III) sorption process. Both equations successfully describe As(III) sorption rates. However, the modified Freundlich equation proved to be superior when both coefficients of determination (R2) and standard errors of estimate (SE) were considered. The SE values from the modified Freundlich equation were consistently lower than those from the Elovich equation. Modified Freundlich equation parameters were regressed against soil chemical and physical properties to indicate possible sorption mechanisms and to identify soil properties that could serve as predictors of arsenite sorption. The regression equations indicated that iron oxides and Eh were the main soil properties controlling arsenite sorption rate.