EFFECT OF ALUMINUM SUBSTITUTION IN GOETHITE ON PHOSPHORUS ADSORPTION .2. RATE OF ADSORPTION

The effects of initial pH, P concentration, Al substitution and method of synthesis on the rate of phosphate adsorption by a series of alpha -FeOOH samples containing up to 30 mol % Al were investigated. The results, plotted as first-order reactions with respect to phosphate disappearance, were characterized by an initial fast phase followed by a pseudo-first-order reaction. An approximation of the magnitude of the fast phase was made by extrapolating the first-order line back to zero time. The difference between the initial and zero time first-order concentration was then considered to be the magnitude of the rapid phase of the reaction. Phosphate concentration, initial pH, and method of synthesis influenced this parameter.