KINETICS OF PHOSPHATE ADSORPTION AND DESORPTION BY HEMATITE AND GIBBSITE1

Abstract

The phosphate adsorption by hematite and gibbsite conformed to the Freundlich equation. The rate of phosphate adsorption was rapid initially and decreased with prolonged reaction time. A two-constant rate equation was developed which successfully described the rate of phosphate adsorption. The low activation energy of phosphate adsorption indicated that the adsorption was a diffusion controlled process.The highly complexing agent, EDTA=, was more effective than oxalate, hydroxyl, and fluoride anions in releasing adsorbed phosphate. The rate of phosphate. The rate of phosphate release was similar to the rate of phosphate adsorption and could be described by the proposed two-constant rate equation. The phosphate adsorption by hematite and gibbsite conformed to the Freundlich equation. The rate of phosphate adsorption was rapid initially and decreased with prolonged reaction time. A two-constant rate equation was developed which successfully described the rate of phosphate adsorption. The low activation energy of phosphate adsorption indicated that the adsorption was a diffusion controlled process. The highly complexing agent, EDTA=, was more effective than oxalate, hydroxyl, and fluoride anions in releasing adsorbed phosphate. The rate of phosphate. The rate of phosphate release was similar to the rate of phosphate adsorption and could be described by the proposed two-constant rate equation. © Williams & Wilkins 1973. All Rights Reserved.