Abstract: “Removal of phosphate in wastewater treatment is crucial to reducing nutrient enrichment and eutrophication of aquatic bodies. This study explored the potential of fired clay pellets for use in phosphate removal during wastewater treatment. The mechanism of removal was evaluated in a batch adsorption study under different experimental conditions. Fired clay pellets were found to be effective in the adsorptive removal of phosphate from aqueous solution with a maximum adsorption capacity of 144mg/g. The experimental data showed a good fit to the pseudo-first-order kinetic model indicating a physical nature of the sorption process and also followed Dubinin-Radushkeivich Isotherm model. Adsorption of phosphate favoured acidic pH with optimum removal at pH 3-4. The values of Gibbs free energy (-16.5 kJ/mol), enthalpy (-8.87 kJ/mol) indicated adsorption was spontaneous and exothermic. The mechanism was found to be predominantly physisorption supported by some diffusion.”

Keywords: adsorption, kinetics, phosphate, clay, isotherm