Adsorption of Phosphorus from Water by Iron Oxide Coated Pumice

摘要

The modification of pumice by coating their surface with iron oxide was investigated in order to apply iron oxide coated pumice (IOCP) in the removal of phosphates from aqueous solution. Scanning electron microscope (SEM) and energy dispersive analysis of X-ray (EDAX) techniques were used to observe the surface properties and morphology of IOCP. The adsorption capacity of phosphate ions from aqueous solutions has been compared for natural pumice and IOCP. Kinetics, effects of pH and temperature, and the adsorption equilibrium for phosphate by IOCP (particle size 0.63-2 mm) have been examined. Additionally, the equilibrium data was regressively analyzed using the Langmuir and Freundlich isotherms. The results showed that IOCP possess more micro pores and a higher surface area, and IOCP had much better adsorbility than natural pumice, the optimum pH of phosphate ion adsorption for IOCP was 4.4. Langmuir equation gave a better fitted to experimental data than Freundlich equation, the monomolecular adsorption capacities of phosphate ion was 0.245 mg/g for IOCP at pH 7, temperature 25 ∩. Meanwhile, Thermodynamic parameters, such as the Gibbs free energy (G), enthalpy (H) and entropy (S) were calculated from graphical interpretation of the experimental data. The results indicated that adsorption is an endothermic process for phosphate ions removal. This study demonstrates that the IOCP can be used as an alternative engineering filtration material for advanced treatment of wastewater.