Phosphate removal by adsorption

Abstract

Phosphate removal efficiencies of 13 natural pumice rock samples obtained from different regions of Turkey were investigated. Samples with high CaO content had high phosphate adsorption capacity. It is concluded that pumice is an effective adsorbent for phosphate if its CaO content is high. The adsorption capacity of a pumice powder sample was calculated from the area under the curve of the plot phosphate concentration vs volume of the effluent as 0.95 mg PO4-3 g(-1) pumice powder. Variation of pH, conductivity(S) and redox potential (mV) was also measured during the column experiment. Langmuir and Freundlich adsorption isotherm constants and correlation coefficients were calculated and compared. It was concluded that the adsorption data of phosphate onto pumice powder fitted to the Freundlich adsorption isotherm more than the Langmuir model. Specific surface areas of the pumice powder were calculated at pH 3, 5, 7 and 9. The compounds present in actual waste water have no significant effect on the removal of phosphate. Pumice powder can be regenerated by dilute NaOH and reused.