Removal of phosphate from waste waters by adsorption

In this study, the adsorption of phosphate on gas concrete from aqueous solutions has been studied as functions of temperature, mixing rates and suspension pH. Over 99% of phosphate removal was found. The chemical composition of the gas concrete has been defined by X-ray analysis. Experimental data was fitted to the Langmuir equation in order to Langmuir coefficients. After calculating Langmuir coefficients, adsorption free energy (DeltaG(ads.)(0)) has been determined. In order to gather information about adsorption mechanism, electrophoretic mobilites of particles were measured at various pHs by using Zeta meter 3.0+. It has been found that the adsorption is driven by the interactions between the ionizations of CaO and Al2O3 and the formation of AlPO4. According to the BET (N-2) measurements, the specific surface area of gas concrete was found as 22 m(2) g(-1). The surface area after adsorption has been found as 17 m(2) g(-1). The surface area covered by adsorbate has been found as 5.23 m(2) g(-1) by using a(s) = n(m)(s) . a(m) . N-A. These two areas determined by BET and Langmuir model were close to each other (BET: 22 m(2) g(-1)-17 m(2) g(-1)).