Preparation of porous hybrid adsorbents based on fluor(calcium silicate)/activated carbon and its application in the removal of iron (III) from ammonium phosphate solutions

Abstract

The high concentration of Fe3+ ions present in ammonium phosphate solutions have a significant effect on product quality and product morphology. Herein, hybrid adsorbents fluor(calcium silicate)/activated carbon (FCS/AC) combined with fluor(calcium silicate) (FCS) and activated carbon (AC) were prepared, characterized, and applied in the removal of Fe3+ ions from ammonium phosphate solutions. FCS/AC held both advantages of FCS and AC indicating a significant adsorption for Fe3+ ions. The adsorption kinetics, isotherms and thermodynamics of Fe3+ onto FCS/AC were investigated. The effect of solution pH, initial Fe3+ concentration, temperature and contact time on the adsorption of Fe3+ onto FCS/AC were also investigated. Desorption-resorption experiments of FCS/AC for Fe3+ ions were examined by the batch method using different eluents. The results showed that FCS/AC was an excellent, low cost and reusable adsorbent for the removal of Fe3+ ions from ammonium phosphate solutions, and the adsorption process appeared to follow the pseudo-second-order kinetic model and Langmuir isotherm model with a maximum Fe3+ adsorption of 15.41 mg/g. Various thermodynamic parameters such as △G0, △H0 and △S0 were calculated indicating the feasibility of the process and spontaneous nature of the adsorption. Keywords: Fluor(calcium silicate)/activated carbon, Ammonium phosphate solutions, Iron (III), Equilibrium isotherm, Kinetics