Phosphate adsorption from aqueous solutions using novel Zn Fe/Si MCM-41 magnetic nanocomposite: characterization and adsorption studies

Abstract

In this manuscript, a novel magnetic nanocomposite adsorbent Zn Fe/Si MCM-41 was prepared, characterized and investigated. The surface morphology of newly prepared nanocomposite had been characterized using TEM, FTIR, XRD and BET analysis. Structural characterizations demonstrated that the Zn Fe/Si MCM-41 was successfully synthesized and that Zn species was present in the form of ZnO. The prepared nanocomposite was used in the removal of phosphate ions in wastewater samples by adsorption batch technique. The adsorption efficiency was increased with the increase in contact time, temperature, initial phosphate ion concentrations and adsorbent dosage, whereby the maximum phosphate ion uptake reached 97 mg/g. A suitable phosphate ions uptake was achieved at pH value 7. The removal process of phosphate anion from waste samples involved a chemisorptions process and followed a pseudo-second-order model. The obtained equilibrium data agreed very well with the Freundlich model, suggesting that the adsorption feature was on heterogeneous surface. The calculated thermodynamic parameters ∆G, ∆H and ∆S indicated that the phosphate ions adsorption process was spontaneous and exothermic in nature. The optimal conditions for the adsorption of phosphate ions onto Zn Fe/Si MCM-41 were a pH of 7, temperature of 340 K and contact time of 82 min. This study implied that a novel Zn Fe/Si MCM-41 can be considered as a promising adsorbent for the removal of phosphate from its wastes.