Preparation of zirconium functionalized magnetic peanut husk crosslinked with polyethyleneimine and its application for the adsorption of phosphates in aqueous solution

Abstract

The removal of phosphates (PO43−) from wastewater is of utmost importance owing to their ability to interfere with the normal functioning of aquatic ecosystems. In this study, a composite based on zirconium coated magnetic peanut husk crosslinked with polyethyleneimine (Zr@MPN-PEI) was synthesized, characterized and its efficiency as an adsorbent was assessed using PO43− as a model pollutant. Zr@MPN-PEI was found to have good physicochemical properties which endeared its use as an adsorbent. The use of glutaraldehyde as a crosslinker may have resulted in an enhanced crosslinking with polyethyleneimine (PEI) which may have contributed to the increased adsorption capacity as confirmed from the comparability studies. The maximum monolayer adsorption capacity of Zr@MPN-PEI could reach 36.6 ± 4.0 mg g−1 (according to P) under ambient temperature with the underlying kinetics best described by the Elovich model. The fitting of adsorption models to the equilibrium data showed that the Temkin model was the best fit as compared with the Langmuir and Freundlich models. The study of the associated thermodynamics showed the adsorption process to be endothermic, feasible and spontaneous. Furthermore, Zr@MPN-PEI was found to be efficient within a broad pH range and possessed good stability and regeneration capabilities due to its ability to retain the loaded zirconium ions as confirmed by the leaching test. These excellent features coupled with its economic viability as confirmed via cost analysis may promote the prospects of Zr@MPN-PEI for practical environmental remediation processes.