Facile synthesis of polyethyleneimine@Fe3O4 loaded with zirconium for enhanced phosphate adsorption: Performance and adsorption mechanism

Coating superparamagnetic iron oxide particles, i.e., Fe3O4, as adsorbents have major advantages over bare adsorbents for water treatment. As a versatile material, zirconium has been extensively studied for phosphate removal. In this study, the Fe3O4 core was pre-coated with branched polyethyleneimine (PEI) first, and then loaded with zirconium to result in a highly selective adsorbent (i.e., Zr-PEI@Fe3O4) for phosphate with a greatly broadened pH range. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), BET surface area, and magnetization were used to characterize the resulting adsorbent and to explore the underlying adsorption mechanism. The adsorption performance of Zr-PEI@Fe3O4 toward phosphate was performed by batch experiment. The results showed that Freundlich model better fit the adsorption isotherms, while the Elovich equation better described the kinetic process. The maximum adsorption capacity of dephosphorization 32.2 mg center dot g(-1) (according to P element) emerged in the condition of 1.0 g center dot L-1 and pH at 2 with 303 K. The process was spontaneous and endothermic. Zr-PEI@Fe3O4 has the potential to remove phosphate from solution due to its easy separation and some good adsorption property.