Cu (II) binded chitosan/Fe₃O₄ nanocomomposite as a new biosorbent for efficient and selective removal of phosphate

The aim of this study was to develop a chitosan-based magnetic adsorbent for selective and effective removal of phosphate from aqueous solutions. For this purpose, Cu-chitosan/Fe₃O₄ nanocomposite was prepared using a facile method and characterized. The prepared adsorbent exhibited more porous surface with higher specific area compared to neat chitosan based on SEM and BET studies. The FTIR and EDX studies indicated the presence of Cu(II) bonded to the adsorbent surface. Crystalline properties of the adsorbent were also studied using XRD. Experimental isotherm data were fitted to nonlinear forms of Langmuir and Freunlich models. The maximum capacity for the modified adsorbent was calculated to be 88mg P₂O₅/g, much higher than that for neat chitosan and chitosan/Fe₃O₄ according to the Langmuir isotherm. The adsorption by the modified adsorbent had fast kinetics and obeyed pseudo-second-order kinetic model. Interestingly, the maximum removal efficiency for the modified adsorbent was observed in neutral pH values, pHs of natural waters. A high selectivity against natural waters common anions as well as good regeneration ability was obtained for the introduced adsorbent.