Synthesis of Ion-Imprinted Bioadsorbents Based on Chitosan and its Usage in Al(III) Removal

Abstract

As a main goal of the study, a new Al(III) ion-imprinted (Al(III)-IP) bioadsorbent beads were synthesized through crosslinking of chitosan (CS) by epichlorohydrin (ECH) using ion-imprinting strategy and the selective Al(III) ion adsorption from aqueous solutions properties of the bioadsorbent were investigated. In the tudy, the surface area of chitosan beads determined by Brunauer–Emmett–Teller, surface properties and morphology were analysed by Scanning Electron Microscope. Some properties of the bioadsorbent were further identified using Differential Scanning Calorimetry, Fourier Transform Infrared Spectroscopy and Thermal Gravimetric Analysis. In the adsorption studies, the adsorption capacities were found to be 48 and 12 mg/g for Al(III)-IP and non-imprinted polymer chitosan beads, respectively. The effect of pH, initial concentration and contact time of the metallic ion in the solution were evaluated on the adsorption behaviour of Al(III) and determined by Atomic Absorption Spectroscopy. In addition, the equilibrium adsorption data were examined with Langmuir and Freundlich isotherm models and it is found that adsorption data fits well with the Freundlich isotherm. The competitive adsorption studies showed clearly that the Al(III)-IP has a much higher adsorption capacity for Al(III) than the NIP with the same chemical composition, and has excellent selectivity for the targeted ion. Moreover, the regeneration and reuse studies showed that the Al(III)-IP beads showed no significant decrease in their adsorption capacities. Finally, according to the calculated thermodynamic parameters, the positive values of ΔG°, ΔS° and ΔH° for Al(III)-IP chitosan beads indicated the endothermic nature of Al(III) adsorption.