Use of Chemically Modified Chitosan for the Adsorptive Removal of Toxic Metal Ions in Aqueous Solutions

Abstract

Chemical modification of chitosan was successfully carried out using three derivatives namely: 3 hydroxybenzaldehyde, 2,3-dihydroxybenzaldehyde, and 3,5-di-tert-butyl-2-hydroxybenzaldehyde by a condensation reaction. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area, thermal gravimetric analysis (TGA), and X-ray diffraction (XRD) methods were performed for characterization of the chitosan-derived Schiff base adsorbent materials. The efficiency of the prepared adsorbents in removing cobalt and nickel ions from aqueous solution was explored, and experimental data were analyzed using isothermal and kinetic models. The BET surface area of chemically modified chitosan was greatly enhanced 125.83 m2 g-1 with mesoporous characteristics. The maximum uptake was recorded at pH 5-6, while the maximum removal capacity was 243.90 mg g-1 for cobalt ions whereas 166.67 mg g 1 was achieved for nickel ions. The kinetic data were better fitted using pseudo-second-order.