Abstract:
Chitosan–silica hybrid adsorbents were prepared and functionalized with thiol urea. The method consisted of sol–gel hybridization of chitosan and silica, followed by the addition of thiol urea on the chitosan moieties in the hybrid particles. The resulting adsorbents were characterized by a range of analytical techniques: Fourier Transform Infra Red (FTIR) and Scanning Electron Micrograph (SEM). The adsorption performance of the chitosan–silica adsorbents for PO43 removal were investigated as a function of the contact time, pH of the feed solution concentration and temperature in aqueous media. Desorption studies were performed for both adsorbent. Adsorption studies was carried out and results showed that Equilibrium was attained within 90 min and maximum removal of 96.6% and 97.4% were achieved under the optimum conditions at pH 4 for both adsorbents respectively. The experimental data were fitted to various isotherm models and results indicated that the equilibrium data fitted better with the Freundlich isotherm than other isotherms. The sorption of PO43- ion unto the adsorbent were non-spontaneous and exothermic. The adsorption process also shows its physisorption. Desorption experiments with 0.5 M HCl inferred high release of phosphate ion after adsorption process. The adsorption of PO43- followed pseudo-second order rate kinetic with R2 value of 0.9763. The results indicated that corn cob derived silica blend with chitosan and thiol-functionalized chitosan- silica can be used as an effective and efficient adsorbent to remove PO43- ions from aqueous solutions
