Preparation and Application of a Xanthate-Modified Thiourea Chitosan Sponge for the Removal of Pb(II) from Aqueous Solutions

As chitosan has low uptake for Pb(II) and high solubility in monoprotic acids, a simple procedure using nontoxic chitosan as a precursor at room temperature was developed to prepare a xanthate-modified thiourea chitosan sponge (XTCS) by lyophilization for enhancing Pb(II) removal in water. The sponge structure of XTCS improved both stability and separation performance. Adsorption results showed that pH markedly affected the adsorption performance of XTCS. The adsorption process attained equilibrium in 45 min with a maximum adsorption capacity of 188.04 mg g(-1) at room temperature. The pseudo second -order kinetic equation and Langmuir isotherm model were suitable to describe the adsorption behavior of XTCS. The physicochemical characteristics of XTCS were investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Results indicated that Pb(II) removal mechanism of XTCS was mainly dependent on complexations of sulfur and nitrogen atoms and ion exchange.