Removal of Pb (II) and V (V) from aqueous solution by glutaraldehyde crosslinked chitosan and nanocomposites

Abstract

In this paper, new adsorbents with high mechanical strength chitosan-graphene oxide (CS-GO) and chitosan-titanium dioxide (CS-TiO₂) were synthesized by using glutaraldehyde as crosslinking agent, and the adsorption behavior of Pb (II) and V (V) on them were investigated. The materials were characterized by scanning electron microscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The effects of initial metal ion concentration and contact time on the removal of V (V) and Pb (II) by CS-GO and CS-TiO₂ were investigated. Characterization results showed that the hydroxyl group of GO/TiO₂ reacted with the amino group of chitosan. A comparison of the kinetic models against experimental data showed that the kinetics react system was best described by the pseudo-second-order model. indicating that chemical adsorption was the main adsorption force. the Langmuir adsorption model and Freundlich model agreed well with the experimental data. The removal capacity of Pb (II) by CS-GO and CS-TiO₂ were lower than those of V (V). The uncross-linked -OH and CO were the main adsorptive sites for Pb (II) removal, while uncross-linked -OH and -NH₂ played an important role in removing V (V). These findings provided insights on the removing lead and vanadium pollution.

Keywords: Adsorption; Chitosan; Composite material; Glutaraldehyde; Lead; Vanadium.