SYNTHESIS OF POLYVINYL ALCOHOL/CHITOSAN HYDROGELS AND INVESTIGATION OF THE ADSORPTION FOR CROM (VI) IONS
Abstract
In this work, the hydrogels based on polyvinyl alcohol and chitosan were prepared. The glyoxal was used as a crosslinker with the aim of forming the three-dimensional network for the structure of these hydrogels. The adsorption capacity of the hydrogels for Cr(VI) ions was investigated with the various concentrations of glyoxal. The adsorption isotherm studies were conducted at 30oC and pH 7 with Langmuir and Freundlich models. The pseudo-first-order and the pseudo-second-order kinetic models were applied to study the adsorption kinetics. The results showed that the experimental data fitted the Langmuir and pseudo-second-order kinetic models. This indicated that Cr(VI) adsorbed on the hydrogel surface by monolayer coverage and chemical adsorption. The removal efficiency for Cr(VI) ion from aqueous solution attained the excellent achievement of 92%, contributed by the prepared hydrogel with a glyoxal content of 31 wt%. Additionally, the characterization of hydrogels was revealed by several analytical methods, including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and UV–visible spectrophotometry (UV-Vis).