Synthesis and characterization of the interpenetratint polymer network hydrogel of starch-g-polyacrylaminde/polyvinyl alcohol for dye removal application

This thesis presented the synthesis of the interpenetrating polymer network (IPN) by free radical grafting and crosslinking reactions with the conventional method. Hydrogels were used as adsorbents for adsorbate of brilliant green dye from an aqueous solution. This work prepared CSt-g-PAM/PVA IPN hydrogels which were divided into two parts; (i) optimization of the amount of the PVA-CSt to obtain the best composition and (ii) optimization of the amount of the AM-CSt to obtain the best composition. The properties of hydrogels were then characterized by Fourier transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermo Gravimetric analysis (TGA), and X-ray diffraction (XRD) techniques. Moreover, the swelling behavior of IPN hydrogels was carried out. As a result, the best compositions of two series were 65%PVA-CSt and 65%AM-CSt. The %mass swelling of 65%PVA-CST and 65%AM-CSt were 1,850 and 4,240% respectively, due to their largest pore size and high thermal stability. Moreover, the adsorption capacity of hydrogel for brilliant green dye rapidly increased with an increase in contact time of adsorption because initially, the adsorption sites were void and dye molecules easily interacted with these sites. Moreover, the thermal stability of hydrogel also improved. The dye adsorption capacities of the IPN hydrogels were 272 mg/g for 65% PVA-CSt and 109 mg/g for 65% AM-CSt, while maximum dye removal of 65% PVA-CSt and 65% AM-CSt were 62% and 29% respectively. The kinetic models, pseudo-first order and pseudo-second order, were applied to examine the kinetics of adsorption. The kinetic experimental data were found to properly correlate with the pseudo-first order kinetic model more than the pseudo-second order. The regenerated hydrogels were subjected to five number of repeated adsorption/desorption cycles without any significant change of adsorption% indicating efficient regeneration and reusability of the hydrogels.