Synthesis of Polyvinyl Alcohol/Maleic Acid Hydrogels by Electron Beam Irradiation for Dye Uptake

Novel polyelectrolyte hydrogels based on maleic acid (MA) and polyvinyl alcohol (PVA) were prepared in the presence of electron beams irradiation as initiator and crosslinker. PVA was used as a template for the polymerization of MA in an aqueous solution. The effect of pH on swelling behavior of the hydrogels was examined. In particular, a reversible swelling behavior between acidic and alkaline solutions was investigated. The structure, thermal properties and morphologies of PVA/MA hydrogels were characterized by FTIR, DSC and SEM, respectively. The swelling ratios of gels increased with the increase MA content, pH values, but decreased with enhanced irradiation dose. PVA/MA has been utilized as an adsorbent for the removal of two textile dyes, Reactive red SH.B and Ismative violet 2R, as model dyes from aqueous solution. Factors affecting dye sorption were extensively investigated. The adsorption capacity for dyes increased with the increase of initial dye concentration, contact time, pH, temperature and MA content in the hydrogels. The equilibrium adsorption data were modeled using Langmuir and Freundlich adsorption isotherms. The results revealed that the adsorption of dyes onto PVA/MA hydrogel fit very well with Langmuir isotherm model.