Performance of acrylic monomer based terpolymer/montmorillonite nanocomposite hydrogels for U(VI) removal from aqueous solutions

摘要

Acrylic monomer based terpolymer/montmorillonite nanocomposite hydrogels (NH-MMTs) synthesized using 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA), 2-acrylamido-2-methlypropane sulfonic acid (AMPS) and 2-hydroxyethyl methacrylate (HEMA) in the aqueous montmorillonite (MMT) suspension were employed as adsorbents for U(VI) removal from aqueous solutions. Adsorption efficiency of the NH-MMTs was strongly enhanced by increasing pH in the range of 3-6. Adsorption capacity of the NHs increased with the MMT weight ratio up to 1% and the complete removal of U(VI) from 1 mmol/L aqueous solutions was achieved by 2 g/L polymer but further increase of MMT up to 6% caused a gradual decrease in adsorption percentage up to 57%. Nearly 98% of U(VI) loaded on the adsorbents could be recovered by 0.1 M HNO3. Consecutive adsorption/desorption cycles showed that the NH-MMTs are re-usable. Kinetic results were analyzed using Paterson's and Nemst Planck approximation's based on homogeneous solid phase diffusion (HSPD). Experimental data were fitted to equilibrium isotherm models, Langmuir, Freundlich, Dubinin-Radushkevich and Temkin. SEM, and FTIR analysis of bare and U(VI) loaded adsorbents were used to elucidate adsorption mechanisms. The results showed that the NH-MMTs tested in this study are very promising for the recovery of U(VI) from water.