Effect of Synthesis Temperature on Adsorbent Performance of Blending Anionic and Cationic Gels in Divalent Metal Ions Adsorption

In this study, the anionic and cationic gels were synthesized separately using copolymerization between N-isopropylacrylamide (NIPAM) and acrylic acid or chitosan through a polymerization reaction using N,N'-methylenebisacrylamide (MBAA) as a cross-linker with various monomer concentrations and synthesis temperature. The anionic and cationic gels were blended to minimize inter-intra particle association and to improve the adsorption ability. The FTIR analysis found that the synthesis of the NIPAM-co-acrylic acid and NIPAM-co-chitosan gels was successfully carried out, indicating no presence of a vinyl group in the functional group. The result showed that the ion adsorption amount of Pb²⁺ ions blending gels increased significantly, almost twice compared to the adsorption before blending. The adsorption amount of Pb²⁺ ions increased with increasing the gel synthesis temperature. The adsorption amount follows the order of Pb²⁺ > Fe²⁺ > Ni²⁺. The adsorption amount of Pb²⁺ tends to decrease with increasing sedimentation volume. The higher the synthesis temperature, the larger the porous diameter formed. These results demonstrate that blending gel of NIPAM-co-chitosan and NIPAM-co-acrylic acid is a feasible alternative for removing heavy metal ions owing to its good adsorption performance.