Fabrication of magnetic macroporous chitosan-g-poly (acrylic acid) hydrogel for removal of Cd2+ and Pb2

Abstract

A novel macroporous magnetic macroporous chitosan-g-poly (acrylic acid) hydrogel adsorbent was fabricated from the Pickering high internal emulsions template stabilized by modified Fe₃O₄ nanoparticles. The structure and composition of modified Fe₃O₄ and macroporous magnetic hydrogel were characterized by TEM, XRD, TG and SEM techniques. The characterization results suggest that the Fe₃O₄ nanoparticles have been modified successfully with organosilane of 3-aminopropyltrimethoxysilane (APTES), and the porous structure of the macroporous hydrogel can be tuned with the amount of stabilized particles, volume fraction of dispersed phase and the amount of the cosurfactant. Adsorption experiments indicate that the adsorption equilibrium was rapidly reached within 20min and the maximal adsorption capacities were determined to be 308.84mg/g for Cd²⁺ and 695.22mg/g for Pb²⁺. After five adsorption-desorption cycles, the adsorbent can retain its high adsorption capacity. The introduction of Fe₃O₄ is beneficial to the recycle of adsorbent after usage.

Keywords: Adsorption; Heavy metal; Macroporous hydrogel; Magnetic; Pickering-HIPEs.