Fabrication of magnetic macroporous chitosan- g -poly (acrylic acid) hydrogel for removal of Cd 2+ and Pb 2+

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.