Removal of copper ions using poly (acrylic acid-co-acrylamide) hydrogel microspheres with controllable size prepared by W/O Pickering emulsions

Abstract

Poly (acrylic acid-co-acrylamide) hydrogel microspheres were prepared via Pickering emulsion polymerization with hydrophobic silica as emulsifiers. The functional groups and the morphology of the hydrogel microspheres were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. The effect of the dosage of hydrophobic silica on Pickering emulsion polymerization was investigated, and the hydrogel microspheres with different particle sizes were used to remove copper ions in water. The results showed that the diameter (D) of the hydrogel microspheres was inversely proportional to the dosage (S) of the hydrophobic silica used. The size of the hydrogel microspheres mainly affected the adsorption equilibrium time, and the maximum adsorption capacity could reach 85 mg/g at pH = 5. The results of desorption experiment demonstrated that copper ions were adsorbed by hydrogel microspheres mainly through chemical interaction. Pickering emulsion polymerization was an efficient and environmentally friendly approach for the fabrication of granular hydrogels.