Synthesis of Fe3O4@SiO2-PHEMA via redox of H2O2 and Fe2+ for efficient removal of Cu2+ from aqueous solution

Abstract A facile and energy-efficient synthesis of Fe3O4@SiO2-PHEMA complex and its application as adsorbent for removal of Cu2+ from aqueous solution were investigated. Fe3O4@SiO2-PHEMA was synthesized by mixing Fe3O4@SiO2 and HEMA monomer and then initiating the polymerization of HEMA monomer by H2O2 under Fe2+ catalyzing at room temperature. As adsorbent, the maximum sorption capacity of Fe3O4@SiO2-PHEMA for Cu2+ was calculated to be 20.7 mg/g at pH 6.0. And the efficient enrichment of Cu2+ on Fe3O4@SiO2-PHEMA depended on its multiple carbonyl groups and the electrostatic interaction between carboxyl groups and Cu2+. The carboxyl groups were from slow hydrolysis of partial ester bonds of PHEMA under acidic conditions. The possible hydrolysis process of ester bonds was facilitated to avoid sorption capacity of Cu2+ decreasing caused by other ions sorption (like Fe2+) during the synthesis of the adsorbent. The adsorption of Cu2+ on Fe3O4@SiO2-PHEMA coincided with Langmuir model. The Fe3O4@SiO2-PHEMA had good dispersity in water and it could be easily collected from wastewaters by a magnet. The results showed that Fe3O4@SiO2-PHEMA was a promising adsorbent in wastewater treatment.