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

A facile and energy-efficient synthesis of Fe 3 O 4 @SiO 2 -PHEMA complex and its application as adsorbent for removal of Cu 2+ from aqueous solution were investigated. Fe 3 O 4 @SiO 2 -PHEMA was synthesized by mixing Fe 3 O 4 @SiO 2 and HEMA monomer and then initiating the polymerization of HEMA monomer by H 2 O 2 under Fe 2+ catalyzing at room temperature . As adsorbent, the maximum sorption capacity of Fe 3 O 4 @SiO 2 -PHEMA for Cu 2+ was calculated to be 20.7 mg/g at pH 6.0. And the efficient enrichment of Cu 2+ on Fe 3 O 4 @SiO 2 -PHEMA depended on its multiple carbonyl groups and the electrostatic interaction between carboxyl groups and Cu 2+ . 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 Cu 2+ decreasing caused by other ions sorption (like Fe 2+ ) during the synthesis of the adsorbent. The adsorption of Cu 2+ on Fe 3 O 4 @SiO 2 -PHEMA coincided with Langmuir model. The Fe 3 O 4 @SiO 2 -PHEMA had good dispersity in water and it could be easily collected from wastewaters by a magnet. The results showed that Fe 3 O 4 @SiO 2 -PHEMA was a promising adsorbent in wastewater treatment.