Preparation of 8‐hydroxyquinoline‐type composite chelating material <scp>HQ‐PHEMA</scp>/<scp>SiO₂</scp> and its adsorption behavior for heavy metal ions

Abstract

Abstract BACKGROUND An 8‐hydroxyquinoline ( HQ )‐type composite chelating material with high performance was designed and prepared. Monomer hydroxyethyl methacrylate ( HEMA ) was first grafted onto silica gel particles via surface‐initiated graft‐polymerization, forming grafted particles PHEMA / SiO 2 with a high grafting degree. Subsequently, through the substitution reaction between 5‐chloromethyl‐8‐hydroxyquinoline ( CHQ ) and the grafted macromolecules PHEMA , HQ groups were bonded onto the grafted particles, obtaining the composite chelating material HQ‐PHEMA / SiO 2 . The chelating adsorption performance and mechanism of HQ‐PHEMA / SiO 2 towards Cu 2+ and Ni 2+ ions was studied, and the adsorption thermodynamics was investigated . RESULTS The experimental results show that HQ‐PHEMA / SiO 2 possesses a strong adsorption affinity for heavy metal ions owing to the high density of the HQ group, and for Cu 2+ and Ni 2+ ions, the adsorption capacities were up to 63.4 mg g −1 and 51.1 mg g −1 , respectively. The adsorption behavior fits the Langmuir model, and the adsorption enthalpy change Δ H is positive, indicating endothermic chemisorption. The value of the entropy change Δ S is also positive, and the higher value of | T Δ S | suggests that the adsorption process is entropically driven . CONCLUSION HQ‐PHEMA/SiO 2 is a promising material for the effective removal of heavy metal ions from water. © 2013 Society of Chemical Industry