ENHANCE THE CU(II) ADSORPTION BY CROSS-LINKING PEI ON THE SURFACE OF SIO2

Abstract

Grafting functional groups that have a high affinity to heavy metal ions on the surfaces of adsorption materials has been widely deployed to enhance the adsorption capacity. Polyethyleneimine (PEI) whose molecule contains many amino functional groups has been used to functionalize diverse silica materials via a two-step procedure. Simplifying the synthesis procedure and enhancing the adsorption capacity are essential demands to increase the removal of heavy metal ions in water. Herein, we used citric acid, which is a multi-functional carboxylic acid, to cross-link PEI chains on the surface of silica particles (PEI/SiO₂) by an one-pot process. The PEI composition in PEI/SiO₂ was about 14.1% by weight, which was lower than the content of PEI in PEI-KH560-SiO₂ (22.8%) synthesized by the conventional two-step procedure. Adsorption studies with Cu(II) revealed that the adsorption of Cu(II) includes both physical and chemical adsorption. The adsorption capacity of PEI/SiO₂ was about 500 mg/g, which was 4.5 times higher than PEI-KH560-SiO₂. The results demonstrated herein offer a simple method to prepare PEI-based composites with a high adsorption capacity to heavy metal ions.