Synthesis and Characterization of Polyethylenimine–Silica Nanocomposite Microparticles

A novel procedure for the synthesis of polyethylenimine (PEI)–silica nanocomposite particles with high adsorption capacities has been developed based on an emulsion templating concept. The exceptional chelating properties of PEI as the parent polymer for the particle core promote the binding abilities of the resulting composite for charged species. Further, the subsequent introduction of silica via the self-catalyzed hydrolysis of tetraethoxysilane facilitates production of robust composite particles with smooth surfaces, enabling potential use in multiphase environments. To enable tailored application in solid/liquid porous environments, the production of particles with reduced sizes was attempted by modulating the shear rates and surfactant concentrations during emulsification. The use of high-speed homogenization resulted in a substantial decrease in average particle size, while increasing surfactant loading only had a limited effect. All types of nanocomposites produced demonstrated excellent binding capacities for copper ions as a test solute. The maximum binding capacities of the PEI–silica nanocomposites of 210–250 mg/g are comparable to or exceed those of other copper binding materials, opening up great application potential in resources, chemical processing, and remediation industries.