Preparation, Characterization and Adsorption into Aqueous Solutions of Polyethyleneimine-Coated Silica Nanoparticles

Abstract

In this study, polyethyleneimine-coated silica nanoparticles (PEI-SiNP) were used to prepare a polymeric material that can effectively and selectively adsorb Au(III) from aqueous solutions. For this purpose, silica nanoparticles were firstly reacted with (3-glycidyloxypropyl)trimethoxysilane (GPTMS) to achieve epoxy functionality. The structures of the silica nanoparticles (SiNP), silica nanoparticles with epoxy functionality (E-SiNP) and polyethyleneimine-coated silica nanoparticles were determined using ATR-FTIR (Attenuated Total Reflectance Fourier Transform Infrared) and XPS (X-Ray Photoelectron Spectroscopy), while their thermal properties were characterized using thermogravimetric analyses (TGA). The Au(III) ion-binding capacity of the PEI-SiNP adsorbent nanocomposite that contain high levels of imine was investigated. The effects of the interactions between pH, contact time, and foreign metal ions on adsorption were tested to determine the optimum conditions. The optimum contact time was 3 hours at pH 2. The adsorption capacity of the adsorbent nanocomposite prepared for Au(III) was found to be 116.27 mg/g. The Langmuir and Freundlich isotherms were used to determine the adsorption behaviors and the Langmuir isotherm model was selected as the best fit model ( R 2 : 0.997). The prepared PEI-SiNP adsorbent nanocomposite showed a high selectivity for the Au(III) ion even when different metal cations such as Cu(II), Cd(II), and Pb(II) were present.