Surface modification of synthetic clay aimed at biomolecule adsorption: Synthesis and characterization

Abstract

This work describes the process for functionalization of laponite through the grafting of 3-mercaptopropyltrimethoxysilane (MPTS). Laponite is synthetic smectite clay with surface area of 350 m2/g. The samples, prior to and after functionalization, were characterized by chemical analyses, thermogravimetric analysis (TGA), x ray diffraction (XRD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), scanning electron microscopy and energy dispersive spectrometry (MEV/EDS). Infrared spectroscopy and elemental analyses confirmed the presence of organic chains and thiol groups in the modified clay. The immobilized and available thiol group, measured according to the Volhard method, totaled 1.4 meq/g of clay, with approximately 90% accessible for Ag+ trapping. These results represent an improvement as compared to other works concerning the functionalization of smectite-type clays in which the effect produced by functional group blockage limits the access of species to less than 10% of the complexing sites.