Synthesis, characterization and environmental application of silica grafted photoactive substances isolated from urban biowaste

Abstract

A waste-derived photoactive substance sourced from the green fraction of urban refuses (CVT230) was immobilized on different types of silica support, one amorphous and the other two with controlled porosity (HMS and SBA). In this fashion, three hybrid systems were obtained, which contained CVT230 as an insoluble photoactive component. They were tested in the photodegradation of 4-methylphenol in aqueous solution irradiated by simulated solar light and results showed that they are able to promote the total photodegradation of the pollutant. The materials, both before and after irradiation, were characterized by high-resolution transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), N₂ gas-volumetric adsorption, infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The SBA silica hybrid system showed the best performance in terms of stability and reusability, after multiple irradiation cycles. This behaviour can be correlated to the silica morphology and texture, being capable to better allocate and stabilize the CVT230 molecules.