TiO2/CdS Photocatalytic Degradation of Carbamazepine

Abstract

Substantial usage of pharmaceuticals and personal care products (PPCPs), which cannot be successfully broken down by traditional methods of water treatment, is leading to contamination in wastewater, groundwater, and even drinking water, posing potential harm to people and to aquatic life. Photocatalytic degradation is an advanced oxidation process (AOP) that provides an effective method for degrading these substances. The goal for this research project is to examine the degradation of carbamazepine (CBZ), a model PPCP, by titanium dioxide (an inexpensive, non-toxic, and popular wide-bandgap semiconductor) combined with cadmium sulfide (which has a smaller bandgap). To this end, this research seeks to determine (1) to what degree the addition of CdS extends—desirably into the visible spectrum—the range of light that can activate the photocatalyst, (2) the optimal ratio of CdS to TiO2, and, of most interest, (3) the possible pathway by which the composite photocatalyst will degrade the model contaminant. This research will primarily focus on analyzing possible pathways based on literature reports and presenting the preliminary designs of experiments to obtain information about the conditions involved in CBZ degradation. The third goal mentioned above can be the focus of more extensive future research involving an analysis of the movements and roles of the electrons and holes of the combined semiconductors, the extent to which hydroxyl radicals effect CBZ degradation, and perhaps also the intermediates involved as CBZ is degraded.