Characterization and Evaluation of Copper Slag as a Bifunctional Photocatalyst for Alcohols Degradation and Hydrogen Production

With the goal of providing an economically viable method for reducing water pollution and health impact by the mezcal industry wastes, photocatalytic degradation of toxic alcohols using copper slag (CS) was evaluated, investigating the possibility for a concurrent hydrogen production. CS was characterized extensively by XRD, XRF, SEM–EDS, UV–Vis and electrochemical techniques to evaluate its properties as a photocatalyst. The slag consists of magnetite, fayalite and a silicate glass phase. CS showed a band gap of 2.75 eV, which is in the values range reported for fayalite, an n-type semiconductor with a clearly defined surface state. The band edge scheme for CS shows energy levels within the range required to perform the photocatalytic water reduction reaction, as well as the oxidation of the studied alcohols and their by-products. Experiments using UV and simulated solar light show that the efficiency of CS is higher in the visible range and that hydrogen production increases in the order methanol > propanol > isoamyl alcohol. An apparent quantum yield for methanol degradation of 40% under simulated solar light was obtained. This provides the prospect for a low cost and potential efficient photocatalyst for the oxidation of organic pollutants in industrial wastewater under solar radiation, with the simultaneous hydrogen generation.