TiO2/ZnO activated carbon composite for the removal of benzotriazole from water by a combination of sorption and photocatalytic processes

Organic xenobiotic substances are emitted into the environment from a number of preparations used in industry and households. Some are relatively persistent and difficult to biodegrade, so they pass relatively easily through wastewater treatment plants into the surface waters and contaminate drinking water sources. The goal of this study is to develop an innovative technological material that will effectively eliminate organic xenobiotics in water. The principle of our method is to combine carbon-based sorbent (biochar and Hydraffin) with a semiconductor layer (TiO2 or ZnO) to synthesize a photoreactive nanocomposite material which, in conjunction with UV/VIS exposure, can efficiently and safely degrade captured organic xenobiotics (benzotriazole, BTR in this study) in water through the processes of sorption and photocatalytic degradation. This nanocomposite should act as more effective alternative to the widely discussed composite biochar-TiO2. Specifically, the composite coated with ZnO provided the highest degradation efficiency of the photochemical process and it also had the highest sorption capacity for BTR because of the interactions with Zn. In this study, nevertheless, both types of composites are tested and compared their efficiency during removal of selected micropollutant representatives from waters.