Photocatalytic process for oily wastewater treatment: a review

The generation of wastewater and its treatment are classified among the biggest challenges for the health and environmental aspect. Pollution of water through petroleum production and processing is a major concern, and its treatment processes are significantly important. This review primarily focusses on the treatment of oily wastewater through advanced oxidation processes, mainly centered on photocatalytic process. Advanced oxidation processes such as H2O2/UV process, Fenton and photo-Fenton process, ozone process, electrochemical oxidation process, wet air oxidation and supercritical water oxidation process, and photocatalytic process have been discussed. The basic functioning mechanism of photocatalysts and their modifications to improve performance have been explained. This review paper primarily focusses to understand the photocatalysis process, its performance and impact on the degradation of harmful and toxic oily pollutant in water through the creation of reactive oxidation species, for example, hydroxyl radical with the help of solar energy and the complete breakdown of pollutants into the simpler forms like H2O and CO2. The review also provides insight on the future perspective for the researchers working in the field of photocatalysis and oily wastewater treatment.Graphical abstract