Photocatalysis Technology for Treatments of Emerging Organic Pollutants in Water

With the progress of environmental analysis technology, a variety of unexpected organic compounds have been detected in natural water worldwide. Emerging organic pollutants (EOPs) are unregulated water pollutants that may contribute to negative effects on living organisms even though their concentrations are low. Caffeine is one of the EOPs. It is commonly found as a constituent in various consumer products (e.g., coffee, tea, soft drink, and energy drink). The occurrence of caffeine in water bodies is mainly due to routine excretion from humans and incomplete removal from conventional wastewater treatment processes. Photocatalysis technology is gaining interest as an alternative approach for water purification. Organic pollutants can be degraded by the attack of free radicals in which produced from light irradiation on photocatalytic materials. This study aimed to evaluate the efficacy of the photocatalytic process for the degradation of caffeine in water. Titanium dioxide (TiO2) was chosen as a photocatalyst because of its high chemical stability, availability, and safety to the environment. Concentrations of caffeine in water were determined by high-performance liquid chromatography (HPLC). The results showed that TiO2-based photocatalysis is potentially able to remove caffeine from the water. 20 mg/L of caffeine was found to be degraded with efficiencies up to 100% under ultraviolet-C irradiation for 3 h. The degradation rate decreased with increasing caffeine concentration thus more reaction time was required to achieve its complete removal. TiO2 coated circular glass sheet can greatly overcome the separation problem of nanosized-TiO2 from the treated water, and it can be reused for fifteen cycles without a significant loss of its activity.