Global prevalence and visible light mediated photodegradation of pharmaceuticals and personal care products (PPCPs)-a review

Abstract

Pharmaceuticals and personal care products (PPCPs) have emerged as environmental contaminants. These materials include diverse group of chemicals such as therapeutic drugs (for human and animals) and household chemicals used by humans mainly to increase the quality of life. PPCPs are characterized by their polar nature with a molecular weight of less than 500 Da, and are either persistent or pseudo-persistent in the environment and display toxicity in bio-organisms. An increase in antibiotic consumption and its subsequent discharge into waterways has resulted in a surge of harmful bacteria which are highly resistant to antibiotics. PPCPs have been detected in surface, ground, drinking water and wastewater treatment plants in USA, Canada, Switzerland, Germany, Australia, and China. These compounds remain unchanged after the biological treatment in the wastewater treatment plants (WWTP) as the microorganisms are inadequate to destroy the PPCPs due to their complex structure. Visible light-mediated advanced oxidation processes (AOPs), including photocatalysis by titanium dioxide (TiO2), and Zinc oxide (ZnO) along with photo- Fenton processes offer an emerging technology for mineralizing PPCPs in water and wastewater. A non-specific oxidant, hydroxyl radical, generated is capable of oxidizing PPCPs to short-chain organic acids, inorganic acids, and CO2 as final products. A focus on the global distribution of PPCPs and ways to remove or mineralize PPCPs using engineered photocatalyst with the operating parameters, strategies, and future perspectives for designing the photocatalysts as well as potential cooperative effects for the photo-Fenton process in degrading PPCPs in water are considered.