Hydrogen-based catalyst-assisted advanced oxidation processes to mitigate emerging pharmaceutical contaminants

Abstract

In the past few years, pharmaceutical compounds have appeared as emerging category of environmental pollutants. These microcontaminants can exhibit adverse acute and chronic effects on natural flora and fauna. The detection of pharmaceutical residues in surface waters (rivers, streams, and lakes), seawater, groundwater, soils, sludges, and wastewater treatment plants has been widely documented. Advanced oxidation processes (AOPs) have garnered extensive attention for abetment of emerging pharmaceutical contaminants and minimize their associated environmental risks. Given a clean and efficient oxidizing agent, hydrogen peroxide (H2O2) has been extensively utilized in AOPs. Integration of H2O2 with different substrates/catalysts boosts up its oxidizing features. H2O2 may be combined with ozone, UV, Fe2+/Fe3+ ions (Fenton and photo-Fenton-like processes) and with heterogeneous systems (TiO2). The generation of strong oxidative hydroxyl radical (HO.) in H2O2-assisted AOP by various types of activating methods is likely to play a critical role in micropollutants treatment, reusing, and risk reduction. Advanced oxidation process catalyzed by H2O2 may consists of combination of following catalysts: UV/H2O2, O3/UV/H2O2, H2O2/TiO2/UV, Fe2+/H2O2, Fe2+/H2O2/UV, Electro –Fenton, O3/H2O2). In this review, we have discussed current reports on various hydrogen peroxide-based advanced oxidation processes for degradation of pharmaceutical pollutants of emerging concern. The ongoing challenges, conclusive remarks and imperative future directions are also outlined.