Organic photoredox catalysts for wastewater remediation: Beyond the established advanced oxidation processes

Contaminants of emerging concern (CECs) constitute a wide class organic molecules, which are found dissolved in wastewaters. Chemical properties CECs as their chemical structures; nevertheless, most the can be removed from wastewaters using Advanced Oxidation Processes (AOPs). However, there examples that have proven recalcitrant to AOPs. In such cases, Reduction (ARPs) include those techniques able achieve degradation contaminants by producing highly reactive reducing radicals. Organic photocatalysts demonstrated an efficient alternative other types Moreover, several photocatalysts, according redox properties, could also act reductants under appropriate scenarios, process has been much less explored than oxidation. As example, Riboflavin (RF) is natural water-soluble molecule, well-known vitamin B2. The photophysical and RF extensively applied for oxidative photodegradation water. More recently, potential expanded photoreduction more pollutants. For instance, benzotriazoles UV-stabilizers (BUVSs) vast family contaminants, successfully degraded presence commercially available derivative (2′,3′,4′,5′-tetraacetylated riboflavin, RFTA) visible light, assisted amine, acts electron donor excited states RFTA, generating RFTA.−. This species ultimately produces reduction selected BUVSs. Photophysical experiments key role radical anion RFTA.−, allowed determining rate constants were correlated observed photodegradations.