title: Trading oxidation power for efficiency: differential inhibition of photo-generated hydroxyl radicals versus singlet oxygen.
abstract: The ability of reactive oxygen species (ROS) to interact with target pollutants is crucial for efficient water treatment using advanced oxidation processes (AOPs), and inhibition by natural organic matter (NOM) can significantly reduce degradation efficiency. We compare OH-based degradation (H2O2-UV) to (1)O2-based degradation (Rose Bengal) of several probe compounds (furfuryl alcohol, ranitidine, cimetidine) interacting in water containing background constituents likely to be found in treatment water such as natural organic matter (NOM) and phosphate, as well as in effluent from a waste-water treatment plant (WWTP). Hydroxyl radicals were much more susceptible to hindrance by all three background matrices (NOM, phosphate and WWTP effluent) tested, while (1)O2 was only slightly inhibited by NOM and not by phosphate or WWTP effluent. A mechanistic model accounting for this inhibition in terms of radical scavenging and inner filter effects was developed, and accurately simulated the results of the NOM interactions. These results underscore the importance of considering the effect of background constituents in the selection of photocatalysts and in the design of AOPs for emerging applications in tertiary treatment of wastewater effluent and disinfection of natural waters.
authors.affiliation: Rice University, Department of Civil and Environmental Engineering, United States.
authors.forename: Jonathon
authors.initials: J
authors.lastname: Brame
authors.affiliation: Shanghai Jiao Tong University, School of Environmental Science and Engineering, United States.
authors.forename: Mingce
authors.initials: M
authors.lastname: Long
authors.affiliation: Rice University, Department of Civil and Environmental Engineering, United States.
authors.forename: Qilin
authors.initials: Q
authors.lastname: Li
authors.affiliation: Rice University, Department of Civil and Environmental Engineering, United States. Electronic address: alvarez@rice.edu.
authors.forename: Pedro
authors.initials: P
authors.lastname: Alvarez
mesh_terms: D006861:Hydrogen Peroxide / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry*; D008956:Models, Chemical; D009930:Organic Chemicals / Q000737:chemistry; D010084:Oxidation-Reduction; D010782:Photolysis; D012395:Rose Bengal / Q000737:chemistry; D026082:Singlet Oxygen / Q000737:chemistry*; D014466:Ultraviolet Rays; D062065:Wastewater / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D006861:Hydrogen Peroxide; D017665:Hydroxyl Radical; D009930:Organic Chemicals; D012395:Rose Bengal; D026082:Singlet Oxygen; D062065:Wastewater
keywords: Advanced oxidation; Hydroxyl radical; Natural organic matter; Reactive oxygen; Singlet oxygen