title: Photodegradation of emerging micropollutants using the medium-pressure UV/H2O2 Advanced Oxidation Process.
abstract: A medium-pressure (MP) ultraviolet (UV) process has been applied to investigate the direct UV photolysis and UV/H2O2 oxidation of selected model micropollutants (naproxen, carbamazepine, diclofenac, gemfibrozil, ibuprofen, caffeine, 2,4-D, 2,4-DCP, and mecoprop). The quantum yields were found to be between 0.0010 and 0.13 at pH = 7. In the MP UV/H2O2 oxidation, the pseudo first-order rate constants for the selected compounds were found to be dependent on their initial concentrations (at mg/L levels) and on the H2O2 concentration. The UV doses required for 50% and 90% removal at various H2O2 levels varied widely among the compounds tested. Second-order rate constants (ranging from 4.1 × 10(9) to 1.4 × 10(10) M(-1) s(-1)) for the reaction between the selected compounds and hydroxyl radicals were determined using a competition-kinetics approach, where para-chlorobenzoic acid (pCBA) was chosen as the reference compound. Further, as an evaluation of electrical energy efficiency, the Figure-of-Merit, Electrical Energy per Order (EEO) was determined for the selected compounds using a batch reactor at 25 and 50 mg/L H2O2 concentrations. The electrical energy (in kWh) required to reduce a pollutant concentration by 90% ranged from 1.3 to 7.1 kWh m(-3).
authors.affiliation: Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada.
authors.forename: Zengquan
authors.initials: Z
authors.lastname: Shu
authors.forename: James R
authors.initials: JR
authors.lastname: Bolton
authors.forename: Miodrag
authors.initials: M
authors.lastname: Belosevic
authors.forename: Mohamed Gamal
authors.initials: MG
authors.lastname: El Din
mesh_terms: D000416:Alberta; D002110:Caffeine / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D006540:Herbicides / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D010084:Oxidation-Reduction; D004364:Pharmaceutical Preparations / Q000737:chemistry; D010782:Photolysis; D011312:Pressure; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*
chemical_list: D006540:Herbicides; D004364:Pharmaceutical Preparations; D014874:Water Pollutants, Chemical; D002110:Caffeine; D006861:Hydrogen Peroxide