title: Advanced oxidation of five contaminants in water by UV/TiO2: Reaction kinetics and byproducts identification.
abstract: The extent and kinetics of degradation of 1,4 dioxane, n-nitrosodimethylamine (NDMA), tris-2-chloroethyl phosphate (TCEP), gemfibrozil, and 17β estradiol in a prepared aqueous matrix by means of UV/TiO2 (ultraviolet light/titanium dioxide) oxidation was evaluated. Degussa P25 TiO2 was employed as a photocatalyst excited by UV light in a 1 L water-jacketed batch photoreactor. The rate of degradation was modeled using a pseudo-first order rate model and the Langmuir-Hinshelwood rate model with a high correlation. Degradation rate constants were found to be maximum at pH 5.0 and 1.5 g L(-)(1) TiO2 dose. For these conditions first order rate constants, values were as follows: 0.29 min(-1) for 1,4 dioxane, 0.50 min(-1) for NDMA, 0.12 min(-1) for TCEP, 0.61 min(-1) for gemfibrozil, and 0.53 min(-1) for 17β estradiol. While for the Langmuir-Hinshelwood rate model, the following constants were found: 0.11 Lmg(-1) and 2.81 mgL(-1) min(-1) for 1,4 dioxane, 0.12 Lmg(-1) and 4.35 mgL(-1) min(-1) for NDMA, 0.06 Lmg(-1) and 1.79 mgL(-1) min(-1) for TCEP, 0.21 Lmg(-1) and 3.27 mgL(-1) min(-1) for gemfibrozil, and 0.15 Lmg(-1) and 3.43 mgL(-1) min(-1) for 17β estradiol. In addition, specific byproducts of degradation were identified using GC/MS analysis. The results obtained from the kinetics analysis showed that UV/TiO2 oxidation is a promising process for treating trace organic contaminants in water, but further research is needed to better understand how to incorporate these findings into pilot and full-scale designs. The toxicity of oxidation byproducts, and their potential for interacting with other compounds should be considered in the treatment of contaminated waters using the UV/TiO2 oxidation process.
authors.affiliation: Department of Civil & Environmental Engineering, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA, 01609, USA; Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, MA, USA. Electronic address: jralvarezcorena@wpi.edu.
authors.forename: Jose R
authors.initials: JR
authors.lastname: Alvarez-Corena
authors.affiliation: Department of Civil & Environmental Engineering, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA, 01609, USA. Electronic address: jberg@wpi.edu.
authors.forename: John A
authors.initials: JA
authors.lastname: Bergendahl
authors.affiliation: Department of Civil & Environmental Engineering, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA, 01609, USA. Electronic address: flhart@wpi.edu.
authors.forename: Fred L
authors.initials: FL
authors.lastname: Hart
mesh_terms: D002384:Catalysis; D004128:Dimethylnitrosamine / Q000737:chemistry; D004958:Estradiol / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry; D015248:Gemfibrozil / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010755:Organophosphates / Q000737:chemistry; D010084:Oxidation-Reduction; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*
chemical_list: D010755:Organophosphates; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; C031324:tris(chloroethyl)phosphate; D004958:Estradiol; D014025:Titanium; D004128:Dimethylnitrosamine; D015248:Gemfibrozil
keywords: Advanced oxidation processes; Emerging contaminants; Heterogeneous photocatalysis; Titanium dioxide; Ultraviolet light