title: Solar photocatalytic degradation of naphthenic acids in oil sands process-affected water.
abstract: Bitumen mining in the Canadian oil sands creates large volumes of oil sands process-affected water (OSPW), the toxicity of which is due in part to naphthenic acids (NAs) and other acid extractable organics (AEO). The objective of this work was to evaluate the potential of solar photocatalysis over TiO2 to remove AEO from OSPW. One day of photocatalytic treatment under natural sunlight (25 MJ/m(2) over ∼14 h daylight) eradicated AEO from raw OSPW, and acute toxicity of the OSPW toward Vibrio fischeri was eliminated. Nearly complete mineralization of organic carbon was achieved within 1-7 day equivalents of sunlight exposure, and degradation was shown to proceed through a superoxide-mediated oxidation pathway. High resolution mass spectrometry (HRMS) analysis of oxidized intermediate compounds indicated preferential degradation of the heavier and more cyclic NAs (higher number of double bond equivalents), which are the most environmentally persistent fractions. The photocatalyst was shown to be recyclable for multiple uses, and thus solar photocatalysis may be a promising "green" advanced oxidation process (AOP) for OSPW treatment.
authors.affiliation: Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada; Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
authors.forename: Tim
authors.initials: T
authors.lastname: Leshuk
authors.affiliation: Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
authors.forename: Timothy
authors.initials: T
authors.lastname: Wong
authors.affiliation: Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada; Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
authors.forename: Stuart
authors.initials: S
authors.lastname: Linley
authors.affiliation: Water Science and Technology Directorate, Environment Canada, 11 Innovation Blvd, Saskatoon, Saskatchewan, S7N 3H5, Canada.
authors.forename: Kerry M
authors.initials: KM
authors.lastname: Peru
authors.affiliation: Water Science and Technology Directorate, Environment Canada, 11 Innovation Blvd, Saskatoon, Saskatchewan, S7N 3H5, Canada.
authors.forename: John V
authors.initials: JV
authors.lastname: Headley
authors.affiliation: Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada; Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada. Electronic address: frank.gu@uwaterloo.ca.
authors.forename: Frank
authors.initials: F
authors.lastname: Gu
mesh_terms: D048908:Aliivibrio fischeri / Q000187:drug effects; D002264:Carboxylic Acids / Q000737:chemistry* / Q000302:isolation & purification* / Q000633:toxicity; D002384:Catalysis; D061329:Oil and Gas Fields; D010782:Photolysis; D013472:Sunlight; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000302:isolation & purification* / Q000633:toxicity; D018508:Water Purification
chemical_list: D002264:Carboxylic Acids; D014874:Water Pollutants, Chemical; C046170:naphthenic acid
keywords: Nanoparticles; Naphthenic acids; Oil sands; Photocatalysis; Titanium dioxide