title: Effect of molecular structure on the relative reactivity of naphthenic acids in the UV/H₂O₂ advanced oxidation process.
abstract: The large volume of oil sands process-affected water (OSPW) produced by the oil sands industry in Northern Alberta, Canada, is an environmental concern. The toxicity of OSPW has been attributed to a complex mixture of naturally occurring acids, including naphthenic acids (NAs). Highly cyclic or branched NAs are highly biopersistent in tailings ponds, thus understanding structure-reactivity relationship for NAs is very important for OSPW reclamation. In this study, we hypothesized that large, branched and cyclic NAs may be better oxidized in the UV/H(2)O(2) process than small, linear and acyclic NAs. Relative rate measurements using binary mixtures of model NA compounds confirmed that reactivity favored compounds with more carbons, and also favored NAs with one saturated ring, relative to the corresponding linear NA. However, for model compound with three rings, no increased reactivity was observed relative to monocyclic NA. UV/H(2)O(2) treatment of OSPW confirmed our findings with model compounds, indicating that the compounds with more carbons are favored for degradation. However, increasing the number of rings (or double bond equivalents) in OSPW NAs did not show any clear structure-reactivity. Microbial degradation studies of the UV/H(2)O(2) treated OSPW should be conducted to examine the overall benefit of this treatment for the real applications.
authors.affiliation: Department of Civil and Environmental Engineering, 3-133 Markin/CNRL Natural Resources Engineering Facility, University of Alberta, Edmonton, AB, T6G 2W2, Canada.
authors.forename: Atefeh
authors.initials: A
authors.lastname: Afzal
authors.forename: Przemysław
authors.initials: P
authors.lastname: Drzewicz
authors.forename: Leónidas A
authors.initials: LA
authors.lastname: Pérez-Estrada
authors.forename: Yuan
authors.initials: Y
authors.lastname: Chen
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Martin
authors.forename: Mohamed
authors.initials: M
authors.lastname: Gamal El-Din
mesh_terms: D001673:Biodegradation, Environmental; D002264:Carboxylic Acids / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry; D015394:Molecular Structure; D061329:Oil and Gas Fields; D010084:Oxidation-Reduction; D013329:Structure-Activity Relationship; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D002264:Carboxylic Acids; D014874:Water Pollutants, Chemical; D006861:Hydrogen Peroxide; C046170:naphthenic acid