Open AccessCan the toxicity of naphthenic acids in oil sands process-affected water be mitigated by a green photocatalytic method?
Author(s) -
Barry N. Madison,
Jessie S. Reynolds,
Lauren Halliwell,
Tim Leshuk,
Frank Gu,
Kerry M. Peru,
John V. Headley,
Diane M. Orihel
Publication year - 2020
Publication title -
facets
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 9
ISSN - 2371-1671
DOI - 10.1139/facets-2019-0053
Subject(s) - photocatalysis , toxicity , oil sands , pimephales promelas , mineralization (soil science) , environmental chemistry , naphthenic acid , chronic toxicity , bioassay , chemistry , acute toxicity , light intensity , pulp and paper industry , nuclear chemistry , minnow , materials science , biology , organic chemistry , ecology , fish <actinopterygii> , fishery , catalysis , corrosion , physics , asphalt , nitrogen , optics , composite material , engineering
Our study evaluates the efficacy of a “green” (i.e., sustainable, recyclable, and reusable) technology to treat waste waters produced by Canada’s oil sands industry. We examined the ability of a novel advanced oxidative method—ultra-violet photocatalysis over titanium dioxide (TiO 2 )-coated microparticles—to reduce the toxicity of naphthenic acid fraction components (NAFC) to early life stages of the fathead minnow ( Pimephales promelas). Lengthening the duration of photocatalysis resulted in greater removal of NAFC from bioassay exposure waters; low- and high-intensity treatments reduced NAFC concentrations to about 20 and 3 mg/L (by Fourier-transformed infrared spectroscopy, FTIR), respectively. Treatments reduced the acute lethality of NAFC to fathead minnows by over half after low-intensity treatment and three-fold after high-intensity treatment. However, incomplete degradation in low-intensity treatments increased the incidence of chronic toxicity relative to untreated NAFC solutions and cardiovascular abnormalities were common even with >80% of NAFC degraded. Our findings demonstrate that photocatalysis over TiO 2 microparticles is a promising method for mitigating the toxicity of oil sands process-affected water-derived NAFC to fish native to the oil sands region, but the intensity of the photocatalytic treatment needs to be considered carefully to ensure adequate mineralization of toxic constituents.