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Aqueous- and solid-phase molybdenum geochemistry of oil sands fluid petroleum coke deposits, Alberta, Canada

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dc.contributor.authorRobertson, Jared M.
dc.contributor.authorNesbitt, Jake A.
dc.contributor.authorLindsay, Matthew B. J.
dc.date.accessioned2022-10-26T16:16:57Z
dc.date.available2022-10-26T16:16:57Z
dc.date.issued2018-11-12
dc.descriptionCopyright © 2018 Elsevier Ltd. All rights reserved.en_US
dc.description.abstractFluid petroleum coke generated at oil sands operations in the Athabasca Oil Sands Region of northern Alberta, Canada, contains elevated concentrations of molybdenum (Mo) and other metals including nickel (Ni) and vanadium (V). Solid-phase Mo concentrations in fluid petroleum coke are typically 10 to 100 times lower than V and Ni, yet dissolved Mo concentrations in associated pore waters are often comparable with these metals. We collected pore water and solids from fluid petroleum coke deposits in the AOSR to examine geochemical controls on Mo mobility. Dissolved Mo concentrations increased with depth below the water table, reaching maxima of 1.4 to 2.2 mg L-1, within a mixing zone between slightly acidic and oxic meteoric water and mildly alkaline and anoxic oil sands process-affected water (OSPW). Dissolved Mo concentrations decreased slightly with depth below the mixing zone. X-ray absorption spectroscopy revealed that Mo(VI) and Mo(IV) species were present in coke solids. The Mo(VI) occurred as tetrahedrally coordinated MoO42- adsorbed via inner- and outer-sphere complexation, and was coordinated in an environment similar to Fe-(hydr)oxide surface complexes. The OSPW likely promoted desorption of outer-sphere Mo(VI) complexes, resulting in higher dissolved Mo concentrations in the mixing zone. The principal Mo(IV) species was MoS2, which originated as a catalyst added upstream of the fluid coking process. Although MoS2 is likely stable under anoxic conditions below the mixing zone, oxidative weathering in the presence of meteoric water may promote long-term Mo release.en_US
dc.description.sponsorshipFunding was provided by the Natural Sciences and Engineering Research Council of Canada (NSERC) and Syncrude Canada Ltd. through the NSERC Industrial Research Chairs program (Grant No. IRCPJ-450684-13). A portion of the research described in this paper was performed at the Canadian Light Source, which is supported by the Canada Foundation for Innovation, NSERC, the University of Saskatchewan, the Government of Saskatchewan, Western Economic Diversification Canada, the National Research Council Canada, and the Canadian Institutes of Health Research.en_US
dc.description.versionPeer Revieweden_US
dc.identifier.citationRobertson, J.M., Nesbitt, J.A. & Lindsay, M.B.J. (2019). Aqueous- and solid-phase molybdenum geochemistry of oil sands fluid petroleum coke deposits, Alberta, Canada. Chemosphere (Oxford), 217: 715–723. https://doi.org/10.1016/j.chemosphere.2018.11.064en_US
dc.identifier.doi10.1016/j.chemosphere.2018.11.064
dc.identifier.urihttps://hdl.handle.net/10388/14271
dc.language.isoenen_US
dc.publisherElsevieren_US
dc.rightsAttribution-NonCommercial-NoDerivs 2.5 Canada*
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/2.5/ca/*
dc.subjectoil sandsen_US
dc.subjectpetroleum cokeen_US
dc.subjectmolybdenumen_US
dc.subjectwateren_US
dc.subjectgeochemistryen_US
dc.subjectX-ray absorption spectroscopyen_US
dc.titleAqueous- and solid-phase molybdenum geochemistry of oil sands fluid petroleum coke deposits, Alberta, Canadaen_US
dc.typeArticleen_US

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