6 research outputs found
Petroleomic analysis of the treatment of naphthenic organics in oil sands process-affected water with buoyant photocatalysts
The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.watres.2018.05.011 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/The persistence of toxicity associated with the soluble naphthenic organic compounds (NOCs) of oil sands process-affected water (OSPW) implies that a treatment solution may be necessary to enable safe return of this water to the environment. Due to recent advances in high-resolution mass spectrometry (HRMS), the majority of the toxicity of OSPW is currently understood to derive from a subset of toxic classes, comprising only a minority of the total NOCs. Herein, oxidative treatment of OSPW with buoyant photocatalysts was evaluated under a petroleomics paradigm: chemical changes across acid-, base- and neutral-extractable organic fractions were tracked throughout the treatment with both positive and negative ion mode electrospray ionization (ESI) Orbitrap MS. Elimination of detected OS+ and NO+ classes of concern in the earliest stages of the treatment, along with preferential degradation of high carbon-numbered O2− acids, suggest that photocatalysis may detoxify OSPW with higher efficiency than previously thought. Application of petroleomic level analysis offers unprecedented insights into the treatment of petroleum impacted water, allowing reaction trends to be followed across multiple fractions and thousands of compounds simultaneously.Natural Sciences and Engineering Research Council of CanadaNSERC Vanier Canada Graduate ScholarshipOntario Graduate Scholarshi
Floating Photocatalysts for Passive Solar Degradation of Naphthenic Acids in Oil Sands Process-Affected Water
Oil sands process-affected water (OSPW), generated from bitumen extraction in the Canadian oil sands, may require treatment to enable safe discharge to receiving watersheds, as dissolved naphthenic acids (NAs) and other acid extractable organics (AEO), identified as the primary toxic components of OSPW, are environmentally persistent and poorly biodegradable. However, conventional advanced oxidation processes (AOPs) are impractically expensive to treat the volumes of OSPW stockpiled in the Athabasca region. Here we prepared floating photocatalysts (FPCs) by immobilizing TiO2 on glass microbubbles, such that the composite particles float at the air-water interface for passive solar photocatalysis. The FPCs were demonstrated to outperform P25 TiO2 nanoparticles in degrading AEO in raw OSPW under natural sunlight and gentle mixing conditions. The FPCs were also found to be recyclable for multiple uses through simple flotation and skimming. This paper thus demonstrates the concept of a fully passive AOP that may be scalable to oil sands water treatment challenges, achieving efficient NA reduction solely through the energy provided by sunlight and natural mixing processes (wind and waves)
Mesoporous Hollow Sphere Titanium Dioxide Photocatalysts through Hydrothermal Silica Etching
Robust, monodisperse, mesoporous titanium dioxide (TiO<sub>2</sub>) submicrometer hollow spheres were synthesized through a
single
step hydrothermal silica etching reaction under mild conditions. Efficient
silica (SiO<sub>2</sub>) removal was achieved without the use of toxic
reagents, and a unique controllable silica redeposition mechanism
was identified, imparting the hollow spheres with excellent structural
integrity. The parameters of the hydrothermal reaction affecting the
etching process, including pH, temperature, and silica concentration,
were systematically investigated and optimized for the production
of silica-templated hollow structures. The resulting processing conditions
yielded TiO<sub>2</sub> hollow spheres with a surface area of ∼300
m<sup>2</sup> g<sup>–1</sup> and anatase phase crystallization,
which exhibited high adsorption capacity for methylene blue dye and
good photocatalytic activity without requiring high-temperature calcination
Photocatalytic Activity of Hydrogenated TiO<sub>2</sub>
Photocatalysis is a promising advanced
water treatment technology, and recently the possibility of using
hydrogenation to improve the photocatalytic efficiency of titanium
dioxide has generated much research interest. Herein we report that
the use of high-temperature hydrogenation to prepare black TiO<sub>2</sub> primarily results in the formation of bulk defects in the
material without affecting its electronic band structure. The hydrogenated
TiO<sub>2</sub> exhibited significantly worse photocatalytic activity
under simulated sunlight compared to the unhydrogenated control, and
thus we propose that high-temperature hydrogenation can be counterproductive
to improving the photocatalytic activity of TiO<sub>2</sub>, because
of its propensity to form bulk vacancy defects