<p>In general, the research focuses on sequestration of naphthenic acids (NAs) from simulated oil sands process water (OSPW) conditions using engineered copolymers known as &beta;-cyclodextrin-based polyurethanes. The thesis research is divided into two main parts; <i>i)</i> synthesis and characterization of &beta;-cyclodextrin-based polyurethanes, and <i>ii)</i> sorption studies of the copolymer materials with NAs from aqueous solutions.</p> <o>In the first part, &beta;-cyclodextrin (&beta;-CD) was crosslinked with five types of linker molecules, respectively, under various synthetic conditions. The various diisocyanates investigated as linkers include the following: 1,6-hexamethylene diisocyanate (HDI), 4,4'-dicyclohexylmethane diisocyanate (CDI), 4,4'-diphenylmethane diisocyanate (MDI), 1,4-phenylene diisocyanate (PDI) and 1,5-naphthalene diisocyanate (NDI). The polyurethanes (PUs) were systematically designed at different mole ratios of monomers by maintaining &beta;-CD and varying the relative mole ratio of diisocyanate monomer from unity to greater values. Diffuse Reflectance Infrared Fourier Transform spectroscopy (DRIFTS), solid state ¹³C CP-MAS NMR, solution state ¹H/¹³C NMR spectroscopy, thermogravimetric analysis (TGA), elemental analysis (CHN), nitrogen porosimetry, and a dye-based (p-nitrophenol; PNP, and phenolphthalein; phth) sorption method were used to characterize the copolymer materials. In general, the &beta;-CD PUs were insoluble in water except for &beta;-CD crosslinked with HDI at the 1:1 mole ratio which was moderately water soluble. All techniques show complementary results about the structural and compositional characterization, particularly for the estimation of the ratios between the co-monomers. The optimal preparation of copolymer materials for sorption-based applications occurs for &beta;-CD/linker monomer mole ratios from 1:1 to 1:3. There is a maximum limit of the crosslinking density which is ~ 1:7 (&beta;-CD:linker) according to the steric effects of the substituents in the annular region of &beta;-CD. Also, the copolymers were generally found to be mesoporous with relatively low surface area (BET; ~10¹ m²/g) and they appear to exhibit swelling in aqueous solution due to hydration as observed from the estimation of the dye-based surface areas using PNP. The surface accessibilities of the &beta;-CD inclusion sites ranged between 1-100%, as evidenced by the decolourization of phenolphthalein (phth) due to the formation of 1:1 &beta;-CD/phth inclusion complexes.</p> <p>In the second part, the inclusion of NAs and its surrogates with three well known types of cyclodextrin (&alpha;-, &beta;-, and &gamma;-CD) was confirmed using negative ion mode electrospray ionization (ESI). The CDs were found to form well-defined 1:1 inclusion complexes. The binding constant (K2) of NAs and its surrogates inclusion with &beta;-CD was determined indirectly using the spectral displacement technique and were found to be 10³-10⁴ M^-1 (surrogates) and ~ 10⁴ M^-1 (NAs), respectively. Furthermore, the binding constants were found to increase with an increase of the lipophilic surface area (LSA) of the surrogates. The sorption results of NAs with three different types of &beta;-CD materials (i.e. &beta;-CD PU, &beta;-CD crosslinked with epichlorohydrin (EP) and a silica-based mesoporous material containing &beta;-CD), showed &beta;-CD PU had a greater affinity. The sorption capacity (~ 0 - 75.5 mg NAs/g copolymer) and binding affinity (~10³ - 10⁴ M^-1) of &beta;-CD PUs varied due to the nature of linker monomer and the mole ratio of the co-monomers. Aromatic-based copolymers showed high sorption binding affinity while aliphatic-based copolymers showed a relatively high sorption capacity at the co-monomer ratio. Finally, Syncrude-Derived NAs showed fluorescent characteristics which contradict the classic definition of NAs. Further studies using UV-Vis and fluorescence emission spectroscopy showed potential development of an analytical method that can be used to quantify NAs in OSPW for <i>in-situ</i> field applications.

The adsorption characteristics of an oil sands tailings water (OSTW) mixture of naphthenic acids were determined using a batch partitioning method for two soils from the Alberta oil sands region. The soils were mineral peat mixtures produced during salvage operations, with Soil 1 having a higher organic carbon fraction (foc) than Soil 2. Naphthenic acids are a significant toxic byproduct of bitumen extraction, and are acutely toxic to aquatic organisms. The sorption of naphthenic acids as affected by a high ionic strength solution was examined using a synthetic groundwater (SGW) mixture.<p>The adsorption isotherms were found to be linear in all cases. All tests were conducted at 4oC, and at a pH of 8.0 ± 0.4, reflective of the conditions in a tailings settling facility near Fort McMurray, AB. The adsorption characteristics of the naphthenic acids in the SGW solution were compared to that of the mixture in Milli-Q water for the two soils. In the presence of SGW, the adsorption coefficient (Kd) for the mixture of naphthenic acids on Soil 1 was an order of magnitude higher than that observed with the same soil and the Milli-Q water mixture, increasing from 1.9 ± 0.2 mL/g to 17.8 ± 1.5 mL/g. The adsorption coefficient for the mixture of naphthenic acids on Soil 2 was also observably higher in the SGW mixture, increasing from 1.3 ± 0.15 mL/g to 3.7 ± 0.2 mL/g. In order to determine whether preferential sorption is exhibited by a particular species within the mixture, the relative fractional abundance of the individual naphthenic acids was plotted as a 3-dimensional histogram for carbon numbers 5 to 37. It was found that for all Z families (where Z is a measure of the number of carbon ring structures), naphthenic acids within the middle range of carbon numbers showed preferential sorption. A two sample t-test confirmed that the naphthenic acids in the carbon number groupings 15 to 24 and 25 to 37 sorbed significantly in the SGW mixture when compared to those in the carbon number grouping of 5 to 14. It was concluded that select constituents of oil sands naphthenic acids mixtures sorb strongly to soil under conditions of elevated salinity and therefore adsorption could be an important attenuating mechanism in groundwater transport. Furthermore, preferential sorption of the individual naphthenic acids is important with respect to toxicity since lower molecular weight naphthenic acids are believed to have a more pronounced toxic effect. Overall, the measured adsorption coefficients indicate that there can be significant sorption of OSTW derived naphthenic acids to soils.

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Oil sands companies produce substantial quantities of tailings known to contain high concentrations of dissolved organic by-products. The use of petroleum coke was proposed as a potential adsorbent for organic contaminant removal from tailings pond water. Physical activation was used to create a greater surface area and porosity within the delayed and fluid coke. Increased temperature (900oC), steam rate (0.5 mL/min), and activated time (6 h) led to high iodine numbers of 670 and 620 mg/g for activated delayed and fluid cokes, respectively. For both best activated cokes, the micropore to mesopore ratio was approximately 50:50. When 5 g/L of activated delayed and fluid cokes were added to the tailings water, 91% of the dissolved organic carbon and 92% of the naphthenic acids were removed. Such analyses indicate that an oil sands waste by-product can be used to treat tailings pond water to remove toxic and corrosive organic contaminants. / Geoenvironmental Engineering

Thesis (M.Sc.)--University of Alberta, 2010. / Title from PDF file main screen (viewed on July 2, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Food Science and Technology, Department of Agricultural, Food, and Nutritional Science, University of Alberta Includes bibliographical references.

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Extraction of bitumen from Alberta oil sands produces 2 to 4 barrels of aqueous tailings per barrel of crude oil. Oil sands process water (OSPW) contains naphthenic acids (NAs), a complex mixture of carboxylic acids of the form CnH2n+ZOx that are persistent and toxic to aquatic organisms. Previous studies have demonstrated that aerobic biodegradation reduces NA concentrations and OSPW toxicity; however, treatment times are long. The objective of this study was to evaluate the feasibility of an immobilized soil bioreactor (ISBR) for treatment of NAs in OSPW and to determine the role of ammonium and ammonium oxidizing bacteria (AOB) in NA removal. ISBRs have been used to successfully remediate water contaminated with pollutants such as pentachlorophenol and petroleum hydrocarbons. A system of two ISBRs was operated continuously for over 2 years with OSPW as the sole source of carbon. Removal levels of 30-40% were consistently achieved at a residence time of 7 days, a significant improvement compared to half-lives of 44 to 240 days reported in the literature. However, similar to biodegradation experiments in the literature, a significant portion (~60%) of the NAs was not degraded. The role of AOB in NA removal was investigated by decreasing ammonium concentration and inhibiting AOB activity with allylthiourea, neither of which significantly affected removal, indicating that AOB did not enhance NA removal. Furthermore, high AOB populations actually inhibited the removal of a simple NA surrogate. Therefore, a moderate ammonium concentration of 0.3 g/L is recommended. NA degradation occurred with nitrate as the sole nitrogen source, however, removal levels were lower than those achieved with ammonium. Exploratory studies involving ozonation or biostimulation were conducted with the aim of increasing NA removal. Ozonation decreased NA concentration by 94% and total organic carbon (TOC) by 6%. Subsequent ISBR treatment removed ~30% of the remaining TOC. Addition of a NA surrogate increased heterotrophic NA-degrading populations due to the increase in available carbon, resulting in a significant increase in NA removal levels. However, use of a surrogate may result in a population that is only adapted to degradation of the NA surrogate. / Thesis (Master, Chemical Engineering) -- Queen's University, 2013-06-20 14:53:47.498

A plume of process-affected groundwater was identified in a shallow sand aquifer adjacent to a tailings impoundment at Syncrude Canada Ltd. Quantitative and qualitative Naphthenic Acid (NA) analyses were performed on groundwater samples to investigate NA fate and transport properties in the subsurface. Analysis of dissolved organic and inorganic components was undertaken to identify, quantify and assess the mobility of other dissolved components of environmental significance. NAs at concentrations up to 87 mg/L were found to represent the major contributor to aquatic toxicity. Attenuation of NAs by biodegradation is not observed based on screening techniques developed to date. Retardation of NAs observed at the field scale, is consistent with weak sorption observed in the laboratory by other authors. Concentrations of ammonium approached 4 mg/L in the plume, however mobility is limited by cation exchange. Aromatics and trace metals are present in low quantities (i. e. <10 ??g/L) and are only detected in groundwater immediately adjacent to the toe of the tailings impoundment. Cl and Na are found at concentrations of up 282 and 579 mg/L respectively. Dissolved oxygen is typically < 1 mg/L within the plume, while redox indicators Mn(II), Fe(II) and methane are detected between <0. 1 - 2. 6, 0. 2 - 3. 5 and <0. 1 - 2. 1 mg/L respectively within the plume. Solid phase geochemistry, determined through solid phase extractions, was coupled with aqueous geochemistry and reactive transport modeling to identify the dominant geochemical processes occurring within the plume. Based on scenarios evaluated using reactive transport modeling, the most likely origin for the presently observed, weakly reducing conditions in the plume appears to be the presence of a small amount of disssolved, degradable organic carbon. The dominant terminal electron acceptors appear to be Fe(III) and Mn(III/IV) in the plume core and dissolved oxygen at the plume fringe. Dissolved Fe and Mn are observed to enter the domain at the upgradient boundary at maximal concentrations of 4. 2 and 0. 7 mg/L respectively. Trace metal geochemistry of the aquifer material was also assessed using solid phase extractions. The potential for trace metal release via reductive dissolution of the native geologic material is considered minimal in this case, based on the weakly reducing nature of the plume and a lack of excessive trace metal content in the aquifer material.

Oil sands operators are being faced with the challenge of reclaiming the large volumes of slurry tailings created during oil sands processing. New regulations mandate that operators must minimize fluid tailings by capturing fines in dedicated disposal areas, leading to a ‘trafficable’ or solid deposit. Adding a polyacrylamide polymer to the tailings and thinly spreading them over a sloped disposal area (a process developed by Shell Canada Energy known as the atmospheric fines drying or AFD process) has been shown to enhance the dewatering of tailings which leads to a dry deposit at a much faster rate than traditional methods. Hydroponic experiments using the emergent aquatic macrophytes cattail (Typha latifolia L.) and common reed (Phragmites australis (Cav.) Trin. ex Steud.) were conducted to investigate the phytotoxicity of waters formed during AFD processing. The phytotoxicity of AFD release waters was compared to the phytotoxicity of traditional mature fine tailings (MFT) reclaim water through the monitoring of plant water uptake and whole plant fresh weight over the course of the experiment. It was found that there are no significant differences between the phytotoxicity observed in the MFT and AFD treatments and it was also found that spring runoff melt water from the AFD deposits is less phytotoxic than the original release water. Two additional hydroponic studies using cattail and common reed were also conducted. The first examined the phytotoxic effects attributable solely to the naphthenic acids isolated from Shell’s Muskeg River Mine tailings, and the second evaluated the phytotoxic effects of amending mature fine tailings with gypsum. It was found that the gypsum amended tailings caused greater phytotoxicity in cattail and common reed than tailings without gypsum added. Furthermore, both species were tolerant to growing in nutrient media spiked with naphthenic acids (40 mg/L). The phytotoxicity experiments conducted also demonstrated that common reed is consistently more tolerant to growing in water associated with oil sands tailings and is therefore the more appropriate choice for use in reclamation strategies involving wetland plants. Mass spectrometry was used to determine the naphthenic acid molecular profiles for Shell oil sands tailings. Using low resolution mass spectrometry, no detectable features or changes to the composition of naphthenic acids attributable to Shell processing were found. High-resolution mass spectrometry provided insight into possible plant mediated changes and biodegradation of naphthenic acids. It appears as though, to some extent, cattail is able to dissipate naphthenic acids, which could explain the susceptibility of cattail to the phytotoxic effects of naphthenic acids. Further research is required to determine whether the changes observed in the naphthenic acid mixture are due to microbial degradation and/or a phytotoxic response of the plants studied.