Non-aqueous extraction of bitumen from oil sands has the potential to reduce fresh water demand of the extraction process and eliminate tailings ponds. In this study, different light hydrocarbon solvents, including aromatics, cycloalkanes, biologically derived solvents and mixtures of solvents were compared for extraction of bitumen from Alberta oil sands at room temperature and ambient pressure. The solvents are compared based on bitumen recovery, the amount of residual solvent in the extracted oil sands tailings and the content of fine solids in the extracted bitumen. The extraction experiments were carried out in a multistage process with agitation in rotary mixers and vibration sieving. The oil sands tailings were dried under ambient conditions, and their residual solvent contents were measured by a purge and trap system followed by gas chromatography. The elemental compositions of the extraction tailings were measured to calculate bitumen recovery. Supernatants from the extraction tests were centrifuged to separate and measure the contents of fine solid particles. Except for limonene and isoprene, the tested solvents showed good bitumen recoveries of around 95%. The solvent drying rates and residual solvent contents in the extracted oil sands tailings correlated to solvent vapour pressure. The contents of fine solids in the extracted bitumen (supernatant) were below 2.9% for all solvents except n-heptane-rich ones. Based on these findings, cyclohexane is the best candidate solvent for bitumen extraction, with 94.4% bitumen recovery, 5 mg of residual solvent per kilogram of extraction tailings and 1.4 wt% fine solids in the recovered bitumen.

In the present work, molecular dynamics (MD) simulation was applied to study the solubility of two water-insoluble drugs, fenofibrate and nimodipine, in a series of micelle-forming PEO-b-PCL block copolymers with combinations of blocks having different molecular weights. The solubility predictions based on the MD results were then compared with those obtained from solubility experiments and by the commonly used group contribution method (GCM). The results showed that Flory-Huggins interaction parameters computed by the MD simulations are consistent with the solubility data of the drug/PEO-b-PCL systems, whereas those calculated by the GCM significantly deviate from the experimental observation. We have also accounted for the possibility of drug solubilization in the PEO block of PEO-b-PCL.

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An increase in the degree of chemical compatibility between drug and polymeric structure in the core has been shown to raise the encapsulation efficiency and lower the rate of drug release from polymeric micelles. In this study, to achieve an optimized polymeric micellar delivery system for the solubilization and controlled delivery of cucurbitacin I (CuI), the Flory-Huggins interaction parameter (chi(sc)) between CuI and poly(epsilon-caprolactone) (PCL), poly(alpha-benzylcarboxylate-epsilon-caprolactone) (PBCL) and poly(alpha-cholesteryl carboxylate-epsilon-caprolactone) (PChCL) structures was calculated by group contribution method (GCM) as an indication for the degree of chemical compatibility between different micellar core structures and CuI. The results pointed to a better compatibility between CuI and PChCL core rationalizing the synthesis of self-associating methoxy poly(ethylene oxide)-b-poly(alpha-cholesteryl carboxylate-epsilon-caprolactone) block copolymer (MePEO-b-PChCL). Novel block copolymer of MePEO-b-PChCL was synthesized through, first, preparation of substituted monomer, that is, alpha-cholesteryl carboxylate-epsilon-caprolactone, and further ring opening polymerization of this monomer by methoxy PEO (5000 g mol(-1)) using stannous octoate as catalyst. Synthesized block copolymers were characterized for their molecular weight and polydispersity by (1)H NMR and gel permeation chromatography. Self-assembled MePEO-b-PChCL micelles were characterized for their size, morphology, critical micellar concentration (CMC), capacity for the physical encapsulation of CuI, and mode of CuI release in comparison to MePEO-b-PCL and MePEO-b-PBCL micelles. Overall, the experimental order for the level of CuI encapsulation in different polymeric micellar formulations was consistent with what was predicted by the Flory-Huggins interaction parameter. Although MePEO-b-PChCL micelles exhibited the highest level of CuI loading, this structure did not show any significant superiority over MePEO-b-PCL in controlling CuI release. The most efficient control over the rate of CuI release was achieved by MePEO-b-PBCL micelles that had more viscous cores than that of MePEO-b-PChCL, instead. The results point to a potential for MePEO-b-PChCL micelles for the solubilization of cholesterol compatible drugs. It also highlights the inadequacy of the Flory-Huggins interaction parameter calculated by GCM in predicting the order of drug release from different polymeric micellar structures.

The extraction of bitumen from the oilsands using solvents has the potential to avoid the environmental problems with wet tailings associated with water-based extraction technology. One of the key performance parameters for this technology is the concentration of fine solids in the recovered bitumen. In this study, the concentration and properties of the fine solids in cyclohexane-extracted bitumen were examined as a function of the water content of the ore. Total water contents from 3.4–13.4 wt % gave the lowest concentrations of fine solids in the bitumen, ca. 0.2 wt % of the initial mass of a low-fines content ore. Higher fine solids contents in the bitumen were observed with water concentrations outside this range and with higher concentrations of fine solids in the initial oilsands ore. The fine solids exhibited a distribution of surface properties, and the most hydrophobic, carbon rich solids were carried into the bitumen even under the most favorable conditions. When the bitumen was more contaminated with fine solids, due to higher fines in the ore or lack of water to bind the fines to the sand, the carbon content of the fine solids decreased. The majority of the carbon in the fine solids was organic material due to bitumen and surface adsorbed components. Despite carbon contents over 20 wt %, XPS analysis showed significant surface silicon and aluminum, and contact angles were in the range of 80–88°, consistent with partial organic coating of the mineral particles. Characterization of the fine solids by SEM, particle size, and mineralogy suggested that the migration of the fine solids into the bitumen, versus remaining with the coarse sand, was significantly affected by the organic surface deposits on the particles.