Surface minable oil sands are a significant source of heavy oil (bitumen) production in Canada. Supercritical fluid extraction (SFE) provides a potential means to recover bitumen, a complex mixture of hydrocarbons, from process and process waste streams generated during the extraction and processing of bitumen from surface mined oil sands. Dynamic extractions were conducted to determine the effect of two modifiers, toluene and methanol, on the extraction of hydrocarbons from bitumen using carbon dioxide (CO2) at supercritical conditions of 24 MPa and 333 K. Toluene was tested at concentrations of 5, 10 and 15 mol% whereas methanol was tested at these concentrations plus at 33.7 mol% in supercritical CO2 (SC-CO2). High temperature simulated distillation (HTSD) was used to determine the distillation profile of the extracted hydrocarbons. SC-CO2 only extracted 39 wt% of the bitumen while a methanol concentration of 33.7 mol% in SC-CO2 extracted 55 wt% and 15 mol% toluene in SC-CO2 extracted 76 wt% of the bitumen. Higher modifier concentrations lead to increased extraction efficiencies. Toluene consistently extracted more hydrocarbons than methanol. The hydrocarbons extracted when toluene was used as a modifier were consistently the heaviest hydrocarbon mixtures, with higher toluene concentrations increasing this compositional effect. (C) 2019 Elsevier B.V. All rights reserved.

Supercritical fluid extraction (SFE) has the potential to recover compounds from a range of solid matrices if a fully continuous process can be commercialized. This paper presents the development of a hydrodynamic model for a continuous pilot scale SFE process, involving countercurrent flow of a slurry and a supercritical fluid. The model developed is based on first principles and focuses on predicting pressure and slurry level within the extraction vessel. The model was validated using pilot scale system data. Using adjusted parameters, the model accurately predicted steady state pressure and provided a good estimate of slurry level.

Malaria is a high priority life‐threatening public health concern in developing countries, and therefore there is a growing interest to obtain artemisinin for the production of artemisinin‐based combination therapy products. In this study, artemisinin was extracted from the Artemisia annua L. plant using supercritical carbon dioxide (SC‐CO2) modified with ethanol. Response surface methodology based on central composite rotatable design was employed to investigate and optimize the extraction conditions of pressure (9.9–30 MPa), temperature (33–67°C), and co‐solvent (ethanol, 0–12.6 wt.%). Optimum SC‐CO2 extraction conditions were found to be 30 MPa and 33°C without ethanol. Under optimized conditions, the predicted artemisinin yield was 1.09% whereas the experimental value was 0.71 ± 0.07%. Soxhlet extraction with hexane resulted in higher artemisinin yields and there was no significant difference in the purity of the extracts obtained with SC‐CO2 and Soxhlet extractions. Results indicated that SC‐CO2 and SC‐CO2+ethanol extraction is a promising alternative for the extraction of artemisinin to eliminate the use of organic solvents, such as hexane, and produce extracts that can be used for the production of antimalarial products.

This work is a case study on the development of a supercritical fluid extraction (SFE) process that began over twenty years ago as part of curiosity driven research and a desire to treat contaminated soils using supercritical fluids. Early work explored the measurement of fundamental thermodynamic and mass transfer properties. Commercialization was a faint long term hope but the relatively low value of the compounds found in contaminated soils (and many wastes), coupled with the typically large volumes, lead to the recognition that a batch or semi-batch SFE process was unlikely to be viable. This lead to the judgement that slurrying the soil was likely a necessary path to success. Research then focused on the impact of water on both thermodynamic and mass transfer behaviour. Ultimately, this drove the development and demonstration of the first, bench-scale, fully-continuous treatment process using slurries. In parallel, an experimental program was studying the effectiveness of SFE for the treatment of upstream oil and gas industry waste. Timing and supportive industrial sponsors provided the opportunity to design, build, and demonstrate a pilot-scale, fully-continuous system for the treatment of multiple waste streams. The system has proved successful following many challenges and several years of work. Tools to model system performance, explore scale-up design and assess economic and environmental impacts have also been developed and continue to be refined. The net result of the experimental and modelling success is a compelling case for commercial application of the technology for the recovery of hydrocarbons from at least one waste stream. The economics offers a net savings to the waste generator, while remaining profitable as a processing facility. Environmentally, the application leads to a net reduction in greenhouse gas emissions and converts valuable materials in waste streams to products.

Intensive operations are required to recover bitumen from oil sands and as a result, process waste streams containing bitumen are generated. Experiments have been conducted to determine the effects of modifiers on the extraction of bitumen using supercritical carbon dioxide (SC-CO2). The data will aid the development and demonstration of a supercritical fluid extraction (SFE) process for bitumen recovery from oil sands process waste streams. Two modifiers, toluene and methanol, have been tested in a bench-scale SFE system at a constant pressure of 24 MPa and temperature of 333 K. Bitumen was added to an extraction vessel and a dynamic extraction was initiated in the presence of a modifier at a concentration of 5, 10 or 15 mol%. Samples of extracted bitumen were collected in two separation vials in series every 5 to 15 minutes. The amount of bitumen extracted was determined from both the amount of bitumen collected in the separation vials and from the amount of bitumen remaining in the extraction vessel. The quality of the bitumen was also investigated by high temperature simulated distillation (HTSD). Results show that, without the addition of a modifier, SC-CO2 extracts 40 wt% of the original bitumen. Increasing the concentration of a modifier (to 5, 10 or 15 mol%) in SC-CO2 results in an increase in the percentage of bitumen extracted for any given CO2 to bitumen ratio. At 15 mol%, toluene is capable of extracting 76 wt% of the original bitumen, a 93% increase from SC-CO2 alone. Compared to the same concentration of methanol, 5 mol% toluene extracts 9 wt% more bitumen. HTSD results show that toluene addition results in heavier bitumen extracts compared to an equivalent molar concentration of methanol or SC-CO2 alone.

Pressure control for a pilot scale continuous supercritical fluid extraction (SFE) process, has been developed for consistent extractions, overall efficiency and process safety reasons. The Internal-Model-Control (IMC) framework (specifically Skogestad's IMC method) was employed for the design of a Proportional-Integral (PI) controller using both the actual pilot process and a hydrodynamic model of the process. Controller performance was assessed for set point changes and disturbance rejection. The best controllers lead to limited overshoot (less than 1 MPa), a response time of 200 s (within +/- 1% of set point) and little oscillatory behaviour. The design and performance results of the controllers generated using the hydrodynamic model were consistent with those of the actual process. Tests at alternate pressure conditions confirmed that the controller design and performance is pressure dependent owing to the nonlinear character of SFE processes.

The oil sands industry is seeking innovative technologies to address the water intensity and the high-energy consumption associated with current oil sands processing technologies. This research therefore investigates the use of supercritical fluid extraction (SFE) as an alternative to the current water-based extraction technology, Bitumen, a complex mixture of hydrocarbons, was extracted from an Athabasca oil sand slurry using supercritical carbon dioxide (SC-CO2). Preliminary experiments revealed the importance of a higher mixing speed and a longer static time on hydrocarbon yields. In a second set of experiments, when toluene was introduced as a modifier, a higher SC-CO2 density (i.e. high pressure, low temperature) led to higher extraction yields. In the absence of toluene, higher temperature conditions (i.e. lower SC-CO2 density) provided higher extraction yields suggesting desorption resistant hydrocarbon components in the oil sand matrix slurry are released as a result of increasing temperature. Using gas chromatography-flame ionization detector (GC-FID), the experiment that produced the highest cumulative hydrocarbon extraction yield was analyzed for product quality and the extracted hydrocarbons were observed to center on C-25. (C) 2015 Elsevier B.V. All rights reserved.

A review of the literature from 2014 related to automotive wastes is presented. Topics include solid wastes from autobodies and tires as well as vehicle emissions to soil and air as a result of the use of conventional and alternative fuels. Potential toxicological and health risks related to automotive wastes are also discussed.

A review of the literature from 2013 related to automotive wastes is presented. Topics include solid wastes from autobodies and tires, and vehicle emissions to soil and air as a result of the use of conventional and alternative fuels. Potential toxicological and health risks related to automotive wastes are also discussed.

Lycopene and β-carotene were extracted from freeze-dried tomatoes (skin+pulp) with pure SC CO2 and SC CO2+5% w/w co-solvent at 40°C, 400bar and flow rates of 0.5 and 1.2L/min. The apparent solubility of lycopene and β-carotene in the multicomponent complex system was determined from dynamic extraction experiments using a laboratory-scale supercritical extraction system. Solubility of pure lycopene and β-carotene in SC CO2 (binary system) was reported in the literature to be of the order of 10−6 mole fraction. The apparent solubility of lycopene extracted from tomatoes with SC CO2 (multicomponent complex system) under the same conditions was almost one order of magnitude smaller. The apparent solubility obtained using oil as a co-solvent was higher than that obtained with ethanol as a co-solvent or pure SC CO2. The differences in solubility are mainly due to the polarity of the co-solvent and the impact of the tomato matrix in the multicomponent complex system.

Hydrocarbon-contaminated soil and groundwater at oil and gas production sites may be additionally impacted by salts due to release of produced waters. However, little is known about the effect of salt on the in-situ biodegradation of hydrocarbons by terrestrial microbes, especially at low temperatures. To study this effect, we prepared a groundwater-soil slurry from two sites in Canada: a former flare pit site contaminated with flare pit residue (Site A), and a natural gas processing facility contaminated with natural gas condensate (Site B). The slurry with its indigenous microbes was amended with radiolabeled hydrocarbons dissolved in free product plus nutrients and/or NaCl, and incubated in aerobic biometer flasks with gyrotory shaking at either 25 or 10°C for up to 5 weeks. Cumulative production of 14CO2 was measured and the lag time, rate and extent of mineralization were calculated. For Site A, concentrations of NaCl ≥1% (w/v) delayed the onset of mineralization of both 14C-hexadecane and 14C-phenanthrene under nutrient-amended conditions, but once biodegradation began the degradation rates were similar over the range of salt concentrations tested (0–5% NaCl). For Site B, increasing concentrations of NaCl ≥1% (w/v) increased the lag time and decreased the rate and extent of mineralization of aliphatic and aromatic substrates. Of particular interest is the observation that low concentrations of salt (≤1% NaCl) slightly stimulated mineralization in some cases.

New vapor pressure data for phenolic compounds (caffeic acid, ferulic acid, and p- and o-coumaric acids) were experimentally obtained and compared to values predicted by a group contribution method. A gas–liquid chromatography method was used to experimentally determine the vapor pressure since this method is reliable, reproducible and rapid. These vapor pressure data were then used to predict second cross virial coefficients of phenolic compounds in supercritical carbon dioxide (SC CO2) using a method based on the residual chemical potential in terms of the virial coefficients and fluctuation theory. The solubility results obtained by this method were compared to those from two other correlations based on the regular solution theory and Chrastil equation. Good agreement was obtained with the correlations when compared to the experimental literature data on the solubility of phenolic compounds in SC CO2.

Naphthenic acids (general formula C(n)H(2n+Z)O(2)) are water-soluble, toxic compounds found in petroleum and bitumen. Some of the current methods for detecting these acids in waters depend on measuring the presence of the carboxylic acid functional group, and therefore many of these methods also detect naturally occurring carboxylic acids that are not naphthenic acids. We report a procedure that includes liquid-liquid extraction, cleanup, and derivatization to form t-butyldimethylsilyl esters prior to gas chromatography-mass spectrometry (GC-MS) analysis. Using low- and high-resolution MS to detect the ion C(15)H(27)O(2)Si(+) (nominal m/z=267) is an excellent indicator of the presence of naphthenic acids at concentrations > or =10microgL(-1).

Carotenoids such as β-carotene are gaining interest in the food industry due to their nutritional and antioxidant properties. Understanding the solubility behavior of carotenoids in supercritical CO2 (SC CO2) is fundamental for any industrial supercritical process application and design. Solubility of β-carotene was measured in both a binary and a multicomponent complex system. Solubility of β-carotene in the binary system was measured using a quartz crystal microbalance technique at temperatures of 40 and 50°C and pressures ranging from 120 to 200bar. Solubility of β-carotene in the multicomponent complex system was determined from dynamic extraction experiments using a laboratory-scale supercritical extraction system. Carotenoids were extracted from freeze-dried carrots with SC CO2 at temperatures of 40 and 50°C and pressures ranging from 120 to 327bar. β-Carotene solubility values for the binary system measured herein and reported in the literature are of the order of 10−7 mole fraction while the solubility values for the multicomponent complex system (β-carotene extracted from carrots with SC CO2) under the same conditions are 5–10 times smaller. Solubility in both systems increased with temperature and pressure. The difference in the solubility values obtained using both systems is mainly due to the matrix effects of the multicomponent complex system such as the cell structure and the interactions of β-carotene with other components such as carbohydrates in the carrot matrix.

At the EkatiTM diamond mine, located 300 km northeast of Yellowknife, wastewater consisting of sewage from the housing facility, flow from the vehicle washing bay and wastewater from neighbouring worksites was previously collected, treated and discharged into a local lake. The discharge was observed to have negative impacts on the lake which included an increased algae growth and lowered dissolved oxygen levels in the lower portion of the lake as early as 1997. Part of the cause of this impact was believed to be increased phosphorus concentrations in the lake originating from the treated wastewater discharge. There was concern that the increased phosphorus levels may affect downstream lakes, in the form of eutrophication and decreased winter dissolved oxygen concentrations. To minimize the impact, BHP Diamonds Inc. relocated the discharge of treated wastewater to its processed kimberlite containment system. The purpose of this study was to understand the fete of phosphorus in the treated wastewater when added to the processed kimberlite containment area. The study involved conducting laboratory investigations to develop adsorption isotherms for phosphorus on the processed kimberlite. The phosphorus adsorption isotherms can be used to evaluate the fate of phosphate in the processed kimberlite containment area. The effects of parameters such as temperature, coagulant, and flocculent addition were determined. The quantity of phosphorus adsorbed per gram of kimberlite was found to be low. At a pH of 7.0, 0.5 kg of kimberlite is needed to reduce the concentration of phosphorus from 10 mg/L to 0.1 mg/L in a volume of 1L of wastewater (i.e. 0.2 mg phosphorus removed/g of dried kimberlite). Even though the kimberlite adsorption of phosphorus is low, there is more than adequate kimberlite available in the tailings to remove the phosphorus loading when the pH is 7.0.

A density-dependent solute solubility parameter has successfully correlated solubilities in supercritical fluids (SCFs). Fifteen solutes, including polar and nonpolar compounds, have been studied in up to four SCFs. A two-parameter, linear fit resulted in a median average absolute relative deviation (AARD) of 20%, ranging from 6.1% to 42%, for the 34 systems studied. A three-parameter power fit provided a median AARD of 12%, ranging from 2.3% to 38%.

Retention capacities were measured in the laboratory for n-hexane and tetrachloroethylene (PCE) in three soils at varying soil water contents. Two experimental techniques were used; 1) saturation/drainage experiments where the soil columns were saturated with the chemical and allowed to drain freely for 24 h, and 2) spill simulations where a known amount of chemical was spilled on the surface of the soil column and allowed to infiltrate for one hour. Results show that the retention capacities on a volume basis were independent of chemical type. However, the retention capacities did decrease with decreasing porosity and increasing soil water content. The decrease of retention capacity with respect to soil water content was significant, with the decreases ranging from 38% to 94%. The implication of this decrease is rapid chemical penetration into the subsurface. Retention capacities obtained from spill simulations were consistently lower than those obtained by the saturation/drainage experiments due to hysteresis.