The dynamic pendant drop method was employed to better understand the adsorption kinetics at the oil/water interface. Various volume ratios of n-heptane/toluene (heptol) have been chosen as solvents to represent the model of crude oil systems. The results show that an increase in the asphaltene concentration reduces the interfacial tension and this reduction is much more pronounced at higher fractions of n-heptane. The Ward–Tordai short-time model was used to estimate the diffusion coefficient of asphaltenes for dilute solutions of asphaltenes in heptol (up to 0.01 wt %). The results show that the asphaltene adsorbed as monomers onto the interface and the bulk nanoaggregates do not contribute to the adsorption process. Furthermore, the results reveal that the asphaltene diffusion coefficient decreases with increasing its concentration and decreasing solvent aliphaticity. The Langmuir adsorption isotherm was used to study the asphaltene behavior at the oil/water interface and to predict the parameters of adsorption kinetics. It was shown that asphaltenes were adsorbed as monomers onto the interface. The results show that at higher n-heptane fractions, more asphaltene molecules are adsorbed onto the interface. A higher concentration of n-heptane in solvent results in faster and more asphaltene adsorption on the oil/water interface leading to lower interfacial tension and thus promotes emulsification. These findings improve our understanding of adsorption kinetics of asphaltenes at the oil/water interface and find applications in oil/water separation and solvent-aided recovery of heavy oil and bitumen.

The Athabasca oil sands are the largest single deposit of too viscous bitumen on Earth. Depending on the depth of the oil sand deposits, the bitumen is typically extracted using either open-pit mining or in situ operations. Oil sands that are deposited in formations shallower than 75 m are generally extracted using openpit mining operations, while deeper deposits are extracted using in situ recovery methods. In situ extraction methods like cyclic steam stimulation and steam-assisted gravity drainage (SAGD) involve the injection of steam into subsurface oil sands formations typically 150-450 meters deep at high pressures (∼1.2-4 MPa) and high temperatures (180-250°C), which mobilizes the viscous bitumen and allows it to be pumped to the surface (Butler, 1991). In 2019, over 1.6 million barrels of oil were produced daily using in situ methods (Oil Sands Magazine, 2020).In a typical SAGD process, steam is injected into an oil sands formation over a long period of time, often between 8 and 15 years, depending on the characteristics of the oil sands reservoirs. Field and experimental observations have demonstrated that the exposure of oil sands materials to heat and steam over a long period of time leads to aquathermolysis reactions, resulting in the generation of gases that include methane (CH 4 ), carbon dioxide (CO 2 ), hydrogen sulfide (H 2 S), hydrogen (H 2 ), ethane (C 2 H 6 ), and carbon monoxide (CO)

Pyridine derivatives Pyridine derivatives R 0380Synthesis of 4-(1-Phenylmethyl-5-imidazolyl)-1,4-dihydropyridines as Calcium Channel Antagonists. -Starting from the 5-formyl substituted imidazole (VI) the symmetrical title compounds (VIII) are obtained by classical Hantzsch condensation meanwhile the asymmetrical substituted dihydropyridine (X) is synthesized via (IX) in two steps by a modified Meyer procedure. -(HADIZADEH*, F.; SHAFIEE, A.; KAZEMI, R.; MOHAMMADI, M.; Indian J.

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We report new interfacial tension (IFT) data of n-pentane/bitumen and n-heptane/bitumen mixtures at T = 298.15–413.15 K, P = 3.45 MPa, and four concentrations of the n-pentane and n-heptane (10, 20, 30, and 40 wt %). The new IFT data show that the dynamics of IFT is much faster at higher temperatures. The results also revealed that in contrast to pure n-alkanes where IFT decreases linearly with temperature the equilibrium IFT values of n-C5/bitumen and n-C7/bitumen mixtures are nonmonotonic and follow a nonlinear behavior. Both n-pentane/bitumen and n-heptane/bitumen mixtures reveal the partitioning of surfactants at the oil/water interface at higher solvent concentrations. In addition, the IFT reduction is more evident by solvent addition at lower temperatures, whereas at higher temperatures, the concentration of solvent does not affect the IFT significantly due to the weakening effect of hydrogen bonding. These results improve our understanding of the bitumen/solvent interfacial tension behavior and find application in the design and optimization of solvent-aided thermal recovery processes and oil/water/solvent separation and treatment.