An experimental technique is developed to measure the interfacial tensions of the crude oil + reservoir brine + CO 2 systems at pressures from (0.1 to 31.4) MPa and two temperatures (27 and 58) °C using the axisymmetric drop shape analysis (ADSA) technique for the pendant drop case. The measured dynamic interfacial tension is gradually reduced to an equilibrium value. For both the reservoir brine + CO 2 system and the crude oil + CO 2 system, the equilibrium interfacial tension decreases as the pressure increases, whereas it increases as the temperature increases. For the reservoir brine + CO 2 system, the interfacial tension data are not available at P g 12.238 MPa and 58 °C because the pendant brine drop cannot be formed in the CO 2 phase. However, for the crude oil + CO 2 system, the equilibrium interfacial tension remains almost constant at P g 8.879 MPa and 27 °C or at P g 13.362 MPa and 58 °C. Under the same conditions, nevertheless, the equilibrium interfacial tension of the crude oil + reservoir brine + CO 2 system is reduced in comparison with that of the crude oil + reservoir brine system. The interfacial tension reduction for the crude oil + reservoir brine + CO 2 system is larger at higher pressures.

Nanostructured enzyme mimics are of great interest as promising alternatives to artificial enzymes for biomedical and catalytic applications. Studying the chemical interactions between antioxidants and nano-enzymes may result in a better understanding of the antioxidant capability of antioxidants and may help improve the function of artificial enzymes to better mimic natural enzymes. In this study, using Co3O4 nanoparticles (NPs) as peroxidase mimics to catalyze the oxidation of chromophoric substrates by H2O2, we developed a platform that acts as a biosensor for hydrogen peroxide and glucose and that can study the inhibitory effects of natural antioxidants on peroxidase mimics. This method can be applied specifically to glucose detection in real samples. Three natural antioxidants, gallic acid (GA), tannic acid (TA), and ascorbic acid (AA), were compared for their antioxidant capabilities. We found that these three antioxidants efficiently inhibit peroxidase-like activity with concentration dependence. The antioxidants showed different efficiencies, in the following order: tannic acid > gallic acid > ascorbic acid. They also showed distinct modes of inhibition based on different interaction mechanisms. This study serves as a proof-of-concept that nano-enzyme mimics can be used to evaluate antioxidant capabilities and to screen enzyme inhibitors.

On the basis of the available vapor pressures for 59 non-hydrocarbon and hydrocarbon compounds, including heavy alkanes up to n-tritetracontane (n-C43H88), a modified α function for the Peng−Robinson equation of state (PR-EOS) has been developed to more accurately determine the vapor pressure for pure non-hydrocarbon and hydrocarbon compounds, especially heavy components. To balance the characterization of both light and heavy compounds, the Pitzer acentric factor is first redefined in terms of reduced vapor pressure at a reduced temperature of 0.6. In comparison to the evaluated α functions used for the PR-EOS, it is found that the newly developed α function with the redefined acentric factor provides a more accurate prediction of vapor pressures with a percentage average absolute deviation of 1.90% and a percentage maximum absolute deviation of 21.22% for the 59 chemical species. In addition, the newly developed α function results in the best prediction of the vaporization enthalpy data with an average absolute deviation of 3.92% in comparison to the other existing α functions evaluated.

Experiments have been conducted to determine the viscosities of water-in-oil (W/O) emulsions in porous media. W/O emulsions were first prepared for different volume fractions of the dispersed phase and then characterized for their properties and rheological parameters including flow index and consistency constant. All prepared W/O emulsions with volume fractions between 6.78% and 33.48% were found to behave as non-Newtonian shear-thinning fluids at fairly high viscosities. The viscosities of the emulsions were measured during emulsion flow in three types of sandpacks. A correlation of the viscosities of the W/O emulsions in porous media was developed by performing a regression on the experimentally measured data. The newly developed correlation was validated, and a sensitivity analysis was performed to examine the effects of tortuosity and emulsion quality. The emulsion quality has a dominant effect on the viscosity of the W/O emulsions and has been included in the correlation for the first time to achieve accurate predictions of the viscosities of W/O emulsions in porous media. The existing correlations for oil-in-water (O/W) emulsions provide underestimated predictions for the viscosities of W/O emulsions, whereas the droplet size distribution does not have a significant impact on the viscosity of the W/O emulsions tested in this study.