On the impact of oil compounds on emulsion behavior under different thermodynamic conditions.

Asphaltene instability in oil causes severe problems such as deposition and more stable emulsions. Formation and stability of W/O emulsions based on location in which they are formed can either be helpful or detrimental for enhanced oil recovery. Changes in oil composition (saturate, aromatic, resin, and asphaltene) can also render the stability of asphaltene. In this study, the formation and staility of emulsions are investigated using changes in the colloidal instability index (CII) at ambient and reservoir conditions. Experiments were conducted for crude oil samples from various reservoirs which showed that when CII is greater than 1.059, due to the excessive instability of asphaltene and its movement toward the water-oil interface, the formed emulsion would be more stable. When CII was below 1.059 though, the asphaltene became stable hence did not tend to be placed at the water-oil interface, thus less stable emulsion was expected. Higher pressures led to an increase in the stability of the emulsion. These changes in the process of emulsion stability are related to two mechanisms of asphaltene absorption and greater shear stresses.

Innovative spiral electrode configuration for enhancement of electrocoagulation-flotation.

The performance of electrocoagulation-flotation (ECF) process can profoundly be affected by the reactor design and electrode configuration. These may, in turn, influence the removal efficiency, flow hydrodynamic, floc formation, and flotation/settling characteristics. The present work aimed at developing a new spiral electrode configuration to enhance the ECF process. To do so, the impacts of parameters such as energy consumption, removal efficiency of the contaminants from industrial wastewater with a composition of turbidity, emulsified oil, and heavy metals (Si, Zn, Pb, Ni, Cu, Cr, and Cd), as well as stirring speed and foaming have been investigated. Comparison was also made between the experimental results of the new electrode configuration with the conventional rectangular cell with plate electrode configuration with the same volume and electrode surface area. The findings revealed that energy consumption of the spiral electrode configuration within the operating times of 10, 20, 30, 32, 48, and 70 min, was approximately 20% lower compared to that of the conventional ECF. Moreover, the maximum and minimum removal efficiency of 97% and 60% were obtained for turbidity and TOC for the stirring speed of 500 rpm and Reynolds number of 10,035, respectively. Finally, the formed gas bubbles tilted toward the center due to the enhanced flow hydrodynamic which resulted in substantial reduction of foam formation.

Surface Energy and Wetting Behavior of Dolomite in the Presence of Carboxylic Acid-Based Deep Eutectic Solvents.

This study endeavors to apply experimental and theoretical analyses to assess the viability of wettability alteration for two carboxylic acid-based deep eutectic solvents (DESs). To prepare these chemicals, oxalic acid and citric acid were used as hydrogen bond donors mixed with choline chloride as the hydrogen bond acceptor in an equimolar ratio. In the theoretical part, dolomite and crude oil were characterized using a three-phase setup. Then, the adhesion propensity of brines/crude oil toward dolomite was evaluated by calculating the work of adhesion. Contact angle and interfacial tension measurements were conducted in the experimental part to investigate the impact of chemicals on brine-crude oil and brine-rock interactions. Results revealed that the oxalic acid-based DES outperformed the citric acid-based DES in terms of interfacial tension reduction. In addition, choline chloride/oxalic acid (1:1) could effectively restore the wettability of the dolomite sample to its original state with a wettability alteration index of 82%. Theoretical calculations also confirmed the wettability alteration potential of DESs. Finally, a correlation was proposed to predict the contact angle of brine on the dolomite surface in the presence of crude oil using surface-energy components of brine, crude oil, and dolomite.

Mitigation of Mineral Deposition in Carbonate and Sandstone Rocks Using Green Scale Inhibitors.

Waterflooding is potentially a viable approach to enhance oil recovery, though its efficacy can profoundly be compromised due to formation damage as a result of inorganic scale deposition. In this study, a series of high-temperature core flooding experiments were conducted to evaluate two green scale inhibitors (SIs) of folic acid and inulin as alternative inhibitors to mitigate mineral deposition. The co-injection of two incompatible brines (with and without SIs) for two flow rates of 0.5 and 3 mL/min into two core samples of dolomite and sandstone was experimentally investigated. The results showed that folic acid would inhibit scale formation as much as 45-49%, at the lower flow rate, compared to inulin with an efficiency of 29-39%, at the higher flow rate. Moreover, computed tomography imaging technique showed that scale formation and fine migration would be dominant mechanisms for formation damage in dolomite and sandstone rocks, respectively. The theoretical study based on surface energy also confirmed the experimental results in terms of the work of adhesion which showed that folic acid would mitigate the calcite deposition on rock surfaces approximately 55%. Finally, a phosphonate-based commercial SI was compared with the green SIs which reaffirmed their potencies.

Isolation of exfoliated colonic epithelial cells, a novel, non-invasive approach to the study of cellular markers.

Human stool is a heterogeneous mixture of non-digestible food residues, bacteria, cells exfoliated from the gastrointestinal mucosa and other secretory products. We have demonstrated that fresh human stools dispersed in a buffered saline solution can be fractionated over Percoll/BSA gradients to yield 9 discrete bands of cells in the density range of rho 1.033 to 1.139 and which could be further purified over Histopaque 1077. Enzyme-linked immunoassays (ELISA) for colon-specific antigen (CSA) and cytokeratins (CK) were positive. Western blot analysis showed the presence of 3 cytokeratin bands in the 40-kDa to 60-kDa range suggestive of cytokeratins 8, 18, and 19. Fluorescence flow-cytometric analysis of these cells using antibodies against CSA, CK, the blood-group antigens, carcinoembryonic antigen (CEA), non-mucus-secreting columnar-epithelium-specific MAb PR1A3, and to mucus-secreting colonic-epithelium-specific MAb PR5D5 showed varying degrees of reactivity. Expression of the blood-group phenotype suggests that cells from the proximal half of the colon had survived the transit, since in the adult expression of this marker is limited to cells from the proximal region of the colon. In this report we demonstrate the feasibility of studying, non-invasively, cell-specific markers on exfoliated cells isolated from stools. The evidence strongly suggests that almost all the cells are of colonic origin.