Hydrodynamics of a Packed Countercurrent Column for the Gas Extraction

The in vivo model on rabbit eyes and the in vitro cytotoxicity on fibroblasts were used to compare irritation effect of aqueous and oily (Miglyol 812) solutions of surfactants. Tween 20, Tween 80 and Cremophor EL were tested in different concentrations (0.1, 1 or 5%) and the in vitro test demonstrated that surfactants in oil are less cytotoxic than in aqueous solutions. In the in vivo study, the aqueous solutions of surfactants were characterized as non-irritant while small changes in conjunctiva were observed after application the oily solutions of surfactants and the preparations were classified as slightly irritant, however this effect was similar when Miglyol was applied alone. In conclusion, it is reported that the MTT assay does not correlate well with the Draize scores.

Association properties of two silicone surfactants based on poly(dimethylsiloxane)-graft-polyethers in aqueous solutions of 2-butoxyethanol, poly(ethylene glycol), and glucose were determined using various techniques such as surface tension, small-angle neutron scattering, and viscosity. Dilute solution phase diagrams were also constructed, and cloud points were measured for different concentrations of both the surfactants in additive aqueous solutions. The thermodynamic parameters for the micellization were obtained from the temperature-dependent data on critical micelle concentration. The influence of given additive on the micellization of silicone surfactants was monitored from the changes in the free energy of micellization values for the surfactant solutions in water and water + additives. The cloud points and the critical micelle concentration values for the surfactant solutions were found to be decreased in the presence of the selected three additives. The analysis of the changes in the relative permittivities and partial molar volumes for the surfactant solutions in the presence of water and water + additives suggests that the solvent environment around the surfactant solute molecules is different in mixed solvent systems vis-a-vis water and the micellization and surface activity of silicone surfactants were dictated predominantly by the preferential hydration of cosolute additives. The analysis of small angle neutron scattering curves for the surfactant aqueous solutions in the presence of additives showed that the micelles formed have oblate ellipsoidal shape at 30 °C with, however, increased characteristic axial ratios than those in pure water. The increase in the concentration of additives has also increased the size of the micelles. The increase in temperatures corresponding to the values close to the turbid boundaries in the phase diagrams caused a transition from the oblate to the disklike micellar shape. The changes in the hydration values of the micellar associates were monitored from the dilute solution viscosity measurements. The dehydration of the micelles in the presence of additives at 30 °C and also at elevated temperatures occur from the interior to the fringe of the core−outer shell parts and to the outer shell successively.

The aim of this laboratory work was a detailed study of oil recovery ability of aqueous surfactant solutions. The first part included determination of relevant physical chemical properties of additive solutions, i. e. interfacial and rheological properties, phase diagram exploration as well as an evaluation of the specific adsorption-retention properties of surfactant polymer solutions in porous media used for oil recovery tests. In the second part, the results of the series of oil displacements were analysed –to give a precise description of the main features of displacements by aqueous surfactant solutions,–to assess their oil recovery efficiency, shown to depend on surfactant concentration in slug injected, consecutive or simultaneous injection mode of polymer and surfactant and additive retention properties in the porous media chosen,–to compare the oil recovery performances of surfactant solutions and microemulsions taken from the same Winsor III type diagram. Finally, application of a Buckley-Leverett type approach was considered to aid in the interpretation of the successive displacement steps observed during flooding by surfactant solutions at low or moderate concentrations.

Comparison of pool boiling heat transfer performance between aqueous cationic and anionic surfactant solutions with similar ionic group

Unique role of ionic liquid [bmin][BF 4] during curcumin–surfactant association and micellization of cationic, anionic and non-ionic surfactant solutions

Soluting effect of amino acids on 1‑decyl‑3‑methylimidazolium bromide and 1‑dodecyl‑3‑methylimidazolium bromide as cationic surfactants and sodium dodecyl sulfate as anionic surfactant in aqueous solutions

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 166232, ’Numerical Challenges in Foam Simulation: A Review,’ by W.R. Rossen, SPE, Delft University of Technology, prepared for the 2013 SPE Annual Technical Conference and Exhibition, New Orleans, 30 September-2 October. The paper has not been peer reviewed. Foam simulation brings various numerical challenges. Some of these problems are largely cosmetic, creating, for instance, fluctuating fluxes and pressure gradient but no significant effect on final recovery. Others severely influence the whole progress of the flood. This paper discusses the origin of the challenges, how to recognize them, how they can be mitigated, and whether they arise from a correct representation of foam physics or are the unintended result of attempts to solve other numerical problems. Introduction Injected gas [carbon dioxide (CO2), hydrocarbon gas, nitrogen, or steam] can be very effective at displacing oil in enhanced- oil-recovery (EOR) processes, but ultimate recovery suffers from poor sweep efficiency. Poor sweep efficiency arises from reservoir heterogeneity, viscous instability, and gravity override of gas. Foam can address all three causes of poor sweep efficiency. Foam is a dispersion of gas separated by water films called lamellae that separate the gas into bubbles; the lamellae are stabilized by surfactant. Thus, foam requires the presence of gas, water, and surfactant. Two fundamental approaches exist for representing the effect of foam on gas mobility. Population-balance models introduce lamella density (number of lamellae per unit volume of gas phase) as a separate variable and perform a balance on lamellae at each location in the formation, along with material balances on water, gas, surfactant, and oil. Thus, an additional partial-differential equation must be solved at each location and timestep, along with those for saturations of the phases. The model then represents gas mobility as a function of lamella density and other factors. Local-equilibrium (LE) models assume that the processes of lamella creation and destruction are always and everywhere at local steady state. It is possible to adapt a population-balance model to LE by setting the expressions for lamella creation and destruction equal to each other. Most LE models, however, represent the effect of bubble size implicitly in relations for gas mobility as a function of water and oil saturations, surfactant concentration in the aqueous phase, and other factors. Foam can be injected in at least four ways: 1. In coinjection, gas and aqueous surfactant solution are injected simultaneously from a single well. Foam forms in the surface facilities where the fluids meet, in the tubing, or shortly after the fluids enter the formation. 2. In surfactant-alternating-gas (SAG) injection, gas and surfactant solution are injected in separate slugs from a single well. Foam forms in the formation where gas meets previously injected surfactant solution or when surfactant solution meets previously injected gas. 3. It is possible to dissolve some surfactants directly into supercritical CO2. Then, there is no need to inject aqueous surfactant solution; injected CO2 with dissolved surfactant forms foam as it meets water in the formation. 4. Surfactant solution and gas can be injected simultaneously from different sections of a vertical well (gas injected below the surfactant solution) or from parallel horizontal wells (gas injected from the lower well). As far as we know, this approach has not been tested with foam in the field. Simulating each of these injection methods involves particular challenges.

Soil flushing by surfactant solution: Pilot-scale demonstration of complete technology

Porphyrin-surfactant interactions in aqueous solutions are known to result in the selfassembly of various supramolecular structures, including pigment-surfactant complexes, J- and H-aggregates, and solubilized dye species. Detailed studies on the mechanisms of the intermolecular interactions governing the above self-assembly processes allow to predict the aggregation state and hence, the photophysical properties of the dye-surfactant assemblies in order to perform a direct synthesis of the desired porphyrin-based nanostructures at the appropriate experimental conditions. This paper describes a novel example of the surfactant-induced J-aggregate formation from the diprotonated hydrophobic tetraphenylporphyrin species in submicellar aqueous anionic surfactant solutions. The above assemblies are characterized by a rod-like morphology and possess supramolecular chirality according to the CD measurements.

The solubility of inorganic salts in surfactant aqueous solutions is very important for both scientific research and inorganic salt industry. In this work, we determine the solubility of three commercially available inorganic salts, NaBr, NaCl, and KBr, in cationic tetradecyltrimethylammonium bromide (TTABr) or anionic sodium dodecyl sulfate (SDS) surfactant solutions from 298.15 to 353.15 K. The data show that the solubility of the three salts in SDS and TTABr solution increases progressively with increasing temperature, which is similar to that in water. The solubility of NaBr, NaCl, and KBr in surfactant aqueous solutions with the concentration under the TTABr or SDS cmc is higher than that in the solutions above the TTABr or SDS cmc. The solubility of NaCl and NaBr in SDS is much lower than that in water and increases slowly along with increasing temperature. For the case of KBr and NaBr in TTABr, it becomes more complicated. Below T = 312.15 K, the solubility of KBr and NaBr is much lower than that in water, but the data becomes higher when it is above T = 340.15 K. This is similar to that in water between T = (312.15 and 340.15) K. The data and the results of inorganic salts in surfactant aqueous solutions should provide the basic data and understanding for the inorganic and surfactant industries.

Aqueous nonionic surfactant solutions are known to undergo a phase transition from lamellar to vesicle when shear force is applied. It is also known that viscosity increases with the phase transition1). Our group has previously reported that the impedance decreases during the phase transition2). However, there are still many unknown aspects of the conduction mechanism in aqueous surfactant solutions of before, after, and during the phase transition. Therefore, in this study, we performed rheo-impedance measurements of aqueous surfactant solutions with different electrolyte concentrations. Furthermore, the dependency of the phase on the rheological parameters was verified using small-angle light scattering.As surfactant, two types of polyoxyethylene lauryl ethers (BL4.2 and BL4SY) were used. As electrolyte, an aqueous Na2SO4 solution of 1.0 × 100 mol/L, 1.0 × 10-1 mol/L, 1.0 × 10-2 mol/L or 1.0 × 10-3 mol/L was prepared. The sample solution was a mixture of Na2SO4 solution, surfactant, and pure water with ratios of 5 wt%, 40 wt%, and 55 wt%, respectively. The sample solution was heated to 40°C, stirred, and allowed to settle until all bubbles disappeared completely. Samples without electrolyte (40 wt% surfactant, 60 wt% pure water) were prepared correspondingly. Rheology was measured with a gap of 1.0 mm over 30 min, at 35 °C, and a shear rate of 10 s-1. Simultaneously, electrochemical impedance was measured continuously with an initial potential of 0 V, in the frequency range of 500 kHz to 1 kHz (5 points per decade), with an amplitude 10 mV using a potentiogalvanostat with FRA (Hz-7000).Phase transitions were observed in all solutions. Electrolyte concentration did not affect the time to phase transition. Capacitive semicircles were observed in all solutions. Curve fitting showed that the resistance of the solutions decreased after the phase transition. This is thought to be due to the difference in the orientation of the structure, which allows for easier transfer of protons and sodium ions in the vesicle than in the lamellar. When the electrolyte concentration was low, the resistance was greater than that of the solution without electrolyte. On the other hand, when the electrolyte concentration was high, the resistance decreased obviously. We are currently investigating the cause of this phenomenon. Details will be reported on the day.1) Diat, D. Roux, F. Nallet, J. Phys. II France, 3, 1427 (1993).2) Isao Shitanda et al., Proceedings of the 90th Annual Meeting of the Electrochemical Society of Japan (2023).

Background Currently there is the tendency for the structure of oil reserves in existing fields to change. Most deposits are at the late stage of development, which is characterized by high water cutting of the well production, increased share of hardly recoverable reserves and, as a consequence, by lower recovery rate. Aqueous solutions of surfactants can play leading role in increasing oil recovery factor. Exposure to aqueous solutions of surfactants improves the rheological and filtration characteristics of oil by reducing the interfacial tension and improving wetting ability. Aqueous solutions of surfactants improve the process of oil displacement by water from the porous medium. Furthermore, the use of surfactants in the enhanced oil recovery technology is preferable as far as preservation of reservoir properties of productive layers is considered. Aims and Objectives The work has been performed to assess the characteristics of widely used water-soluble nonionic, anionic and biological surfactants for predicting the factors of oil-saturated reservoir development. Objective of the research is to compare performance of nonionic surfactants (OP-10, AF9-12), anionic surfactant (sulfonol) and biological surfactant (KSHAS-M). Methods Surface tension and interfacial tension of aqueous surfactant solutions was determined using ST-1 stalagmometer. To select the input data for predicting the development of deposits, of greatest interest are research results obtained during oil displacement from natural sandstone, as most approaching to the real conditions. In this connection, quartz sand adsorption of a surfactant was studied and determined under static conditions. The contact angle on the «surfactant solution - air» boundary was determined using the contact angle computing program. Conclusion The studies involved a number of indicators that characterize the important properties of surfactants: surface and interfacial tension, adsorption capacity, wetting angle, displacing properties. Experiments conducted in the laboratory show that biosurfactants are similar in their effect to the synthetic surfactants, but have more pronounced physical and chemical properties, are ecologically safe, and most promising for extraction of hardly recoverable reserves using flooding. Biosurfactant KSHAS-M possesses advantages in terms of superficial and interfacial tension, adsorptive capacity, values of interfacial angle, extrusive properties.

Experiments in various porous media have shown that multiple parameters come into play when an oleic phase is displaced by an aqueous solution of surfactant. In general, the displacement efficiency is improved when the fluids become quasi-miscible. Understanding the phase behavior oil/water/surfactant systems is important because microemulsion has the ability to generate ultralow interfacial tension (<10(-2) mN m(-1)) that is required for miscibility to occur. Many studies focus on microemulsion formation and the resulting properties under equilibrium conditions. However, the majority of applications where microemulsion is present also involve flow, which has received relatively less attention. It is commonly assumed that the characteristics of an oil/water/surfactant system under flowing conditions are identical to the one under equilibrium conditions. Here, we show that this is not necessarily the case. We studied the equilibrium phase behavior of a model system consisting of n-decane and an aqueous solution of olefin sulfonate surfactant, which has practical applications for enhanced oil recovery. The salt content of the aqueous solution was varied to provide a range of different microemulsion compositions and oil-water interfacial tensions. We then performed microfluidic flow experiments to study the dynamic in situ formation of microemulsion by coinjecting bulk fluids of n-decane and surfactant solution into a T-junction capillary geometry. A solvatochromatic fluorescent dye was used to obtain spatially resolved compositional information. In this way, we visualized the microemulsion formation and the flow of it along with the excess phases. A complex interaction between the flow patterns and the microemulsion properties was observed. The formation of microemulsion influenced the flow regimes, and the flow regimes affected the characteristics of the microemulsion formation. In particular, at low flow rates, slug flow was observed, which had profound consequences on the pore scale mixing behavior and resulting microemulsion properties.

A micellar liquid chromatographic method was developed for the green enantioseparation of racemic amino alcohols using an aqueous solution of the mixed surfactants as an alternative for organic solvents. In this study, the derivatives of the amino alcohols were synthesized using highly reactive chiral esters of (S)-levofloxacin (Lfx) under microwave conditions, and an aqueous solution of the surfactants (Brij-35 and SDS) was used for the enantioseparation of the synthesized diastereomeric derivatives (DDs) of amino alcohols using reversed-phase HPLC. The activated ester of Lfx was synthesized by reacting with N-hydroxybenzotriazole and characterized using UV, IR, 1 H NMR, high-resolution mass spectrometry, and elemental analysis. The DDs of racemic amino alcohols were separated on a C18 column using micellar LC. Chromatographic conditions were optimized by varying the concentration of the surfactants in aqueous solution and by varying the concentration and pH of the buffer. The green assessment score was calculated for the developed method (score: 82, an excellent green method). In addition, the density functional theory calculations were performed to develop the lowest energy-optimized structures of DDs. The method was validated according to the International Conference of Harmonization guidelines, and the retention factor (k), selectivity factor (α), resolution factor (RS ), limit of detection (0.198 ng mL-1 or 0.291 pM mL-1 ), and limit of quantification (0.594 ng mL-1 or 0.873 pM mL-1 ) were calculated.

Boiling phenomena with surfactants and polymeric additives: A state-of-the-art review