Sodium Dodecyl Sulfate Solution Research Articles

Human Endothelial Cell Seeding in Partially Decellularized Kidneys.

The excessive demand for organ transplants has promoted the development of strategies that increase the supply of immune compatible organs, such as xenotransplantation of genetically modified pig organs and the generation of bioartificial organs. We describe a method for the partial replacement of rat endothelial cells for human endothelial cells in a rat's kidney, obtaining as a final result a rat-human bioartificial kidney. First, in order to maintain parenchymal epithelial cells and selectively eliminate rat endothelial cells, three methods were evaluated in which different solutions were perfused through the renal artery: 0.1% sodium dodecyl sulfate (SDS), 0.01% SDS, and hyperosmolar solutions of sucrose. Then, partially decellularized kidneys were recellularized with human endothelial cells and finally transplanted in an anesthetized rat. The solution of 0.1% SDS achieved the highest vascular decellularization but with high degree of damage in the parenchyma side. On the contrary, 0.01% SDS and hyperosmolar solutions achieved a partial degree of endothelial decellularization. TUNEL assays reveal that hyperosmolar solutions maintained a better epithelial cell viability contrasting with 0.01% SDS. Partially decellularized kidneys were then recellularized with human endothelial cells. Histological analysis showed endothelial cells attached in almost all the vascular bed. Recellularized kidney was transplanted in an anesthetized rat. After surgery, recellularized kidney achieved complete perfusion, and urine was produced for at least 90 min posttransplant. Histological analysis showed endothelial cells attached in almost all the vascular bed. Therefore, endothelial decellularization of grafts and recellularization with human endothelial cells derived from transplant recipients can be a feasible method with the aim to reduce the damage of the grafts.

Influence of Adsorption Characteristics of Surfactants Sodium Dodecyl Sulfate and Aerosol–OT on Dynamic Process of Water-Based Lubrication

Surfactant solutions are widely used in industry, and their steady-state lubrication properties have been comprehensively explored, while the “dynamic process” between steady states attracts much less attention. In this study, the lubrication behaviors of sodium dodecyl sulfate (SDS) and sodium bis (2–ethylhexyl) sulfosuccinate (Aerosol–OT, AOT) solutions were comparatively and extensively discussed. Experimental results showed that the duration of the dynamic process of AOT solution lubrication was significantly shorter than that of SDS. The essence of the dynamic process was revealed from the aspects of the running-in of solid surfaces and the adsorption process of surfactant molecules. Unlike the general recognition that the friction force evolution mainly corresponds to the running-in of surfaces, this study indicated that the dynamic adsorption behavior of surfactant molecules mainly contributes to this process. Various experiments and analyses showed that the smaller steric hindrance and lower orientation speed of SDS molecules led to longer diffusion into the confined contact zone and a longer duration of friction force decrease. This work enhances our understanding of the dynamic friction process in water-based lubrication, which could also have important implications for oil-based lubrication and its industrial applications.

Method of generation, measurement of the size and number of microbubbles in NaCl and SDS solutions of different concentrations

The research work shows the method of generating and registration of bubbles which is provided by the finely disperse membrane, the air compressor, the water pump and the optical image registration unit and analyses of images. In order to estimate the size of the fixed bubbles the specialized software on Python programming language was used as a tool of analysis. The software outcomes are presented in the form of diagrams of the distribution of the number of bubbles by the diameter. The results of experiments for solutions of sodium chloride salt and sodium dodecyl sulfate of various concentrations indicated the possibility of controlling both the diameter and the amount of produced air bubbles. One of the main findings of the scientific work is determination of the concentration of sodium chloride, which leads to inhibition of the effect of Sodium dodecyl sulfate on the distribution of bubbles by their size in the experiments.

Circular Dichroism Spectra of α-Chymotrypsin-SDS Solutions Depend on the Procedure of Their Preparation.

We recorded the far- and near-UV circular dichroism (CD) spectra of solutions of α-chymotrypsin and sodium dodecyl sulfate (SDS) with the final surfactant concentration significantly above the critical micellization concentration. Solutions were prepared using three different procedures. The reference procedure was to mix the chymotrypsin solution with the SDS solution once, immediately achieving the final SDS concentration. In alternative procedures, the protein solutions initially contained some SDS and were mixed with pure SDS solutions at a concentration to provide the same final surfactant as the reference mixing. We demonstrate that the supplementation to the selected final concentration of SDS of the pure chymotrypsin solution leads to different CD spectra than the supplementation to this final concentration of SDS in the chymotrypsin solution containing a small concentration of a few millimolar SDS. These differences disappear when the initial concentration of SDS in the protein solution, which we then supplement to the indicated final concentration, is higher. This suggests the irreversibility of the processes caused by the addition of SDS to chymotrypsin and the influence of the initial amount of this surfactant on the processes occurring with its further addition to the solution. For quantitative analysis of far-UV CD spectra in terms of populations of protein secondary structure elements, we used four well-established software packages. All programs consistently indicate that the observed differences in the far-UV CD spectra can be explained by the differences in the increase in the population of helical forms in chymotrypsin under the influence of SDS.

Thermochemical characteristics of some glycylpeptides interaction with anionic micelles in a phosphate-buffered saline solution of sodium dodecyl sulfate

The dissolution enthalpies of glycylglycine (GlyGly), glycylglycylglycine (GlyGlyGly) and glycyl-L-tyrosine (GlyTyr) in phosphate-buffered saline solution and micellar solution (sodium dodecyl sulfate (SDS) + phosphate-buffered saline solution) were measured calorimetrically at pH = 7.4 and T = 298.15 K. The thermochemical characteristics of the interaction of peptides with micelles are defined as the transfer enthalpies of peptides into a micellar solution of sodium dodecyl sulfate in a phosphate-buffered saline solution. A comparison of the obtained results revealed the influence of the ionic state, chain length and hydrophobicity of peptides on the characteristics of their interaction with anionic micelles. The effect of micelle contraction upon interaction with peptide zwitterions was found. The differences in the dissolution enthalpies in the buffer and in pure water are described by the contributions of acid dissociation of peptides, which is accompanied by a change in the fractions of the zwitter-ionic and anionic forms with a change in pH.

Contamination in Sodium Dodecyl Sulfate Solutions: Insights from the Measurements of Surface Tension and Surface Rheology

The presence of contamination in sodium dodecyl sulfate (SDS) solutions in the form of dodecanol (LOH) is known to drastically affect the resulting interfacial properties such as surface tension (SFT) and rheology. Dodecanol molecules, which are the product of SDS hydrolysis and are inherently present in SDS solutions, have higher surface activity compared to SDS because they are less soluble in water. A characteristic dip in the SFT isotherm is an indicator of the dodecanol contamination in the sample. The presence of an electrolyte in the solution impacts the surface activity of SDS and its critical micelle concentration, and could yield SFT isotherms that closely match those obtained for pure SDS samples. The interpretation of the isotherms in such cases could thus lead to misinterpretation of the surface purity. In this work, we have examined the SFT isotherms for SDS solutions in both the absence and presence of electrolyte. We have fitted the isotherms to three different thermodynamic adsorption models to estimate the amount of dodecanol present in the sample. We have applied the estimated values for the LOH content in a two-component rheological model to predict the viscoelasticity of such surfactant-laden surfaces. We have compared these results with the experimentally measured interfacial rheological properties. Our findings demonstrate that the presence of impurities can be captured under dynamic expansion and contractions, even for solutions containing background electrolyte.

Decellularized Three‐Dimensional Biomimetic Scaffolds as In Vitro Model For Tendon And Meniscus Regeneration

Traumatic and degenerative injuries to the meniscus and tendon still pose challenges to treatments available in the fields of orthopedics and sports medicine. In search of more effective therapeutic procedures based on biological strategy, regenerative medicine advances like medical science carrying‐out preclinical and clinical research necessary for establishing therapeutic efficacy and safety. This research aimed to establish the new concept of three‐dimensional decellularized biomimetic scaffolds as in vitro models to investigate the tendon and meniscus regenerative medicine approaches. For this purpose, the menisci of the swine's knee and the tendons of the deep flexor muscles of the bovine's fingers were resected, cleaned, fragmented and frozen (‐20°C) for 48 hours. After this, the fragments were thawed and decellularized by immersion in sodium dodecyl sulfate (0.5%) and Triton‐X100 (1%) solution for 72 hours. To faithfully simulate a degenerative injury, 0.05 mL of collagenase type‐1 (1mg.mL‐1/37°C/1hour) was injected into the central region of the meniscal samples. To simulate the traumatic injury, incisions were made on the surface of the samples with a scalpel. The fragments were washed in running water (3 days), immersed in formaldehyde (4%), washed again, stored in ethanol (70%), frozen (‐30°C), and submitted to the lyophilization process or embedding in paraffin for histological procedures. For microscopic characterization of tissue and injury sites, histological sections were stained with Hematoxylin and Eosin (HE) or Picrosirius and analyzed under a light microscope with a polarization filter. The results, based on qualitative analysis, demonstrate the preservation of macroscopic and microscopic architecture of the scaffold matrix, the efficacy of the decellularization procedure, and the accuracy in creating the traumatic and degenerative sites of injury. These results allow us to conclude the success of this research in establishing the concept of decellularized three‐dimensional scaffolds as a new biomimetic models applicable for in vitro assays evolving regeneration of traumatic and degenerative injuries of tendons and menisci, contributing to the advancement of preclinical research on regenerative medicine approaches.

Combination of Hypotonic Lysis and Application of Detergent for Isolation of Polyhydroxyalkanoates from Extremophiles.

Production of polyhydroxyalkanoates (PHA), microbial biopolyesters, employing extremophilic microorganisms is a very promising concept relying on robustness of such organisms against microbial contamination, which provides numerous economic and technological benefits. In this work, we took advantage of the natural susceptibility of halophilic and thermophilic PHA producers to hypotonic lysis and we developed a simple and robust approach enabling effective isolation of PHA materials from microbial cells. The method is based on the exposition of microbial cells to hypotonic conditions induced by the diluted solution of sodium dodecyl sulfate (SDS) at elevated temperatures. Such conditions lead to disruption of the cells and release of PHA granules. Moreover, SDS, apart from its cell-disruptive function, also solubilizes hydrophobic components, which would otherwise contaminate PHA materials. The purity of obtained materials, as well as the yields of recovery, reach high values (values of purity higher than 99 wt.%, yields close to 1). Furthermore, we also focused on the removal of SDS from wastewater. The simple, inexpensive, and safe technique is based on the precipitation of SDS in the presence of KCl. The precipitate can be simply removed by decantation or centrifugation. Moreover, there is also the possibility to regenerate the SDS, which would substantially improve the economic feasibility of the process.

Creating Hyperthin Membranes for Gas Separations.

Interest in creating membranes that can separate gases has intensified in recent years owing, in large part, to climate change. Specifically, the need for separating CO2 and N2 from flue gas in an economically viable fashion is now considered urgent. This Perspective highlights two recent developments from my laboratory—defect repair of polyelectrolyte multilayers (PEMs) using micellar solutions of sodium dodecyl sulfate (SDS) and the surface modification of a highly permeable polymer, poly[1-(trimethylsilyl) propyne] (PTMSP)—which I believe have significant implications not only for this CO2/N2 problem but also for the ever-growing area of layer-by-layer (LbL) thin films. A brief mention is also made of past efforts that have been aimed at creating hyperthin membranes from porous surfactants and from PEMs with a view toward gas separations.

In-situ petroleum hydrocarbons contaminated soils remediation by polymer enhanced surfactant flushing: Mechanistic investigation

Chemicals injection for in-situ remediation of contaminated soils has attracted great attention. Efficiency of this technology relies on various parameters. Among them, chemical formulation of flushing agents has a key role. In this study, synergistic effect of Sodium Dodecyl Sulfate (SDS) ionic surfactant and Xanthan Gum (XG) biopolymer on the emulsification and solubilization of two types of petroleum hydrocarbon pollutants was investigated. Interfacial tension (IFT) measurements, bottle tests, droplet size distributions determination, and visual fluid flow experiments at pore-scale were conducted to assess pollutants removal strength of the proposed polymer enhanced surfactant flushing strategy. Results showed that although SDS surfactant reduced the equilibrium IFT of system to appropriate low value (i.e. less than 3 mN/m), it was not able to form stable oil-in-water emulsions. Nevertheless, addition of XG biopolymer, with no remarkable effect on IFT, improved emulsions formation and stability. Fluid flow experiments showed that oil snap-off and emulsion division are essential mechanisms of in-situ emulsion formation. A significant amount of hydrocarbon pollutants remained in porous medium after injection of 10 pore volumes of SDS. While, smaller size emulsions, as well as better contaminants removal were achieved for SDS solution with 4000 ppm XG at much lower injected pore volumes.

Enhanced clathrate hydrate phase change with open-cell copper foam for efficient methane storage

Rapid phase change of hydrate with high gas storage capacity is very important for the application of natural gas hydrates technology. Three discs of open-cell copper foam (CF) with different pore densities (or pores per inch, PPI) herein were immersed in sodium dodecyl sulfate (SDS) solution for enhancing methane storage in solid hydrate. The promotion effects of CF on the methane hydrate formation in the metal-embedded systems were investigated via an unstirred tank reactor. The results demonstrated that the surface of CF skeleton is covered with abundant micro holes and micro grooves, which can provide many metal nuclei for gas–water crystallization. The nest-like metal skeleton acts as crisscross “highway” for the crystallization heat transfer. Methane hydrate was quickly formed in the SDS/CF systems, but CF with the pore densities of 5 and 30 PPI was not favorable for conversion of more water to hydrate. Compared with these two composite systems, the SDS solution with the 15 PPI CF were able to store more methane at a faster formation rate. A theoretical model based highly porous two-phase systems was used to predict the effective thermal conductivity (ETC) of the metal foam filled with hydrate. It was found that the ETC of the hydrate/CF composite was significantly enhanced by employing CF matrix, and the low pore density CF had a more positive impact on improving the ETC of the composite. Further comparative experiments conducted at various pressures indicated that the solutions with 15 PPI CF exhibited higher methane storage capacities and larger hydration rates than the simple SDS solution, especially at the low pressure.

Use of green-modified micellar liquid chromatography for the determination of Imidocarb dipropionate residues in food samples

Imidocarb dipropionate (IMD) is broadly utilized in veterinary medicine as an antimicrobial to cure many illnesses, particularly anaplasmosis in livestock. Consequently, the rapid determination of IMD residues in edible bovine food samples is of high significance to guarantee food safety. In the meantime, the environmental influences must be considered to reduce the hazardous impacts of control laboratories. Modifying micellar liquid chromatography (MLC) using a natural deep eutectic solvent (NADES), generated utilizing choline chloride (ChCl) and ethylene glycol (EG), was successfully applied to determine imidocarb (IMD) residues in bovine food samples including meat, liver, kidney, and milk. An experimental design approach was employed for multivariate optimization of important mobile phase factors comprising the concentration of sodium dodecyl sulfate (SDS) in mole L-1, and the percentage volumes of NADES, and ethanol (EtOH). The optimal sustainable mobile phase composition was conquered through the Box Behnken design (BBD) optimization approach considering chromatographic peak height, and peak width at 50% of its height (W 50%) as influential responses. The optimal composition of the modified micellar mobile phase was found to be 0.075 M aqueous SDS solution with Ethanol and NADES in the ratio (40:50:10) with pH adjusted to 4.0 using 0.2 M acetic acid solution. At this optimal composition, IMD was efficiently eluted within 0.8 min when the flow rate was 1 mL/min with no interference by endogenous components and proteins in bovine food samples. Pretreatment of food samples was performed by extracting with an aqueous solution of SDS surfactant only. No organic solvent was required during the extraction step. To validate the presented methodology, the regulations of the Food and Drug Administration (FDA) for bioanalytical analysis were applied. The greenness of the proposed method was estimated utilizing three measures involving the Complementary Green Analytical Procedure Index (ComplexGAPI), the Analytical GREEnness metric (AGREE), and the modern White Analytical Chemistry (WAC) assessment tool. Using these tools, a comparative study was conducted between the proposed method and previously reported liquid chromatographic methods. The proposed method was found to be the most sustainable.

Microencapsulation of camphor using trimethylsilylcellulose

Microencapsulation of camphor by trimethylsilylcellulose was performed using oil-in-water emulsion method. Trimethylsilylcellulose (TMSC) with the DS value of 2.41 (CHN analysis) was synthesized by dissolving commercial cellulose in N, N-dimethylacetamide/LiCl followed by reacting with hexamethyldisilazane. Sodium dodecyl sulfate (SDS) in acidic aqueous solution and tetramethylammonium chloride (TMACl) in water were attempted as emulsifiers. The oil phase composed of TMSC and camphor in ethyl acetate was dispersed in emulsifier solution. The mass ratio of TMSC to camphor and emulsifier concentration were optimized to produce high quality microcapsules. Using the mass ratio of 3:7 and 1% (w/v) SDS solution gave well separated microcapsules of TMSC_C_SDS (1). The diameter size in the micron range (10–110 mm) and high camphor content (∼21.07%) were obtained from this sample. The larger size of the capsules obtained from TMACl system indicated the coalescence of the oil droplets. The hydrolysis of the external surface of the microcapsules was observed in the SDS system. However, this caused a minor effect on the cellulose stability in TMSC_C_SDS (1). The freshly prepared microcapsules of TMSC_C_SDS (1) showed the fast release of camphor during first 2 h and reached the equilibrium after 7 h.

Application of superomniphobic electrospun membrane for treatment of real produced water through membrane distillation

A superomniphobic polyvinylidene fluoride (PVDF-F) membrane was fabricated through electronspinning to obtain an excellent antiwetting and antifouling property for the effective and efficient treatment of real produced water. Compared with pristine PVDF and hydroxyl functionalized PVDF (PVDF-O) membrane, PVDF-F membrane had a larger pore diameter, while its pure water flux was found to be lower than both. Neither liquids with high surface tension (water, ethanol) or low surface tension (sodium dodecyl sulfate (SDS) as surfactant, mineral oil) could wet the PVDF-F surface even up to 3 min of contact. During membrane distillation (MD) of 3.5 wt% of aquoues NaCl solution, PVDF-F could withstand 0.4 mM SDS solution without any wetting as seen from the conductivity of the permeate, which was not the case for the PVDF and PVDF-O membranes. After 18 h of MD operation using produced water, a significantly thick fouling layer was found on the PVDF and PVDF-O membranes containing Ca3(PO4)2, Sr3(PO4)2 and Mg3(PO4)2. However, PVDF-F had a very thin and reversible organic fouled layer, causing only 40% reduction in permeate flux and with a low permeate conductivity of 20 μS cm−1. This layer was easily removed by cleaning using distilled water and 80% of the flux was recovered. On the 2nd and 3rd MD cycle, the reduction in permeate flux was within 10%. The superomniphobic PVDF-F nanofibrous membrane was run for three successful consecutive MD cycles during produced water processing without any significant fouling as well as wetting.

Qualitative and quantitative methods detection of SDS based on polyelectrolyte microcapsules

Sodium dodecyl sulfate (SDS) is the most widely used anionic surfactant. Its frequent use causes environmental pollution and negative effects on living organisms (even at low concentrations ≈ 20 μg/ml). Thus, cheap and fast methods are needed to detect this surfactant in wastewater and surface waters in order to prevent the negative effects of SDS on the environment and human beings. We discovered that sodium dodecyl sulfate is capable of destroying polyelectrolyte microcapsules, which has been demonstrated by the number of sedimented polyelectrolyte microcapsules (PMC) before and after incubation in SDS solution. Therefore, it was proposed to use PMCs to create qualitative and quantitative diagnostic systems for the determination of SDS in solution. The qualitative system is a polyelectrolyte microcapsules containing polyallylamine labeled with a fluorescent dye—FITC. An excess SDS concentration of more than 5 μg/ml in the analyzed medium leads to the destruction of PMC and an increase in the fluorescence intensity of the solution, which is recorded by a fluorometer. The quantitative diagnostic system is based on turbidimetry of the PMC suspension before and after incubation in an anionic surfactant solution. This system has a range of detectable SDS concentrations from 10 to 50 μg/ml, with a standard deviation of no more than 11%.

Endpoint Recombinase Polymerase Amplification (RPA) Assay for Enumeration of Thiocyanate-degrading Bacteria.

An endpoint recombination amplification reaction (RPA) assay for assessing the abundance of the gene encoding thiocyanate dehydrogenase (TcDH) in Thiohalobacter has been developed. The RPA reaction was performed at 37°C for 30‍ ‍min, terminated by the addition of sodium dodecyl sulfate (SDS) solution, and the DNA concentration of the RPA product was fluorometrically measured. The abundance of TcDH in 22 activated sludge samples and 7 thiocyanate-degrading enrichment cultures ranged between 2.5×103 and 1.5×106 copies μL–1, showing a linear relationship (R2=0.83) with those measured using a conventional quantitative PCR assay.

Spreading dynamics of liquid-liquid driving

Surface tension gradient due to concentration difference and temperature difference induces liquid convection, known as Marangoni effect. The Marangoni effect has been extensively studied to understand its fundamental physics and its industrial applications. In this paper we study Marangoni effect of droplet in a three-phase liquid system. In this system, silicone oil is chosen as a driving liquid, and n-hexadecane is used as a driven liquid. A high-speed camera is used to capture the spreading process of n-hexadecane driven by silicon oil on the sodium dodecyl sulfate (SDS) solution. The experiment shows that n-hexadecane driven by silicone oil spreads from inside out, forming a ring structure. According to spreading dynamic behavior of internal boundary and external boundary of n-hexadecane ring, we study the spreading pattern of internal boundary and external boundary of n-hexadecane ring, and the influence of silicone oil volume on the spreading process. Analysis shows that the spreading law of internal silicone oil conforms to single droplet spreading at the liquid interface. In the initial spreading stage, the spreading of four-phase contact line (internal boundary) among silicone oil, air, n-hexadecane and water are dominated by gravity, The scale law of spreading distance <i>R</i> of four-phase contact line and <i>t</i> is in a range of <inline-formula><tex-math id="M5">\begin{document}$ R \sim {t}^{1/4} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20211682_M5.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20211682_M5.png"/></alternatives></inline-formula>－ <inline-formula><tex-math id="M6">\begin{document}$ R \sim {t}^{1/2} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20211682_M6.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20211682_M6.png"/></alternatives></inline-formula>. Owing to the gravity influence, the larger the volume of silicone oil, the faster the four-phase contact line spreads. The volume of silicone oil has no effect on the scaling law of the whole spreading process. The next spreading stage, the spreading of the contact line is dominated by the interfacial tension gradient. The scale law of spreading distance <i>R</i> and <i>t</i> conforms to <inline-formula><tex-math id="M7">\begin{document}$ R \sim {t}^{3/4} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20211682_M7.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20211682_M7.png"/></alternatives></inline-formula>. Under silicone oil driven, the liquid thickness of n-hexadecane at the four-phase contact line (internal boundary) among air, silicone oil, N-hexadecane and water increases, thus changing the contact angle at three-phase contact line (external boundary) among air, n-hexadecane and water. The change of contact angle leads the interfacial tension gradient to produce. The interfacial tension gradient drives external boundary to spread. Because the spreading of the three-phase contact line is dominated by interfacial tension gradient, the scale law of spreading distance <i>R</i> of three-phase contact line and time <i>t</i> conforms to <inline-formula><tex-math id="M8">\begin{document}$ \sim {t}^{3/4} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20211682_M8.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20211682_M8.png"/></alternatives></inline-formula>.

Wetting Mechanism and Experimental Study of Synergistic Wetting of Bituminous Coal with SDS and APG1214.

To solve the problem of poor dust wettability during coal mine dust treatment, sodium dodecyl sulfate (SDS) and alkyl glycoside (APG1214) were selected for compounding. An efficient, environmentally friendly, economical wetting agent was prepared. First, through molecular dynamics simulation studies, it was determined that the tail group C of SDS and APG1214 was adsorbed on the surface of bituminous coal, and the head groups S and O were adsorbed on the surface of water. The simulation result is found to be consistent with the surfactant solution dust removal theory, which proves the confidence of simulation. Then, by comparing the interaction of water–SDS and APG1214–bituminous coal and water–bituminous coal systems and the number of hydrogen bonds, the wetting mechanism of the SDS and APG1214 solution on bituminous coal was revealed. Finally, the surface tension, contact angle, and wetting time of different SDS and APG1214 solutions were determined by experiments and they decreased with decreasing mass fraction of SDS at the same concentration. The surface tension of the SDS and APG1214 solution and the number of micelles affected the wettability of bituminous coal. The optimal concentration of the SDS and APG1214 solution was 0.7%, and the optimal ratio was SDS/APG1214 = 1:3.

Nanoemulsions stabilized by anionic and non-ionic surfactants for enhanced oil recovery in ultra-low permeability reservoirs: Performance evaluation and mechanism study

Nanoemulsions stabilized by surfactant have a high application potential in enhancing oil recovery in ultra-low permeability reservoirs. In this work, a new nanoemulsion flooding system were prepared by microemulsion dilution method using D-limonene, non-ionic surfactant fatty alcohol polyoxyethylene ether (AEO), anionic surfactant Sodium dodecyl sulfate (SDS), n-amyl alcohol and NaCl solution. The displacement performances of nanoemulsions were evaluated by spontaneous imbibition and displacement experiments, and the enhanced oil recovery (EOR) mechanisms were studied by Zetasizer Nano Z instrument, interfacial tensiometer, and contact angle meter. The results showed that the nanoemulsion system with optimal mass fraction (0.30 wt%) could get an additional oil recovery of 20.32% and reduce the injection pressure by 10.62%. Besides, the spontaneous imbibition recovery could reach 51.39%, which was 10.04% higher than that of SDS+AEO. The greater EOR effects of the nanoemulsion system can attribute to three perspectives. Firstly, nanoemulsions with particle sizes ranging from 80 nm to 100 nm make it possible to enter small pore throats of ultra-low permeability reservoirs to start-up crude oil without increasing insert pressure. Secondly, the nanoemulsion system exhibits ultra-low IFT (less than 1 ×10−2mN/m) and can change the core surface from hydrophobic to hydrophilic, which could roll up the crude oil and separate them from the rock surface. Finally, the dissolving effect of the oil phase can disperse crude oil to enhance the solubilization effect of the micelles and extract more crude oil. The findings of this study can help for better understanding of the application of nanoemulsions to enhance oil recovery in ultra-low permeability reservoirs.

SURFACE TENSION AND ASSOCIATION IN AQUEOUS SOLUTION SURFACTANTS IN THE PRESENCE OF POLYACRYLAMIDE

The surface tension of aqueous solutions of cationic (dodecylammonium and dodecylpyridinium chlorides) and anionic (sodium dodecylsulfate) surfactants was measured in the presence of polyacrylamide in the solution. A synergistic effect of reducing the surface tension of mixed solutions of cationic surfactants, in the region of sufficiently high concentrations of mixed solutions of sodium dodecyl sulfate, with polyacrylamide in the range of molar ratios of the mixture components - n (Surfactants : PAA) = 1: 1; 1: 0.25 was established. The values ​​of the maximum adsorption, the values ​​of the area per molecule or associate of surfactants in the adsorption layer, as well as the standard Gibbs free energy of adsorption of surfactant - PAA associates are calculated. In accordance with Rosen's model, the composition of mixed adsorption layers at the solution-air interface is calculated, as well as the parameter of intermolecular interaction in adsorption layers between molecules, cationic and anionic ions surfactants and PAA. The values ​​of the critical micelle concentration (CMC) of individual surfactants in aqueous solutions exceed the CMC of the studied surfactants in the presence of PAA, which promotes micelle formation.