Surface Tension Of Surfactant Solutions Research Articles

Flow pattern and pressure loss of foam flow in horizontal pipes: Role of surfactant type and dynamic surface tension

In this work, the flow patterns and pressure losses of 12 kinds of gas–liquid systems (two different surfactants were selected, and their concentrations were changed in an aqueous solution, which served as the test liquid) in horizontal pipes were studied. To explore the potential mechanisms influencing flow patterns, the equilibrium and dynamic surface tensions of surfactant solutions were surveyed, and the aggregate morphologies of surfactants were observed by using cryo-TEM. Based on the experimental findings, a generalized flow pattern map was proposed. Furthermore, the relationship between the pressure loss and the flow pattern of the foam flow was investigated. The results revealed two types of foam flow: full-foaming flow (FFO) and foam flow containing liquid (FCL). Each type of flow had three subflow patterns. The formation of different flow patterns is closely related to the ability of surfactant molecules to adsorb on bubbles and reduce surface tension in a short period, which is affected by aggregates and their structures. The product of the Weber and Bond numbers was determined to be the appropriate combination of non-dimensional numbers for the proposed generalised flow pattern map. Moreover, above a critical Bond number of the gas–liquid system, FFO cannot be formed. Finally, the flow pattern can be effectively separated according to pressure drop data.

Study on the effect of electrolyte on surface tension of surfactant solution and wettability of coal dust

It is valuable to study the effect of electrolytes on the surface tension and wettability of surfactant solutions for industrial production. Surface tension test, coal dust sink test, and molecular dynamics simulation are employed to investigate the influence of four electrolytes (NaCl, NaAc, Na2CO3, MgCl2) on nonionic surfactant AEO-9 and anionic surfactant SDBS. The study showed that AEO-9 had a more extraordinary ability to reduce surface tension when the surfactant was applied alone. The surface tension achieved by SDBS solution was lower when compounded with electrolytes. The influence degree of electrolytes on the surface tension of SDBS solutions was shown as MgCl2>NaCl≈Na2CO3>NaAc. In contrast, the influence on the surface tension of AEO-9 solutions was insignificant. In addition, adding electrolytes to the low-concentration surfactant solution can markedly reduce the surface tension. When selecting the electrolytes compounded with anionic surfactants, the electrolyte cation is recommended to choose elements with a larger main groups number in the same periodic element from the periodic table and electrolyte anions that can form more hydrogen bonds with water molecules. The results of the coal dust sink test are different from the results of the surface tension measurement. Regardless of whether the electrolyte is added, the sink time of coal dust in the AEO-9 solution is shorter than that in the SDBS solution, and the wettability is better at the same concentration. The results of this study may guide the selection and design of dust suppression solutions.

Effects of static magnetic field on the surface tension of surfactant solutions

AbstractThe magnetic field (MF) effects resulting from water or solution treatments are still of significant interest. However, a relatively small number of papers have been published dealing with the pure surfactant solutions alone. On the other hand, surfactants are applied in many industrial processes as well as in everyday life and are also present in different waste waters. Therefore, it seemed interesting to investigate whether some effects would appear after the MF treatment of pure aqueous surfactant solutions. In the earlier published papers after MF action the changes in water evaporation rate and the surface tension were found for both the cationic dodecyltrimethylammonium bromide (DTAB) and anionic sodium dodecyl sulfate (SDS) solutions. The gradient MF originated from three connected ring magnets inside which the solutions were placed. The objective of this paper is to study whether using the same magnets but in a different position the effects of the MF are observed. The given surfactant solution in a closed vessel was placed in an uniform MF when the magnets were in the “lying” position. The investigated solutions on the magnet surface remained for 24 h. In this paper, despite SDS and DTAB also the cationic hexadecyltrimethylammonium bromide (CTAB) and nonionic Triton X‐100 solutions were applied. It appeared that in the uniform MF the surface tension of cationic and anionic surfactant solutions changes. However, larger changes were observed in the gradient MF. Generally, the changes of surface tension depend on the surfactant kind and its concentration. Stronger MF influence was found for the cationic surfactant and almost no changes were observed for nonionic Triton X‐100.

Prediction of surface tension of solution in the presence of hydrophilic silica nanoparticle and anionic surfactant by ATR-FTIR spectroscopy and chemometric methods

In the current research, an analytical method was proposed for the quantitative determination of surface tension of anionic surfactant solutions in the presence of hydrophilic silica nanoparticles using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy and chemometric methods. The surface tension behavior of anionic surfactant solutions considerably changes by the addition of silica nanoparticles with different particle size. The spectral data of solutions were used for prediction of surface tension using two calibration methods based on support vector machine regression (SVM-R) as a non-linear algorithm and partial least squares regression (PLS-R) as a linear algorithm. For preprocessing of data, baseline correction and standard normal variate (SNV) were also applied. Root mean square error of prediction (RMSEP) in SVM-R and PLS-R methods were 4.203 and 4.507, respectively. Considering the complexity of the samples, the SVM-R model was found to be reliable. The proposed method is fast and easy for measurement of the surface tension of surfactant solutions without any sample preparation step in chemical enhanced oil recovery (C-EOR).

A study on the dynamic surface tension of surfactant solutions at dilute concentrations

The dynamic surface tension (ST) for Aerosol-OT (AOT) molecules adsorbing onto a freshly created bubble surface in a 10 mM NaCl(aq) solution was measured at extremely dilute concentrations using a pendant bubble tensiometer. An air bubble was formed one after another inside the same uniform solution at two different states of the free surface on the top of the solution in quartz cell: (i, bubble #1) a nearly clean air-water interface and (ii, bubble #2) a thermodynamic equilibrated air-water interface. Whilst the dynamic ST of bubble #1 decreased noticeably faster than that of bubble #2, both these bubbles reached the same equilibrium ST. AOT molecules kept adsorbing onto the free surface during the ST measurement of bubble #1, which caused the concentration of AOT in bulk to decrease significantly at dilute concentrations. During the measurement of bubble #2, the bulk concentration remained constant. Subsequently, the dynamic ST data of bubble #2 precisely described the adsorption of AOT molecules onto a freshly created air-water interface. Consequently, the adsorption onto the free surface played an important role in the dynamic ST measurement for surfactant solutions at extremely dilute concentrations. This new experimental procedure was capable of precisely measuring the dynamic ST of surfactant solution at extremely low concentrations.

Quantifying the Counterion-Specific Effect on Surfactant Adsorption Using Modeling, Simulation, and Experiments.

Ionic surfactants behave differently in the presence of various counterions, which plays an important role in many scientific and engineering processes. Previous work has shown that the counterion-specific surface tension can be reproduced with classical adsorption models, but the underlying origin of this effect has not been explained. In this paper, we extend our previously developed adsorption model to account for the specific counterion adsorption. This model can accurately predict the surface tension of surfactant solutions like sodium dodecyl sulfate (SDS) in the presence of the monovalent salts LiCl, NaCl, KCl, and CsCl. The predicted surface excess and surface potential are validated by corresponding sum-frequency generation (SFG) spectroscopy experiments. We also used molecular dynamic (MD) simulation to explain the origin of the counterion-specific effect for surfactant behavior. Our study shows that for SDS, binding of the counterion to both the headgroup and a few CH2 fragments close to the surfactant head contributes to the counterion-specific effect. In general, SDS behaves like a large ion, and it prefers to bind with large counterions such as Cs+, which is consistent with Collins's law of matching water affinity. Therefore, large counterions enhance the surface adsorption and lower the surface tension the most.

The Accumulated Effect of the Number of Ethylene Oxide Units and/or Carbon Chain Length in Surfactants Structure on the Nano-Micellar Extraction of Flavonoids.

Classical extraction methods used for isolation of active substances from plant material are expensive, complicated and often environmentally unfriendly. The ultrasonic assistance micelle-mediated extraction method (UAMME), based on green chemistry principles, seems to be an interesting alternative. This work aimed to find a connection between the chemical structure of non-ionic surfactants and the efficiency of the extraction process. The effect of hydrophobic chain length and number of ethoxy groups on the quality of Bidens tripartite extracts was investigated. Several ethoxylated fatty alcohols were used: Ceteareth-20, Steareth-20, Oleth-20, Oleth-10, Oleth-5, C12-C13 Pareth-12, C12-C15 Pareth-12 and Ceteareth-12. The bioflavonoid compositions with the HPLC method was determined. The hydrophilic lipophilic balance (HLB) of studied surfactants, as well as the surface tension of surfactant solutions, were compared, to determine the explanation for the obtained differences in bioflavonoids concentration. The structural changes influenced by polyphenol extraction were monitored using Dynamic Light Scattering (DLS) measurements. In this work, probably for the first time, the connection between the chemical structure of non-ionic surfactants and the efficiency of the extraction process was found. The experimental and theoretical approach rationalized the choice of an appropriate eluent. We propose some structurally dependent factors, whose optimal value gave a high efficiency to the UAMME.

A note on the synergistic effect of surfactants and nanoparticles on rising bubble hydrodynamics

Various mixtures of surfactants and nanosilica particles were investigated to assess their influence on rising bubble hydrodynamics. For this purpose, local velocities of rising bubbles were measured experimentally. Also, the effects of concentration of three types of surface-modified silica nanoparticles on density, viscosity, and surface tension of surfactant solutions were determined. Experimental results revealed that the simultaneous presence of nanoparticles and surfactant molecules led to the decrease of local velocities of rising bubbles. The presence of nanoparticles in surfactant solutions leads to a more reduction of bubble local velocity. This could be caused by the formation of surfactant-nanoparticle complexes and their adsorption at the gas-liquid interface. However, the increase of concentration of nanoparticles from 0.02 to 0.04 %wt led to an increase in bubble local velocities. That effect may be related to adsorption of surfactants to nanoparticle-liquid interfaces i.e. low surface coverage of surfactant, may increase local surface tension and lead to increasing the mobility of bubble surface.

ФОРМИРОВАНИЕ МЕТОДОЛОГИЧЕСКОГО ПОДХОДА ИССЛЕДОВАНИЯ ПОВЕРХНОСТНО-АКТИВНЫХ ВЕЩЕСТВ ДЛЯ УВЕЛИЧЕНИЯ НЕФТЕОТДАЧИ ПЛАСТОВ (НА ПРИМЕРЕ МЕСТОРОЖДЕНИЯ УДМУРТСКОЙ РЕСПУБЛИКИ)

Актуальность работы. В настоящее время большинство нефтяных месторождений России вступили в позднюю стадию разработки. В связи с истощением запасов легкоизвлекаемой нефти все большие усилия направляются на создание технологий и способов разработки, которые позволяют добывать углеводороды в осложненных условиях. Для дальнейшей разработки месторождений с трудноизвлекаемыми запасами требуется внедрение новых методов увеличения нефтеотдачи и применение новых реагентов. Значительная роль в данном вопросе отводится химическим методам, в частности применению растворов поверхностно-активных веществ. Воздействие водных растворов поверхностно-активных веществ улучшает реологические и фильтрационные характеристики нефти посредством снижения межфазного натяжения и повышения смачивающей способности. В связи с вышеизложенным актуальным представляется задача выбора поверхностно-активных веществ для применения в системе заводнения пластов, а также разработка методологических подходов по их подбору. Цель: формирование методологического подхода исследования поверхностно-активных веществ, применяемых в системе заводнения, для увеличения нефтеотдачи пластов. Объект: карбонатные коллектора месторождений Удмуртской Республики. Методы: лабораторные исследования составов в свободном объеме, прибор для определения поверхностного натяжения растворов поверхностно-активных веществ – сталагмометр «Рубин-02 А» (ГОСТ Р 50097-92), фильтрационные исследования на единичных образцах керна с моделированием пластовых условий на установках УИК-5ВГ и AFS-300 (ОСТ 39-204-86 и 39-195-86), центрифугирование (ГОСТ 16887-71). Результаты. Обозначена актуальная проблема – процесс подбора технологии поверхностно-активных веществ для эффективного применения в системе заводнения с целью достижения наибольшей нефтеотдачипластов. Проанализированы поверхностно-активные вещества, нашедшие активное промышленное применение на месторождениях России и за ее пределами. Проведена оценка физико-химических и технологических свойств поверхностно-активных веществ российского производства в соответствии с паспортными характеристиками, требованиями Положений предприятия-недропользователя и определена пригодность химических реагентов к дальнейшему применению. Рассмотрены методика и результаты определения коэффициента вытеснения нефти водным раствором поверхностно-активных веществ на образцах керна, отобранных с месторождений Удмуртской Республики. Предложен экспресс-метод оценки нефтевытесняющей способности поверхностно-активных веществ, являющийся более экономичным и энергоресурсным по сравнению со стандартными фильтрационными исследованиями. По результатам проведения фильтрационных испытаний на керне установлено, что предлагаемый метод сопоставим с проведенными исследованиями. В целом предложенная методология выбора состава поверхностно-активных веществ возможна для внедрения в локальные нормативные документы предприятия-недропользователя и использования с целью подбора необходимого реагента для увеличения нефтеизвлечения.

Role of the Counterions in the Surface Tension of Aqueous Surfactant Solutions. A Computer Simulation Study of Alkali Dodecyl Sulfate Systems

We have investigated the surface tension contributions of the counterions, surfactant headgroups and tails, and water molecules in aqueous alkali dodecyl sulfate (DS) solutions close to the saturated surface concentration by analyzing the lateral pressure profile contribution of these components using molecular dynamics simulations. For this purpose, we have used the combination of two popular force fields, namely KBFF for the counterions and GROMOS96 for the surfactant, which are both parameterized for the SPC/E water model. Except for the system containing Na+ counterions, the surface tension of the surfactant solutions has turned out to be larger rather than smaller than that of neat water, showing a severe shortcoming of the combination of the two force fields. We have traced back this failure of the potential model combination to the unphysically strong attraction of the KBFF counterions, except for Na+, to the anionic head of the surfactants. Despite this failure of the model, we have observed a clear relation between the soft/hard character (in the sense of the Hofmeister series) and the surface tension contribution of the counterions, which, given the above limitations of the model, can only be regarded as an indicative result. We emphasize that the obtained results, although in a twisted way, clearly stress the crucial role the counterions of ionic surfactants play in determining the surface tension of the aqueous surfactant solutions.

Interactions of modified Gemini surfactants: Interactions with direct dyes and dyeing properties in cotton fabrics

This study investigated dye–surfactant interactions between a series of modified Gemini surfactants and commercial direct dyes in aqueous solution and their corresponding effects on cotton fabric dyeing. A surface tension meter was also used to measure surface activities of compounds containing electrolyte under conditions similar to those in dyeing processes. The surface tension measurements showed lower than normal surface tension in surfactant solutions containing electrolyte. From the UV-Vis spectra, the isosbestic point indicated that dye–surfactant complexes had formed and existed as hydrophilic interaction between direct dyes and modified Gemini surfactants. When dyeing cotton fabric with red dye and orange dye, the presence of these surfactants decreased dye uptake rate but increased for blue dye because the dye–surfactant interaction had formed a hydrophilic complex.

Predicting Surface Tensions of Surfactant Solutions from Statistical Mechanics.

The importance of surfactants to various industries necessitates a predictive understanding of their surface tension and adsorption behavior in terms of molecular characteristics. Previous models are highly empirical, require fitting parameters, and have limited applicability at various temperatures. Here, we provide a surface tension model based on statistical mechanics that (1) is thermodynamically consistent, (2) provides a higher predictive power, wherein surface tension can be calculated for any tail length, concentration, and temperature from molecular parameters, and (3) provides a physical understanding of the important molecular interactions at play. This model is applicable to both nonionic and ionic surfactants, where the effects of the electric double layer have been taken into account in the latter case. For nonionic surfactants, we were able to extend our model to predict dynamic surface tension as well. We have validated our model with tensiometry experiments for various surfactants, concentrations, and temperatures. In addition, we have validated our model with a diverse set of literature data, wherein agreement within a few mN M-1 and a correct prediction of phase change behavior is shown. The model could enable a more informed design of surfactant systems and serve as the theoretical basis for theory on more complex surfactant systems such as mixtures.

Insights into the complex interaction between hydrophilic nanoparticles and ionic surfactants at the liquid/air interface.

Combinations of nanoparticles and surfactants have been widely employed in many industrial processes, i.e., boiling and condensation in heat transfer and hydraulic fracturing in shale oil and gas production, etc. However, the underlying mechanism for various phenomena resulting from the addition of nanoparticles into the surfactant solutions is still unclear. For instance, there are contradictory conclusions from the literature regarding the variations of surface tension upon the addition of nanoparticles into surfactant solutions. In this work, the dominating factors determining if the surface activity of the surfactant solution will increase or conversely decrease when adding certain kinds of nanoparticles have been investigated. Two typical hydrophilic nanoparticles, SiO2 and TiO2 with anionic or cationic surfactants, respectively, have been considered. The surface tension has been measured in a wide range of nanoparticle and surfactant concentrations. It was found that the surface tension of the ionic surfactant solution can be further reduced only if nanoparticles of the same charge were added. For instance, a system containing 0.25 CMC SDS and 1 wt% SiO2 behaves similar to a 0.34 CMC SDS-only solution. Interestingly, the observed synergistic effect is found to be more significant if the surfactant concentration is much lower than its CMC for a given nanoparticle content. Moreover, the effect is perfectly reversible. When the nanoparticles were separated from the system, the surface tension values recovered fully to that of the pure surfactants. If nanoparticles of opposite charge were added, however, the surface tension of the surfactant solution increased. Zeta potential measurement and centrifugal treatment have been employed to reveal the interplay between nanoparticles and surfactants and the adsorption behavior of their assemblies at the liquid/air interface. Based on the experimental outcomes, a possible physical mechanism was proposed. It was concluded that the electrostatic repulsion between surfactant molecules and nanoparticles should be the dominant factor responsible for the observed reversible synergistic effect. Our study is expected to contribute to a better understanding of the interfacial phenomenon in nanoparticle-surfactant complex systems.

Wettability prediction of such polymers as polyethylene and polytetrafluoroethylene by aqueous solutions of classical surfactants and biosurfactants

The measurements of the contact angle (θ) of aqueous solutions of rhamnolipid (RL), n-octyl-β-d-glucopyranoside (OGP), Triton X-100 (TX-100) and sodium dodecylsulfate (SDDS) on the polyethylene (PE) surface were carried out. The θ values on PE and polytetrafluoroethylene (PTFE) were also determined theoretically by using the values of surface tension of polymers and the Lifshitz-van der Waals component of water surface tension. On the basis of θ values of surfactant solutions on PE the critical micelle concentration of RL, OGP, TX-100 and SDDS, critical surface tension of PE wetting (γC), Gibbs surface excess concentration of these surfactants at the PE-water interface, work of adhesion of surfactant solutions to PE, fraction of PE occupied by surfactant molecules and Gibbs standard free energy of surfactants adsorption at the PE-water interface were established. The γC of PE wetting from the relationship between the adhesion and surface tension of surfactant solutions and standard Gibbs free energy of adsorption from the Langmuir equation were determined. The standard Gibbs free energy of adsorption at the PE-water interface was compared to that at the water-air one. The good agreement between the measured and calculated θ values of RL, OGP, TX-100 and SDDS solutions on PTFE and PE was obtained.

Determination of Surface Tension of Surfactant Solutions through Capillary Rise Measurements: An Image-Processing Undergraduate Laboratory Experiment

In this work, we described an image processing procedure for the measurement of surface tension of the air–liquid interface using isothermal capillary action. The experiment, designed for an undergraduate course, is based on the analysis of a series of solutions with diverse surfactant concentrations at different ionic strengths. The objective of the work is to illustrate some concepts such as Gibbs isotherm and surface excess for the case of ionic surfactants. To perform the experiment, it is necessary to use glassware commonly found in a chemistry lab along with an USB microscope and digital image processing program (available in the public domain). The experiment can be completed in a 4 h laboratory session.

Experimental Investigation of Coal Dust Wettability Based on Surface Contact Angle

Wettability is one of the key chemical properties of coal dust, which is very important to dedusting. In this paper, the theory of liquid wetting solid was presented firstly; then, taking the gas coal of Xinglongzhuang coal mine in China as an example, by determination of critical surface tension of coal piece, it can be concluded that only when the surface tension of surfactant solution is less than 45 mN/m can the coal sample be fully wetted. Due to the effect of particle dispersity, compared with the contact angle of milled coal particle, not all the contact angles of screened coal powder with different sizes have a tendency to increase. Furthermore, by the experiments of coal samples’ specific surface areas and porosities, it can be achieved that the volume of single-point total pore decreases with the gradual decreasing of coal’s porosity, while the ultramicropores’ dispersities and multipoint BET specific surface areas increase. Besides, by a series of contact angle experiments with different surfactants, it can be found that with the increasing of porosity and the decreasing of volume percentage of ultramicropore, the contact angle tends to reduce gradually and the coal dust is much easier to get wetted.

SYNTHESIS AND CHARACTERIZATION O F SODIUM METHYL ESTER SULFONATE FOR CHEMICALLY-ENHANCED OIL RECOVERY

Attention has been given to reduce the cost of surfactant by using castor oil as an alternative natural source of feedstock. A new surfactant, sodium methyl ester sulfonate (SMES) was synthesised using ricinoleic acid methyl ester, which is obtained from castor oil, for enhanced oil recovery in petroleum industries. The performance of SMES was studied by measuring the surface tension with and without sodium chloride and its thermal stability at reservoir temperature. SMES exhibited good surface activity, reducing the surface tension of surfactant solution up to 38.4 mN/m and 27.6 mN/m without and with NaCl, respectively. During the thermal analysis of SMES, a 31.2% mass loss was observed from 70 ˚C to 500 ˚C. The phase behavior of the cosurfactant/SMES-oil-water system plays a key role in interpreting the performance of enhanced oil recovery by microemulsion techniques. Flooding experiments were performed using a 0.5 pore volume of synthesized SMES solutions at three different concentrations. In each case chase water was used to maintain the pressure gradient. The additional recoveries in surfactant flooding were found to be 24.53%, 26.04% and 27.31% for 0.5, 0.6 and 0.7 mass% of surfactant solutions, respectively.

Influence of the additives of low-molecular alcohols on the adsorption of mixtures of tween and sodium dodecyl sulfate at the liquid–gas interface

The influence of nonelectrolyte additives (low-molecular alcohols) on the surface tension of individual and mixed solutions of nonionic and anionic surfactants at the air interface and on the patterns of their flotation extraction is investigated. The alcohol additives are found to reduce the surface tension of both individual and mixed surfactant solutions. Additive Fainerman–Miller model is shown to be used to predict the equilibrium surface tension of the surfactant solutions with alcohols.

Alkyl-imidazolium glycosides: non-ionic—cationic hybrid surfactants from renewable resources

A series of surfactants combining carbohydrate and imidazolium head groups were prepared and investigated on their assembly behavior. The presence of the imidazolium group dominated the interactions of the surfactants, leading to high CMCs and large molecular surface areas, reflected in curved rather than lamellar surfactant assemblies. The carbohydrate, on the other hand, stabilized molecular assemblies slightly and reduced the surface tension of surfactant solutions considerably. A comparative emulsion study discourages the use of pure alkyl imidazolium glycosides owing to reduced assembly stabilities compared with APGs. However, the surfactants are believed to have potential as component in carbohydrate based surfactant mixtures.

Proteins as Surfactant Enhancers for Environmental and Industrial Applications

Data are presented on the effect of small proteins on the surface activity of synthetic surfactants and their blends as assessed by standard surface science methods. Surface tension of surfactant solutions, interfacial tension between those solutions and water insoluble substrates, and contact angle between these solutions and a solid surface were determined. It is shown that both small individual proteins, such as lysozyme and β-lactoglobulin, as well as proteins in a yeast extract, significantly and predictively reduce critical micelle concentration of multiple widely used surfactants: ionic, non-ionic and amphoteric. Typically, lower minimal interfacial tension could be achieved with a protein synergist, than with the same surfactant in the absence of protein. Examples of industrially important applications of a protein synergist are described. In one of them, the protein accelerates wetting and spreading of surfactant solutions on the hydrophobic surface of green leaves, with concomitant enhancement of the solution uptake by the leaf. In another example, the activity of bacterial lipase, an important industrial enzyme, towards a segregated oil substrate is enhanced by a surfactant-protein synergist blend, as compared to the same surfactant in the absence of a protein synergist