Surface Tension Of Aqueous Solutions Research Articles

Insight into the Inflection Point of Surface Tension in Aqueous Solution of Imidazolium-Based Ionic Liquids

Insight into the Inflection Point of Surface Tension in Aqueous Solution of Imidazolium-Based Ionic Liquids

Surface tension of aqueous solutions of large organic salts: Tetrabutylammonium acetate solutions

Aqueous solutions of simple ionic salts such as NaCl and NaBr have higher surface tensions compared to that of pure water and the surface tension of the solution increases with the increasing concentration of the salt. In contrast, the aqueous solutions of the ion sodium acetate (NaAc), which has an anion with both hydrophilic and hydrophobic parts, have a surface tension less than that of pure water, with the surface tension decreasing with salt concentration. The presence of large cations in the salt may change these trends. In this work, the interfacial tension of aqueous solutions of the organic ionic salt tetrabutylammonium acetate (TBAAc) is measured and compared with that of tetrabutylammonium bromide (TBAB). The surface tension of TBAAc aqueous solutions with mole fractions ranging from 0.00417 to 0.04191 were measured for temperatures ranging from 288.2 to 308.2 K and compared with the surface tension of TBAB solutions at similar concentrations. The experimental results showed that the interfacial tensions of TBAAc and TBAB aqueous solutions decreased with increasing concentration, leveling at around 0.04 mol fraction. At each concentration, the interfacial tensions of the TBAAc solutions were larger than those of the TBAB solutions. For the TBAAc and TBAB solutions, the surface excess concentrations of the salts in the solutions are calculated. The impact of these results structures and properties of these solutions are discussed.

Исследования поверхностной и адсорбционной активности модифицированного лигносульфонатного реагента для регулирования параметров бурового раствора

The possibility of obtaining a modified lignosulfonate reagent based on acrylic and lignosulfonate components is considered. To study the effect of electrolytes on the surface activity of a complex reagent based on acrylic and lignosulfonate components, the surface tension of aqueous solutions of inorganic salts of NaCl and CaCl2 of different concentrations was determinedwith the introduction of 0.1 to 2% of the reagent. The assessment of adsorption activity was carried out on the basis of constructingan isotherm of surface tension at the liquid-liquid interface under static conditions in time at a constant concentrationof the reagent. The possibility of a modified lignosulfonate reagent to effectively reduce the conditional viscosity of clay drilling mud in the temperature range from 20 to 180°C has been established.

Development and mechanistic study of hydrophobic shale inhibitors for water-based drilling fluids

Maintaining wellbore stability is a constant and hot issue in the drilling industry. The hydrophilic nature of rocks makes them susceptible to destabilization by physicochemical reactions with water-based drilling fluids. Amine-based inhibitors have been widely studied because of their effectiveness in inhibiting rock hydration. On the basis of maintaining the original inhibition mechanism of amine-based inhibitors, a hydrophobic amine-based inhibitor [(named hydrophobic organic amine (HOA)] was prepared by hydrophobically modifying the amine-based inhibitor. It has the ability to change the hydrophilicity of rocks, which is expected to further enhance the inhibition performance of amine-based inhibitors. The inhibition performance of the HOA was evaluated through experiments measuring the relative inhibition ratio, rolling recovery ratio, linear expansion rate, and water absorption rate. The performance of HOA in conventional drilling fluid systems was also systematically evaluated. HOA exhibited exceptional temperature resistance and the ability to suppress clay swelling. At an HOA dosage of 1.0%, bentonite exhibited relative inhibition ratios of 92.9% and 87.5% before and after aging at 150 °C, respectively, along with a rock fragment rolling recovery ratio of 75.1% (compared to 11.4% in pure water). The inhibition mechanism of HOA was investigated through contact angle, zeta potential, particle size distribution, and surface tension experiments. HOA had the inhibition mechanism of traditional amine-based inhibitors, that is, it could neutralize the negative charge on the surface of the clay, reduce the hydration repulsion between the clay layers, and effectively inhibit the clay hydration. Furthermore, HOA could also electrostatically adsorb onto the shale surface to form a hydrophobic layer, thereby reversing the wetting of hydrophilic rocks and reducing their water intake capacity. In addition, HOA could significantly reduce the surface tension of aqueous solutions. HOA, which can change the hydrophilicity of rocks, has better inhibition performance on rock hydration and is expected to become the next generation of amine-based inhibitors.

Comparison of six approaches to predicting droplet activation of surface active aerosol – Part 2: Strong surfactants

Abstract. Surfactants have been a focus of investigation in atmospheric sciences for decades due to their ability to modify the water uptake and cloud formation potential of aerosols. Surfactants adsorb at the surface and can decrease the surface tension of aqueous solutions. In microscopic aqueous droplets with finite amounts of solute, surface adsorption may simultaneously deplete the droplet bulk of the surfactant. While this mechanism is now broadly accepted, the representation in atmospheric and cloud droplet models is still not well constrained. We compare the predictions of five bulk–surface partitioning models documented in the literature to represent aerosol surface activity in Köhler calculations of cloud droplet activation. The models are applied to common aerosol systems, consisting of strong atmospheric surfactants (sodium myristate or myristic acid) and sodium chloride in a wide range of relative mixing ratios. For the same particles, the partitioning models predict similar critical droplet properties at small surfactant mass fractions, but differences between the model predictions increase significantly with the surfactant mass fraction in the particles. Furthermore, significantly different surface tensions are predicted for growing droplets at given ambient conditions along the Köhler curves. The inter-model variation for these strong surfactant particles is different than previously observed for moderately surface active atmospheric aerosol components. Our results highlight the importance of establishing bulk–surface partitioning effects in Köhler calculations for a wide range of conditions and aerosol types relevant to the atmosphere. In particular, conclusions made for a single type of surface active aerosol and surface activity model may not be immediately generalized.

Surface Activity, Wetting, and Aggregation of a Perfluoropolyether Quaternary Ammonium Salt Surfactant with a Hydroxyethyl Group.

This paper reports the synthesis of a novel quaternary surfactant containing a hydroxyethyl group (PFPE-C) and the surface properties of its aqueous solution (investigated by comparisons with two structurally similar chemicals, dodecyl-(2-hydroxyethyl)-dimethylammonium chloride (DHDAC) and PFPE-A). The minimum surface tension (γCMC) and critical micelle concentration (CMC) of the PFPE-C aqueous solution were 17.35 mN/m and 0.024 mmol/L, respectively. This study confirms that surfactants containing hydroxyethyl groups efficiently reduce the surface tension of aqueous solutions, and fluorocarbon surfactants exhibit better surface activity than ordinary hydrocarbon surfactants with similar structures. The micellization, aggregation, air-water interfacial adsorption, and wettability of PFPE-C aqueous solutions have been systematically investigated. Highly concentrated PFPE-C aqueous solutions exhibit good wettability on PTFE and paraffin films. Moreover, the aggregates of PFPE-C in the aqueous solution were clearly seen as vesicles on Cryo-TEM micrographs. Primary biodegradation results indicate that 19% of PFPC-C can be degraded within one week.

Simple method for quantification of anionic biosurfactants in aqueous solutions.

Biosurfactants are microbial products that have applications as cleaning agents, emulsifiers, and dispersants. Detection and quantification of biosurfactants can be done by various methods, including colorimetric tests, high performance liquid chromatography (HPLC) coupled to several types of detectors, and tests that take advantage of biosurfactants reducing surface tension of aqueous liquids, allowing for spreading and droplet formation of oils. We present a new and simple method for quantifying biosurfactants by their ability, on paper, to reduce surface tension of aqueous solutions, causing droplet dispersion on an oiled surface in correlation with biosurfactant content. We validated this method with rhamnolipids, surfactin, sophorolipids, and ananatoside B; all are anionic microbial surfactants. Linear ranges for quantification in aqueous solutions for all tested biosurfactants were between 10 and 500µM. Our method showed time-dependent biosurfactant accumulation in cultures of Pseudomonas aeruginosa strains PA14 and PAO1, and Burkholderia thailandensis E264. Mutants in genes responsible for surfactant production showed negligible activity on oiled paper. In summary, our simple assay provides the opportunity to quantify biosurfactant contents of aqueous solutions, for a diversity of surfactants, by means readily available in any laboratory.

Thermodynamic Characterization of Rhamnolipid, Triton X-165 and Ethanol as well as Their Mixture Behaviour at the Water-Air Interface.

In many industrial fields, in medicine or pharmacy, there are used multi-component mixtures of surfactants as well as more and more often mixtures containing biosurfactants. Thus, in our study the mixtures of rhamnolipid (RL), ethanol (ET) and Triton X-165 (TX165) were applied. For these mixtures the surface tension of aqueous solutions with constant concentration and composition of ET and RL as well as the variable concentration of TX165 was measured. Based on the obtained results and the literature data, thermodynamic analyses of the adsorption process of ET, RL, TX165, binary mixtures of ET + RL, ET + TX165 and RL + TX165 as well as the ternary mixtures of RL + ET + TX165 at the water-air interface were made. This analysis allows to propose a new equation for calculation of the total ethanol concentration at the water-air interface using the Guggenheim-Adam adsorption isotherm. The constants in the Langmuir and Szyszkowski equations for each component of the studied mixtures as well as the composition of the mixed monolayer at the water-air interface were also successfully analysed based on the contribution of particular surface active compounds to the water surface tension reduction as well as based on the Frumkin isotherm of adsorption.

Surface tension models for binary aqueous solutions: a review and intercomparison.

The liquid-air surface tension of aqueous solutions is a fundamental quantity in multi-phase thermodynamics and fluid dynamics and thus relevant in many scientific and engineering fields. Various models have been proposed for its quantitative description. This Perspective gives an overview of the most popular models and their ability to reproduce experimental data of ten binary aqueous solutions of electrolytes and organic molecules chosen to be representative of different solute types. In addition, we propose a new model which reproduces sigmoidal curve shapes (Sigmoid model) to empirically fit experimental surface tension data. The surface tension of weakly surface-active substances is well reproduced by all models. In contrast, only few models successfully model the surface tension of aqueous solutions with strongly surface-active substances. For substances with a solubility limit, usually no experimental data is available for the surface tension of supersaturated solutions and the pure liquid solute. We discuss ways in which these can be estimated and emphasize the need for further research. The newly developed Sigmoid model best reproduces the surface tension of all tested solutions and can be recommended as a model for a broad range of binary mixtures and over the entire concentration range.

Synthesis and dilute aqueous solution properties of cationic antistatic surfactant functionalized with hydroxyl and ether groups

Abstract Polyester fibers tend to generate and accumulate electrical charges under friction and induction. This significantly affects the production and use process and even poses the risk of electric shocks and fire. Quaternary ammonium salt surfactants with a positive charge can be adsorbed on negatively charged polyester fibers and have excellent antistatic properties. Therefore, we have synthesised a cationic antistatic surfactant functionalised with hydroxyl and ether groups: N-hexadecyl-N,N-dimethyl-N-butanoxy glycerol ether ammonium chloride (HDBGA). The structure was characterized by 1H NMR, FTIR and ESI/MS. The excellent properties of HDBGA in aqueous solution were investigated by measuring the Krafft point (TK), surface tension, conductivity, and steady-state fluorescence. Also antistatic tests were carried out. The results show that the TK of HDBGA is below 0 °C indicating that it can still be applied in cold water. The new quaternary ammonium compound could effectively decrease the surface tension of aqueous solution to 31.28 mN m−1, where the critical micelle concentration (CMC) at 298.15 K was 3.83 × 10−4 mol L−1. In addition, the static electricity and static half-life values of the polyester cloths treated with the HDBGA solutions were also measured, as well as the effects on the fabric properties. The product exhibited excellent antistatic properties and satisfactory wash resistance, and the fabric fibers were not damaged.

Synthesis of modified polycarboxylate superplasticiser and its effect on cement properties

A polyether, acrylic acid and oleic acid were used as raw materials to synthesise oleic acid modified polycarboxylate superplasticiser (OA-PCE) by emulsion polymerisation. The synthesis process was optimised using orthogonal experiments. The colloidal interfacial chemistry results showed that the OA-PCE was more capable of reducing the surface tension of aqueous solutions than an unmodified traditional polycarboxylate superplasticiser (JS-PCE) and its adsorption capacity on cement particles was greater. The isothermal adsorption behaviour of the two kinds of PCEs on cement conformed to the Freundlich isothermal adsorption equation; it was a physical adsorption process by electrostatic action. The effect of OA-PCE dosage on the flowability of cement slurry was preliminarily investigated by rheological behaviour tests. According to the yield stress, plastic viscosity and thixotropic ring area of the slurry, a dosage of 0.35 wt% OA-PCE produced the optimum effect. The compressive strength of concrete made with 0.35 wt% OA-PCE at 4 h and 7 days was, respectively, 117.1% and 88.3% higher than that of the control group and met the standards for the use of concrete in metro pipe sheets. OA-PCE synthesised by emulsion polymerisation is therefore significant for the development of PCEs both in terms of the polymerisation method and practical applications.

Thermodynamic Analysis of the Adsorption and Micellization Activity of the Mixtures of Rhamnolipid and Surfactin with Triton X-165.

The surface tension of aqueous solutions of Triton X-165 with rhamnolipid or surfactin mixtures was measured. The obtained results were applied for the determination of the concentration and composition of the Triton X-165 and biosurfactants mixture at the water–air interface as well as the contribution of the particular component of the mixtures to water surface tension reduction and the mutual influence of these components on the critical micelle concentration. The determination of these quantities was based on both the commonly used concepts and a new one proposed by us, which assumes that the composition of the mixed monolayer at the water–air interface depends directly on the pressure of the monolayer of the single mixture component and allows us to determine the surface concentration of each mixture component independently of surface tension isotherms shape. Taking into account the composition of the mixed monolayer at the water–air interface, the standard Gibbs adsorption free energy was considered. The obtained results allow us to state that the concentration of both mixture components corresponding to their saturated monolayer and the surface tension of their aqueous solution can be predicted using the surfactants’ single monolayer pressure and their mole fraction in the mixed monolayer determined in the proposed way.

Species Surface Distribution and Surface Tension of Aqueous Solutions of MIBC and NaCl Using Molecular Dynamics Simulations.

Methyl isobutyl carbinol (MIBC) is a high-performance surfactant with unusual interfacial properties much appreciated in industrial applications, particularly in mineral flotation. In this study, the structure of air–liquid interfaces of aqueous solutions of MIBC-NaCl is determined by using molecular dynamics simulations employing polarizable and nonpolarizable force fields. Density profiles at the interfaces and surface tension for a wide range of MIBC concentrations reveal the key role of polarizability in determining the surface solvation of Cl− ions and the expulsion of non-polarizable Na+ ions from the interface to the liquid bulk, in agreement with spectroscopic experiments. The orientation of MIBC molecules at the water liquid–vapor interface changes as the concentration of MIBC increases, from parallel to the interface to perpendicular, leading to a well-packed monolayer. Surface tension curves of fresh water and aqueous NaCl solutions in the presence of MIBC intersect at a reproducible surfactant concentration for a wide range of salt concentrations. The simulation results for a 1 M NaCl aqueous solution with polarizable water and ions closely capture the MIBC concentration at the intercept. The increase in surface tension of the aqueous MIBC/NaCl mixture below the concentration of MIBC at the intersection seems to originate in a disturbance of the interfacial hydrogen bonding structure of the surface liquid water caused by Na+ ions acting at a distance and not by its presence on the interface.

Measurement and Correlation of Density, Viscosity, and Surface Tension for Imidazolium Bromide Ionic Liquids [CnMIM]Br (n = 2, 3, 4) Aqueous Solutions

The density, viscosity, and surface tension of aqueous solutions containing three imidazolium bromine ionic liquids (ILs) [CnMIM]Br with different alkyl chain lengths (n = 2, 3, 4) are determined within the temperature ranging from 283.15 to 343.15 K and at ambient pressure, respectively. The effect of the alkyl chain length of the imidazolium cation on the properties of the solutions is investigated. The experimental density and viscosity are satisfactorily described with the linear model and the Vogel–Tammann–Fulcher type equation, respectively. On the basis of the experimental data, the energy barrier and the surface entropy/enthalpy are calculated. The results show that the density and surface tension of aqueous ILs solution decrease and the viscosity increases with the increase of carbon atom number in imidazole ring carbon chain under the same conditions. The surface ordering in each aqueous solution follows [C2MIM]Br > [C3MIM]Br > [C4MIM]Br. The calculation of the molecular/ionic cluster interaction energy shows that there is a strong interaction between IL and water molecules, and the strong interaction between water and bromine ions is the main factor determining the properties of the solution. The data and results can provide a reliable support for the design and process calculation of chemical absorption cycle with water/IL working pairs.

The effect of preparation time and aeration rate on the properties of bulk micro-nanobubble water using hydrodynamic cavitation

Fundamental research on bulk micro-nanobubbles (BMNBs) has grown rapidly due to the demand for their industrial applications and potential role in interfacial sciences. This work focuses on examining properties of such bubbles, including the number, concentration, zeta potential, and surface tension in water. For this purpose, BMNBs were generated by the hydrodynamic cavitation (HC) mechanism. Distilled water and air in the experiments were the liquid and gas phases, respectively. The characterization of bulk microbubbles (BMBs) and bulk nanobubbles (BNBs) were performed through focused beam reflectance measurement (FBRM) and nanoparticle tracking analysis (NTA) techniques, respectively. Zeta potential and surface tension of aqueous solutions were measured at different time and aeration rates. The results showed that aeration rate and preparation time had an important role in the properties of BNBs (concentration, bubble size, and surface charge) and BMBs (number, and bubble size). The instability of BMBs led to the rapid changes in the dissolved oxygen (DO) content in the water. The number of BMBs decreased when preparation time and aeration rate increased, but their size remained constant. By enhancing the preparation time and aeration rate, the concentration of BNBs improved first and then reduced. Additionally, the surface tension of an aqueous solution containing BNBs was significantly lower than that of pure water.

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.

Prediction of Aqueous Solution Surface Tension of Some Surfactant Mixtures and Composition of Their Monolayers at the Solution—Air Interface

Measurements of the surface tension of the aqueous solution of SDDS mixture with fluorocarbon surfactants (FC) were carried out and considered in light of the surface tension of aqueous solutions of individual surfactants. Similar analyses were made for many other aqueous solutions of binary and ternary mixtures, taking into account the literature data of the surface tension of aqueous solutions of TX100, TX114, TX165, SDDS, SDS, CTAB, CPyB and FC. The possibility of predicting the surface tension of the aqueous solution of many surfactant mixtures from that of the mixture components using both the Szyszkowski, Fainerman and Miller and Joos concepts was analyzed. The surface tension of the aqueous solutions of surfactant mixtures was also considered based on the particular mixture component contribution to the water surface tension reduction. As a result, the composition of the mixed surface layer at the solution–air interface was discussed and compared to that which was determined using the Hua and Rosen concept. As follows from considerations, the surface tension of the aqueous solution of binary and ternary surfactant mixtures can be described and/or predicted.

Tensiometry as a Simple Analytical Method for Quantification of Solubility and Release of Aroma Molecules in Aqueous Media.

Dynamic tensiometry is shown to be a high-potential analytical tool in assessing physico-chemical characteristics of fragrance molecules, such as solubility limit, volatility as well as much rarely assessed interfacial activity of these amphiphilic molecules. Surface tension of aqueous solutions of selected essential oils has been measured as a function of time and fragrance concentration using maximum bubble pressure method. The effect of the temperature and saline solution on the rate of dissolution in water was assessed. Dynamic surface tension turned to be sensitive to the composition of fragrances, as demonstrated on examples of natural and synthetic mixtures. Furthermore, presented work reveals the possibility of maximum bubble pressure tensiometry method to quantify the amount of fragrance compositions in flavored salts, including the artificially aged carrier samples. Suggested here analytical approach can be used for the detection of the purity of essential oils, for the optimization of compositions and of the manufacturing processes of fragrances-containing products, as well as for the assessment of the release/evaporation of fragrances from carrier systems.

Effect of Surface Tension, Foaming Stabilizer, and Graphene Oxide on the Properties of Foamed Paste.

Foamed paste has attracted much attention because of its excellent thermal insulation performance and diverse applications in infrastructure projects. However, there are still some shortcomings hindering the further application of foamed paste, such as the low mechanical strength and the lack of effective methods to evaluate the properties of foaming bubbles. In this study, surface tension was used as the key parameter to characterize the properties of bubbles. A novel nanomaterial, graphene oxide was employed to enhance the mechanical strength of foamed paste, which was also effective in decreasing the surface tension of aqueous solution. A central composite design scheme was employed to evaluate the influence of three selected factors, surface tension, Sodium Phosphate/foaming reagents mass ratio, and graphene oxide/binder mass ratio, on the engineering properties of foamed paste. Additionally, mercury intrusion porosimetry and scanning electron microscope were employed to elucidate the structure of pores, X-ray diffraction and thermogravimetric analysis were employed to further analyze the hydration products at the microscopic scale. This study reveals that surface tension holds great potential in predicting the engineering properties or performances of foamed paste, and a new mechanism may be developed for explaining the influence of graphene oxide on the pore structure of cementitious materials by evaluating the surface tension of pore solution.

Surface Tension Measurements of Aqueous Liquid-Air Interfaces Probed with Microscopic Indentation.

To elucidate the intricate role that the sea surface microlayer (SML) and sea spray aerosols (SSAs) play in climate, understanding the chemical complexity of the SML and how it affects the physical-chemical properties of the microlayer and SSA are important to investigate. While the surface tension of the SML has been studied previously using conventional experimental tools, accurate measurements must be localized to the thickness of the air-liquid interface of the SML. Here we explore the atomic force microscopy (AFM) capabilities to quantify the surface tension of aqueous solution droplets with (sub)micrometer indentation depths into the interface. Sample droplets of hexanoic acid at molar concentrations ranging from 0.1 to 80 mM and SML from a recent wave flume study were investigated. A constant-radius AFM nanoneedle was used to probe ca. 200 μL droplets with 0.3-1.2 μm indentation depths. As a comparison, the surface tension of bulk samples was also measured using a conventional force tensiometer. The data for the hexanoic acid show an excellent overlap between the AFM and force tensiometer surface tension measurements. For the surface tension measurements of the SML, however, the measured values from the AFM were 2.5 mN/m lower than that from the force tensiometer, which was attributed to the structural and chemical complexity of the SML, differences in the probing depth for each method, and the time scale required for the surface film to restructure as the needle is retracted away from the liquid surface. Overall, the study confirmed the accuracy of the AFM method in quantifying the surface tension of aqueous solutions over a wide range of concentrations for surface-active organic compounds. The methodology can be further used to reveal small, yet important, differences in the surface tension of complex air-liquid interfaces such as liquid systems where the type and concentration of surfactants vary with the distance from the air-liquid interface. For such complex systems, AFM measurements of the surface tension as a function of the probing depth and pulling rate may reveal a sublayer film structure of the liquid interface.