Surface Tension Of Aqueous Solutions Research Articles

Effect of temperature on the surface properties of α,ω-amino acids in dilute aqueous solutions

In this work, experimental results for surface tension of aqueous solutions of 3-aminopropanoic acid, 4-aminobutanoic acid, 5-aminopentanoic acid and 6-aminohexanoic acid at T = (293.15, 298.15, 303.15 and 308.15) K at several concentrations are presented. The results were used to evaluate the limiting experimental slopes of surface tension with respect to mole fraction at each temperature. Surface tension measurements were taken using a LAUDA TVT-2 drop volume tensiometer with temperature control better than 0.1 K at T = (293.15, 298.15, 303.15 and 308.15) K The thermodynamic behavior of the aqueous α,ω-amino acid solutions is compared with that reported for α-amino acids in water. The surface behavior is discussed in terms of the effect of the hydrocarbon chain and the position of polar groups on water structure. The temperature dependence of the limiting slopes of surface tension with respect to mole fraction, derived from surface tension measurements, is discussed.

Surface tensions and densities of concentrated aqueous solutions of citric acid

Abstract Surface tensions of aqueous solutions of citric acid (unsaturated solutions and solutions with microcrystals) were measured in the temperature range from 283.15 K to 323.15 K. They were determined by the pendant drop method. Their values are compared with those that exist in the literature. Together with measured surface tensions, the corresponding densities were also determined by using an oscillating tube densimeter. Basing on measured densities and surface tensions, the parachor values and apparent molar volumes of aqueous citric acid solutions were calculated and discussed.

The molar surface Gibbs free energy and its application for aqueous solutions of ionic liquid N-butyl-pyridinium dicyanamide [C4py][DCA

The values of density and surface tension for aqueous solutions of [C4py][DCA] were determined from 0.01000 to 0.5000 mol kg−1 at T = (288.15–318.15) K. The values of the molar volume for aqueous solutions of [C4py][DCA], V, were calculated and increase with the increase in temperature and molarity. On the basis of a new thermodynamic function-molar surface Gibbs free energy, gs, a semi-empirical model for the IL solutions is proposed. It can be used to predict the surface tension, and the predicted values of the surface tension for aqueous [C4py][DCA] are in good agreement with the corresponding experimental ones. In terms of the concept of the molar surface Gibbs free energy, a new Eotvos equation is obtained. Each parameter of the new Eotvos equation has a clear physical meaning, energy dimension: the absolute value of slope is the mole surface entropy, s, and intercept is the molar surface enthalpy, h, which is temperature-independent.

Experimental Study on Foam Properties of Mixed Systems of Silicone and Hydrocarbon Surfactants

AbstractSilicone surfactants are inevitably involved in industrial applications in combination with hydrocarbon surfactants, but properties of the mixtures of silicone and hydrocarbon surfactants have received little attention, especially foam properties of the mixtures. In this study, aqueous solutions of respective binary mixtures of a nonionic silicone surfactant with anionic, cationic, and nonionic hydrocarbon surfactants were prepared for evaluation of their foam properties. Surface tension of aqueous solutions of the mixtures were measured with the maximum bubble pressure method. Foaming ability and foam stability of the mixtures were then evaluated with the standard Ross–Miles method. The findings show that the addition of the silicone surfactant results in a decrease in surface tension for aqueous solutions of the hydrocarbon surfactants. The critical micelle concentration (CMC) of the hydrocarbon surfactants is also changed by the additive silicone surfactant. Additionally, clear foam synergistic effects were observed in the mixtures of silicone and hydrocarbon surfactants, regardless of the ionic types of the hydrocarbon surfactant. The foam stability of the hydrocarbon surfactant was shown to generally improve with the increasing concentration of the silicone surfactant. Even so, aqueous solutions of different ionic hydrocarbon surfactants in the presence of the silicone surfactant will give different foam stabilities. The results of the present study are meant to provide guidance for the practical application of foams generated by the mixtures of the silicone and hydrocarbon surfactants.

Boiling heat transfer enhancement with surfactant on the tip of a submerged hypodermic needle as nucleation site

The addition of small concentration surfactant additive in pure water decreases the surface tension of aqueous solution considerably, and, critical micelle concentration (cmc) decides the limit of reduction in surface tension with increasing additive concentration. The objective of the present investigation is to study bubble growth in aqueous 2-Ethyl-1-Hexanol solution, and compare it with pure water experimentally. The bubble growth was studied at 880pmm concentration of 2-Ethyl-1-Hexanol which is critical micelle concentration (cmc). A single bubble was generated using the right angle tip of a hypodermic needle as a nucleation site. Bubble growth was studied using high speed camera operating at 1000 frames per second. The investigation was conducted at two values of heat fluxes to check the effect of heat flux on bubble growth. At low heat flux (q=20kW/m2), the bubble departure diameter was found to be almost equal for both water and aqueous surfactant solution. At high heat flux (q=100kW/m2), bubble departure diameter increases in water, but, decreases significantly in aqueous surfactant solution. The bubble release frequency was nearly equivalent for both solutions at low heat flux, but, increases for aq. surfactant solution at high heat flux, which indicates augmentation in boiling heat transfer.

A model to calculate concentration-dependent surface tension of binary systems

Surface tension for aqueous solutions of 1,2,3-Propanetriol, 2-Propanol, Ethylacetate, Dimethylacetamide, Dimethylformamide and 1-Butanol was measured as functions of composition using the method of Wilhelmy plate at 295.15, 300.15, 305.15, 310.15, and 315.15 K with emphasis on the dilute composition region. In this work, a modified model based on the thermodynamic definition of surface tension using Gibbs free energy was proposed. The well-known Wilson equation was applied to represent the excess Gibbs free energy of the system. Also, a four-parameter surface tension equation for a binary system was used. The accuracy of the model was evaluated using experimental data of 130 binary systems including polar, non-polar, aqueous and non-aqueous solutions reported in the literature and conducted in this work. The prediction performance of the model was compared with the studied models by calculating the mean relative standard deviation between the calculated and experimental values. According to the results, the new model reveals the best prediction among the other models.

Effects of osmolytes on solvent features of water in aqueous solutions

The solvatochromic solvent features of water (dipolarity/polarizability, π*, hydrogen bond donor acidity, α, and hydrogen bond acceptor basicity, β) of water have been determined in aqueous solutions of erythritol, glucose, inositol, sarcosine, xylitol and urea with concentrations from 0 to ~3 M and higher. The concentration effects of the osmolytes on the solvent features of water were characterized and compared with those reported previously for sorbitol, sucrose, trimethylamine N-oxide (TMAO), and trehalose. The solvent features of water in solutions of all osmolytes except TMAO and sarcosine were established to be linearly interrelated. It is shown that the concentration effects of essentially all nonionic osmolytes depend on osmolytes’ lipophilicity, molecular polarizability, and polar surface area. It is demonstrated that solubility of various compounds in aqueous solutions of glucose, sucrose, sorbitol, and urea of varied concentrations may be described in terms of solvent dipolarity/polarizability of water in these solutions. Surface tension of aqueous solutions of sucrose and sorbitol may also be described in the same terms. The relative permittivity of aqueous solutions of glucose and sucrose may be described in terms of the solvent hydrogen bond donor acidity of water. It is suggested that the effects of nonionic osmolytes on behavior of proteins and nucleic acids in aqueous media may be considered in terms of the altered solvent features of water instead of “nano-molecular crowding” effect.

Aggregate formation of glycyrrhizic acid

Abstract Glycyrrhizic acid is derived from the licorice root. The compound is amphiphilic with a large hydrophobic aglycone group, and two glucuronic acids and a carboxyl group constituting the hydrophilic part. Therefore, glycyrrhizic acid can form aggregates or lower the surface tension of aqueous solutions owing to its specific amphiphilic structure. The aqueous solubility of glycyrrhizic acid is relatively low (0.15 mM) and dependent on the solvent pH due to the weak acidity resulting from the carboxylic groups. Glycyrrhizic acid is quite soluble in a buffer solution at pH 4.5, and its ability to affect the surface tension of the buffer solution increases from pH 5. The critical micelle concentration (cmc) was estimated to be 2.9 mM (γ cmc = 55.2 mN/m) and 5.3 mM (γ cmc = 56.8 mN/m) at pH 5 and 6, respectively. The surface tension also decreased gradually at pH 7, but the critical point was not observed in the curve. At pH 7, the pyrene fluorescent probe method and light scattering measurements did not show a clear cmc. Small angle X-ray scattering experiments revealed that the aggregates were rod-like micelles with an estimated radius and length of 1.5 nm and 21 nm, respectively, at 5 mM in a pH 5 solvent. Transmission electron microscopy confirmed that glycyrrhizic acid forms rod-like micelles. These results suggest that glycyrrhizic acid has potential applications as a biosurfactant in various fields.

Synthesis and study of nonionic surfactants based on propylene oxide and lauric acid

Nonionic surfactants were synthesized at various molar ratios of propylene oxide and lauric acid. Propoxylation products were identified by a number of physico-chemical analytical methods. The tensiometric method was used to measure the surface tension of aqueous solutions of the products at interface with air, find their high surface activity, and determine certain colloidal-chemical parameters (critical micelle concentration, surface pressure, maximum adsorption, minimum cross-sectional area of a molecule, change in the Gibbs free energy in micelle-formation and adsorption processes). Laboratory studies of the oil-collecting capacity of these substances were carried out for the example of a thin oil film on the surface of water with varied degree of mineralization.

The Density and Surface Tension of Aqueous Solutions of Propionate Ionic Liquids: [C4mim][Pro] and [C6mim][Pro] at Different Temperatures

The propionate acid ionic liquids, 1-alkyl-3-methylimidazolium propionate [C4mim][Pro] and [C6mim][Pro] were prepared by the neutralization method and characterized by 1H NMR spectroscopy and differential scanning calorimetry. The values of density and surface tension of aqueous [C4mim][Pro] and [C6mim][Pro] with various molalities were determined at different temperatures, and the coefficient of thermal expansion, the apparent molar volume and the parachor for these solutions were calculated. The values of the apparent molar expansibility of the solute obtained from data of the apparent molar volume are in good agreement with the values calculated by the Harned–Owen equation. An empirical equation for prediction of surface tension for aqueous [C4mim][Pro] and [C6mim][Pro] was put forward and the values of the surface tension predicted by the empirical equation are very similar and highly correlated with the corresponding experimental values and the results predicted by the parachor semi-empirical method for solutions.

Surface tension of water and C10EO8 solutions at the interface to hexane vapor saturated air

The drop profile method is used to study the influence of hexane vapor in the air atmosphere on the surface tension of water. It was shown that the results depend essentially on the air humidity. At the interface with dry air a fast and strong decrease of surface tension was observed. In humid air and in a measurement cell filled with water, the process is slower and the resulting surface tension is higher. The experimental conditions are defined at which stable results can be measured.A new theoretical model is developed to describe the influence of alkane vapor in the gas phase on the surface tension of aqueous solutions of the reorientable surfactant C10EO8. This model assumes that a first interfacial layer is composed by surfactants mixed with alkane, and a second layer which is formed by alkane only. The experimental equilibrium surface tension data for the studied C10EO8 solutions agree very well with those calculated from the given model.

マイクロ波照射中のイオン液体を含む水溶液の表面張力

Surface tension of any fluid is crucial for multiphase systems and is often manipulated during industrial processes by introducing surfactants. Normally, water used in an industry includes impurity such as salt. In this study, effect of sodium chloride concentrations, microwave power and time on surface tension of aqueous solution was investigated under microwave irradiation. It has found that surface tension decreased quickly, while temperature increased during microwave. Once the radiation is turned off, the temperature returns rapidly as expected. However, surface tension recovery was much slower than temperature. Moreover, the recovery and reduction amounts by non-thermal effect depend on the power and concentrations.

A09 マイクロ波照射による各種水溶液の表面張力の特異挙動(口頭発表)

A09 マイクロ波照射による各種水溶液の表面張力の特異挙動(口頭発表)

Synthesis and aggregation behaviors of tail-branched surfactant Guerbet-cetyl trimethyl ammonium chloride

A novel cationic surfactant Guerbet-cetyl trimethyl ammonium chloride (G-CTAC) was synthesized by combining several traditional synthetic processes in laboratory. The molecular structure of G-CTAC was characterized by Fourier transform infrared (FT-IR) spectra and proton nuclear magnetic resonance (1HNMR). This new amphiphile exhibited excellent performances in aqueous solution, which was investigated by surface tension measurement, contact angle on parafilm, particle size of aggregates, transmission electron microscopy (TEM), emulsifying experiments, and antistatic tests. It was found that the new quaternary ammonium compound could effectively decrease the surface tension of aqueous solution to 26.2 mN m−1 with the critical micelle concentration (CMC) being 5.9 mmol L−1. In addition, the cationic surfactant synthesized could efficiently decrease the contact angle of aqueous solution on paraffin surface. We suppose that these unique properties are attributed to the presence of the branching Guerbet-cetyl being hydrophobic group in the molecule. Moreover, according to TEM observations, this quaternary ammonium compound was inclined to aggregate into vesicles spontaneously without induction of any other additives in aqueous solution. Antistatic tests and emulsifying experiments were also conducted to explore the potential applications of this new material.

Effect of frothers and dodecylamine on bubble size and gas holdup in a downflow column

Bubble size and gas holdup were characterized in a two phase gas–water system in a laboratory downflow column. The effect of the cationic surfactant dodecyl amine (MW 185, HLB 10.7) and the frothers MIBC (MW 102, HLB 6.05) and polyglycol F507 (MW 425, HLB 8.63) on the bubble size and gas holdup were investigated. In addition, the effect of blends of MIBC-dodecyl amine (DDA) and F507-DDA on these parameters was assessed. The bubble Critical Coalescence Concentration (CCC) followed the order MIBC>DDA>F507. When blending the frothers with DDA at a concentration below its CCC, the frother CCC decreased and bubbles of finer size were obtained below and above the frother CCC. Static surface tension measurements of aqueous solutions with frothers and DDA as well as with frothers-DDA blends show coadsorption of DDA at the air/aqueous solution interface. The surface tension of aqueous solutions prepared with the blends decreased with the addition of DDA and varied linearly with the frother concentration within the concentration range studied. The gas holdup in the downflow column was determined by the bubble size and decreased with the bubble size. It is shown that frother-DDA blends gave the lowest gas holdup in the downflow column. This work is relevant for the reverse flotation of quartz from iron ores using amine collectors in cells with downflow systems.

Dynamic surface tension of С10ЕО8 at the aqueous solution/hexane vapor interface as measured by bubble pressure tensiometry

Abstract The dynamic surface tension of aqueous solutions of C10EO8 at the interfaces with air and saturated hexane vapor was measured by the maximum bubble pressure tensiometer BPA for adsorption times t ≥ 0.01 s. It can be shown that the dynamic surface pressure of C10EO8 solutions in a saturated hexane atmosphere increases at short adsorption times with increasing surfactant concentration. The theory of diffusion controlled adsorption of two surfactants from the water and gas phases, respectively, was used for data analysis. The obtained experimental results agree with a model based on a reorientation of the C10EO8 molecules, assuming a strong intermolecular interaction between hexane and C10EO8 molecules in the surface layer. Alternatively, an additional enhancement of C10EO8 adsorption activity can be assumed due to the presence of hexane molecules at the interface.

Methylcellulose, a Cellulose Derivative with Original Physical Properties and Extended Applications

This review covers the preparation, characterization, properties, and applications of methylcelluloses (MC). In particular, the influence of different chemical modifications of cellulose (under both heterogeneous and homogeneous conditions) is discussed in relation to the physical properties (solubility, gelation) of the methylcelluloses. The molecular weight (MW) obtained from the viscosity is presented together with the nuclear magnetic resonance (NMR) analysis required for the determination of the degree of methylation. The influence of the molecular weight on the main physical properties of methylcellulose in aqueous solution is analyzed. The interfacial properties are examined together with thermogelation. The surface tension and adsorption at interfaces are described: surface tension in aqueous solution is independent of molecular weight but the adsorption at the solid interface depends on the MW, the higher the MW the thicker the polymeric layer adsorbed. The two-step mechanism of gelation is confirmed and it is shown that the elastic moduli of high temperature gels are not dependent on the molecular weight but only on polymer concentration. Finally, the main applications of MC are listed showing the broad range of applications of these water soluble cellulose derivatives.

E122 マイクロ波照射による電解質水溶液の表面張力の特異挙動(OS-11:熱物性)

E122 マイクロ波照射による電解質水溶液の表面張力の特異挙動(OS-11:熱物性)

Adsorption Mechanism of Lignosulfonate at the Air/Liquid Interface

Lignosulfonate is a type of natural polymer surfactant. Its capability to reduce the surface tension of aqueous solution depends on its adsorption configuration at the air/liquid interface. The dynamic surface tension, the air/liquid interfacial film properties of lignosulfonate at different solution concentrations, pH values and ionic strengths had been measured in the present work. The results showed that the adsorption equilibrium of lignosulfonate at the air/liquid cannot be achieved in a short period; the diffusion coefficient of lignosulfonate from the liquid to the air/liquid interface decreased with the increasing of pH value, while it increased with the increasing of ionic strength. Lignosulfonate could form soluble monomolecular film at the air/liquid interface, whereas the film was unstable. The stability of lignosulfonate monomolecular film became poor with the increasing of solution concentration, ionic strength and decreasing of pH value. Combining with our previous research results, the adsorption mechanism of lignosulfonate at the air/liquid interface was proposed.

증점제를 함유한 미분무수의 목재화재 소화효과

Viscosity agents were added to water to improve extinguishing performance of low pressure water mist suppression system on wood cribs fire, and a small scale wood cribs fire experiment was conducted to measure the extinguishing performance. CMC and agar were used for viscosity agent and as the amount of viscosity agent enlarges, it showed the increase of the viscosity of aqueous solution and the decrease of the fluidity. On wood cribs fire experiment, the extinguishing efficiency was improved with supplemental viscosity agent as it enhanced the adhesive time of aqueous solution on the wood, and therefore expanded the contact time of fire surface. The surface tension of aqueous solution was decreased with the addition of agar which to be assumed as an increase factor of extinguishing efficiency. By the extinguishing experimental result, the most effective extinguishing agent was CMC 0.6 wt.%, with the flame suppression time and the extinguishing time were reduced by 70s and 93s respectively at this concentration.