Critical Surface Tension Values Research Articles

Green Synthesis, Surface Activity, Micellar Aggregation, and Foam Properties of Amide Quaternary Ammonium Surfactants.

A series of amide quaternary ammonium surfactants with the formula C n H2n+1CONH(CH2)2N+(CH3)3·CH3CO3 - (n = 9, 11, 13, 15) were synthesized using a fatty acid, N,N-dimethylethylenediamine, and a green reagent dimethyl carbonate. A comparative study of the four surfactants in terms of surface activity, aggregation characteristics, and foam properties was conducted. The results show that these amide quaternary ammonium surfactants reduce the surface tension of water to a minimum value of 23.69 mN·m-1 at a concentration of 1.55 × 10-4 mol·L-1 and self-assemble spontaneously into aggregates, which are mostly vesicles. Furthermore, with increasing the alkyl chain length, their critical micelle concentration (CMC) values and surface tension values at the CMC (γCMC) decrease and then increase, and the degree of counterion binding (β) decreases. It is also found that these amide quaternary ammonium surfactants exhibit excellent foam ability and foam stability.

Thermophysical property prediction of biodiesel mixtures at extreme conditions using molecular dynamics simulation

Liquid biofuels such as biodiesel are playing an increasing role in renewable energy utilisation, but accurate predictions of fuel properties at extreme conditions remain challenging. In this study, molecular dynamics (MD) simulation with classical force field is performed to obtain the thermophysical properties of biodiesel over extended ranges of temperatures and pressures. The predicted properties include the critical temperature, critical density, critical pressure, surface tension, viscosity, thermal conductivity and diffusion coefficient. The specific MD setup for fuel thermophysical property prediction is examined. It is observed that the long-range dispersion interaction is essential to accurately predicting the surface tension, and averaging over a sufficient number of independent replication simulations is required to eliminate the statistical error when using the Green-Kubo method for viscosity calculation. The reliability of MD approach is validated against experimental data at normal temperature and pressure. The equilibrium MD simulation has an advantage over nonequilibrium MD simulation when building databases of fuel properties. Moreover, the properties of biodiesel are compared with conventional diesel to elucidate the effects of fuel composition and molecular structure of the fuel surrogates on fuel thermophysical properties. For biodiesel utilisation, higher values of critical temperature, surface tension and viscosity, lower diffusivity together with the increased aggregation tendency in bath gas indicate the needs of further optimisation of injection system to achieve the desired mixing in combustion applications.

Interfacial properties of nonionic hybrid surfactant with double branches of fluorocarbon and hydrocarbon

To obtain superior surface-active properties while minimizing environmental risks, new fluorinated surfactants (F2HX-nEO) were designed to include a hybrid multi-chain with a short fluorocarbon (–CF2CF3) and nonionic ethylene oxide. They were simply synthesized by a straightforward reaction involving the addition of ethylene oxide to a hybrid fluorine alcohol, and their surface-active properties were optimized by controlling the hydrocarbon length and number of ethylene oxide units. Therefore, the desirable values of critical micelle concentration (0.3 mmol/L) and surface tension (24.3 mN/m) were obtained in spite of containing the short fluorocarbon chain. Particularly, F2HX–nEO showed excellent wetting properties on hydrophobic surfaces and very low toxicity level, which can be used in various fields as a promising alternative to long fluoroalkyl chain surfactants.

Energy characteristics of sands of deposits in the Ivanovo region

It is proposed to use the energy potential of rock-forming minerals obtained in the process of rock synthesis as an energy criterion for ranking raw materials for the production of construction materials. The energy of atomization and its specific values calculated based on the principles of crystal energy are used as a quantitative parameter. The estimation of two deposits of sands of the Ivanovo region on energy of atomization, specific mass energy of atomization, specific volume of energy of atomization (energy density) is carried out. It was found that, despite the difference in the chemical, mineral composition and origin of rocks, macroenergy parameters have similar values. The energy density value allows classifying the considered sands as high-energy-dense. The possible level of use of this energy reserve due to mechanical crushing of raw material is established. Quantifying potential energy of the system that fallen after crushing the material in the surface was carried out based on the values of critical surface tension and specific surface area of raw materials (formed after the process of mechanical grinding). The level of possible use of the potential energy reserve due to the formation of a new material surface was characterized by the activity of the surface of fine samples. The obtained values of surface tension and surface activity showed that the sands of the Nekhtskoe deposit, in comparison with the sands of the Khromtsovskoye deposit, are preferable to be used as an active fine-dispersed component for obtaining binding compositions.

Monolayer Nanoparticle‐Covered Liquid Marble Production with Low Surface Tension Liquids

AbstractAs an emerging droplet system, monolayer nanoparticle‐covered (mNPc) liquid marbles have shown fascinating properties and application values. Their formation process has been clear, but liquid availability for production has yet to be clarified. This study addresses this issue from the angle of surface tension, revealing critical surface tension and contact angle values for mNPc liquid marble production with both rolling and compression methods. Water‐ethanol and water‐surfactant systems are employed as testing liquids. With irreversible pinning as criterion, critical surface tension values that allow mNPc liquid marble formation are obtained with the two kinds of liquids, forming ranges from 38.6 to 31.8 mN m−1, and from 36.7 to 27.6 mN m−1, for the rolling and compression methods, respectively. Correspondingly, contact angles in the ranges from 132° to 126° and from 116–124° are regarded as the lower limits for mNPc liquid marble production with the rolling and compression methods, respectively. In addition, rupture and deformation behaviors under low surface tension are systematically investigated and a depinning approach that facilitates marble formation is proposed. This study could provide important guidance for various applications that require low surface tension liquids to produce mNPc liquid marbles.

Effect of carbon chain lengths of cationic surfactant on inhibition rate of acid-rock reaction

Reduce the rate of acid-rock reaction is a key problem in the acidizing field. In order to reduce the damage of adsorption of traditional gelled acid in carbonate porous media, and further reduce its damage to permeability of dense carbonate rock after stimulation. Cationic surfactants can change the surface properties of rocks and control the contact area between H+ and rock surface. In order to explore the effect of different carbon chain lengths of cationic surfactants on retarding properties of acid-rock reaction, the critical micelle concentration(Ccmc) and critical surface tension value(γcmc) of seven different carbon chain lengths of cationic surfactants are determined. The results indicate that Ccmc decreases significantly with the increasing of carbon chain length. The adsorption morphology of CnTAC(n = 8,10,12,14,16,18,22) species at the solid-solution interfaces is dominated by monolayer. On negatively charged calcite surface, a large number of cationic species RNH3+ can easily adsorb on abundant CO32− sites, which causes a significant increase of zeta potential for calcite. Meanwhile, the wettability of hydrophilic solid surface is modified from strongly hydrophilic to weakly hydrophilic after adsorption to control the surface rate of acid-rock reaction. The acid solution with a concentration of 1.02 × 10−2 mol/L C14TAC has the best retarded performance which the retardation rate is 71.01%. This research is helpful to understand the retarding performance of surfactant, improving the retarded acid system and the effect of carbonate reservoir stimulation.

Aggregation Behavior of Polyether Based Siloxane Surfactants in Aqueous Solutions: Effect of Alkyl Groups and Steric Hindrance.

A series of polyether based siloxane surfactants with different branched chain and alkyl groups were synthesized by thiol-ene reaction and Piers-Rubinsztajn reaction. The effect of the siloxane structures (alkyl groups and branched chains) on the adsorption and aggregation behavior in aqueous solution was investigated by surface tension, fluorescence, dynamic light scattering (DLS), freeze-fracture transmission electron microscopy (TEM), and TEM. The molecular structures of siloxane can obviously influence their surface activities and thermodynamics. Replacing the methyl of trimethylsiloxyl groups with longer alkyl groups (ethyl, propyl, and butyl) and branching trimethylsiloxyl resulted in an obvious decrease of the values of critical micelle concentration (CMC) and surface tension at CMC (γCMC). Dense surface films packed with CH3 groups result in the lower surface tensions being disordered by longer alkyl groups or branched chains of siloxane hydrophobic groups. And the minimum surface area per surfactant molecule ( Amin) values of Si3-PG, Et-Si3-PG, Pro-Si3-PG, and But-Si3-PG successively decrease about 3.5 Å with each increasing -CH2- group. All polyether based siloxane surfactants can form nonuniform size spheroidal aggregates in aqueous solution. Concerning the driving force, the micellization process was spontaneous but less spontaneous compared with adsorption.

The surface characteristics of biopolymer-coated tomato and cucumber epicarps: effect of guar, Persian and tragacanth gums

The present study introduces guar gum (GG), tragacanth gum (TG) and Persian gum (PG) as novel potential coating materials for fruits and vegetables. Coating solutions of these gums were prepared at different concentrations and their surface properties for coating cucumber and tomato were investigated. Results showed that tomato and cucumber epicarps were both low-energy surfaces with surface tensions of 35.86 and 34.33 mN/m, respectively. The polar and dispersive components of tomato surface were determined to be 6.86 and 27.47 mN/m, respectively. For cucumber, these parameters were estimated to be 2.45 and 33.42 mN/m, respectively. The critical surface tension values for tomato and cucumber were calculated to be 20.73 and 26.27 mN/m, respectively. The surface tension values of gum solutions were found to be in the order of GG > TG > PG. The adhesion (Wa) and cohesion (Wc) coefficients of the gum solutions varied in the ranges of 70.99–77.06 and 86.66–141.81 mN/m, respectively. At all gum concentrations, the spreading coefficient (Ws) changed in the order of GG 0.91). The apparent viscosities of the gum solutions altered in the order of TG (46.35–2584.72 mPa s) > GG (30.05–884.2 mPa s) > PG (8.18–49.45 mPa s) over the studied concentration range (0.01–1%).

Synergistic Interaction and Aggregation Behavior in a Mixture of a Tripolar Zwitterionic Surfactant and an Anionic Surfactant

AbstractThe aggregation behavior of a tripolar zwitterionic surfactant (C14C6Tri) with sodium dodecyl sulfate (SDS) in aqueous solution at various molar fractions was investigated using surface tension, turbidity, dynamic light scattering, ζ potential, and cryogenic transmission electron microscopy. The C14C6Tri carries 2 cationic ammonium headgroups and 1 anionic sulfonate headgroup, and the 2 ammonium headgroups are linked by a 6‐methylene chain while the sulfonate group is connected with one of the ammonium headgroups by a 3‐methylene chain. The surface activity parameters, the composition of mixed micelles, and the interaction parameter (β) were evaluated using an ideal mixing model and the regular solution model. The strong synergistic effect between C14C6Tri and SDS leads to a striking reduction in the critical micellar concentration and surface tension values. Both the interaction parameters at the air–water interface (βσ) and in the mixed micelles (β m) are large negative values. Moreover, the aggregate structures of the C14C6Tri/SDS mixture can be regulated by changing the molar fraction and the concentration. Upon increasing the molar fraction of SDS, the aggregate transitions take place from spherical micelles to vesicles, rod‐like micelles, and spherical micelles at a total surfactant concentration of 2.00 mM, while only small spherical micelles exist as the total surfactant concentration increases to 20.00 mM. The large headgroup, multi‐binding sites and variable conformation of C14C6Tri are responsible for the abundant aggregation behaviors.

Energy characteristics of finely dispersed rock systems

In their genesis, rocks accumulate their energy potential – free energy of rock-forming minerals and the rock in general that is an important criterion of raw material genetic classification for construction materials production. The free energy value for the macrostate of a substance (rock) is atomization energy. The critical surface tension value can be used as an energy characteristic for destroyed rock in a finely dispersed state. If condensed phase surfaces carry no significant electrostatic charge, then main surface forces that determine the interaction between solids are dispersion ones evaluated by the Hamaker constant value. These energy parameters can enable forecasting various physical and mechanical properties of minerals and rocks and thereby increase the efficiency of construction materials production where synthesis is based on the complete rock destruction. Since compared chemical compositions of minerals forming rocks revealed a predominant silicon dioxide content in them, the aim of this paper was to establish a possible relationship between the silicon dioxide content and energy characteristics for finely dispersed rock systems of various genetic types. The selected objects of research were different genesis rocks typically used in the construction materials industry and quartz as a main rock-forming mineral. Test samples of rocks in a finely dispersed state were obtained by dry milling. It is established that an increase in silicon dioxide content in the limestone – quartz series leads to higher atomization energy, specific mass atomization energy and free surface energy with intensified dispersion interaction between particles evaluated by an increase in the Hamaker constant.

Production of massoia lactone by Aureobasidium pullulans YTP6-14 isolated from the Gulf of Thailand and its fragrant biosurfactant properties.

In order to add to the existing knowledge about structural diversity of biosurfactants, marine environment was chosen to discover a new type of biosurfactant-producing fungus. A number of fungi were collected from the Gulf of Thailand and examined for biosurfactant productivities. A dimorphic fungus, Aureobasidium pullulans YTP6-14, produced several different biosurfactants in both heavy oil and aqueous layers of the culture. Surface tension of the aqueous layer was decreased to 31·4mNm-1 and oil displacement area reached 53cm2 /10μl after 7days of cultivation. Critical micelle concentration and minimum surface tension values of the crude biosurfactants prepared from the aqueous layer were 39mgl-1 and 31·6mNm-1 respectively. Surface tension values remained unchanged over a wide range of pH and NaCl concentrations, suggesting their nonionic feature. LC/MS and NMR analyses revealed that one of the main active compounds in the aqueous layer was 5-hydroxy-2-decenoic acid delta-lactone, known as massoia lactone. Massoia lactone indeed showed significant surface tension reduction capacity of 43·3mNm-1 at 1mgml-1 . This is the first report for the production of a fragrant biosurfactant, massoia lactone by a fungus A.pullulans. Massoia lactone has been industrially prepared from aromatic bark of an endangered tree species, Cryptocarya massoy, growing in rainforests. This report expands the diversity of biosurfactants produced by A. pullulans and also points to its possibility in contributing to the green sustainable chemistry, and ultimately rainforest conservation.

Synthesis and properties of polyester-based polymeric surfactants from diterpenic rosin

A series of polymeric surfactants, poly acrylic acid rosin polyethylene glycol esters (P-AAR-PEG), have been synthesized from natural diterpenic rosin. Their structures were characterized by Fourier Transform Infrared Spectrometer (FTIR) and their molecular weights were characterized by Gel Permeation Chromatography (GPC). Their critical micelle concentration (CMC), surface tension (γCMC), foaming property (FP), and hydrophile-lipophile balance (HLB) value were evaluated. Their thermal properties were measured by Thermal Gravimetric Analyzer (TGA) and fluid behaviors were studied by Rotational Rheometer. The influence of concentration on the properties of oil-in-water emulsions was examined and contrasted the stability of emulsion by the mean droplet size between day1 and day7. The weight-average molecular weight of P-AAR-PEG ranged from 1770 to 5071. CMC values of P-AAR-PEG were ranged from 0.33 to 0.87g/L and the corresponding γCMC values were ranged from 37.8 to 39.1mN/m respectively. Their CMC and γCMC values decreased and then increased with the increment of molecular weight of hydrophile group. Rheological measurements indicated that the P-AAR-PEG solutions changed from pseudoplastic property to Newtonian with increasing shear rate. P-AAR-PEG1000 had good emulsion ability to turpentine in water. When the concentration of P-AAR-PEG1000 was 8wt%, the emulsion remained stable for more than 7days.

Synthesis and properties evaluation of sulfobetaine surfactant with double hydroxyl

A series of sulfobetaine surfactants {N-[(3-alkoxy-2-hydroxyl)propoxy] ethyl-N,N-dimethyl-N-(2-hydroxyl)propyl sulfonate} ammonium chloride were synthesized with raw materials containing linear saturated alcohol, N,N-dimethylethanolamine, sodium 3-chloro-2-hydroxyl propane sulfonic acid and epichlorohydrin. The molecule structures of sulfobetaine surfactants were characterized by FTIR, 1HNMR and elemental analysis. Surface tension measurements can provide us information about the surface tension at the CMC (γCMC), pC20, Γmax and Amin. The pC20 values of sulfobetaine surfactants increase with the hydrophobic chain length increasing. Amin values of the surfactants decrease with increasing hydrophobic chain length from 10 to 14. The critical micelle concentration (CMC) and surface tension (γCMC) values of the sulfobetaine surfactants decrease with increasing hydrophobic chain length from 10 to 16. The lipophilicity of surfactant was enhanced with the increase of the carbon chain, however, the ability of anti-hard water was weakened. The minimum oil/water interfacial tension of four kinds of sulfobetaine surfactants is 10−2–10−3 mN/m magnitude, which indicates that the synthesized bis-hydroxy sulfobetaine surfactants have a great ability to reduce interfacial tension in the surfactant flooding system. The surface tension (γCMC) values of synthesized surfactants were lower compared with conventional anionic surfactant sodium dodecyl sulfonate.

Synthesis of Fluorinated Polymers and Evaluation of Wettability.

Two kinds of fluorinated polymers were synthesized: an acrylate polymer having a fluorinated triethylene glycol as a pendant group (2a) and a fluoroalkyl acrylate polymer (2b). The contact angle of these fluorinated polymers against water, non-fluorinated alcohols and fluorinated alcohols were evaluated. As compared with the fluoroalkyl polymer (2b), fluoroethylene glycol polymer (2a) showed smaller contact angle against water and non-fluorinated alcohols. This supports the proposition that changing the alkyl chain into the ethylene glycol-type chain gave some interaction between etheric oxygen and water or non-fluorinated alcohols. In addition, fluoroalkyl acrylate polymer (2b) showed remarkably low values of critical surface tension.

How To Functionalize Ceramics by Perfluoroalkylsilanes for Membrane Separation Process? Properties and Application of Hydrophobized Ceramic Membranes.

The combination of microscopic (atomic force microscopy and scanning electron microscopy) and goniometric (static and dynamic measurements) techniques, and surface characterization (surface free energy determination, critical surface tension, liquid entry pressure, hydraulic permeability) was implemented to discuss the influence of perfluoroalkylsilanes structure and grafting time on the physicochemistry of the created hydrophobic surfaces on the titania ceramic membranes of 5 kD and 300 kD. The impact of molecular structure of perfluoroalkylsilanes modifiers (possessing from 6 to 12 carbon atoms in the fluorinated part of the alkyl chain) and the time of the functionalization process in the range of 5 to 35 h was studied. Based on the scanning electron microscopy with energy-dispersive X-ray spectroscopy, it was found that the localization of grafting molecules depends on the membrane pore size (5 kD or 300 kD). In the case of 5 kD titania membranes, modifiers are attached mainly on the surface and only partially inside the membrane pores, whereas, for 300 kD membranes, the perfluoroalkylsilanes molecules are present within the whole porous structure of the membranes. The application of 4 various types of PFAS molecules enabled for interesting observations and remarks. It was explained how to obtain ceramic membrane surfaces with controlled material (contact angle, roughness, contact angle hysteresis) and separation properties. Highly hydrophobic surfaces with low values of contact angle hysteresis and low roughness were obtained. These surfaces possessed also low values of critical surface tension, which means that surfaces are highly resistant to wetting. This finding is crucial in membrane applicability in separation processes. The obtained and characterized hydrophobic membranes were subsequently applied in air-gap membrane distillation processes. All membranes were very efficient in MD processes, showing good transport and selective properties (∼99% of NaCl salt rejection). Depending on the membrane pore size and used modifiers, the permeate flux was in the range of 0.5-4.5 kg·m(-2)·h(-1) and 0.3-4.2 kg·m(-2)·h(-1) for 5 kD and 300 kD membranes, respectively.

Gamma processes of shear flocculation, oil agglomeration and liquid–liquid extraction

Gamma flotation process is characterized by emphasis on the control of solution surface tension and the separation of minerals in suspension with this technique is based on the differences in wettability of minerals. The wettability properties of mineral surfaces can be defined in terms of their values of critical surface tension of wetting (γc) as a quantifying parameter, which is an essential property to achieve selectivity in surface chemistry-based separation processes. That is, the gamma flotation technique utilizes the differences in the critical surface tension of wetting (γc) of minerals. Similar to the flotation method, shear flocculation, oil agglomeration and liquid–liquid extraction processes also utilize differences in wettability of minerals. Therefore, the separations of minerals by the control of surface tension in the shear flocculation, oil agglomeration and liquid–liquid extraction methods can be provided. In this study, the separations of some minerals with these processes have been investigated by using the control of the solution surface tension and the successful results could be reached. Consequently, these new separation processes have been defined as ‘gamma shear flocculation’, ‘gamma oil agglomeration’ and ‘gamma liquid–liquid extraction’.

Bubble point pressures of binary methanol/water mixtures in fine‐mesh screens

Binary methanol/water mixture bubble point tests involving three samples of fine‐mesh, stainless steel screens as porous liquid acquisition devices are presented in this article. Contact angles are measured as a function of methanol mass fraction using the Sessile Drop technique. Pretest predictions are based on a Langmuir isotherm fit. Predictions and data match for methanol mole fractions greater than 50% when pore diameters are based on pure liquid tests. For all three screens, bubble point is shown to be a maximum at a methanol mole fraction of 50%. Model and data are in disagreement for mole fractions less than 50%, which is attributed to variations between surface and bulk fluid properties. A critical Zisman surface tension value of 23.2 mN/m is estimated, below which contact angles can be assumed to be zero. Solid/vapor and solid/liquid interfacial tensions are also estimated using the equation of state analysis from Neumann and Good. Published 2013 American Institute of Chemical Engineers AIChE J 60: 730–739, 2014

The wetting of powders of acetylsalicylic acid, salicylic acid, phenacetin and paracetamol.

The wetting of powders of acetylsalicylic acid, salicylic acid, phenacetin and paracetamol has been assessed using methanol--water mixtures to give a range of surface tensions. The results have been interpreted in terms of the critical surface tension, adhesion tension and spreading coefficients. The critical surface tension values are surprisingly low which may be due to adsorption of the methanol at the solid surface, exposing its CH3 group to the liquid. The adhesion tension and spreading coefficient values could be useful guides in formulation.

Correlation of Flocculation and Agglomeration of Dolomite with its Wettability

Wettability is an important parameter which affects the shear flocculation and oil agglomeration behaviors of minerals. The critical surface tension of wetting (γc) as a wettability parameter describes wetting characteristics of any mineral. In this study, the correlation of shear flocculation and oil agglomeration processes of dolomite with its wettability parameter is investigated. The experimental studies have indicated that these processes improved with decreasing wettability depending on the increase of oleate adsorption despite a simultaneous increase in the zeta potential of dolomite. On the other hand, the flocculation and agglomeration of dolomite decreased with decreasing surface tension and did not occur below a particular value of surface tension, corresponding to the critical surface tension of wetting (γc) and the critical solution surface tension (γc-a) values, respectively. Also, the γc-a values are slightly higher than the γc values, indicating that the agglomeration of the particles requires a lower wettability.

Evaluation of Surface Free Energy of Various Fruit Epicarps Using Acid–Base and Zisman Approaches

Surface free energy (SFE; γSV) of 16 fruit epicarps present on the Chilean market was calculated by two approaches: the acid–base and Zisman. The results show that the fruit epicarps were low surface energy since the magnitude of γSV falls within a narrow range, between 37 and 44 mJ m − 2. Zisman approach gave a critical surface tension values, γcr lower than the SFE calculated by the acid–base approach. Significant differences in SFE between the fruits may be explained by the variation in the chemical composition of epicuticular waxes. The polar (\(\gamma^{\rm AB}_{\rm SV}\)) and apolar (\(\gamma^{\rm LW}_{\rm SV}\)) components of the SFE were also calculated and a mathematical relation was between both values was found. Values of \(\gamma^{\rm AB}_{\rm SV}\) and \(\gamma^{\rm LW}_{\rm SV}\) could also be associated with the fruit family and the tissue origins in the ovary region. Finally, it has been shown that fruit epicarps exhibited predominantly electron-donator behaviour since \(\gamma_{\rm SV}^- > \gamma_{\rm SV}^+\). We believe that the results reported here can potentially impact in food engineering because the compatibility of coatings and fruit epicarps depends on the interaction of their respective chemical and physical properties.