Determination Of Surface Tension Research Articles

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.

Non-invasive high throughput approach for protein hydrophobicity determination based on surface tension.

The surface hydrophobicity of a protein is an important factor for its interactions in solution and thus the outcome of its production process. Yet most of the methods are not able to evaluate the influence of these hydrophobic interactions under natural conditions. In the present work we have established a high resolution stalagmometric method for surface tension determination on a liquid handling station, which can cope with accuracy as well as high throughput requirements. Surface tensions could be derived with a low sample consumption (800 μL) and a high reproducibility (<0.1‰ for water) within a reasonable time (3.5 min per sample). This method was used as a non-invasive HTP compatible approach to determine surface tensions of protein solutions dependent on protein content. The protein influence on the solutions' surface tension was correlated to the hydrophobicity of lysozyme, human lysozyme, BSA, and α-lactalbumin. Differences in proteins' hydrophobic character depending on pH and species could be resolved. Within this work we have developed a pH dependent hydrophobicity ranking, which was found to be in good agreement with literature. For the studied pH range of 3-9 lysozyme from chicken egg white was identified to be the most hydrophilic. α-lactalbumin at pH 3 exhibited the most pronounced hydrophobic character. The stalagmometric method occurred to outclass the widely used spectrophotometric method with bromophenol blue sodium salt as it gave reasonable results without restrictions on pH and protein species.

Evaporation of aqueous solutions of organic acids through spread films of sodium polystyrene sulfonate/dodecyl trimethyl ammonium bromide complex

The Wilhelmy plate technique was used to determine surface tension isotherms of aqueous solutions of formic and acetic acids with concentration up to 30 vol% and with a film of solution of sodium polystyrene sulfonate/dodecyl trimethyl ammonium bromide complex spread to the surface. The formation conditions of films with the extreme concentration of the complex were determined. Such films reduce the evaporation rate of binary liquids by 3-6% and demonstrate selective properties increasing the water content in the vapor by 2-5 abs%.

Characterization of air/water interface adsorption of a series of partially fluorinated/hydrogenated quaternary ammonium salts

Abstract The adsorption at air/water interface of a series of partially fluorinated/hydrogenated quaternary ammonium salts was characterized by the determination of static and dynamic surface tension, critical micelle concentration, surface excess, area per molecule and Krafft temperature. In particular, the variation of these parameters was studied as a function of fluorinated and hydrogenated chain length. Modification of fluorinated and hydrogenated moieties allows to finely tune all the aforementioned physical surface properties: increasing the number of fluorinated carbon atoms boosts both effectiveness and efficiency of surfactant in reducing surface tension, kinetics of migration to interface are favored fastening reaching of equilibrium conditions, critical micelle concentration is reduced and surface excess is increased. Conversely increasing the length of the hydrogenated moiety reduces both effectiveness and efficiency of surfactant, migration to interface is slackened, c.m.c. is increased, and surface excess is depresses. Area per molecule and Krafft temperature appear to be affected mainly by the total number of carbon atoms introduced in the molecules whatever the nature of the substituent (fluorine or hydrogen).

An investigation on surface tension of Sn-based lead free solders

Combining Miedema model, Chou geometric model and Butler equation, the surface tension of binary system and ternary system of Sn-based lead free solder alloys was calculated, and element aggregation and surface tension factor were discussed as well. The investigation result shows that predict value is agree well with the experimental data. Moreover, basic physical parameters such as surface tension of pure metal, electronic density, molar atomic volume, electro-negativity determine surface tension factor, and the surface tension of pure metal determine the element aggregated performance in the surface of liquid Sn-based lead free solder at same time.

Surface tension and liquid viscosity measurement of ethyl fluoride (R161) under saturation condition

Surface light scattering (SLS) has been used for the simultaneous determination of surface tension and liquid kinematic viscosity of ethyl fluoride (R161) under saturation conditions in the temperature ranges between 293K and very close to the critical temperature with the expanded uncertainties(k=2) of ±2% for the liquid kinematic viscosity and ±1.5% for the surface tension. In addition, the surface tension of R161 was also measured over the temperature range from (244 to 334)K using the differential capillary rise method. All the surface tension and viscosity results were correlated as a function of temperature, and the average absolute deviations between the experimental and calculated values were 0.04mNm−1 and 1.11%, respectively.

Inhibitive properties comparison of different polyetheramines in water-based drilling fluid

Polyetheramines as shale hydration inhibitors in water-based drilling fluids have attracted great interests in recent years. In this paper, in order to clarify the relationship between inhibitive properties and molecular structures of polyetheramines, several inhibitive experimental methods including bentonite inhibition test, shale cuttings hot-rolling dispersion test, sedimentation volume measurement, and API filtration measurement were adopted to evaluate the inhibition variation of different polyetheramines. Furthermore, a series of analytical methods such as surface tension determination, zeta potential measurement, XRD, contact angle measurement, and water adsorption test were performed to identify the relationship between the inhibitive performance and molecular structures. The factors including molecular weight, number of amine group, and molecular chain affecting the interaction between polyetheramines and clay particles were analyzed. Polyetheramine with molecular weight of 230 and oxypropylene segment can reduce the interlayer spacing of the hydrated clay to the minimum and exhibit the best performance in comparison with others. The coordination of electrostatic adsorption with monolayer arrangement, hydrogen bonding, and hydrophobic shielding effect contributed to the top level of inhibition.

Determination of surface tension and contact angle by the axisymmetric bubble and droplet shape analysis

The algorithms of solution to the Young–Laplace equation, describing the shape of an axisymmetric droplet on a flat horizontal surface, with various ways of setting the initial data and geometric parameters of a droplet, were derived and tested. Analysis of the Young–Laplace equation showed that a family of curves that form the droplet surface is the single-parametric one with the accuracy of up to the scale factor, whose role is played by the capillary length, and the contact angle determines the curve turn at a contact point, but it does not affect the shape of the curve. The main natural parameter defining the family of the forming curve is the curvature at the droplet top. The droplet shape is uniquely determined by three independent geometric parameters. This fact allows us to calculate the physical properties, such as the capillary length and contact angle, measuring three independent values: height, droplet diameter, and diameter of the droplet base or the area of the axial cross section of the droplet or its volume.

Standardization of Polyherbal Extract for Type-2 Diabetes

Aims: This study was aimed to standardize the polyherbal extract containing Annona squamosa, Phyllanthus emblica, Berberis aristata and Curcuma longa for the management of type-2 diabetes. The standardization of polyherbal formulation is indispensable in order to achieve the quality, purity, safety and efficacy of drugs. Study Design: Physico-chemical investigations, Physical characteristics, Qualitative phytochemical analyses, fluorescence analysis and HPLC analysis. Materials and Methods: The Standardization of polyherbal extract was based on systematic organoleptic evaluation, physico-chemical investigation, physical characteristics, heavy metal analysis, fluorescence analysis, phytochemical screening, total alkaloid content, determination of viscosity, surface tension, density and HPLC analysis were carried out by official method. Results: Organoleptic evaluation resulted that it was yellowish green in colour with characteristic odour, bitter, pungent taste and fine texture. All the applied Physico-chemical parameters like total ash, acid insoluble, water soluble ash, extractive values, observed pH, moisture content, crude fibre, foaming index were found to be within limit. The limits obtained from physical and other parameters could be used as reference in quality control. The phytochemical analysis indicated the presence of alkaloids, carbohydrates, flavonoids, volatile oils, tannins, saponins, phytosterols and mucilage. Absence of detectable levels of heavy metal confirmed that extract was non-toxic in nature. HPLC studies confirm the presence of marker compounds in each extract. Conclusion: On the basis of observations and experimental results, the study can be used as reference standard for the further quality control research as it significantly ensures the use of genuine and uniform material and well-designed methodologies for standardization and development of poly herbal extract.

Synthesis, Characterization, and Performance of a Novel Polymeric Cationic Surfactant Based on Low Molecular Weight Chitosan and 3‐Chloro‐2‐Hydroxypropyl Dimethyl Dehydroabietyl Ammonium Chloride (CHPDMDHA)

AbstractA series of novel polymeric cationic surfactants based on low molecular weight chitosan (LWCS) and 3‐chloro‐2‐hydroxypropyl dimethyl dehydroabietyl ammonium chloride (CHPDMDHA), LWCS‐g‐CHPDMDHA, were obtained by the grafting modification of LWCS with CHPDMDHA as grafting agent. The structure of LWCS‐g‐CHPDMDHA was confirmed by FT‐IR and 1H NMR, and the degree of quaternizing substitution (DS) of LWCS‐g‐CHPDMDHA was determined according to the results of elemental analysis. The aggregation behavior and surface activities of LWCS‐g‐CHPDMDHA in aqueous solution were investigated by transmission electron microscopy (TEM) and determination of surface tension, respectively. The experimental results showed that the DS and molecular weight (Mw) of LWCS have significant influence on the critical micelle concentrations (CMC) and the surface tensions at the CMC (γcmc). The shape of aggregates changed with the variation of concentration of LWCS‐g‐CHPDMDHA in aqueous solution. When the LWCS‐g‐CHPDMDHA was utilized as an emulsifier, the increase of DS of LWCS‐g‐CHPDMDHA and Mw of LWCS were favorable for improving the stability of emulsions composed of water and benzene.

Direct Numerical Simulation of droplet formation processes under the influence of soluble surfactant mixtures

The present study is concerned with Direct Numerical Simulation (DNS) of the formation of droplets under the influence of a multicomponent surfactant system, where coupling effects become important. The presented numerical method is based on an Arbitary Lagrangian Eulerian (ALE) interface-tracking method. Collocated second-order Finite Volume/Finite Area methods are employed to discretise the governing equations. Since strong coupling effects among the surfactant species are present, a block-coupled solution procedure is adopted for interfacial surfactant transport. Various sorption models are included. The method is verified by a set of analytical test cases and validated against experimental results regarding droplet formation processes as they are studied in interfacial science in the context of Profile Analysis Tensiometry (PAT) for determination of surface tension.

Construção de uma balança simples para determinação da tensão superficial de líquidos

Neste trabalho está sendo proposto a construção de uma balança com materiais de baixo custo para determinação da tensão superficial de líquidos. A confiabilidade das medidas foi comprovada comparando os resultados obtidos com aqueles apresentados na literatura para líquidos simples, e empregando o método da ascensão capilar para o caso de outros líquidos. Por este método, os erros sistemáticos dos resultados obtidos foram reduzidos consideravelmente. O princípio de funcionamento do dispositivo consiste na medida da força necessária para desprender uma lâmina de vidro parcialmente imersa em um líquido. Os valores da tensão superficial são calculados com base nos conceitos de momento de forças, e considera as interações intermoleculares entre a lâmina e a superfície do líquido.

Investigation on the ion pair amphiphiles and their in vitro release of amantadine drug based on PLGA–PEG–PLGA gel

The amantadine drug and oleic acid surfactant are used to form amantadine-based ion pair amphiphiles based on proton transfer reaction between the drug and the surfactant molecules. The ion pair amphiphiles are characterized by 1H-nuclear magnetic resonance, Fourier transform infrared spectroscopy, and X-ray diffraction. Self-assembly properties of amantadine-based ion pair amphiphiles are studied by surface tension determination, transmission electron microscopy, zeta potential, and dynamic light scattering. The aggregation behavior studies indicate that the as-prepared ion pair amphiphiles can self-assemble into vesicles with the size of 200–300 nm in aqueous solution. The drug release results show that the amantadine release rate could be well controlled by incorporating the amantadine-based ion pair vesicles in poly (lactic-co-glycolic acid)-poly (ethylene glycol)-poly (lactic-co-glycolic acid) (PLGA–PEG–PLGA) copolymer hydrogel. The drug release from the AT–OA vesicle-loaded PLGA–PEG–PLGA hydrogel is significantly inhibited in comparison with the AT-loaded PLGA–PEG–PLGA hydrogel. The present work thus demonstrates that the vesicle-loaded hydrogel is a good candidate for the drug delivery system with long-term controlled drug release behavior.

Experimental determination of the viscosity at very low shear rate for shear thinning fluids by electrocapillarity

Non-Newtonian fluids can present a complex rheological behaviour involving shear-thinning, viscoelastic or thixotropic effects. We focus here on the characterization of generalized Newtonian fluids as shear-thinning fluids. Rotational rheometers are torque-sensitive, which makes the measurement of viscosity at low shear-rates very difficult, in particular for low viscosity fluids. An accurate knowledge of this value is, however, particularly important for the characterization of several types of flows, in particular those featuring a free surface, a symmetry axis or a symmetry plane. The experimental determination of viscosity and surface tension is enabled from the propagation of attenuated capillary waves. An optical technique has been implemented in order to determine the shear-thinning viscosity at values of the shear-rate as small as 10−3s−1 from measurements of the spatial attenuation and wavelength. We have performed measurements on two different polymer solutions; we show that this technique is complementary to the classical rotational rheometer techniques since it gives access to the zero shear viscosity, which could not be measured by using rotational rheometers. The present technique is thus used to characterize the Newtonian plateau, while a rotational rheometer is used to characterize the fluid behaviour at moderate to high shear rates.

Determination of dynamic surface tension and viscosity of non-Newtonian fluids from drop oscillations

The oscillations of free-falling drops with size range from pl to μl have been used to measure the transient shear viscosity and the dynamic surface tension of shear-thinning fluids on the timescale of 10−5–10−2 s. The method is first validated with Newtonian fluids. For a given surface tension, the lower and upper limits for accurate measurement of the viscosity are determined as a function of drop size. The dynamic properties of two types of shear-thinning fluids with varying viscoelasticity are reported: aqueous suspensions of the antifungal drug griseofulvin and of the organic light-emitting diode material poly(3,4-ethylenedioxythiophene): polystyrene-sulphonate. In both cases, the free-falling drop retains the high-shear viscosity.

Surface Tension and Contact Angle Analysis with Design of Propellant Measurement Apparatus

Propellant management devices located within the propellant tanks of spacecraft and satellites operating in microgravity environment are used to control propellant distribution within the tank to improve vehicle dynamics and performance. In the microgravity environment, viscous and capillary forces can dominate body forces, and special considerations of these effects must be taken into account when designing a unique propellant management device for each mission and propellant combination. New high-performance green propellants are under development to improve performance and reduced mission costs, and to elicit efforts to further improve design of fuel-tailored propellant storage and feed systems. This paper presents the design and implementation of apparatuses intended to obtain high-quality imagery of liquids in exotic environments consistent with propellant tanks for rockets and spacecraft, as well as a review and comparison of several droplet photograph analyzing techniques used to determine surface tension and wall contact angle. This paper’s review of testing and analysis techniques, as well as its development of a testing apparatus that can sustain an adequately pressurized environment for cryogenic gases in addition to chemical compatibility for solvent-based propellants, can be used to design spacecraft or satellite propellant management devices that operate with newly emerging propellants.

Subpixel Edge Detection in the Problem of Determining the Surface Tension from an Axisymmetric Drop Profile

We consider the determination of surface tension from the image of the profile of a sessile or pendant drop. The accuracy of drop edge detection is investigated and accuracy-enhancing methods are proposed, in particular, compensation of systematic errors associated with edge blurring and curvature. The proposed edge detector is virtually free from systematic error and can be used also in other problems. A convenient practical method has been developed for calibrating the camera scale with the aid of calibration objects of simple fixed shape, such as a disk or a rectangle. The method is based on overlapping the calibration object with the image. We also consider the stability of surface tension reconstruction in the presence of outliers, e.g., outliers due to the overlapping of the drop contour by a foreign object. An iterative algorithm is proposed for automatic outlier exclusion, which improves the accuracy of determination of the drop parameter.

Experimental Study on the Thermal Stability of Surfactant Aqueous Solutions

Based on the determination of the equilibrium surface tension for anionic surfactant SDS and non-ionic surfactant TrionX-100 under different concentrations, the two surfactants continuous boiling test and the SDS for the hydrolysis tests were carried out. Objective is to analyze the diminishing process for active ingredient of the surfactants. Results show that the liquid with surfactant is capable of reducing the surface tension. With the increment of surfactant concentration, the surface tension decreases gradually, and the surface tension is minimized under the critical micelle concentration (CMC); When the concentration lower than CMC, the surface-active of TritonX-100 presented is stronger than the SDS. At continuous boiling experiment, the thermal stability of TritonX-100 solution is better than the SDS. When the SDS aqueous solution is in the sealed environment with set temperature and the continuous boiling environment under experiment situation, the active ingredients of SDS solution will change and the equilibrium surface tension will be undermined. Owing to the chemical losses, the inherent characteristics of solution perform dramatically different from the original one during boiling experiment, which includes the hydrolytic destruction and micro-layer pyrolysis chemical effects.

Liquid Viscosity and Surface Tension of R1234yf and R1234ze Under Saturation Conditions by Surface Light Scattering

In the present study, surface light scattering (SLS) was used for the simultaneous determination of liquid kinematic viscosity and surface tension of 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) and of trans-1,3,3,3-tetrafluoroprop-1-ene (R1234ze) under saturation conditions. A new SLS apparatus was built up and checked with 1,1,1,2-tetrafluoroethane (R134a), and a good agreement of our data from SLS with literature could be found. With the new apparatus, R1234yf and R1234ze were investigated in the temperature ranges between (293 and 365) K and between (295 and 373) K. For determination of the liquid kinematic viscosity the expanded uncertainties on a confidence level of more than 95 % (k = 2) are estimated to be ± 2 % for reduced temperatures Tr (= T/Tc) < 0.95, and ± 6 % for Tr close to 0.99. For the surface tension, the expanded uncertainties are less than ± 1.5 % (k = 2) in the whole temperature range.

Aquatic model for engine oil degradation by rhamnolipid producing Nocardiopsis VITSISB.

The present study was focused on isolation, screening, characterization and application of biosurfactant producing marine actinobacteria. Twenty actinobacteria were isolated from marine water sample and were primarily screened for biosurfactant production using hemolytic activity method. Among the 20 isolates, six showed positive result for hemolytic activity and those were taken for further secondary screening tests such as oil collapse method, oil spreading method and emulsification method. From the results of secondary screening analysis, two isolates (SIS-3 and SIS-20) were selected and further used to carry out biosurfactant characterization test such as pH, density, surface tension and viscosity determination. Comparing biosurfactant characterization results, SIS-3 was chosen for further analysis and application. FT-IR and GC–MS were carried out for analysis of biosurfactant from isolate SIS-3 and the compound detected was rhamnolipid. The isolate (SIS-3) was identified as Nocardiopsis using 16S rRNA gene sequencing and named as ‘Nocardiopsis VITSISB’ (KC958579) which was further applied for immobilizing whole cells for engine oil degradation by constructing an aquatic model and using natural products such as soybean meal, sugarcane juice as nutrient source. The oil was efficiently degraded by rhamnolipid producing Nocardiopsis VITSISB (KC958579) within 25 days which indicated that the strain can act as a natural candidate for the bioremediation of oil spill in ocean.