Maximum Bubble Pressure Technique Research Articles

The surface tension of pure Zn measured by means of the maximum bubble pressure method

The surface tension σ of pure Zn and its temperature coefficient have been measured by means of the maximum bubble pressure technique over the temperature range [Tm, Tm+250 °C], where Tm is the melting temperature. Alumina and quartz capillaries of various radii were used. Alumina capillaries were coated with boron nitride to discard possible wetting and high purity argon was used as bubbling gas. In addition, σ was measured while heating, cooling, or introducing the capillaries in the melt at several chosen temperatures. All measurements with alumina capillaries showed a negative temperature coefficient while those with quartz capillaries gave a positive temperature coefficient. These results are compatible with Nogi et al. conclusion in the sense that positive temperature coefficients reported in the literature should be ascribed to oxygen and/or impurity effects enhanced in volatile metals. In particular we argue that the positive temperature coefficient is a consequence of the concomitant action of several factors, namely, vaporization of Zn, oxygen traces in the bubbling gas, and the oxygen and Si produced in the chemical reactions involving quartz and liquid zinc.

To the Nature of Surfactant Adsorption onto Metallic Surfaces: Interaction with Metal or Hydrophobic Effect? Adsorption of Hexylamine on Platinum

We investigated the adsorption of hexylamine (in its hydrated form, hexylammonium ion) on the solution-platinum interface in 1 M HClO4 in the presence of 0.1 M Fe2+ and 0.1 Fe3+ by potentiodynamic and impedance methods, and also at the solution-air interface by the maximum bubble pressure technique. We show that the physical adsorption of hexylamine at both interfaces is described by the Dhar-Flory-Huggins isotherm equation. The values of adsorption constant and free adsorption energy are close for both interfaces. For the solution-air interface, the hydrophobic effect is the main reason for the surfactant adsorption at this interface. Based on the closeness of the main adsorption characteristics for both interfaces, we suggest that the adsorption of hexylamine on platinum occurs mainly due to the hydrophobic interaction of hexylamine polar molecules with water polar molecules as well. It has been shown that for the solution–platinum interface, the share of the hydrophobic effect is about 60%, and that of the van der Waals interaction is about 40%.

Measurement of corium surface tension using the maximum bubble pressure

The paper proposes a description of the maximum bubble pressure (MBP) technique that has been used to measure the density and the surface tension of high temperature molten materials (up to 2550 °C). The technique has been implemented in the VITI facility in order to characterize corium thermophysical properties. The facility is presented together with its instrumentation and uncertainty assessment. In a first step, the VITI-MBP device has been qualified by measuring reference material surface tension at room temperature (ultrapure water) and at high temperatures (Pure Alumina, 99.99%). Then, original results of corium density and surface tension have been obtained considering the corium C32 (32% oxidized corium) at the melting point 2470 °C. These results have been compared to former RASPLAV test results showing good agreement.

Surface Tension and Density of Cr–Mn–Ni Steels with Transformation Induced Plasticity Effect

Thermophysical properties of liquid metal alloys play a crucial role in the variety of processes. Present work reports experimental investigations of two new transformation induced plasticity (TRIP) steels. A classical maximum bubble pressure technique is successfully used to measure surface tension and density of the liquid TRIP‐steel samples in the temperatures range of 1500–1800 °C. Experiments are performed in two different measurement cells from TU Freiberg and Commissariat a l'Energie Atomique (CEA), Cadarache. Capillaries are made of zirconia partially stabilized with yttrium oxide, and the samples are molten in Al2O3 crucibles. Measurements are conducted under the argon atmosphere. Surface tension of the investigated samples rises up to 1700 °C and further remains the same. Density of the new steels obtained in this study is in good agreement with the previously reported values for Fe–Cr alloys with similar Cr content. Density of the alloy is estimated as 875 488–11 885 × T (±218.85 kg m−3) for a 15%Cr alloy and 796 042–06 897 × T (±199 kg m−3) for a 19%Cr alloy.

Effect of Boron Micro-alloying on the Surface Tension of Liquid Iron and Steel Alloys

Thermo-physical properties of the liquid metals and alloys play an essential role in modeling and controlling metallurgical processes. In particular, surface tension of metals has a strong impact on wetting various surfaces. Boron is added in numerous iron-based alloys as micro-alloying component. In existing literature, there is no general agreement with the effect of boron on the surface tension. The present study focuses on investigations of boron micro-alloying on the surface tension of iron and CrMnNi alloys by the maximum bubble pressure method (MBP). In contrast to other techniques, maximum bubble pressure technique is less affected by the evaporation of surface-active elements and the purity of the atmosphere around the sample. Measurement of the surface tension was accomplished before and after in situ addition of boron to the molten metal phase. Samples were molten in ZrO2 and Al2O3 crucibles and yttria-PSZ capillaries were used for the experiments. Measurements were carried out at 1550 °C in argon atmosphere and argon as bubbles formation media. Results of the experiments indicate a minor effect of boron on the surface tension of liquid iron. Effect of boron on the surface tension of steels is discussed in the context of other surface-active elements present.

The dynamics of surface adsorption and foam formation of carbonate modified nonionic surfactants

For a group of nonionic surfactants with polar head groups synthesized by copolymerization of ethylene oxide and carbon dioxide, the adsorption dynamics at the water-air surface were investigated by dynamic surface tension measurements using the maximum bubble pressure technique. From the apparent diffusion coefficients at different concentrations, the diffusion coefficients of surfactant monomers and micelles were deduced and compared to conventional nonionic surfactants. These transport properties were correlated with results from foamability studies in Bartsch tests as well as sparging tests. The obtained foam volumes show a good correlation with the diffusion coefficients of the surfactant monomers multiplied with the concentration of available monomers, the cmc. The same relation is found for the foam stability, expressed in the foam half lifetime. The correlations show for surfactant solutions well above the critical micelle concentration that the transport of surfactant monomers to the interface rather than the micelles is the essential step in both, the foam formation as well as the foam stabilization, following a simple Fickian diffusion law.

The Effect of Particles on Surface Tension and Flotation Froth Stability

It is widely accepted that particles stabilise flotation froths and that stable froths result in improved flotation performance. Predicting the effect of particle addition on froth stability is, however, challenging. Dynamic surface tension measurement using maximum bubble pressure presents an attractive technique to investigate the effect of surfactant and particles at the air-water interface. The range of bubble lifetimes that can be studied (typically 0.1 to 60 s) is analogous to variations in air rate in flotation cells, and the corresponding changes in surface tension give an indication to the diffusion and adsorption rates of particles at the interface. In this paper, we use dynamic surface tension measurements to investigate the effect of particles on bubble surfaces at the microscale and link this to bulk froth stability measurements carried out using a froth column. Using the maximum bubble pressure method, the results show that the addition of particles results in lower surface tension, both at the dynamic (i.e. short) bubble lifetimes and towards equilibrium (i.e. 60 s bubble lifetime). This corresponds with the bulk froth stability measurements, where the three-phase system yielded more stable froths than the surfactant only system. Furthermore, increased particle loading at the air-water interface, whether through higher surfactant concentrations or lower air rates (longer bubble lifetimes), gave lower surface tension and higher froth stability. This demonstrates the link between bubble loading and froth stability. It is proposed that the maximum bubble pressure technique can be used to predict froth stability for two- and three-phase systems, enabling the effect of particle loading to be accounted for and quantified. Moreover, the technique has the potential to allow rapid determination of particle and surfactant diffusion at the air-water interface and prediction of the corresponding effect on bulk froth behaviour.

Transition of Blast Furnace Slag from Silicate Based to Aluminate Based: Density and Surface Tension

The effects of the Al2O3 concentration and Al2O3/SiO2 ratio on the density and surface tension of molten aluminosilicate CaO-SiO2-Al2O3-9 mass pct MgO-1 mass pct TiO2 slag were investigated at temperatures from 1723 K to 1823 K (1450 °C to 1550 °C) using the Archimedean method and the maximum bubble pressure (MBP) technique, respectively. The mechanism of the changes in density and surface tension with composition was analyzed from the viewpoint of the degree of polymerization in the structure and the types of oxygen species in the melts. At a fixed CaO/SiO2 ratio of 1.20, the density decreased with increasing Al2O3 content up to 25 mass pct, subsequently increasing. Increasing the Al2O3/SiO2 ratio from 0.47 to 0.92 caused an increase in the density at a fixed CaO content, and the density decreased slightly when the Al2O3/SiO2 ratio was greater than 0.92. Based on the structural information, the density decreased when the Al2O3 content enhanced the network structure and increased when the (Q2 + Q3)/(Q0 + Q1) ratio and structural complexity decreased. The surface tension increased with increasing Al2O3 content and Al2O3/SiO2 ratio. On the one hand, the surface-active component of SiO2 decreased; on the other hand, the concentration of [AlO4]5− tetrahedra and metal cations that act as charge compensators increased at the melt surface. A model based on the anionic and cationic radii and the Butler equation was employed to predict the surface tension, and an iso-surface tension diagram was obtained at 1773 K (1500 °C).

New Dynamic-Surface-Tension Analysis Yields Improved Residual Surfactant Measurements in Flowback and Produced Waters

Summary Surfactant is a significant component within fracturing-fluid additives that is used for enhancing oil and gas production following stimulation of unconventional reservoirs. To help ensure optimal applications of surfactants, operating and service companies have been searching for tools for tracking surfactant residuals in flowback and produced waters, which possibly can be correlated with well productivity. This paper discusses the residual surfactant concentration measured in produced water from example Barnett shale formation wells by use of a dynamic surface tension (DST) technique, which yields much more accurate measurements. DST measurement by maximum bubble-pressure technique is well-known, but it has not been used explicitly for the application of residual surfactant measurement in produced water. A comparison of DST includes evaluating the diffusion coefficient to the reaction kinetics of adsorption of a known molecule(s) in produced water. Short-time kinetics of adsorption of different molecules vary on the basis of chemical nature and molecular size. Ultraviolet–visible (UV–Vis) spectroscopy is used to confirm the results. An estimate of residual concentrations from UV–Vis appears to be coherent with DST-measurement values. Such measurements can be useful in determining the surfactant concentration during pumping and the surfactant performance during and after hydraulic-fracturing operations. Additionally, these measurements serve a vital role in tailoring the surfactant additive to specific reservoir conditions to achieve higher oil recovery. Real-time production results from these different wells are analyzed and appear dependent on the corresponding residual surfactant concentrations from produced waters. This unique technique is new to the authors’ knowledge for its use to study and analyze produced water for surfactant-additive concentration.

Investigation of 2-cyclohexenylcyclohexanone as steel corrosion inhibitor and surfactant in hydrochloric acid

2-Cyclohexenylcyclohexanone is investigated by potentiodynamic and impedance techniques as corrosion inhibitor for carbon steel in 20mass% hydrochloric acid solutions and as surfactant at solution–air interface by the maximum bubble pressure technique. It is shown that the Langmuir adsorption of inhibitor takes place at solution–air and solution–steel interfaces. The closeness of the adsorption constants for both interfaces and the agreement of the free adsorption energy values suggests that the inhibitor adsorption on steel is caused mainly hydrophobic interaction inhibitor molecules with solution and less depends on inhibitor interaction with steel.

Investigation of Cyclohexylidenecyclohexanon Steel Corrosion Inhibitor as Surfactant

A modified organic waste of the caprolactam production is investigated by electrochemical impedance spectroscopy technique as a corrosion inhibitor of carbon steel in 20% hydrochloric solution. It is shown that cyclohexylidenecyclohexanon is a basic inhibiting component in such inhibitor. The inhibitor is investigated also as surfactant at the solution – air interface by means of the maximum bubble pressure technique. It is shown that the Langmuir adsorption of inhibitor takes place at solution – air and solution – steel interfaces. Equilibrium adsorption constant values make (1.7±0.4)×103 M-1 and (4.0±0.8)×103 M-1 respectively. Free adsorption energy was estimated as (–28±0.5) kJ mol-1 and (–30±0.6) kJ mol-1 respectively. The closeness of the adsorption constant and the free adsorption energy values suggest that the inhibitor adsorption on steel is caused basically by the hydrophobic interaction of inhibitor molecules with the solution molecules and less depends on the interaction with steel.

Effect of β-casein on surface activity of Quillaja bark saponin at fluid/fluid interfaces

Effect of a model bovine milk protein, β-casein, on surface activity of Quillaja bark saponin (QBS) from Sigma was studied at three fluid/fluid interfaces: air/water, tetradecane/water and olive oil/water. In all cases, the protein concentration was fixed at 10−6 mol L−1, and QBS concentration was varied between 5·10−7 and 1·10−3 mol L−1. Dynamic interfacial tension on the timescale 5 s–3600 s was measured using a drop shape analysis technique. For the air/water system, they were complemented with short-term (50 ms–5 s) measurements using a maximum bubble pressure technique. The dynamic results together with the extrapolated equilibrium surface pressures are discussed from the point of view of a complexation between β-casein and QBS, with the surface activity of the complex changing with its stoichiometry. At low biosurfactant/protein ratios, the interfacial tension at all three interfaces passes through a maximum, corresponding to a transient decrease of both foam and emulsion formation ability. In addition, the effect of QBS on deterioration of β-casein's surface activity upon ageing at room temperature is discussed.

Interfacial tensions of binary mixtures of ethanol with octane, decane, dodecane, and tetradecane

This contribution is devoted to the experimental characterization of interfacial tensions of a representative group of binary mixtures pertaining to the (ethanol + linear hydrocarbon) series ( i.e. octane, decane, dodecane, and tetradecane). Experimental measurements were isothermically performed using a maximum differential bubble pressure technique, which was applied over the whole mole fraction range and over the temperature range 298.15 K < T/K < 318.15 K. Experimental results show that the interfacial tensions of (ethanol + octane or decane) negatively deviate from the linear behavior and that sharp minimum points on concentration, or aneotropes, are observed for each isotherm. The interfacial tensions of (ethanol + dodecane or tetradecane), in turn, are characterized by combined deviations from the linear behavior, and inflecting behavior observed on concentration for each isotherm. The experimental evidence also shows that these latter mixtures are close to exhibit aneotropy. For the case of (ethanol + octane or decane) mixtures, aneotropy was clearly induced by the similarity of the interfacial tension values of the constituents. The inflecting behavior of the interfacial tensions of (ethanol + dodecane or tetradecane), in turn, was observed in the vicinity of the coordinates of the critical point of these mixtures, thus pointing to the fact that the quasi-aneotropic singularity that affects these mixtures was provoked by the proximity of an immiscibility gap of the liquid phase. Finally, the experimental data of interfacial tensions were smoothed with the Scott–Myers expansion, from which it is possible to conclude that the observed aneotropic concentrations weakly depend on temperature for all the analyzed mixtures.

Vapor−Liquid Equilibria and Interfacial Tensions of the System Ethanol + 2-Methoxy-2-methylpropane

Isobaric vapor−liquid equilibrium data have been measured for the binary system ethanol + 2-methoxy-2-methylpropane at (50, 75, and 94) kPa and over the temperature range (308 to 345) K. Equilibrium determinations were performed in a vapor−liquid equilibrium still with circulation of both phases. The dependence of interfacial tensions of this mixture on concentration was also determined at atmospheric pressure and 303.15 K, using the maximum bubble pressure technique. According to experimental results, the mixture exhibits positive deviation from ideal behavior, and azeotropic behavior was observed at (75 and 94) kPa. In addition, the determined interfacial tensions exhibit negative deviation from the linear behavior, and aneotropy is present. The vapor−liquid equilibrium data of the binary mixture satisfy the Fredenlund’s consistency test and were well-correlated by the nonrandom two-liquid, Wilson, and UNIQUAC equations for all of the measured isobars. Interfacial tensions, in turn, were satisfactorily correlated using the Redlich−Kister equation.

Phase equilibria and interfacial tensions in the systems methyl tert-butyl ether + acetone + cyclohexane, methyl tert-butyl ether + acetone and methyl tert-butyl ether + cyclohexane

Isobaric vapor–liquid equilibrium (VLE) data have been measured for the ternary system methyl tert-butyl ether + acetone + cyclohexane, and for its methyl tert-butyl ether based binaries, at 94 kPa and in the temperature range 323–340 K. Equilibrium determinations were performed in a vapor–liquid equilibrium still with circulation of both phases. The dependence of interfacial tensions of these mixtures on concentration was also determined, at atmospheric pressure and 303.15 K, using the maximum bubble pressure technique. From the experimental results, it follows that the investigated mixtures exhibit positive deviation from ideal behavior and azeotropy is present for the methyl tert-butyl ether + acetone system at 94 kPa. The application of a model-free approach allows concluding about the reliability of the present vapor–liquid equilibrium data for all the indicated mixtures. Furthermore, the determined interfacial tensions exhibit negative deviation from linear behavior for all the analyzed mixtures. The vapor–liquid equilibrium data of the binary mixtures were well correlated using the NRTL, Wilson and UNIQUAC equations, while their interfacial tensions were smoothed using the Redlich–Kister equation. Scaling of these models to the ternary mixture allows concluding that both the VLE data and the interfacial tensions can be reasonably predicted from binary contributions.

Vapor–liquid equilibria and interfacial tensions for the ternary system acetone + 2,2′-oxybis[propane] + cyclohexane and its constituent binary systems

Isobaric vapor–liquid equilibrium data have been measured for the ternary system acetone + 2,2′-oxybis[propane] + cyclohexane, and its constituent binaries at 94 kPa and in the temperature range 324–350 K in a vapor–liquid equilibrium still with circulation of both phases. The dependence of the interfacial tensions of these mixtures on concentration was also determined at atmospheric pressure and 303.15 K, using the maximum bubble pressure technique. From the experimental results, it follows that both the ternary and binary mixtures exhibit positive deviations from ideal behavior and, additionally, azeotropy is present for the binaries that contain acetone. The application of a model-free approach allows conclusions about the reliability of the present vapor–liquid equilibrium data for all the indicated mixtures. Furthermore, the determined interfacial tensions exhibit negative deviation from linear behavior for all the analyzed mixtures, and aneotropy is observed for the acetone + cyclohexane mixture. The vapor–liquid equilibrium data of the binary mixtures were well correlated using the NRTL, Wilson and UNIQUAC equations. In a similar manner, the interfacial tensions of the binary mixtures were smoothed using the Redlich–Kister equation. Scaling of these models to the ternary mixture allows concluding that both the vapor–liquid equilibrium data and the interfacial tensions can be reasonably predicted from binary contributions.

Vapor–liquid equilibrium, densities, and interfacial tensions for the system benzene + propan-1-ol

Isobaric vapor–liquid equilibrium data at 50, 75, and 94 kPa have been determined for the binary system benzene + propan-1-ol, in the temperature range 320–370 K. The measurements were made in a vapor–liquid equilibrium still with circulation of both phases. Mixing volumes have been also determined from density measurements at 298.15 K and 101.3 kPa and, at the same temperature and pressure; the dependence of interfacial tension on concentration has been measured using the maximum bubble pressure technique. According to experimental results, the mixture presents positive deviation from ideal behaviour and azeotropy is present at 50, 75, and 94 kPa. The mixing volumes of the system change from negative to positive as the concentration of benzene increases, and the interfacial tensions exhibit negative deviation from the linear behaviour. The activity coefficients and boiling points of the solutions were well-correlated with the mole fraction using the Wohl, Wilson, UNIQUAC, NRTL equations and predicted by the UNIFAC group contribution method. Excess volume data and interfacial tensions were correlated using the Redlich–Kister model.

Dynamic capillary pressure measurements in the short time range by applying a fast growing drop technique

The capillary pressure technique is the method of choice for any tensiometry measurements in microgravity, as all bubbles and drops have a spherical shape. A combination of fast drop formation based on a known constant liquid flow and fast data acquisition of measured capillary pressure gives access to dynamic interfacial tensions in the range of milliseconds. Also the maximum drop pressure method, an equivalent to the maximum bubble pressure technique as fastest dynamic surface tension method, can be practised by the same set-up. The technique was developed already 15 years ago [ii] and now further refined during the MAP FASES* supported by the European Space Agency [ii]. Besides a detailed description of the technical parameters, experimental results for emulsion relevant systems are presented. The set-up presented here is based on a commercial drop and bubble profile analysis tensiometer which appears to be a kind of in-situ technique for membrane emulsification processes. The instrumental set-up is suitable also for oscillating drop and bubble experiments up to frequencies of several hundreds Hz.

Application of the maximum bubble pressure technique for dynamic surface tension studies of surfactant solutions using the Sugden two-capillary method

Exact knowledge of the dead time as part of the bubble lifetime in the maximum bubble pressure method is an important prerequisite for accurate dynamic surface tension measurements. The duration of the dead time depends essentially on the capillary geometry and affects significantly the measured surface tensions of concentrated surfactant solutions. Increase of the dead time leads to a significant surface tension decrease of a freshly formed bubble surface due to the significantly higher residual adsorption of the surfactant molecules. It is shown that correct dynamic surface tensions are obtained with the experimental procedure of Sugden's method only when in addition to the fixed frequency of bubble formation, also the dead time values for the two capillaries are kept constant.

Dynamic adsorption of opposite-charged Gemini surfactant mixture at air/water interface

Dynamic surface tension (DST) of the mixed aqueous solution of opposite-charged gemini surfactants C9 pPHCNa with C 10-2-E 2-C 10·2Br was measured using the maximum bubble pressure technique. The mole fraction of C9 pPHCNa ( α 1, on a surfactant-only basis) in the bulk solution was from 1 to 0.6. Plateaus were observed in the DST curves of the mixtures at total concentration of 0.8 mmol L −1 except the case with α 1 = 0.6. This was attributed to the C 10-2-E 2-C 10 2+/C9 pPHC 2− ion-pairs with high surface activity adsorbing significantly, which led to desorption of the monomer molecules already at the surface. The micelles in the solution also affected the dynamic adsorption since all the investigated concentrations of mixed systems were above their cmcs. Dissociation of micelles offered both the monomers and the ion-pairs to adsorb at the surface, resulting in the DST curve moving down when the total concentration of the system was increased.