Surface Tension Measurements Research Articles

Surface Activity of Hydrophobized Modified Starch Hydrolysates in Mixed Systems

The manuscript presents research focusing on the adsorption and emulsion properties of starch hydrolysates modified through acetylation, oxidation, and cross-linking. The techniques used in this study included measurements of equilibrium surface tension (du Noüy ring) dynamic surface tension (drop shape analysis), and the preparation and evaluation of emulsion stability (TURBISCAN). The surface activity of the acetylated starch hydrolysates is affected by the degree of acetylation. The acetylated starch 0.02Ac-H exhibited higher surface activity than the more highly substituted derivative 0.1Ac-H. Furthermore, it was shown that the surface activity of the components increased as the acetylated oxidized starch underwent hydrolysis. The fractions collected after 180 min using a membrane with a low separation capability (8 kDa) revealed the highest capacity for reducing surface tension. In binary systems consisting of starch derivatives and surfactants, synergistic effects in reducing surface tension were particularly noticeable in systems containing ionic surfactants. The addition of a cationic surfactant to the modified starch hydrolysate solution (1:6 mol/mol) resulted in a significantly more efficient saturation of the air/water interface. This study demonstrated that emulsions stabilized with modified starch hydrolysates remained stable over time, even when these hydrolysates constituted up to 60% of the emulsifier mixture.

Orientational Disorder of Alcohol Molecules at Their Solution Surfaces in Low Concentration Range: A Molecular Dynamics Simulation Study.

Molecular dynamics (MD) simulations of short-chain alcohols (methanol, ethanol, and 1-propanol) in solution were carried out to examine the orientational disordering (randomizing) of alcohol molecules at the surface under diluted conditions. Recent vibrational sum frequency generation (VSFG) spectroscopy, combined with photoelectron spectroscopy, has successfully measured the disordering structure at low concentrations. The present MD simulations accurately reproduce this observation for the first time. To ensure reliable results through MD simulations, several widely used force field models for water and alcohol, including polarizable models, were examined. This examination involved a comparison of structural and thermodynamic quantities, such as surface density times orientation and surface excess concentration, which were obtained through surface-specific measurements like VSFG spectroscopy and surface tension measurements. It is found that the width of the density profile for alcohol molecules at the surface, along the surface normal, increases as the concentration decreases in the diluted condition, which is consistent with the results obtained from the previous neutron and X-ray grazing incidence reflection experiments. A molecular mechanism explaining the disordering of alcohol molecules with decreasing concentration is also discussed.

Coalescence Frequency in O/W Emulsions: Comparisons of Experiments with Models.

We have studied the coalescence of oil in water emulsions under the influence of gravity. The emulsions were made with alkane oils and surfactants with varying physical chemistry. We chose cationic alkyl trimethylammonium bromides of different chain lengths and nonionic surfactants of ethylene oxide and sugar head groups, including polymeric surfactants. We observed phase separation in two steps. Creaming of the oil drops is followed by their rapid coalescence, increasing the average drop size and resulting in complete surfactant surface coverage of the interfaces. Full phase separation occurs after much longer times Tc when the emulsion drops coalesce dramatically. We have used a model by Dinh et al. to relate Tc to the coalescence frequency and hence to the activation energy for the rupture of the films between two neighboring drops. Our results support the view that the coalescence of stable emulsions (stable at least for a few hours) is a thermally activated process and is controlled by the surface compression elastic modulus. This modulus was determined using surface tension measurements and calculations using the Gibbs adsorption equation. The observed differences between ionic and nonionic systems are attributed to a two-step film rupture process in the case of ionic surfactants, which is not found in nonionic systems.

Sub-second Surface Tension Measurement of Steels Containing Manganese in Aerodynamic Levitation

Sub-second Surface Tension Measurement of Steels Containing Manganese in Aerodynamic Levitation

The Entropy of Mixing in Self-Assembly and the Role of Surface Tension in Modeling the Critical Micelle Concentration

A theory for the micelle formation of nonionic head-tail amphiphiles (detergents) in aqueous solutions is derived based on the traditional molecular thermodynamic modeling approach and a variant of the Flory–Huggins theory that goes beyond lattice models. The theory is used to analyze experimental values for the critical micelle concentration of n-alkyl-ß-D-maltosides within a mass action model. To correlate those parts of the micellization free energy, which depend on the transfer of hydrophobic molecule parts into the aqueous phase, with molecular surfaces, known data for the solubility of alkanes in water are reanalyzed. The correct surface tension to be used in connection with the solvent-excluded surface of the alky tail is ~30 mN/m. This value is smaller than the measured surface tension of a macroscopic alkane–water interface, because the transfer free energy contains a contribution from the incorporation of the alkane or alkyl chain into water, representing the change in free volume in the aqueous phase. The Flory–Huggins theory works well, if one takes into account the difference in liberation free energy between micelles and monomers, which can be described in terms of the aggregation number as well as the thermal de Broglie wavelength and the free volume of the detergent monomer.

Isolation, Screening and Identification of Biosurfactant Producing Strain Nocardiopsis dassonvillei var B2 From Oil Contaminated Soil.

Petroleum and other oil manufacturing industries contribute to environmental pollution by releasing hazardous hydrocarbons. Biosurfactants offer a sustainable solution for mitigating oil pollution through emulsification processes, safeguarding agricultural soils, aquatic ecosystems, and human health. This study focuses on isolating, screening, and identifying actinomycetes producing biosurfactant from oil-polluted soil in the naval dockyard of Visakhapatnam. Biosurfactant production was successfully achieved utilizing Kim's medium, which was supplemented with olive oil serving as the carbon source. The evaluation involved preliminary identification tests, including oil displacement, Parafilm-M, and lipase activity assays, using sodium lauryl sulfate as the standard reference. Surface tension and emulsification index measurements were conducted, and the chemical composition of glycolipids and phospholipids was elucidated using phenol-sulfuric acid and phosphate assays. Glycolipids, specifically identified as rhamnolipids, were confirmed via cetyltrimethylammonium bromide (CTAB) testing and quantitatively analyzed using the orcinol method. The cell-free broth exhibited antagonistic activity against Gram-positive and negative bacilli.16S rRNA sequencing-based phylogenetic analysis was carried out by the NCIM, Pune, with the gene sequence being deposited in GenBank. Further characterization of isolate B2 included scanning electron microscopy (SEM) analysis, as well as physiological and biochemical assays. This study highlights the ability of Nocardiopsis dassonvillei var. B2, isolated from oil-polluted soil, to produce biosurfactants, specifically glycolipids identified as rhamnolipids. Our findings represent the first reported instance of biosurfactant production from isolate B2 originating from the naval dockyard in Visakhapatnam, Andhra Pradesh, India.

Hydrophobicity of Benzene-Based Surfactants and Its Effect on Bubble Coalescence Inhibition.

Bubble coalescence plays a critical role in optimizing biological and industrial processes, impacting efficiency in areas such as fermentation, wastewater treatment, and foaming control. While the relationship between chemical structure and bubble coalescence has been thoroughly explored for inorganic ions, limited data exist on organic ions and surfactants, despite their widespread use in these industries. This study addresses this gap by investigating the effects of surfactant hydrophobicity and bubble size on coalescence behavior at a flat air-liquid interface and within a bubble column. Surface tension measurements were employed to assess surfactant hydrophobicity, while bubble size and coalescence time were analyzed to determine their respective influences. The results reveal a novel quantitative relationship between surfactant hydrophobicity and the half-coalescence inhibition concentration (HCIC), a new variable introduced in this study. This relationship demonstrates that as hydrophobicity increases, the HCIC also rises, providing a new relationship between surfactant hydrophobicity and bubble coalescence. While it is well-known that more hydrophobic molecules delay coalescence, this is the first time a direct, proportional relationship has been established with HCIC, offering a new parameter for predicting and controlling coalescence phenomena.

Sustainable biomass derived natural surfactant of soybean seeds in fly ash industrial waste utilization for carbon storage: Evaluation of environmental impact

The rising carbon emissions challenge global environmental sustainability and climate stability. This study aims to advance climate change mitigation by integrating fly ash and natural surfactant into CO2 sequestration strategies. Fly ash, a by-product of industrial processes, presents an opportunity for innovative reuse. By combining fly ash with a natural surfactant extracted from soybean seeds, both industrial waste management and greenhouse gas reduction can be addressed. The surfactant was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, surface tension, and electrical conductivity measurements, confirming saponin presence with a critical micelle concentration of 0.3 wt%. Pressure decay studies revealed that a (5 wt% fly ash + NS) demonstrated the highest CO2 absorption, supported by microscopic analysis. Further research on optimizing reaction conditions and kinetics of mineralization could enhance this method’s efficiency and scalability for broader application.

Surface Tension of Two Near-Ideal Binary Liquid Mixtures and the Influence of Adjacent Vapors.

The measured surface tension of a binary liquid is found to depend strongly on the constituents of the adjacent vapor and on whether equilibrium has been achieved, giving insight into the complex interfacial configuration. This dependence is quantified by three techniques that offer complementary insights: surface tension measurements with a constrained sessile drop surrounded by different vapors, surface tension measurements by surface light scattering spectroscopy in a sealed cell at equilibrium, and molecular dynamics simulations of the equilibrium surface tension and excess surface concentration. Ensuring homogeneity of the binary liquid, which is essential for surface light scattering, was found to be nontrivial and was assured by high-sensitivity Schlieren imaging. Two pairs of liquids, n-pentane with 2-methylpentane and n-pentane with n-hexane, were investigated. The first pair was motivated by the observed improvement in the effectiveness of binary fluids versus a single constituent in wickless heat pipes studied in microgravity. The second pair was used for comparison. Experimental evaluation of different volume fractions of the two liquids showed strong dependence of surface tension on the relative concentration of different molecules near the interfacial region. For the above pairs of liquids, which appear to form ideal mixtures in bulk, we present sufficiently precise surface tension measurements to indicate unexpectedly complex behaviors at interfaces.

Effect of Methyl Red on the surface properties of DTAB in CH3OH–H2O

The purpose of this study is to investigate the effect of Methyl Red (MR) on the micellization and surface properties of a cationic surfactant, dodecyl trimethylammonium bromide (DTAB), in CH3OH–H2O mixed solvent systems at varying CH3OH parts by volumes (0.1, 0.2, 0.3, and 0.4) and temperatures (298.15 K, 308.15 K and 318.15 K). Surface tension and conductivity measurements were conducted to obtain the critical micelle concentration (CMC) and various surface properties such as premicellar slope (dγdlogC), maximum surface concentration (Γmax), minimum surface area occupied (πCMC), free energy of adsorption (ΔGadso), adsorption efficiency (pC20), packing parameter (P), and aggregation number (Nagg). The results indicate that the presence of MR significantly influences the behavior of DTAB in the mixed solvent system. In the absence of MR, the CMC increased with higher CH3OH content, while MR reduced the CMC, promoting micelle formation through dye-surfactant-ion-pair (DSIP) formation. Surface properties were enhanced in the presence of MR leading to higher surface pressure. Additionally, the free energy of adsorption (ΔGadso) became more negative with MR, indicating a more favorable adsorption process. Correlations of (dγdlogC), Γmax,γ0/γcmc, pC20, Nagg, CMC/C20 with the parts by volume of CH3OH at 298.15 K, 308.15 K, and 318.15 K are discussed with and without MR. The obtained results were used to examine the effect of MR on the surface properties of DTAB in the CH3OH–H2O medium. The change in properties can be explained in terms of the change in polarity of the medium and dye-surfactant ion pair (DSIP) formation.

Synthesis of Polyether Block Copolymers from 1,2-Epoxybutane and AEOn and Comparative Study of Physicochemical and Application Properties before and after the Synthesis.

In this study, the AEOnBO2 series of block polyoxybutenol ethers was synthesized by combining the AEO series of polyoxyethylene and preparing 1,2-epoxybutane (BO) block polyether using a semicontinuous method. The synthesis was performed by HPLC, MALDI-TOF-MS, FT-IR, and 1H NMR for structural analysis. The interaction parameters and surface tension of the systems before and after synthesis were studied using surface tension meter. The diffusion process of the systems before and after synthesis was studied using a KRÜSS bubble pressure tensiometer. The surfactant properties of AEOn and AEOnBO2 were evaluated by static and dynamic surface tension measurements. Each system formed a saturated adsorption layer in a water solution. The critical micelle concentration decreased dramatically after the introduction of BO groups, and the diffusion-adsorption process was consistent with the kinetic mechanism of hybrid diffusion. The microscopic self-assembled aggregate micellar behavior of all the systems was investigated using DLS, TEM, and SEM. The micellization process in all systems was spontaneous and enthalpy-driven, forming spherical aggregates, with the BO block reducing the aggregate diameter of the feedstock from 220.06 nm to about one-third of 80.02 nm. In addition, the dynamic contact angle, application, and physicochemical properties such as foaming and foam stabilization of each system were investigated. The contact angle was reduced from 70 to 50° at 120 s of stabilization, with a foam volume of 80 mL in all systems at 200 s. However, the AEOnBO2 showed accelerated foam decay at 500 s, with an increase in the contact angle from 70 to 50° at 200 s, but the AEOnBO2 showed accelerated foam decay at 500 s, with a decrease in the contact angle from 70 to 50° at 120 s stabilization. At 200 s, the foam volume of all systems was 80 mL, but AEOnBO2 showed an accelerated foam decay process, which shows that the BO group can accelerate the foam decay, and the comparative results show that the BO group can also optimize other application properties and physicochemical properties.

Influence of Gamma irradiation on shape memory polymer nano-composite for satellite deployment mechanism

This research investigates the impact of gamma irradiation on epoxy-MWCNT nanocomposites for satellite deployment mechanisms. Nanocomposites, enhanced with surfactants, were meticulously prepared and subjected to controlled gamma irradiation (250–1000 kGy) utilizing the Cobalt-60 facility Industrial Mega Gamma-1 at NCRRT in Egypt. Surface tension measurements explored surfactant effects on epoxy-MWCNT composites in acetone. Acetone reduced tension from 26.7 to be 24.2 (mN/m). Surfactants (Tween 80, SDS) effectively lowered tension (24.4 mN/m), while surfactant-free systems had higher tension (25.1 mN/m). Cationic surfactant (CTAB) slightly increased tension (25.4 mN/m) but aided MWCNT dispersion. Nonionic and anionic surfactants showed superior dispersing power, aligning with MWCNTs and enhancing dispersion. Thermogravimetric analysis (TGA) unveiled alterations in the thermal stability of epoxy-MWCNT nanocomposites induced by radiation, particularly evident at elevated doses (500 and 1000 kGy). Notably, surfactant-modified specimens exhibited discernible effects on various thermal stability parameters. DMA analysis revealed radiation-induced changes in viscoelastic properties. Unirradiated epoxy exhibited a Tg of 58 °C, while 250 kGy irradiation enhanced crosslinking (Tg: 64 °C). Higher doses (500 kGy, 1000 kGy) caused marginal Tg changes. Surfactant-modified samples showed varied effects, with Tween 80 emphasizing its role in phase separation. Results highlighted radiation’s influence on stiffness and energy dissipation. Shape memory behavior indicated increased recovery time with higher doses, except at 250 kGy. Epoxy-MWCNT exhibited a stable recovery time, suggesting a MWCNT stabilizing effect. Fixation rates consistently reached 100%, indicating improved shape recovery influenced by MWCNTs and surfactants. This study provides insights into optimizing nanocomposites for satellite deployment applications.

Wetting and interfacial behavior of imidazolium-based ionic liquids and water: A comprehensive review

Ionic liquids (ILs) have garnered considerable attention for their diverse applications, notably in controlling wettability on specific solid substrates, which holds ramifications for various processes reliant on interfacial behaviour encompassing adhesion and wetting. This review encompasses key advancements in IL wetting behavior and its implications. Factors such as drop size, temperature, alkyl chain structure, anion type, water concentration, and external electric fields influence the contact angle of ILs and their aqueous solutions. Despite challenges arising from IL property susceptibility to water content and wettability measurement sensitivity to solid surface, this review navigates the extent of IL wetting research, addressing line tension, surface tension measurement, and hydrogen bonding. The study aspires to furnish profound insights into IL wetting dynamics, informing IL-based fluidic technology design and elucidating intricate static and dynamic wetting attributes in analogous complex fluids.

Preparation and performance evaluation of CNF‐enhanced polyether‐modified polysiloxane defoamer

AbstractIn this article, polyether‐modified polysiloxanes were synthesized by the reaction of poly(methyl hydrogen siloxane) (PMHS) with Allyl alcohol polyether B‐400. FT‐IR, laser particle size analysis, hydrophilic–lipophilic balance (HLB) value test, and surface tension measurements were used to characterize its structures and properties. The results show that the control law for the HLB value of polyether‐modified polysiloxanes was obtained as follow: the HLB value increases with increasing hydrogen content of PMHS. When the polyether‐modified polysiloxanes were used to emulsify the polysiloxane, at the HLB value of 10.5, the average particle size of the emulsion was about 0.23 μm with a narrow particle size distribution. The emulsion has good emulsifying and dispersing properties, as well as excellent foam elimination and foam inhibition performance. When the cellulose nanofibrils (CNF) was used as a protective agent for the preparing of the polysiloxane defoamer, the stability of the emulsion does not affect, but its foam elimination and foam inhibition of emulsion can be further improved at the presence of CNF. The lowest surface tension of CNF‐enhanced polyether‐modified polysiloxane defoamer is about 22.4 mN m−1, which has good surface property. When the concentration of CNF‐enhanced polyether‐modified polysiloxane defoamer was 0.1 g L−1, the foam elimination time and foam inhibition time were 5.8 s and 38 min, respectively, at the temperature (80°C) and alkali environment (pH 13).

Propensity of hydroxide and hydronium ions for the air-water and graphene-water interfaces from abinitio and force field simulations.

Understanding acids and bases at interfaces is relevant for a range of applications from environmental chemistry to energy storage. We present combined abinitio and force-field molecular dynamics simulations of hydrochloric acid and sodium hydroxide highly concentrated electrolytes at the interface with air and graphene. In agreement with surface tension measurements at the air-water interface, we find that HCl presents an ionic surface excess, while NaOH displays an ionic surface depletion, for both interfaces. We further show that graphene becomes less hydrophilic as the water ions concentration increases, with a transition to being hydrophobic for highly basic solutions. For HCl, we observe that hydronium adsorbs to both interfaces and orients strongly toward the water phase, due to the hydrogen bonding behavior of hydronium ions, which donate three hydrogen bonds to bulk water molecules when adsorbed at the interface. For NaOH, we observe density peaks of strongly oriented hydroxide ions at the interface with air and graphene. To extrapolate our results from concentrated electrolytes to dilute solutions, we perform single ion-pair abinitio simulations, as well as develop force-field parameters for ions and graphene that reproduce the density profiles at high concentrations. We find the behavior of hydronium ions to be rather independent of concentration. For NaOH electrolytes, the force-field simulations of dilute NaOH solutions suggest no hydroxide adsorption but some adsorption at high concentrations. For both interfaces, we predict that the surface potential is positive for HCl and close to neutral for NaOH.

Surface, micellization, and thermodynamic behavior of cetyltrimethylammonium bromide in sodium polystyrene sulfonate with and without methyl red in water–ethanol mixed solvent media at varying temperatures: A tensiometric analysis

In this study, we aim to systematically investigate the surface, micellization, and thermodynamic properties of Cetyl Trimethyl Ammonium Bromide (CTAB) in Sodium Polystyrene Sulfonate (NaPSS) solutions with and without methyl red (MR) dye in water–ethanol mixed solvent media (0, 0.1, 0.2, and 0.3 vol fraction of ethanol at 298.15 ± 0.2 K, 308.15 ± 0.2 K, and 318.15 ± 0.2 K. By employing surface tension measurements, we seek to uncover the effects of solvent composition, temperature, polyelectrolyte presence, and dye addition on the Critical Micelle Concentration (CMC) and other key surface and thermodynamic parameters. The CMC, slope (dγdlnC), and γCMC values determined from γ versus ln [CTAB] for the CTAB + NaPSS + MR diminish in contrast to the CTAB + NaPSS in the chosen solvent and the temperature range studied. However, with a rising temperature and ethanol volume fraction, the CMC value rises while the obtained γCMC values fall. Various surface and thermodynamic parameters like γCMC,Amin,Γmax, ΠCMC, adsorption efficiency (PC20), packing parameter (P), aggregation number (Nagg), micellization Gibbs’ energy (ΔGm0), adsorption of Gibbs’ energy (ΔGads0), effective Gibbs’ energy (ΔGeff0), minimum Gibbs’ energy (ΔGmin), and many other parameters have been determined, comparatively discussed, and analyzed for CTAB + NaPSS and CTAB + NaPSS + MR systems. This research provides a deeper understanding of the fundamental behaviors of these complex systems, their stability, and their feasibility, with potential implications for their practical applications in fields such as drug delivery, wastewater treatment, and the formulation of personal care products.

Surface tension measurement and modeling for ternary aqueous solutions of N, N-diethylethanolamine + 2-amino-2-methyl-1-propanol/piperazine + water at T = (293.15 to 318.15) K

The surface tensions of ternary aqueous mixtures composed of N, N-diethylethanolamine (DEEA) (1), 2-amino-2-methyl-1-propanol (AMP) or piperazine (PZ) (2) and H2O (3) was measured at temperatures ranging from (293.15 to 318.15) K and 101 kPa. The systems with mass fractions of w1 = (0.20, 0.25, 0.30 and 0.35) DEEA, and w2 = (0.02 to 0.10) AMP/PZ were investigated. According to the experimental data, the surface tension deviation (Δγ) was obtained and the values were negative under the studied condition. Δγ values were fitted using a polynomial based on the Scatchard model with the average absolute deviation (AAD) ＜ 0.099 mN∙m−1 and the average relative deviations (ARD) ＜ 0.31 %. Moreover, the surface tension values were fitted using Fu-Li-Wang (FLW) and the extended Wilson models. The results revealed that both models can well correlate the surface tension as a function of temperature and composition. FLW model exhibited better fitting results with smaller AAD of less than 0.24 mN∙m−1 and ARD less than 0.68 %, respectively. Additionally, surface enthalpy (Hγ) and surface entropy (Sγ) were estimated based on the temperature dependence of surface tension.

Investigation of the double layer structure of 1-butyl-3-methylimidazolium thiocyanate at the air-water interface using sum-frequency generation vibrational spectroscopy.

The interfacial structure and adsorption behavior of 1-butyl-3-methylimidazolium thiocyanate ionic liquids (ILs) aqueous solutions were investigated using sum-frequency generation vibrational spectroscopy (SFG-VS) and surface tension measurements. Polarization-dependent measurements revealed a dramatic increase in the SFG signal for both CH and CN stretching modes with increasing ILs concentration, reaching a maximum at a mole fraction of 0.01. This concentration dependence was accompanied by a dramatic drop in surface tension. Upon further increasing the concentration, surface tension varied slightly and reached a constant value, while the SFG signal decreased significantly. Quantitative polarization analysis showed that as the bulk concentration increased, the apparent molecular orientation of the SCN- transition dipole at the interface changed from 51° to 46°, and the tilt angle of CH3 group of the butyl chain attached to the imidazole cationic ring changed from 18° to 32°. The decrease in the SFG signal can be explained by the formation of a double layer adsorption structure at the air/water interface. It was also demonstrated that the anions were adsorbed at the interface simultaneously with the cationic group, rather than by successive adsorption as proposed in a previous study. Using the Shereshefsky model, the thermodynamic Gibbs free energy of adsorption deduced from surface tension data was compared with SFG results.

Surface Tension of Cu-Ti Alloys and Wettability in a Liquid Alloy-Refractory Material-Gaseous Phase System.

The study involved measurements of surface tension of liquid binary copper-titanium alloys with respect to their chemical composition and temperature as well as investigations of the liquid alloy-refractory material-gaseous phase system wettability using usual refractory materials, i.e., graphite, aluminum oxide and magnesium oxide. The experiments were performed with the use of the sessile drop method and a high-temperature microscope coupled with a camera and a computer. The aim of this study was to determine the influence of titanium content in the Cu-Ti alloy on the surface tension and contact angle at the interface between the liquid alloy and the refractory material. The influence of temperature on these parameters was also examined. The tests were carried out for copper-titanium alloys with a maximum content of 1.5% wt. Ti, in the temperature range of 1373 to 1573 K. The test results indicate that as the titanium content in the alloy increases, its surface tension increases slightly. However, an increase in temperature causes a decrease in the surface tension of the alloys. In the case of an alloy containing 1.5% wt. Ti, surface tension at a temperature of 1373 K reaches 1351 mN∙m-1, and at a temperature of 1573 K, it decreases to 1315 mN∙m-1. As the temperature and titanium content in the alloy increase, a decrease in the contact angle is observed. The highest values of contact angles were recorded in the case of contact of the liquid alloy with graphite. For an alloy containing 0.1% wt. Ti at a temperature of 1373 K, the contact angle reaches 132°, while at a temperature of 1573 K, it decreases to 128°. For an alloy containing 1.5% wt. Ti, the values of contact angles are 100° and 96°, respectively. However, the contact angles have the lowest values for magnesium oxide. In the case of a temperature of 1573 K and an alloy containing 1.5% wt. Ti, the contact angle reaches 49°. Such a significant impact of titanium content on the contact angles may be due to its high affinity for oxygen (contact with a substrate made of Al2O3 and MgO and its reactivity with carbon (contact with graphite).

Investigation the binding and partition properties of azithromycin drug using drug-surfactant mixed micelles in the presence of trisodium citrate electrolyte

The significance of mixed micelle in pharmaceutical industries is improving the binding and solubility of poorly water-soluble drugs. This work highlighted the effect of organic counterion (NAC) for improving the micellization association of zwitterionic (CAPB) and cationic drug (DPC) by surface tension measurements. The Corrin–Harkins (CH) approach assessed the CAPB, DPC and CAPB-DPC counterion binding values for DPC in the aqueous and NAC media at 25 °C. The counterion binding B for CAPB-DPC from αDPC 1.0–0.0 was found 0.536, 0.3801, 0.368, 0.355, 0.310 and 0.272 in the presence of NAC which indicated that DPC improved the counterion binding in the mixed micellar system. The Gibb’s free energy of micellization (ΔGmic°) were increased and became more negative, suggesting that the CAPB–DPC interaction was controlled by electrostatic interaction. Furthermore, the application of mixed micelle was utilized to enhance the binding constant (LogKb) and partition coefficient (LogKx) of the poorly water-soluble drug (AZI) in aqueous and NAC media at 25 °C using a UV spectrophotometer. From UV spectra, The LogKb and LogKx of AZI were lower in single micellar systems and higher in mixed micellar systems of CAPB-DPC. The maximum LogKb values at αDPC 0.4 were found 3.091, 3.233, 3.417, and 3.368 and LogKx values were found 4.749, 4.919, 5.087 and 5.049 in the presence of 0.0, 0.5, 3.0 and 20 mmol L−1 of NAC. AZI molecules are found in the palisade layer of mixed micelle when the DPC mole fraction is less than αDPC 0.6, while more than αDPC 0.6 causes steric hindrance, increasing hydrophobicity in the system. Furthermore, surfactant-drug mixed micelles could serve as poorly drug-solubilizing agents, as well as a multidrug delivery system in pharmaceutical applications.