Surfactant Fraction Research Articles

Interface properties and applications in laundry of the BS12-SAS mixed systems

In the BS12/SAS mixed systems, the solution exhibits acidity. BS12 can act as a cationic surfactant to form anionic-cationic complexes with SAS. In this study, the surface properties and application characteristics of the BS12/SAS mixed systems were investigated. The static surface tension, dynamic surface tension, and contact angle of BS12, SAS, and their different mixed molar ratios were measured at 25 °C to evaluate interaction parameters, activity coefficient, molar fraction, and thermodynamic variables of surfactants in the mixed micelles. The results demonstrated that the BS12/SAS mixed systems deviated from the ideal state due to the strong molecular attraction between the two components, resulting in a synergistic effect. The mixed systems exhibited higher surface activity and lower critical micelle concentration. Thermodynamic analysis indicated that the spontaneous micellization of binary mixtures of BS12 and SAS occurred through both enthalpy-driven and entropy-driven processes. The adsorption kinetics data revealed that the mixed systems followed a diffusion-adsorption process. Contact angle measurements demonstrated that BS12/SAS possesses superior ability to reduce surface tension, which facilitated rapid droplet diffusion and efficient wetting of the matrix within a short time period. Furthermore, the aggregation behavior of individual surfactants and the two composite systems in aqueous solutions was analyzed using DLS and TEM to investigate their effects on the wetting, emulsification stability, foaming stability, and decontamination capability of liquid paraffin.

Surfactant-Polymer Complexation and Competition on Drug Nanocrystal Surfaces Control Crystallinity.

Nanosizing drug crystals has emerged as a successful approach to enabling oral bioavailability, as increasing drug crystal surface area improves dissolution kinetics and effective solubility. Recently, bottom-up methods have been developed to directly assemble nanosized crystals by leveraging polymer and surfactant excipients during crystallization to control crystal size, morphology, and structure. However, while significant research has investigated how polymers and other single additives inhibit or promote crystallization in pharmaceutical systems, there is little work studying the mechanistic interactions of multiple excipients on drug crystal structure and the extent of crystallinity, which can influence formulation performance. This study explores how the structure and crystallinity of a model hydrophobic drug crystal, fenofibrate, change as a result of competitive interfacial chemisorption between common nonionic surfactants (polysorbate 80 and sorbitan monooleate) and a surface-active polymer excipient (methylcellulose). Classical molecular dynamics simulations highlight how key intermolecular interactions, including surfactant-polymer complexation and surfactant screening of the crystal surface, modify the resulting crystal structure. In parallel, experiments generating drug nanocrystals in hydrogel thin films validate that drug crystallinity increases with an increasing weight fraction of surfactant. Simulation results reveal a connection between accelerated dynamics in the bulk crystal and the experimentally measured extent of crystallinity. To our knowledge, these are the first simulations that directly characterize structural changes in a drug crystal as a result of excipient surface composition and relate the experimental extent of crystallinity to structural changes in the molecular crystal. Our approach provides a mechanistic understanding of crystallinity in nanocrystallization, which can expand the range of orally deliverable small molecule therapies.

Effect of Electrostatic Interactions in Wormlike Micelles of Surfactants Based on Betaine and Charged Tertiary Amine with the Same Hydrophobic Groups

The viscoelastic properties and structure of solutions of mixed wormlike micelles based on a zwitterionic surfactant, oleylamidopropyldimethylcarboxybetaine (OAPB), and positively charged oleylamidopropyldimethylamine (OAPA) have been studied at different ratios between the components. At a small fraction of the cationic surfactant, OAPA, the solution exhibits viscoelastic properties characteristic of semidiluted solutions of entangled wormlike micelles, the presence of which has been confirmed by cryogenic electron microscopy data. It has been found that, as the molar fraction of the charged surfactant increases to 0.1, the viscosity and relaxation time of the solutions decrease by a factor of three, and the values of the storage modulus remain unchanged at short stress action times. The studied surfactants have a similar structure; therefore, when replacing zwitterionic OAPB molecules by positively charged OAPA molecules, the main factor of variations in the properties and structure is the enhancement of the electrostatic repulsion on the micelle surface. It has been shown that this factor leads to a decrease in the average length of micelles and an increase in their number, which have a weak effect on the rheological properties of the system as long as the length of the micelles is larger than the length of the subchains in the network. With an increase in the molar fraction of OAPA from 0.1 to 0.5, the viscosity and relaxation time drop drastically by several orders of magnitude and the viscoelastic response of the solution is lost; i.e., the network is destroyed. This transition from a semidilute solution to a dilute one is explained by a decrease in the length of the wormlike micelles and the formation of spherical ones. Cryogenic electron microscopy images have confirmed the formation of a mixture of long and short wormlike micelles with spherical micelles at an OAPA molar fraction of 0.5.

Ternary Mixed Micelle Hexadecyltrimethylammonium Bromide-Dodecyltrimethylammonium Bromide-Sodium Deoxycholate: Gibbs Free Energy of Mixing and Excess Gibbs Energy of Mixing.

Pharmaceutical, food, and cosmetic formulations often contain binary or ternary surfactant mixtures with synergistic interactions amongst micellar building blocks. Here, a ternary mixture of the surfactants hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, and sodium deoxycholate is examined to see if the molar fractions of the surfactants in the ternary mixed micellar pseudophase are determined by the interaction coefficients between various pairs of the surfactants or by their propensity to self-associate. Critical micelle concentrations (CMC) of the analyzed ternary mixtures are determined experimentally (spectrofluorimetrically using pyrene as the probe molecule). Thermodynamic parameters of ternary mixtures are calculated from CMC values using the Regular Solution protocol. The tendency for monocomponent surfactants to self-associate (lower value of CMC) determines the molar fractions of surfactant in the mixed micelle if there is no issue with the packing of the micelle building units of the ternary mixed micelle. If a more hydrophobic surfactant is incorporated into the mixed micelle, the system (an aqueous solution of surfactants) is then the most thermodynamically stabilized.

Quartz Crystal Microbalance as a Predictive Tool for Drug-Material of Construction Interactions in Intravenous Protein Drug Administration

As a growing number of protein drug products are developed, formulation characterization is becoming important. An IgG drug product is tested at concentrations from 0.0001–0.1 mg/mL for adsorption behavior to polymer surfaces polyvinyl chloride (PVC) and polypropylene (PP) upon dilution in normal saline (NS) using quartz crystal microbalance with dissipation (QCM-D). The studies mimicked IgG antibody interaction during IV administration with polymeric surfaces within syringes, lines, and bags. Drug product was characterized with excipients, with focus on surfactant. Drug solutions were run over polymer-coated sensors to measure the adsorption behavior of the formulation with emphasis on the behavior of each of the formulation's components. Over 60 sensorgram data sets were correlated with assayed protein solution concentrations in mock NS-diluted infusions of drug product in the equivalent concentrations to QCM experiments to build a preliminary predictive model for determining fraction of drug and surfactant adsorbed and lost at the hydrophobic surface during administration. These results create a method for reliably and predictively estimating drug product adsorption behavior and protein drug dose loss on polymers at different protein drug concentrations.

Influence of Air Mass Source Regions on Signatures of Surface-Active Organic Molecules in Size Resolved Atmospheric Aerosol Particles.

The physical and chemical properties of atmospheric aerosol particles depend on their sources and lifetime in the atmosphere. In coastal regions, sources may include influences from marine, continental, anthropogenic, and natural emissions. In this study, particles in ten diameter-size ranges were collected, and particle number size distributions were measured, at Skidaway Island, GA in May and June 2018. Based on air mass back trajectories and concentrations of major ions in the particles, the air mass source regions were identified as Marine Influenced, Mixed, and Continental Influenced. Organic molecules were extracted from the particles using solid-phase extraction and characterized using tensiometry and high-resolution mass spectrometry. The presence of surfactants was confirmed in the extracts through the observation of significant surface tension depressions. The organic formulas contained high hydrogen-to-carbon (H/C) and low oxygen-to-carbon (O/C) ratios, similar to surfactants and lipid-like molecules. In the Marine Influenced particles, the fraction of formulas identified as surfactant-like was negatively correlated with minimum surface tensions; as the surfactant fraction increased, the surface tension decreased. Analyses of fatty acid compounds demonstrated that organic compounds extracted from the Marine Influenced particles had the highest carbon numbers (18), compared to those of the Mixed (15) and Continental Influenced (9) particles. This suggests that the fatty acids in the Continental Influenced particles may have been more aged in the atmosphere and undergone fragmentation. This is one of the first studies to measure the chemical and physical properties of surfactants in size-resolved particles from different air mass source regions.

Properties and Phase Behavior of Water‐Tween‐Kerosene Microemulsions and Prediction of Their Viscosity

AbstractMicroemulsion systems are of interest to researchers due to their low energy requirements and thermodynamic stability in a wide range of applications, including enhanced oil recovery, gas absorption, drug delivery, and chemical reaction environments. In this research, the viscosity of microemulsions was characterized and then predicted. Tween 20 and Tween 80 were used as surfactants and n‐butanol as co‐surfactant. Different types of prepared Winsor microemulsions were described using the phase diagram and then were evaluated regarding their viscosity, particle size, and electrical conductivity. The mean droplet size and viscosity of the microemulsion were 8–200 nm and 10.4–39.1 cp, respectively. Finally, a new equation is suggested to predict microemulsion viscosity as a function of the ratio of the dispersed phase fraction to the surfactant fraction.

Improvement of aggregation behavior, toxicity and antimicrobial properties of hydroxypiperidinium surfactants by the formation of mixed micelles with Tween 80

The aggregation behavior of mixed micellar solutions based on cationic hexadecylpiperidinium surfactants containing one or two hydroxy substituents and nonionic surfactant Tween 80 have been investigated by tensiometric, fluorimetric, and dynamic light scattering methods. The values of the critical micelle concentration were determined at varying component ratio. Based on the data obtained and their analysis using the Clint’s and Rubingh’s models one can conclude about a negative deviation from the ideal mixing (synergistic effect). It has been found out that the piperidinium surfactants, both in individually form and in mixed compositions with 0.5 molar fraction of nonionic surfactant showed high antimicrobial activity comparable to that of commercial antibiotics, while the presence of Tween 80 significantly reduced the acute toxicity of the system. A study of the membranotropic properties of piperidinium surfactants and the mixed systems, as well as an analysis of their effect on the permeability of the cell wall and cytoplasmic membrane of Staphylococcus aureus suggested that the antimicrobial effect was not associated with the destruction of the cell membrane, but was due to specific interactions of surfactants with cell components.

Greywater treatment in a green wall using different filter materials and hydraulic loading rates

Green walls in urban environments can be both an aesthetic feature and be of practical use in greywater treatment. This study evaluates the effect of different loading rates (4.5 l/d, 9 l/d, and 18 l/d) on the efficiency of treating actual greywater from a city district in a pilot-scale green wall with five different filter materials as substrates (biochar, pumice, hemp fiber, spent coffee grounds (SCG), and composted fiber soil (CFS)). Three cool climate plant species, Carex nigra, Juncus compressus, and Myosotis scorpioides, were chosen for the green wall. The following parameters were evaluated: biological oxygen demand (BOD), fractions of organic carbon, nutrients, indicator bacteria, surfactants, and salt. Three of the five materials investigated – biochar, pumice, and CFS - showed promising treatment efficiencies. The respective overall reduction efficiencies of BOD, total nitrogen (TN) and total phosphorus (TP) were 99%, 75%, and 57% for biochar; 96%, 58%, and 61% for pumice; and 99%, 82% and 85% for CFS. BOD was stable in the biochar filter material with effluent concentrations of 2 mg/l across all investigated loading rates. However, higher loading rates had a significantly negative effect on hemp and pumice for BOD. Interestingly, the highest loading rate (18 l/d) flowing over pumice removed the highest levels of TN (80%) and TP (86%). Biochar was the most effective material in removing indicator bacteria, with a 2.2–4.0 Log10 reduction for E. coli and enterococci. SCG was the least efficient material, giving a higher BOD in the effluent than in the influent. Therefore, this study presents the potential of natural and waste-derived filter materials to treat greywater effectively and the results can contribute to the future development of nature-based greywater treatment and management practices in urban areas.

Mixed Micelle Properties of Anionic Dimeric Surfactants with Anionic, Cationic, and Nonionic Surfactants

Herein, we have investigated the mixed micellar behavior of carboxylate anionic dimeric surfactants (CAD12 and CAD16) with commercial surfactants; anionic type i.e., sodium dodecyl sulfate, cationic i.e., cetyltrimethylammonium bromide and nonionic i.e., polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether. The CMC values of mixed surfactants obtained from conductivity data decrease with a mole fraction of dimeric surfactants. The micellar characteristics (ideal CMC) and mutual interaction parameters (β) have been computed with the aid of theoretical models proposed by Clint, and Rubingh. In addition to this, thermodynamic parameters of micellization like 0 ΔG0mic, ΔH0mic, and ΔS0mic were evaluated and discussed.

Model Catanionic Vesicles from Biomimetic Serine-Based Surfactants: Effect of the Combination of Chain Lengths on Vesicle Properties and Vesicle-to-Micelle Transition

Mixtures of cationic and anionic surfactants often originate bilayer structures, such as vesicles and lamellar liquid crystals, that can be explored as model membranes for fundamental studies or as drug and gene nanocarriers. Here, we investigated the aggregation properties of two catanionic mixtures containing biomimetic surfactants derived from serine. The mixtures are designated as 12Ser/8-8Ser and 14Ser/10-10Ser, where mSer is a cationic, single-chained surfactant and n-nSer is an anionic, double-chained one (m and n being the C atoms in the alkyl chains). Our goal was to investigate the effects of total chain length and chain length asymmetry of the catanionic pair on the formation of catanionic vesicles, the vesicle properties and the vesicle/micelle transitions. Ocular observations, surface tension measurements, video-enhanced light microscopy, cryogenic scanning electron microscopy, dynamic and electrophoretic light scattering were used to monitor the self-assembly process and the aggregate properties. Catanionic vesicles were indeed found in both systems for molar fractions of cationic surfactant ≥0.40, always possessing positive zeta potentials (ζ = +35-50 mV), even for equimolar sample compositions. Furthermore, the 14Ser/10-10Ser vesicles were only found as single aggregates (i.e., without coexisting micelles) in a very narrow compositional range and as a bimodal population (average diameters of 80 and 300 nm). In contrast, the 12Ser/8-8Ser vesicles were found for a wider sample compositional range and as unimodal or bimodal populations, depending on the mixing ratio. The aggregate size, pH and zeta potential of the mixtures were further investigated. The unimodal 12Ser/8-8Ser vesicles (<DH> ≈ 250 nm, pH ≈ 7-8, ζ ≈ +32 mV and a cationic/anionic molar ratio of ≈2:1) are particularly promising for application as drug/gene nanocarriers. Both chain length asymmetry and total length play a key role in the aggregation features of the two systems. Molecular insights are provided by the main findings.

Composition and temperature effects on the solution structure of SDS/octanol/brine by SANS, NMR and microscopy.

We investigate the solution structures of model sodium dodecyl sulfate/octanol/brine ternary mixtures across the lamellar (Lα), vesicle (L4) and micellar (L1) phases employing small angle neutron scattering (SANS), optical microscopy and nuclear magnetic resonance (NMR). Specifically, we examine the effect of co-surfactant octanol (0.2-9.48 w/v%) and temperature (25-65 °C) along dilution lines at fixed octanol : SDS ratios (0.08-1.21). A transition from Lα to sponge phase (L3) above 35 °C is found along the octanol : SDS = 1.21 isopleth, with phase coexistence above ϕ ≈ 0.14 weight fraction of surfactant and co-surfactant. The lamellar bilayers swell upon dilution, with an approximately linear increase of d-spacing, accompanied by a decrease of the Caillé parameter, indicative of greater membrane rigidity. At a lower octanol : SDS ratio of 0.62, coexistence of oblate micelles and vesicles is observed with preferential formation of vesicles at low concentrations. Dilution of the L1 phase, along octanol : SDS = 0.08, results in elongated micelles, as the NaCl : SDS ratio increases, while higher temperatures favour the formation of less elongated micelles. Our results provide a detailed map of the equilibrium structures found in the Lα vicinity of this extensively investigated flow-responsive surfactant system.

Preparation and characterization of antioxidant gel foam for preventing coal spontaneous combustion

New antioxidant gel foam is prepared to improve its stability and effectiveness in preventing coal spontaneous combustion. The physicochemical composite inhibitor is prepared by introducing procyanidins into a super absorbent polymer. And then the inhibitor is incorporated into the gel foam (surfactant, foam stabilizer, and gel system), the combined properties of foam, gel and inhibitor are utilized to prevent coal spontaneous combustion. The optimal composition ratio of antioxidant gel foam is obtained by single-factor experiments and response surface methodology. The microstructure of the foam is characterized. The properties of antioxidant gel foam in preventing coal spontaneous combustion are compared and analyzed through cementation, film-forming, and temperature-programmed experiments. The results reveal that the foam properties of the antioxidant gel foam are better when the mass fractions of surfactant, foam stabilizer, gel system, and inhibitor are 0.92 %, 0.49 %, 0.34 %, and 0.55 %, respectively. The inhibitor constitutes a high-water retention skeleton structure of foam wall and stabilizes the platform boundary. The antioxidant gel foam has small bubble size, uniform distribution, and excellent stability. The foam coarsening process is slow, which can fully wet the coal and reduce the coal temperature. Simultaneously, the antioxidant has better cementation and film-forming properties, which can cement the crushed coal and form a complete gel film, blocking the air leakage channels and isolating the contact between the coal and oxygen. Besides, the inhibition effect of antioxidant on coal spontaneous is better than that of water-based foam, polymer-stabilized foam, and ordinary gel foam. It can effectively slow down the oxygen consumption rate, gas production rate, and exothermic intensity during coal oxidation, the inhibition rate at 100 °C is 74.48 %. This study provides an antioxidant gel foam with good foam properties and inhibition effect, which can effectively reduce the oxidation rate of coal and prevent its spontaneous combustion through the physical effects on covering, wetting, and cementing, as well as inhibiting the chemical reaction between coal and oxygen.

Adsorption of cationic/nonionic surfactant mixtures on polyester

AbstractExperiments were performed to characterize the adsorption of the cationic surfactant benzalkonium chloride (BZK) on polyester as well as measure the effect of the cationic surfactant on polyester surface charge. Additional studies were performed to examine the effect of adding nonionic surfactants on surface charge. In studies of adsorption of BZK on polyester, different behaviors were observed at pH values 6 and 10, with adsorption reaching a maximum at pH 10 but not at pH 6. In probing the zeta potential and isoelectric point (IEP) of polyester exposed to solutions composed of BZK (cationic surfactant) and an ethoxylated alcohol (nonionic surfactant), it was seen that the IEP could be shifted to higher pH levels by increasing the mole fraction of nonionic surfactant in a cationic/nonionic surfactant solution. A maximum in the IEP was obtained at a certain mole fraction for most cases. The shift in the IEP was hypothesized to be driven by increased deposition of the cationic, since the nonionic itself did not significantly change the IEP. The cooperative interactions between cationic and nonionic species were theorized to be driven not so much by attractive interactions, but other interactions, such as minimization of cationic charge repulsion.

Symmetry (Asymmetry) of the Molar Excess Gibbs Free Energy Function of the Binary Mixed Micelles of Bile Acid Anion and Classical Cationic Surfactant: Influence of Sterically Shielded and Sterically Unshielded Polar Groups of the Steroid Skeleton

Binary mixtures of surfactants build a binary mixed micelle in which the ratio of surfactants usually differs from the initial ratio of surfactants in their binary mixture. The thermodynamic stabilization of the binary mixed micellar pseudophase about the hypothetical ideal state (intermolecular interactions between the different particles and the conformational states of the particles are identical to those of monocomponent states) is described by the molar excess Gibbs free energy (gE). The dependence of gE on the molar fraction of surfactant i (xi) from the binary mixed micelle can be described by a symmetric function (symmetry is described to the line parallel to the y-axis and passes through xi = 0.5) or by an asymmetric function. Theoretical analysis (canonical partition function, conformational analysis) examines how the presence of different polar functional groups, some of which are sterically shielded from the steroid skeleton of bile salts (surfactant), affect the symmetry of the function gE of the binary mixed micelle of the cholic acid anion (bile salts) and classic cationic surfactant (hydrophobic tail and polar head). Suppose the steroid skeleton of the bile salt contains non-sterically shielded polar groups (or the temperature is relatively high). In that case, gE is a symmetric function. At the same time, if the steroid skeleton also contains sterically shielded polar groups, then the gE function is asymmetric.

Regular solution theory for nonlinear composition dependency of enantioselectivity by mixed micelle

Mixtures of chiral and achiral building blocks of supramolecules exhibit interesting cooperative properties, as indicated by the nonlinear relationship between chiral properties and the mole fraction of chiral building blocks. However, the nonlinear composition dependence of the chiral recognition capability of spherical mixed micelles is poorly understood. This study hypothesized that the phenomenon could be described by the regular solution theory reported to be able to describe critical micelle concentration (CMC) and partition coefficients of the mixed micelle by interaction parameters β and B, respectively. The CMC and mole fraction of chiral surfactant in the mixed micelle were simulated by using the theory of varying β and CMC of the two surfactants. Equations that describe the enantioselectivity are newly derived in this work, and the dependency of the enantioselectivity on B was studied in detail. The regular solution theory was applied to the mixed micellar electrokinetic chromatography (MEKC) for the first time. It was found that the formula can describe the nonlinear composition dependency of the enantioselectivity of the mixed MEKC. The partition coefficient determined by MEKC was in agreement with the β versus B relation, which was previously reported.

Reactive molecular dynamics simulation of thermo-physicochemical properties of non-covalent functionalized graphene nanofluids

In this paper, the effect of adding sodium dodecyl benzenesulfonate(SDBS), sodium dodecyl sulfate (SDS), and triton X-100 on the thermophysical properties and the stability of water/ethylene glycol- graphene (G)- nanofluids (NFs) was investigated. Final observations demonstrate that the viscosity of NFs with 0.036 wt% of surfactants in comparison with 0.013 wt% NFs improved by 6.29%, 79.36%, and 39.13% for triton X-100, SDS, and SDBS, respectively. In addition, by increasing the fraction of SDS surfactant from 0.036 to 0.051 wt% thermal conductivity was enhanced by 84%. It was found that the thermophysical properties of NFs were more affected than their stability by adding surfactants. The results of this study can be used to produce G-NFs with optimized thermophysical properties and stability by using suitable surfactants.

Diesel blends produced via emulsification of hydrothermal liquefaction biocrude from food waste

Hydrothermal liquefaction (HTL) is a promising method for producing biocrude oil from wet biowaste. However, the complex composition of the HTL biocrude has several undesirable qualities, including high viscosity, total acid number (TAN), oxygen and nitrogen heteroatom content, and lesser higher heating value (HHV) in comparison to petroleum fuels. This study investigated the production of diesel blends and their fuel quality by emulsification of HTL biocrude with the aid of a block copolymer surfactant through centrifugation and ultrasonification. Four emulsion treatment variables were considered: biocrude fraction, surfactant fraction, retention time, and RPM (rotations per minute) for centrifuge or temperature for ultrasonic. Emulsification produced fuel blends with better HHV, viscosity, and TAN in comparison to HTL biocrude oil, and high solubility levels were achieved with surfactant addition and increased retention time. Maximum biocrude solubilities of 65.43 and 75.67 wt% were obtained for centrifugation and ultrasonification, respectively. Meanwhile, the highest HHV of centrifuge and ultrasonic emulsions was 45.39 and 45.73 MJ/kg, respectively. Emulsification led to viscosities as low as 5.91 and 6.06 mm2/s for centrifuge and ultrasonic samples, respectively. The TAN of emulsions were much lower than the biocrude: 14.18–41.31 and 16.22–50.31 mg KOH/g for centrifugation and ultrasonification, respectively. Thermogravimetric analysis, elemental analysis, combustion characteristics, and thermal properties gave further insight into the fuel quality of the emulsions and any deviations from the predicted HHV, viscosity, and TAN fuel properties, as well as comparison to ASTM specifications for biodiesel blends. The results show that emulsification of HTL biocrude could be an efficient and economical pathway for producing renewable diesel blends.

A Normalized HLD (HLDN) Tool for Optimal Salt-Concentration Prediction of Microemulsions

Optimal condition-based microemulsion is key to achieving great efficiency in oil removal. One useful empirical equation to predict an optimal condition is a hydrophilic–lipophilic deviation (HLD). However, the K constants of each surfactant should be the same to combine the HLD equations for the mixed surfactant. Recently, a normalized hydrophilic-lipophilic deviation (HLDN) was presented to avoid this limitation. This work sought to determine the phase behaviors and predict the optimal salt concentrations, using HLDN for the mixed surfactant. Sodium dihexyl sulfosuccinate (SDHS) as an anionic surfactant, and alcohol alkyl polyglycol ether (AAE(6EO4PO)) as a nonionic surfactant, were both investigated. Alkanes and diesel were used as a model oil. The results showed that AAE(6EO4PO) enforced both the hydrophilic and the hydrophobic characteristics. The Winsor Type I-III transition was influenced by the ethylene oxide, while the propylene oxide presence affected the Winsor Type III-II inversion. For the HLDN equation, the average interaction term was 1.82 ± 0.86, which markedly showed a strong correlation with the fraction of nonionic surfactant in the mixed systems. The predicted optimal salt concentrations using HLDN of SDHS-AAE(6EO4PO) in the diesel systems were close to the experimental results, with an error of &lt;10% that is significantly beneficial due to the shorter time required for optimal determination.

Effects of surfactants on thermal performance and pressure drop in mini-channels- An experimental study

Background: The results of previous studies indicated that the addition of surfactant to the base fluid affects considerably the behavior of the solution. As a result, it is important to focus on the effects of surfactant on the pressure drop and heat transfer within the mini-channel. Methods: In this experimental study, the effects of Tween 80 and SDS surfactants on the pressure drop and heat transfer in the mini-channel are investigated. The effects of Reynolds number and volume fraction of surfactants are studied. Findings: The results show that the pressure drop boosts as the volume fraction of Tween 80 surfactant is increased. With boosting the volume fraction of Tween 80 surfactant, the Nusselt number is increased and the maximum Nusselt number can be observed for the highest values of Reynolds number and volume fraction. For the water/Tween 80 solution, in most operating conditions and volume fractions, the performance evaluation criterion has the value larger than unity. It is also observed that with using the SDS surfactant, the friction factor decreases. For this surfactant, with boosting the Reynolds number, the drag reduction parameter decreases and reaches the lowest value at the Reynolds number in the range of 5000 to 5500.