Surfactant Mixtures Research Articles

Mild surfactant systems containing rhamnolipids for personal cleansers—Building the viscosity and studying the performance

AbstractBiosurfactants represent a promising choice for the development of environmentally friendly and gentle personal care cleansers. Building viscosity is one of the major challenges to apply biosurfactants. In this study, sodium lauroyl sarcosinate (LS) and sodium lauroamphoacetate (LA) were used as bases to build wormlike micelles, and subsequently rhamnolipids were introduced to build mild surfactant systems. The LS‐LA mixture had the highest viscosity at the mass ratio of 1:5 and pH 6.0. After adding 1 wt% and less rhamnolipid, relatively high viscosity can be maintained. The viscosity of LS‐LA‐rhamnolipid can be increased by adding NaCl and more significantly by the addition of carrageenan due to its synergistic interactions with the surfactant mixture. In addition, the foaming properties of the systems are characterized with different amounts of rhamnolipid and carrageenan, which are correlated with the bulk viscosity and interfacial elasticity of the diluted solution used for the foaming test. Rhamnolipids have both high mildness and cleaning efficacy and adding rhamnolipids can significantly increase the mildness of the system. This study offers practical solutions for the incorporation of rhamnolipids or other biosurfactants in the formulation of personal care cleansers.

Interaction, Surface Activity, and Application of Mixed Systems of Alcohol Ether Sulfate Anionic Surfactants with Multiple Ethylene Oxide Groups and Gemini Quaternary Ammonium Surfactant.

The surface activities and application properties for the mixtures of cationic surfactants tetramethylene-1,4-bis[N,N-bis(hydroxypropyl)-hexa/decyloxypropylammonium] bromide (GC10-P) and tetramethylene-1,4-bis[N,N-bis(hydroxyethyl)-hexa/decyloxypropylammonium] bromide (GC10-E) and anionic surfactant isomeric sodium fatty alcohol ether sulfates (iso-AE9S) were investigated using both the tensiometry and the conductometry. The interaction parameters and thermodynamic micellization parameters of GC10-P/iso-AE9S and GC10-E/iso-AE9S mixtures were evaluated by Clint-Rubingh and Motomura theoretical models. When the mole fraction of α1 for GC10-P/iso-AE9S mixed system was 0.2, the critical micelle concentration (CMC) reached a minimum of 1.61 × 10-4 mol/L, and the minimum critical micelle concentration of the GC10-E/iso-AE9S mixed system is 2.67 × 10-5 mol/L at α1 = 0.6. The CMC value of the mixed system is 1-2 orders of magnitude lower than that of any single component. The results indicate that the synergistic effects of the investigated mixed systems (evaluated by βm) are in order of GC10-P/iso-AE9S < GC10-E/iso-AE9S, with maximum βm values of -17.98 and -9.78, respectively. The change in zeta potential indicates that the poly(ethylene oxide) chain has weakened the charge density of the hydrophilic headgroup of the anionic surfactant. The interfacial tension at the oil-water interface in the mixed system of anionic/cationic surfactants is lower than that of any single component, exhibiting a higher interfacial activity. The mixed system exhibits a decreased contact angle and superior wetting ability over any single component, and it also enhances foam performance, emulsification performance, and degreasing performance.

Unveiling the formation capacity of multicomponent oleogels: Performance of lecithin interacting with monostearate derivatives

Oleogels have been explored as fat substitutes due to their healthier composition compared to trans and saturated fats, also presenting interesting technological perspectives. The aim of this study was to investigate the compositional perspective of multicomponent oleogels. Structuring ability of lecithin (LEC) (20 or 90 wt% of phosphatidylcholine – PC) combined with glycerol monostearate (GMS), sorbitan monostearate (SMS) or sucrose monostearate (SAC) in sunflower oil was evaluated from oleogels properties. The thermal and rheological properties, microstructure and stability of the oleogels were affected by the difference in the chemical composition of LEC and the ratio between LEC and different surfactants. Interestingly, low-phosphatidylcholine LEC (L20) performed better, although systems formed with reduced amounts of LEC tended to be softer (LEC-GMS) and present high oil holding capacity (LEC-SMS). The mixtures of LEC and monostearate-based surfactants showed different behaviors, depending on the surfactant polar head. In LEC-GMS systems, LEC hindered the self-assembly of GMS in sunflower oil, compromising mechanical properties and increasing oil release. When combined with SMS, LEC acted as a crystal habit modifier of SMS, forming a more homogeneous microstructure and producing stronger oleogels with greater oil binding capacity. However, above the threshold concentration, LEC prevented SMS self-assembly, resulting in a weaker gel. A positive interaction was found in LEC-SAC formulations in specific ratios, since SAC cannot act as a single oleogelator. Results show the impact of solubility balance played by LEC and fatty-acid derivatives surfactant when combined and used as oleogelators. This knowledge can contribute to a rational perspective in the preparation and modulation of the properties of edible oleogels.

Phase Behavior and Rheological Properties of AES/CAPB/H2O Ternary System

Cleaning products are often formulated as mixtures of surfactants because the properties of surfactant mixtures are easier to adjust than those of a single surfactant. Therefore, it is of great significance to study the phase diagram of surfactant mixtures. In this paper, the phase behavior of the alkyl ethoxysulfate (AES)/cocamidopropyl betaine (CAPB)/H2O ternary system was investigated at room temperature using polarizing optical microscopy (POM) and small angle X-ray scattering (SAXS), and the identified phases of the samples with various compositions were used to construct the ternary phase diagram of the AES/CAPB/H2O system which contains normal micellar phase (L1), normal hexagonal phase (H1), lamella phase (Lα), and one transition region (L1 → H1). The viscosity distribution of the AES/CAPB/H2O system was determined by a Brookfield DV2T touch screen viscometer. In addition, the effects of the weight percentage of CAPB and salts on the viscosity and rheological properties of the AES/CAPB/H2O system were also investigated. This work not only enriches the phase diagram of surfactant systems, but also has important guiding significance for the design and development of cleaning products.

Characterization of Oil-in-Water Emulsions Prepared with Triblock Copolymer Poloxamer 407 and Low-Molecular-Mass Surfactant Mixtures as Carriers of Grape Pomace Waste Polyphenols

Background: Natural antioxidants, such as grape pomace polyphenols, can be extracted by a surfactant-based green technology and incorporated into various emulsions. Therefore, this work aimed to investigate the physical stability and rheological characteristics of oil-in-water emulsions stabilized with poloxamer 407 (P407) and its mixtures with the low-molecular-mass surfactants Brij S20 (BS20) and Tween 60 (T60). Also, the influence of polyphenolic grape pomace extracts on the physical stability and rheological characteristics of the emulsions was examined. Methods: Grape pomace polyphenols were extracted by aqueous solutions of P407 and BS20/P407 and T60/P407 mixtures. Two different types of oil-in-water emulsions were examined: emulsions prepared with pure surfactants and emulsions prepared with surfactant-based polyphenol extracts of grape pomace. Both types contained 20% sunflower oil. Characterization of the emulsions comprised droplet size evaluation, rheology characteristics and creaming stability. Results: All the emulsions showed shear-thinning flow, while the rheological characteristics and creaming instability depended on the proportion of P407 in the emulsifier mixtures. Incorporation of grape pomace extracts had no effect on the investigated properties of the emulsions. Conclusion: The presence of extracted polyphenols in emulsifier mixtures had no significant effects on the emulsions’ physico-chemical characteristics and stability. Therefore, the investigated emulsions can be considered suitable carriers for polyphenol-rich extracts.

Surfactant foam injection for remediation of diesel-contaminated soil: A comprehensive study on the role of co-surfactant in foaming formulation enhancement

Aqueous foam injection is a promising technique for in-situ remediation of soil and aquifers contaminated by petroleum products. However, the application efficiency is strongly hindered by foam's instability upon contact with hydrocarbons. Addressing this, we propose a new binary surfactant mixture of Sodium Dodecyl Sulfate (SDS) and Cocamidopropyl Hydroxysultaine (CAHS). This study investigates CAHS's role as a co-surfactant in enhancing foam stability against antifoaming diesel oil under static and dynamic conditions. Using a dynamic foam analyzer (DFA-100), we assessed static foam's stability by monitoring decay profiles and bubble growth over time. The results revealed that the highest stability can be reached at a CAHS to SDS ratio of 50:50, increasing the half-life of the foam by 7.7 times. Remarkably, our analyses at bulk and bubble scales also elucidated the mechanisms behind the enhanced foam stability of the proposed binary surfactant mixture in the absence and presence of diesel. Additionally, in a 1D sand column, the SDS-CAHS mixture demonstrated more than twofold improvement of the Resistance Factor, attributed to the better survival of the lamellae due to the reduced rate of their destruction. This formulation also yielded a recovery improvement of >10 % compared to SDS foam. The significant improvements in stability and performance of the SDS-CAHS (50:50) mixture were credited to a robust pseudo-emulsion film formation, creating a higher oil entry barrier. This reinforcement and the surfactant molecules' synergistic interactions at the gas-liquid-oil interface significantly contributed to the overall effectiveness.

Effect of alcohol on synergistic interaction between amino sulfonate amphoteric surfactant and zwitterionic cocamidopropyl hydroxysultaine in aqueous solution

Micellization behavior for quasi-binary mixtures of an amino sulfonate amphoteric surfactant, sodium 3-(N-dodecyl ethylenediamino)-2-hydropropyl sulfonate (DES), with a zwitterionic surfactant cocamidopropyl hydroxysultaine (CAHS) both in water-glycerol and in water-glycol and the effect of alcohol were investigated using both the tensiometry and the conductometry. In the framework of regular solution theory and based on the pseudophase separation model, the Rubingh’s model, the Rodenas’ model and the Clint’s model were adopted to successfully estimate the related micellar and thermodynamic parameters. The synergistic interaction between DES and CAHS along with the nonideal mixing are observed in the entire range of mixing. Besides the hydrophobic effect, the compatibility in molecular conformation, the steric hindrance, the feeble electrostatic repulsion, the interaction between dipoles and the formation of hydrogen bond can account for the dependence of the mixed critical micelle concentration and the micellar composition on the content in bulk solution. In comparison with the case of glycerol, the presence of glycol partly disfavors the micellization process. Thermodynamic parameters show that the entropy makes an overwhelming contribution to the spontaneous micellization process, the release of mixing heat promotes the formation of stably mixed micelle, the greater share of entropy in the presence of glycol than in the presence of glycerol displays the disadvantage in the micellization process as well as the dependence of both the free energy change and the share of entropy on the mixing ratio in bulk solution is approximately symmetric with respect to about 0.500.

Molecular Dynamics Simulations of the Short-Chain Fluorocarbon Surfactant PFHXA and the Anionic Surfactant SDS at the Air/Water Interface.

The research and development of alternatives to long-chain fluorocarbon surfactants are desperately needed because they are extremely toxic, difficult to break down, seriously harm the environment, and limit the use of conventional aqueous film-forming foam fire extinguishing agents. In this study, mixed surfactant systems containing the short-chain fluorocarbon surfactant perfluorohexanoic acid (PFHXA) and the hydrocarbon surfactant sodium dodecyl sulfate (SDS) were investigated by molecular dynamics simulation to investigate the microscopic properties at the air/water interface at different molar ratios. Some representative parameters, such as surface tension, degree of order, density distribution, radial distribution function, number of hydrogen bonds, and solvent-accessible surface area, were calculated. Molecular dynamics simulations show that compared with a single type of surfactant, mixtures of surfactants provide superior performance in improving the interfacial properties of the gas-liquid interface. A dense monolayer film is formed by the strong synergistic impact of the two surfactants. Compared to the pure SDS system, the addition of PFHXA caused SDS to be more vertically oriented at the air/water interface with a reduced tilt angle, and a more ordered structure of the mixed surfactants was observed. Hydrogen bonding between SDS headgroups and water molecules is enhanced with the increasing PFHXA. The surface activity is arranged in the following order: PFHXA/SDS = 1:1 > PFHXA/SDS = 3:1 > PFHXA/SDS = 1:3. These results indicate that a degree of synergistic relationship exists between PFHXA and SDS at the air/water interface.

Influence of typical liquid fuels on foam properties of critical components of environmentally friendly aqueous film-forming foams

In this study, the influence mechanism of typical fuels (oils) on the foam properties of mixture of hydrocarbon and fluorocarbon surfactants was investigated. A mixed solution was prepared based on a nonionic hydrocarbon surfactant (APG-0810) and a zwitterionic C6 fluorocarbon surfactant (short-chain). The effect of different oils (heptane, kerosene, diesel, and transformer oil) on the physical property parameters, foamability, oil resistivity of foam and single vertical liquid film of the mixture are systematically investigated. Results indicate that the viscosity of mixture increases, but the conductivity, surface activity, and initial foam height decreases with addition of the four oils. The drainage and volume decay of the foam are accelerated by the presence of oils. In addition, the presence of oils accelerates liquid film thinning through affecting drainage, especially for the oil with higher density, water solubility, and volatility. The four oils showed different effect on foam properties due to the difference in nature and emulsification of them. Among them, the foam properties under the action of heptane is the best, and the oil resistivity of foams is the best. This study can provide theoretical guidance for oil resistivity of hydrocarbon and fluorocarbon surfactant stabilized foams.

Rheological properties of fluorine-free foams stabilized by aluminum hydroxide nanoparticles and mixture of siloxane and hydrocarbon surfactants

Fluorine-free foam stabilized by nanoparticle (NP) is expected to become a new generation of environmental-friendly firefighting foam. Many problems on properties of NP-stabilized fluorine-free foams remain to be studied. The present paper focuses on the rheology and foam stability of fluorine-free foam stabilized by aluminum hydroxide NPs. The surface tension, conductivity, foamability, viscosity, and viscoelasticity of mixed dispersions were measured. The stability, viscosity, viscoelasticity, and thixotropy of foam was analyzed deeply by model fitting and mechanism explanation. The results show that the rheological properties and foam stability of mixed dispersions are both enhanced by the presence of NPs, and the enhancement amplitude increased with NP concentration. Both dispersions and NP-stabilized foams exhibit shear thinning behavior, and the viscosity variations in dispersions conform to the Cross model well. As NP concentration increases, the linear viscoelastic range of foam becomes wider, the flow point of NP foam is delayed, demonstrated enhanced viscoelasticity. The thixotropic recovery of foam decreases with the increasing NP concentration, and foam thixotropic recovery decreases with the increase of irreversible deformation degree. This study can provide design idea for the development of fluorine-free firefighting foam.

Finite size effects and optimization of the calculation of the surface tension in surfactant mixtures at liquid/vapour interfaces

The surface tension of monolayers with mixtures of anionic and nonionic surfactant at the liquid/vapour interface is studied. Previous works have observed that calculations of the surface tension of simple fluids show artificial oscillations for small interfacial areas, indicating that the surface tension data fluctuate due to the finite size effects and periodic boundary conditions. In the case of simulations of monolayers composed of surfactant mixtures, the surface tension not only oscillates for small areas but can also give non-physical data, such as negative values. Analysis of the monolayers with different surfactant mixtures, ionic (DTAB, CTAB, SDS) and nonionic (SB3-12), was done for density profiles, parameters of order and pair correlation functions for small and large box areas and all of them present similar behaviour. The fluctuations and the non-physical values of the surface tension are corrected when boxes with large interfacial areas are considered. The results indicate that in order to obtain reliable values of the surface tension, in computer simulations, it is important to choose not only the correct force field but also the appropriate size of the simulation box.

Development and Ex-Vivo Skin Permeation of Sildenafil Citrate Microemulsion System for Transdermal Delivery

Background: This study aimed to develop a microemulsion (ME)-based skin delivery platform containing sildenafil citrate (SC)-ME and evaluate its in vitro skin permeability. Methods: Accurate MEs were prepared using pseudo-ternary phase diagrams and a full factorial design with three variables at two levels. After the design phase, suitable ratios of oil, water, and a mixture of surfactant (S) and cosurfactant (CS) were selected to prepare various SC-ME formulations. These SC-MEs were analyzed for stability, droplet size, in vitro SC release, skin permeability, and viscosity properties. Results: The droplet size of the ME samples ranged from 6.24 to 32.65 nm, with viscosities between 114 to 239 cps. Release profiles indicated that 26 to 60% of SC was released from the different SC-MEs within 24 hours. All ME formulations significantly enhanced the permeability coefficient (P) through rat skin. Specifically, the flux (Jss) in SC-ME7 increased by approximately 117 times (Jss = 0.0235 mg/cm2.h) compared to the control sample (0.0002 mg/cm2.h). Conclusions: The study concluded that the proportions of the water or oil phase and the S/CS mixture in the MEs significantly influenced the physicochemical characteristics and permeation parameters. The selected MEs improved both the permeability coefficient and the rate of permeation through rat skin. The enhanced drug delivery through and into deep skin layers is a key attribute of an ideal dermal ME. These findings suggest that MEs could serve as effective transdermal delivery systems for SC and similar drugs. However, in vivo assays and clinical research are needed to confirm the therapeutic efficacy of MEs.

Synthesis of PtNi Nanoparticles to Accelerate the Oxygen Reduction Reaction.

We report the synthesis of core-shell Ni-Pt nanoparticles (NPs) with varying degrees of crystallographic facets and surface layers rich in Pt via a seed-mediated thermolytic approach. Mixtures of different surfactants used during synthesis resulted in preferential surface passivation, which in turn dictated the size, chemical composition, and geometric evolution of these PtNi NPs.Electrochemical investigations of these pristine core-shell Ni-Pt structures in the oxygen reduction reaction (ORR) show that their catalytic functionalities outperform the commercial Pt/C reference catalyst. The enhanced electrocatalytic ORR performances of these Pt-based PtNi NPs are correlated with the weakened oxygen binding strength or surface-adsorbed hydroxyl (OH) species on active Pt surface sites induced by the downshift of the d-band center as a result of compressive strain effects. Our studies offer a robust synthetic approach for the development of core-shell nanostructures for enhanced ORR catalysis.

Amplitude modulation in surfactant and polymer-based water-in-oil emulsions: A novel approach to enhance separation rate and mitigate chaining effects

Oil wells can eventually run out of oil if used for an extended period. Various polymers and surfactants are used to enhance oil recovery to extend the useful life of a well and improve the recovery process. These chemicals are added to make the extraction process easier. However, the emulsion that results from this process can be difficult to break down because of the added chemicals. Therefore, special measures are necessary to recover the crude oil effectively by breaking the emulsion. Electrocoalescers are specialized large-scale units designed for the purpose of separating water from emulsions. Improving the performance of an electrocoalescer involves achieving faster dehydration of the emulsion while ensuring safe operation. This means increasing the rate of water separation without compromising safety. The proposed technique aims to improve separation by modulation of the AC electric field. This modulation consists of a step with a high-amplitude electric field, followed by a step with a low-amplitude electric field, then repeated. This work involves a study of four types of emulsions that were used: (1) water-in-oil emulsion without surfactant/polymer, (2) polymer-stabilized water-in-oil emulsion, (3) surfactant stabilized water-in-oil emulsion, and (4) surfactant and polymer mixed-stabilized water-in-oil emulsion. The electrocoalescence process has faster kinetics compared to conventional methods. Modulation facilitates drop chaining during high voltage and effective coalescence during low voltage. It has been observed that an increase in the conductivity of the dispersed phase can lead to an increase in non-coalescence. The surfactant (SDS) and polymer (HPAM) mixture become more challenging to separate.

Emerging pollutants in textile wastewater: an ecotoxicological assessment focusing on surfactants.

Water and several chemicals, including dyestuffs, surfactants, acids, and salts, are required during textile dyeing processes. Surfactants are harmful to the aquatic environment and induce several negative biological effects in exposed biota. In this context, the present study aimed to assess acute effects of five surfactants, comprising anionic and nonionic classes, and other auxiliary products used in fiber dyeing processes to aquatic organisms Vibrio fischeri (bacteria) and Daphnia similis (cladocerans). The toxicities of binary surfactant mixtures containing the anionic surfactant dodecylbenzene sulfonate + nonionic fatty alcohol ethoxylate and dodecylbenzene sulfonate + nonionic alkylene oxide were also evaluated. Nonionic surfactants were more toxic than anionic compounds for both organisms. Acute nonionic toxicity ranged from 1.3mg/L (fatty alcohol ethoxylate surfactant) to 2.6mg/L (ethoxylate surfactant) for V. fischeri and from 1.9mg/L (alkylene oxide surfactant) to 12.5mg/L (alkyl aryl ethoxylated and aromatic sulfonate surfactant) for D. similis, while the anionic dodecylbenzene sulfonate EC50s were determined as 66.2mg/L and 19.7mg/L, respectively. Both mixtures were very toxic for the exposed organisms: the EC50 average in the anionic + fatty alcohol ethoxylate mixture was of 1.0mg/L ± 0.11 for V. fischeri and 4.09mg/L ± 0.69 for D. similis. While the anionic + alkylene oxide mixture, EC50 of 3.34mg/L for D. similis and 3.60mg/L for V. fischeri. These toxicity data suggested that the concentration addition was the best model to explain the action that is more likely to occur for mixture for the dodecylbenzene sulfonate and alkylene oxide mixtures in both organisms. Our findings also suggest that textile wastewater surfactants may interact and produce different responses in aquatic organisms, such as synergism and antagonism. Ecotoxicological assays provide relevant information concerning hazardous pollutants, which may then be adequately treated and suitably managed to reduce toxic loads, associated to suitable management plans.

Bioremediation of trichloroethylene-contaminated groundwater using green carbon-releasing substrate with pH control capability

In this research, a sustainable substrate, termed green and long-lasting substrate (GLS), featuring a blend of emulsified substrate (ES) and modified rice husk ash (m-RHA) was devised. The primary objective was to facilitate the bioremediation of groundwater contaminated with trichloroethylene (TCE) using innovative GLS for slow carbon release and pH control. The GLS was concocted by homogenizing a mixture of soybean oil, surfactants (Simple Green™ and soya lecithin), and m-RHA, ensuring a gradual release of carbon sources. The hydrothermal synthesis was applied for the production of m-RHA production. The analyses demonstrate that m-RHA were uniform sphere-shape granules with diameters in micro-scale ranges. Results from the microcosm study show that approximately 83% of TCE could be removed (initial TCE concentration = 7.6 mg/L) with GLS supplement after 60 days of operation. Compared to other substrates without RHA addition, higher TCE removal efficiency was obtained, and higher Dehalococcoides sp. (DHC) population and hydA gene (hydrogen-producing gene) copy number were also detected in microcosms with GLS addition. Higher hydrogen concentrations enhanced the DHC growth, which corresponded to the increased DHC populations. The addition of the GLS could provide alkalinity at the initial stage to neutralize the acidified groundwater caused by the produced organic acids after substrate biodegradation, which was advantageous to DHC growth and TCE dechlorination. The addition of m-RHA reached an increased TCE removal efficiency, which was due to the fact that the m-RHA had the zeolite-like structure with a higher surface area and lower granular diameter, and thus, it resulted in a more effective initial adsorption effect. Therefore, a significant amount of TCE could be adsorbed onto the surface of m-RHA, which caused a rapid TCE removal through adsorption. The carbon substrates released from m-RHA could then enhance the subsequent dechlorination. The developed GLS is an environmentally-friendly and green substrate.

Optimizing Preparation of Fish Scale Collagen Peptide/Sacha Inchi (Plukenetia volubilis L.) Seed Oil Nanoemulsion

AbstractThis study presents results of extracting hydrolyzed collagen peptide from fresh‐water fish scale and using it to prepare a nanoemulsion based on Sacha inchi (Plukenetia volubilis L.) seed oil and collagen peptide. The sacha inchi seed oil is extracted from the seeds of Sacha Inchi (abbreviated as sachi) plant and contains approximate 45 % triple omega 3–6‐9 (ω‐3, ω‐6, ω‐9) content. Pseudo‐ternary phase diagrams of three components: aqueous collagen solution, sachi seed oil, and surfactant/co‐surfactant (Smix) have been constructed. The parameters including the composition of Smix, sachi seed oil, and aqueous collagen solution have been selected to optimize the technology factors for the emulsion process. A quadratic regression equation was chosen, and experimental planning following the Box‐Behnken model using response surface methodology was used to optimize the preparation conditions for the nanoemulsion. The average droplet size of the emulsion systems is the object function for optimization. The Smix is a mixture of surfactant (Tween80) and propylene glycol (PG) with different ratios of Tween80/PG of 1/1, 2/1, 3/1, and 4/1, corresponding to the formation of four emulsion systems, code 1, 2, 3, 4, respectively. The optimal parameters for each emulsion system are different, however, the aqueous collagen solution contains a higher proportion in emulsions. Under the optimal conditions, the predicted values of the objective function of emulsions code 1–code 4 ranged from 95.62 to 185.14 nm, increasing together with the Tween80 ratio in Smix. The experiment values of the objective function of emulsions code 1–code 4 prepared under the optimal conditions are 104.22, 133.70, 159.27, and 207.87 nm, respectively. These values are close to the predicted values, suggesting that the suitability of the experiment and theory. Additionally, the stability of the nanoemulsion prepared under the optimal conditions is also evaluated. A stable nanoemulsion is potentially for loading nutraceuticals and vitamins for applications in personal health care and medicinal fields.

Volumetric properties of three nonylphenol ethoxylated nonionic surfactant mixtures with methanol: Experimental study and modeling with Tammann-Tait and PC-SAFT equation of state

Although physicochemical properties are essential for production and equipment design in oil and gas industries, there is still a lack of data for some systems because of hazardous temperature and pressure conditions. This work provides a volumetric behavior study of three different mixtures composed of nonylphenol ethoxylated nonionic surfactant (IGEPAL CO-520, CO-630, and CO-720) + methanol in the entire mole fraction composition range for temperatures from 313.15 K to 413.15 K and pressures up to 100.0 MPa. These systems behave as a regular liquid, with a volume contraction predominance. It was observed that for high methanol molar content, there is an increase in the cohesive forces because of the ethoxylated chain increases in oxyethylene units. Nevertheless, it was observed that the hydrogen bonds between ether oxygens and hydroxyl hydrogens decrease by increasing temperature, as given by internal pressure data and PC-SAFT modeling. Besides, a new set of parameters for the PC-SAFT equation of state is provided to calculate volumetric and second-order derivative properties.

Evaluation of oral supplementation of free and nanoencapsulated Minthostachys verticillata essential oil on immunological, biochemical and antioxidants parameters and gut microbiota in weaned piglets.

Early weaning is an important stressor that impairs the piglet´s health, and essential oils appear as promising candidates to improve it instead of antibiotics. The aim of this study was to evaluate the effect of oral supplementation of free and nanoencapsulated Minthostachys verticillata essential oil (EO and NEO, respectively) on immunological, biochemical and antioxidants parameters as well as on gut microbiota in weaned piglets. EO was extracted by hydrodistillation and nanoencapsulation was performed by high-energy method using Tween 80 and Span 60 as surfactants. EO and NEO were chemically analyzed by gas chromatography-mass spectrometry (GC-MS). The cytotoxic effects of both EO and NEO was evaluated on Caco-2 cell line. For in vivo assay, male weaned piglets (age: 28 days, mean initial body weight: 11.63 ± 0.37kg) were randomly distributed in six groups of six animals each (n = 6) and received orally EO (10.0mg/kg/day) or NEO (2.5, 5.0 and 10.0mg/kg/day), named hereinafter as EO-10, NEO-2.5, NEO-5 and NEO-10, for 30 consecutive days. Animals not treated or treated with surfactants mixture were evaluated as control and vehicle control. Subsequently, histological, hematological and biochemical parameters, cytokines production, oxidative markers, CD4+/CD8+ T cells and gut microbiota were evaluated. GC-MS analysis was similar in both EO and NEO. The NEO was more toxic on Caco-2 cells than EO. Oral supplementation of EO-10 or NEO-10 improved growth performance compared to control group NEO-2.5 or NEO-5 (p < 0.05) groups. NEO-2.5, NEO-5 and NEO-10 did not alter the morpho-physiology of digestive organs and decreased malondialdehyde (MDA) levels in liver compared to control (p < 0.05) or EO-10 groups (p < 0.05, p < 0.01). In addition, NEO-10 showed an increase in CD4+/CD8+ T cells ratio (p < 0.001), and induced the highest serum levels of IL-10 (p < 0.01). Serum triglycerides levels were significantly lower in animals treated with EO-10 or NEO-2.5, NEO-5 and NEO-10 compared to control group (p < 0.001). Gut microbiota analysis showed that NEO-10 favor the development of beneficial intestinal microorganisms to improve parameters related to early weaning of piglets. In conclusion, EO and NEO improved parameters altered by early weaning in piglets however, NEO was safer and powerful. Therefore, NEO should be further studied to be applied in swine health.

Interaction of sodium dodecyl sulfate and triton X-100 with ofloxacin drug using conductivity and UV–visible spectroscopic techniques in aqueous alcohols media at several temperatures

The current investigation explores the association and complexation of the mixture of anionic surfactant, sodium dodecyl sulfate (SDS), and antibiotic drug, ofloxacin (OFC) as well as nonionic surfactant, Triton X-100 (TRX) and OFC drug respectively in several additive solutions. The investigations were performed by applying conductivity and UV-Visible spectroscopic techniques. The impacts of drug concentration, types of solvents, and composition of aq. solutions of alcohols (methanol (MeOH), ethanol (EtOH), and 1-propanol (1-PrOH)) as well as temperature change have been investigated on the micelle formation of SDS + OFC mixture. The micellization of SDS + OFC and TRX + OFC systems has been characterized by the determination of critical micelle concentration (CMC) from conductivity vs. SDS concentration (conductivity technique) and Absorbance vs log[TRX] (UV-Visible spectroscopic technique) plots respectively. The micellization of SDS was delayed owing to the introduction of the OFC drug while the effect has been intensified as a function of OFC concentration. At a fixed OFC concentration and temperature, the CMC values were acquired to be augmented with the upsurge of alcohol concentration. The enhancement of the CMC changes has been perceived with the escalation of temperature at a definite concentration of OFC in water and 5% (w/w) aq. alcohols media. The disfavor of micellization of TRX in aq. EtOH solutions in comparison to aqueous solution also detected from UV-Visible spectroscopic technique. The binding constant (Kb) for the complexation of TRX with OFC drug was determined using the Benesi-Hildebrand plot. The Kb values were obtained to be affected by the change of solvent and temperature. The negative free energy change (∆Gmo/ ∆Gbo) of the micellization and complexation demonstrate the spontaneous occurrence of micelle formation and complex development. The enthalpy changes (∆Hmo) of micellization were negative (exothermic process) and entropy changes (∆Smo) were positive (highly disordered and entropy-dominated micellization). Other thermodynamic properties ((∆Hbo and ∆Sbo) and thermodynamics of transfer) have been evaluated and illustrated as well, for the working systems.