Ethoxylated Sorbitan Esters Research Articles

Effect of ethoxylated sorbitan ester surfactants on the chromatographic efficiency of poly(ethylene glycol)-based monoliths

The effect of adding ethoxylated sorbitan ester surfactants (Tweens®) to poly(ethylene glycol) diacrylate-based monolithic recipes was investigated. Five different Tweens® have been evaluated to investigate the exact role of non-ionic surfactants in poly(ethylene glycol) diacrylate-based monolith preparations. These monoliths were characterized by scanning electron microscopy, infrared spectroscopy, and nitrogen physisorption analysis. Different morphological features, and surface areas were observed when different types of Tween® were included in the recipe; Tween® 20 and 85 showed small globules, while Tween® 40, 60 and 80 exhibited larger globular structures with different sizes and degrees of coalescence. The different Tween®-based monoliths were investigated for the chromatographic separation of mixtures consisting of hydroxybenzoic acids and alkylbenzenes. These columns were mechanically stable, except for Tween® 80. The highest methylene selectivity and the best overall performance were achieved by Tween® 60. The efficiency was increased by increasing the concentration of the Tween® 60 and the amount of poly(ethylene glycol) diacrylate Mn 700 in the recipes up to 30 wt%, each. Further increases in either Tween® 60 or poly(ethylene glycol) diacrylate Mn 700 led to formation of non-permeable columns. The optimized column was successfully used for separation of mixtures of nonsteroidal anti-inflammatory and sulfa drugs, with a maximum efficiency of 60,000 plates/m.

Global ethoxylated sorbitan esters market to witness a CAGR of 5.8% during 2018-2024

Global ethoxylated sorbitan esters market to witness a CAGR of 5.8% during 2018-2024

The Mode of Action of Adjuvants-Relevance of Physicochemical Properties for Effects on the Foliar Application, Cuticular Permeability, and Greenhouse Performance of Pinoxaden.

We comprehensively studied the complexity of the mode of action of adjuvants by uncoupling the parameters contributing to the spray process during foliar application of agrochemicals. The ethoxylated sorbitan esters Tween 20 and Tween 80 improved the efficiency of pinoxaden (PXD) in controlling grass-weed species in greenhouse experiments by aiding retention, having humectant properties, maintaining the bioavailability, and increasing the cuticular penetration of PXD. The nonethoxylated sorbitan esters Span 20 and Span 80 showed minimal effects on retention, droplet hydration, or cuticular penetration, resulting in reduced PXD effects in the greenhouse. Tris(2-ethylhexyl)phosphate (TEHP) does not contribute much to retention and spreading but strongly enhances the diffusion of PXD across isolated P. laurocerasus cuticular membranes. As TEHP was most efficient in controlling the growth of grass-weed species, we propose that the direct effect of penetration aids on cuticular permeation plays a key role in the efficiency of foliar-applied agrochemicals.

Influence of non-ionic surfactant type on the salt sensitivity of oregano oil-in-water emulsions

During the last decade, there has been a growing interest for more “label-friendly” ingredients in food industry, as well as in pharmaceuticals, and cosmetics. Thus, a lot of research has been developed to the antimicrobial and/or antioxidant characteristics of essential oils. We, therefore, examined the influence of environmental stress conditions (i.e. salt addition and acidification) on the stability of oregano essential oil emulsions that were stabilized by either Tween 80 or Inutec SP1. Whereas Tween 80 is a non-ionic, food-grade ethoxylated sorbitan ester, Inutec SP1 is a biodegradable and renewable hydrophobically modified inulin. Whereas the emulsions prepared with Tween 80 exhibited phase separation (oiling off) at all salt concentrations studied, the emulsions stabilized with Inutec SP1 remained stable for several days; pH variation on the other hand exhibited no significant effect on the stability. Diffusion ordered spectroscopy measurements by nuclear magnetic resonance (DOSY NMR) as well as viscosity measurements suggested the dehydration of the polyoxyethylene (POE) head groups of Tween 80 upon NaCl addition. Measurements by a Quartz crystal microbalance with dissipation, on the other hand, presented no NaCl effect on the thickness of the adsorbed Tween 80 layer to a hydrophobic surface. Besides the effect of NaCl addition or pH variation, the influence of the ripening inhibitor concentration in the lipid phase and/or temperature variation on the Ostwald ripening levels were also investigated. Emulsions containing a 50:50 ratio of oregano essential oil to sunflower oil stored at 4°C exhibited a significant reduction in Ostwald ripening rate. This study has implications for the development of essential oil emulsions to be used as antimicrobial agent when exposed to environmental stress conditions.

Adsorption at air-water and oil-water interfaces and self-assembly in aqueous solution of ethoxylated polysorbate nonionic surfactants.

The Tween nonionic surfactants are ethoxylated sorbitan esters, which have 20 ethylene oxide groups attached to the sorbitan headgroup and a single alkyl chain, lauryl, palmityl, stearyl, or oleyl. They are an important class of surfactants that are extensively used in emulsion and foam stabilization and in applications associated with foods, cosmetics and pharmaceuticals. A range of ethoxylated polysorbate surfactants, with differing degrees of ethoxylation from 3 to 50 ethylene oxide groups, have been synthesized and characterized by neutron reflection, small-angle neutron scattering, and surface tension. In conjunction with different alkyl chain groups, this provides the opportunity to modify their surface properties, their self-assembly in solution, and their interaction with macromolecules, such as proteins. Adsorption at the air-water and oil-water interfaces and solution self-assembly of the range of ethoxylated polysorbate surfactants synthesized are presented and discussed.

Thermodynamic Parameters and their Dependence on Temperature in the Range 298–353 K for Ethoxylated Sorbitan Ester Tween 20, 40, 60 and 80 Surfactants

AbstractThermodynamic parameters of liquid ethoxylated sorbitan ester (Tween 20, 40, 60 and 80) surfactants have been evaluated. For the estimation of these parameters, molar volumes (V) and volume expansion coefficients (α) at different temperatures are employed. These dilatometric studies are predominantly directed towards the establishment of the invariant nature of Sharma's parameter (S0). The S0 and all other parameters values are used to discuss and throw light on the internal structure, molecular order, molecular packing, molecular movement and intermolecular interactions.

Surface and Solution Properties of Amphiphilic Drug‐Nonionic Surfactant Systems

AbstractA surface tension study was performed on mixed amphiphilic drug‐nonionic surfactant systems. The drugs used were adiphenine hydrochloride and nortriptyline hydrochloride whereas surfactants were ethoxylated sorbitan esters and polyethylene oxide–polypropylene oxide–polyethylene oxide triblocks. The critical micelle concentration (CMC) and CMCid (CMC at ideal mixing condition) values suggest nonideal and attractive interactions among the components. The micellar mole fraction values calculated using Rubingh's model indicate predominance of the nonionic surfactant in micelle formation. The mole fraction of surfactant in mixed monolayer values are greater than values, indicating a greater contribution of surfactant in monolayer formation. Thermodynamic parameters, viz. Gibbs energy of micellization , Gibbs energy of adsorption , and excess free energy of mixed micelles and monolayers were also evaluated. All these values suggest stable mixed micelle and mixed monolayer formation.

Cloud Point Studies of Tween and Glycol in the Presence of Salts

This article deals with the cloud point studies of ethoxylated sorbitan ester, Tween in the presence of glycols, and salts. Cloud point temperature of Tween 20 (5 mol dm−3) and Tween 80 (1 mol dm−3) has been determined in the presence of various salts in addition to glycols. The glycols chosen for these studies were triethylene glycol (TEG), and ethylene glycol mono butylether (EGMBE). At concentration below 0.02 M these salts have no significant effect on cloud point temperature in all cases. The cloud point temperature of Tween+TEG and Tween+EGMBE found to decrease in the presence of sodium chloride (NaCl) and potassium chloride (KCl). The cloud point temperature of Tween 20 + TEG and Tween 20 + EGMBE found to increase in the presence of urea and nicotinamide. The change in cloud point was found to be more in case of nicotinamide as compare to urea. The influence of an additive on the cloud point depends on how it affects the intermicellar interactions. An effort has been made to understand the interaction between solvent and additives leading to a change in solubility of Tween.

Mixed Micellization and Interfacial Properties of Polyoxyethylene Sorbitan Esters with Cetylpyridinium Chloride: A Tensiometric Study

AbstractIn this work a surface tensiometric method was used to study the effect of the chain length of non‐ionic surfactants, viz. ethoxylated sorbitan esters, on micellar composition, critical micellar concentration, mutual interaction parameter (β12), and activity coefficients of the mixed micelles formed with the cationic surfactant cetylpyridinium chloride at 25 °C. The micellar characteristics evaluated using the Clint, Rubingh, and Blankschtein models deviated significantly from ideality, and were used to ascertain the validity of these theories. Thermodynamic stability in terms of Maeda's approach and interfacial properties is also discussed.

Formulation of food-grade microemulsions with glycerol monolaurate: effects of short-chain alcohols, polyols, salts and nonionic surfactants

The formulation of food-grade microemulsions with glycerol monolaurate (GML) for antimicrobial applications has been studied. The compositions included water, GML, short-chain alcohols (such as ethanol), polyols (propylene glycol and glycerol), salts (organic, such as sodium benzoate, sodium lactate and sodium propionate, and inorganic, such as NaCl) and several nonionic surfactants [such as ethoxylated sorbitan esters, sucrose esters (SEs)]. The phase behavior of these systems is discussed with respect to the influence of composition on the degree of oil solubilization in the aqueous phase. The oil solubilization was dramatically improved in the presence of the short-chain alcohols and polyols, organic salts contributed to the improvement of oil solubilization as hydrotropes. Tween 20 being the most hydrophilic surfactant in Tweens solubilized the maximum oil, but in the presence of SEs it is hard to form oil-in-water microemulsions. Viscosity measurements along selected dilution lines indicate that at a certain composition the system inverts from a water-in-oil to an oil-in-water microemulsion.

Antimicrobial effect of food-grade GML microemulsions against Staphylococcus aureus

Food-grade GML (Glycerol Monolaurate, the glycerol monoester of lauric acid) microemulsions based on multi-component mixtures and enhanced antimicrobial effects have been studied. The compositions included water, GML, several surfactants (ethoxylated sorbitan esters, sucrose esters), alcohols (pentanol and dodecanol), salt (potassium sorbate). The influence of surfactants, alcohols and salt on the phase behavior is discussed in this paper. Four improved formulations of microemulsion systems with large O/W regions have been obtained and demonstrated the enhanced antimicrobial activities against Staphylococcus aureus, compared to Glycerol Monolaurate. Subsequently, one formulation with the highest antimicrobial activity was further studied with respect to the influence of each component on the antimicrobial effect. The results showed that among all the components, GML had the significantly highest (P < 0.01) inhibition ratio 63.52% and played a dominating role in the antimicrobial activities. Therefore, it was concluded that food-grade GML microemulsions had enhanced antimicrobial activities against S. aureus, with a major contribution of GML.

Improvement in fermentation characteristics of degermed ground corn by lipid supplementation

With rapid growth of fuel ethanol industry, and concomitant increase in distillers dried grains with solubles (DDGS), new corn fractionation technologies that reduce DDGS volume and produce higher value coproducts in dry grind ethanol process have been developed. One of the technologies, a dry degerm, defiber (3D) process (similar to conventional corn dry milling) was used to separate germ and pericarp fiber prior to the endosperm fraction fermentation. Recovery of germ and pericarp fiber in the 3D process results in removal of lipids from the fermentation medium. Biosynthesis of lipids, which is important for cell growth and viability, cannot proceed in strictly anaerobic fermentations. The effects of ten different lipid supplements on improving fermentation rates and ethanol yields were studied and compared to the conventional dry grind process. Endosperm fraction (from the 3D process) was mixed with water and liquefied by enzymatic hydrolysis and was fermented using simultaneous saccharification and fermentation. The highest ethanol concentration (13.7% v/v) was achieved with conventional dry grind process. Control treatment (endosperm fraction from 3D process without lipid supplementation) produced the lowest ethanol concentration (11.2% v/v). Three lipid treatments (fatty acid ester, alkylphenol, and ethoxylated sorbitan ester 1836) were most effective in improving final ethanol concentrations. Fatty acid ester treatment produced the highest final ethanol concentration (12.3% v/v) among all lipid supplementation treatments. Mean final ethanol concentrations of alkylphenol and ethoxylated sorbitan ester 1836 supplemented samples were 12.3 and 12.0% v/v, respectively.

Formation and investigation of microemulsions based on jojoba oil and nonionic surfactants

AbstractThe properties of jojoba oil make it uniquely suited as a raw material for the cosmetics industry. Water‐based, thermodynamically stable preparations of jojoba oil are essential in many formulations. New microemulsions were prepared based on jojoba oil and different nonionic surfactants, namely polyoxyethylene‐(ethylene oxide)10‐oleyl alcohol (Brij 96V) and ethoxylated sorbitan esters (Tweens). The effects of the surfactants and of primary alcohols as cosurfactants on the isotropic regions of the phase diagram were elucidated. It was found that, up to a certain cosurfactant chain length, the isotropic region expanded considerably as chain length increased. The size of the isotropic region also increased as a function of the ethylene glycol content of the aqueous phase in microemulsions based on ethoxylated alcohol but shrank when ethylene glycol was included in microemulsions prepared with ethoxylated sorbitan esters. Secondary structural phase transitions from water‐in‐oil to bicontinous and to oil‐in‐water structures (as determined by measuring conductivity and viscosity) were found to be related to jojoba oil content. Dynamic light scattering and small angle X‐ray scattering studies established that incorporation of jojoba oil into Brij 96V micelles caused micellar transformation from elongated to spherical droplets and a decrease in the aggregation number.

Transitions and loci of solubilization of nutraceuticals in U-type nonionic microemulsions studied by self-diffusion NMR

U-type microemulsions based on five food-grade ingredients, water, R(+)-limonene, ethanol, propylene glycol, (or glycerol) and ethoxylated sorbitan esters (Tween 60 or Tween 80) were studied. The U-type phase diagram is characterized by a unique composition, fully dilutable with the aqueous phase that inverts progressively from an L2 phase to an L1 phase via a bicontinuous structure without phase separation. The ‘oil concentrate’ (surfactant, oil, alcohol) is loaded with water-insoluble solubilizates (phytosterols, lutein and lycopene) a few times more than the solubility capacity of the oil phase (without the surfactant). The maximum solubilization capacity (μ-value) was obtained for phytosterols and the minimum solubilization capacity was for lycopene. All solubilization values decrease with aqueous phase dilution. If solubilization is calculated on the basis of the oil content (α-value) or the oil + surfactant (γ-value) it is obvious that the interface plays a key role in the solubilization.The lipophilic solubilizates (by SD-NMR) are tightly packed and well accommodated at interfaces that convex (hydrophobic-in-nature) toward the water (water-in-oil microemulsions). Solubilization at the bicontinuous interface is lower and the solubilizates are loose packed. Once phase inversion occurs, and the interface becomes more hydrophilic and transforms into oil-in-water microemulsion, the solubilization becomes minimal, and most of the solubilizate desorbs. Phytosterols and lycopene induce the transition from W/O to bicontinuous and it occurs at lower water content (ca. 25 wt% aqueous phase in the presence of solubilizate vs. 35 wt% in its absence). The transition from bicontinuous to O/W is mostly unaffected (or undetected) since the interface flattens out and the solubilizate does not affect the curvature much. Lutein displays different behavior, the transition, from bicontinuous phase to O/W, occurs at higher water contents because its adsorption and packing are significantly tighter. Solubilization capacities of each of the nutraceuticals were determined for all dilution compositions.

Self-diffusion nuclear magnetic resonance, microstructure transitions, and solubilization capacity of phytosterols and cholesterol in Winsor IV food-grade microemulsions.

Microemulsions are of growing interest to the food industry as vehicles for delivering and enhancing solubilization of natural food supplements with nutritional and health benefits. The incorporation of molecular phytosterols, cholesterol-lowering agents, in food products is of great interest to the food industry. In this work is demonstrated the use of water dilutable food-grade microemulsions consisting of ethoxylated sorbitan ester (Tween 60), water, R-(+)-limonene, ethanol, and propylene glycol as vehicles for enhancing the phytosterols solubilization. Phytosterols were solubilized up to 12 times more than the dissolution capacity of the oil [R-(+)-limonene] for the same compounds. The solubilization capacity of phytosterols and cholesterol along a dilution line in a pseudo-ternary phase diagram [on this dilution line the weight ratio of R-(+)-limonene/ethanol/Tween 60 is constant at 1:1:3] was correlated to the microstructure transitions along the dilution line. Structural aspects were studied by self-diffusion NMR spectroscopy. The ability of phytosterols to compete with cholesterol for penetration into bile salt micelles in the gut may be limited to rich aqueous systems (O/W microemulsion).

Synthesis of stable mesostructured zirconia: Tween surfactant and controlled template removal

Mesostructured zirconia has been synthesized by using zirconium chloride and PEO nonionic ethoxylated sorbitan ester (Tween-20, -40, -60 or -80) as a zirconium source and structure-directing agent in an aqueous medium. To remove the occluded surfactants, UV/ozone treatment has been utilized instead of calcination due to thermal instability. This results from a special molecular structure of Tween surfactant. From XRD, SEM and TEM analyses, the materials treated with UV light and in-situ generated ozone has a wormhole structure and ill-defined or well-defined spherical particles.

Food-grade microemulsions based on nonionic emulsifiers: media to enhance lycopene solubilization.

Water-dilutable food-grade microemulsions consisting of ethoxylated sorbitan esters, and in some cases blended with other emulsifiers, water, (R)-(+)-limonene, ethanol, and propylene glycol, have been prepared. These microemulsions are of growing interest to the food industry as vehicles for delivering and enhancing solubilization of natural food supplements with nutritional and health benefits. Lycopene, an active natural lipophilic antioxidant from tomato, has solubilized in water-in-oil, bicontinuous, and oil-in-water types of microemulsions up to 10 times the oil [(R)-(+)-limonene] dissolution capacity. The effects of aqueous-phase dilution, nature of surfactant (hydrophilic-lypophilic balance), and mixed surfactant on solubilization capacity and solubilization efficiency were studied. Structural aspects studied by self-diffusion NMR were correlated to the solubilization capacity, and transformational structural changes were identified.

Co-surfactant of ethoxylated sorbitan ester and sorbitan monooleate for enhanced flushing of tetrachloroethylene.

This work evaluated the flushing efficiency of tetrachloroethylene (PCE) using the co-surfactant of non-ionic ethoxylated sorbitan ester (Tween) and oilphilic sorbitan monooleate (Span 80), which formed more hydrophobic micelles than Tween alone. The flushing efficiency was evaluated with laboratory columns filled with silica and aquifer sand. Results from column flushing were also compared to those of batch solubility experiments to study the removal mechanism by the co-surfactant solution. Compared to Tween 80 alone, the molar solubilization ratio and the affinity between the micelles and PCE increased 84% and 90%, respectively, by the co-surfactant solution of Tween 80 and Span 80 mixed at a 4:1 ratio. Flushing with 1% Tween 80 solution yielded a steady PCE recovery of 7% for both silica and aquifer sand in each pore volume (PV). Flushing with co-surfactant of 1% Tween 80 + Span 80 (4:1) further increased PCE recovery to 10% for silica sand and 13% for aquifer sand per PV. A comparison of results from column flushing and batch solubility tests indicated that the primary flushing mechanism of PCE using the co-surfactant solution of Tween 80 + Span 80 (4:1) was micellar solubilization.

Phase behavior of microemulsions based on food-grade nonionic surfactants: effect of polyols and short-chain alcohols

Abstract The improved water and oil solubilization in the presence of polyols (propylene glycol, PG, and glycerol, Gly) and short-chain alcohol (ethanol) in U-type nonionic W/O and O/W food microemulsions was investigated. The phase behavior of systems based on Tweens (ethoxylated sorbitan esters) was compared with non-food-grade systems based on C18:1E10 (Brij 96v). Short-chain alcohol (ethanol in food-grade systems) together with polyols (glycerol and propylene glycol) when added to a three component system (oil–surfactant–water) induce the formation of both water-in-oil (W/O) and oil-in-water (O/W) microemulsions. Alcohols and polyols destabilize the liquid crystalline phase and extend the isotropic region to higher surfactant concentrations. The total monophasic area, AT, at R(+)-limonene/ethanol of 1/1 (w/w) and aqueous phase of water/PG of 1/1 (w/w), was 73 and 64% of the total area of the phase diagram for Brij 96v and Tween 60, respectively. The transition from a W/O microemulsion into an O/W microemulsion happens gradually, and continuously without any phase separation. The total monophasic area depends also on the type of the oil, on the composition of the polar and apolar phases, and on the nature of the polyol. The results are discussed in terms of BSO equation, spontaneous curvature, H0, film flexibility, κ and κ , surfactant oil and surfactant cosolvent compatibility and the participation of the polyol at the interface. The difference in temperature sensitivity of PG-based microemulsions vs. temperature sensitivity of Gly-based is demonstrated and explained.

Improved oil solubilization in oil/water food grade microemulsions in the presence of polyols and ethanol.

Microemulsions based on five-component mixtures for food applications and improved oil solubilization have been studied. The compositions included water, oil phase [such as R(+)-limonene and medium-chain triglycerides (MCT)], short-chain alcohols (such as ethanol), polyols (propylene glycol and glycerol), and several surfactants and their corresponding mixtures (nonionic, such as ethoxylated sorbitan esters, polyglycerol esters, sugar ester, and anionic, such as phosphatidylcholine). The phase behavior of these systems is discussed with respect to the influence of polyols and short-chain alcohols on the degree of solubilization of oils in the aqueous phase. The alcohol and polyols modify the interfacial spontaneous curvature and the flexibility of the surfactant film, enhancing the oil solubilization capacity of the microemulsions. The solubilization of R(+)-limonene was dramatically improved in the presence of the alcohol and polyols, whereas the improvement of solubilization for triglycerides containing MCT was less pronounced. In some systems high oil solubilization was achieved, and some of them can be easily diluted to infinity both with the aqueous phase and with the oil phase. Viscosity measurements along selected dilution lines [characterized by a single continuous microemulsion region starting from a pseudo binary solution (surfactant/oil phase) to the microemulsion (water/polyol corner)] indicate that at a certain composition the system inverts from a W/O to an O/W microemulsion.