Linker‐modified microemulsions for a variety of oils and surfactants

This research evaluated middle-phase microemulsion formation by varying the mole ratio of anionic and cationic surfactants in mixtures with four different oils (trichloroethylene, n-hexane, limonene, and n-hexadecane).Mixtures of a double-tailed anionic surfactant (sodium dihexyl sulfosuccinate, SDHS) and an unbalanced-tail (i.e., doubletailed with tails of different length) cationic surfactant (benzethonium chloride, BCl) were able to form microemulsions without alcohol addition. The amount of NaCl required to form the middle-phase microemulsion decreased dramatically as an equimolar anionic-cationic surfactant mixture was approached. Although the mixture of anionic and cationic surfactants demonstrated a higher critical microemulsion concentration (cµc) compared to the anionic surfactant alone, the Winsor Type IV single-phase microemulsion started at lower surfactant concentrations for the anionic-cationic mixture than for the anionic surfactant alone. Under optimum middlephase microemulsion conditions, mixed anionic-cationic surfactant systems solubilized more oil than the anionic surfactant alone. Pretreatment detergency studies were conducted to test the capacity of these mixed surfactant systems to remove oil from fabrics. It was found that anionic-rich mixed surfactant formulations yielded the largest oil removal, followed by cationic-rich systems.

Section: Resultssupporting

confidence: 84%

Section: Methodsmentioning

confidence: 99%

Microemulsion phase behavior of anionic‐cationic surfactant mixtures: Effect of tail branching

Upadhyaya¹,

Acosta²,

Sabatini³

2006

“…Microemulsion phase studies were performed in flat-bottom vials with Teflon-lined screw caps using standard methods [6,7,20,21]. Equal volumes of oil and water (5 mL) were added into the vial at different NaCl concentrations (salinity scan).…”

Section: Methodsmentioning

confidence: 99%

“…Another important property associated with the n parameter is the rigidity of the surfactant membrane or the interfacial rigidity (E r ). Based on a series of phase studies with linker molecules [17,[20][21][22], systems with higher n values produced a rigid surfactant membrane (high E r values).…”

Section: Introductionmentioning

confidence: 99%

Interfacial Properties of Extended‐Surfactant‐Based Microemulsions and Related Macroemulsions

Witthayapanyanon

Phan

Heitmann

et al. 2009

Self Cite

Extended surfactants containing an intermediatepolarity spacer, such as polypropylene oxide, in between the hydrophilic head and the hydrocarbon tail are known to result in superior solubilization and low interfacial tension, though they exhibit slow kinetics. The present work seeks to evaluate both equilibrium and kinetic aspects of extendedsurfactant-based micro-and macroemulsions. The interfacial morphology of the extended surfactant membrane, i.e., characteristic length (n) and interfacial rigidity (E r ) at optimum middle-phase microemulsion conditions, was characterized using the net-average curvature model. The results showed that extended surfactants resulted in a relatively rigid interfacial membrane compared with conventional surfactants having similar hydrocarbon chain length. In addition, both n and E r parameters increased with the length of the polypropylene oxide spacer. Increasing E r values correlated to the slow coalescence rates of extended surfactant emulsified systems. Two alternative approaches (the addition of combined linkers and co-surfactant) are shown to overcome the slow kinetics of coalescence while maintaining desirable high solubilization and low interfacial tension.

“…2 can be neglected. Experimental procedures for determining the EACN values for oils were described by Acosta et al in [29], where they determined the EACN values of isopropyl myristate and squalene. In our research, we conducted a sodium chloride scan at a fixed 0.1 wt% C 12 -12PO-2EO sulfate surfactant concentration for different oils.…”

Section: Determination Of the Equivalent Alkane Carbon Number Of Vegementioning

confidence: 99%

Environmentally Friendly Vegetable Oil Microemulsions Using Extended Surfactants and Linkers

Linh

Withayyapayanon

Harwell

et al. 2008

Self Cite

106

Microemulsion formation of triglyceride oils at ambient conditions (temperature and pressure) and without the addition of co-oil and/or alcohols is challenging at best. Undesirable phases, such as macroemulsions, liquid crystals and sponge phases, are often encountered when formulating triglyceride microemulsions. The purpose of this study is to investigate the use of extended surfactants, lipophilic linkers, and hydrophilic linkers in enhancing triglyceride solubilization and interfacial tension reduction. We have studied two classes of extended surfactants, linear alkyl polypropoxylated sulfate (LAPS) surfactants and linear alkyl polypropoxylated ethoxylated sulfate (LAPES) surfactants. Linkers evaluated were oleyl alcohol (lipophilic linker), sodium mono and dimethyl naphthalene sulfonate (SMDNS), and polyglucoside (hydrophilic linkers). Oils studied include olive, peanut, soybean, canola and sunflower oils. The effect of electrolyte concentration on microemulsion phase behavior was studied. The microemulsion ''fish'' diagram was obtained by plotting the total surfactant and linker concentrations versus the electrolyte concentration.We were able to form Winsor Type I, II, III and IV microemulsions at ambient conditions and without co-oil or short and medium chain length alcohol addition. Winsor Type III and IV triglyceride microemulsions are particularly useful in numerous applications such as cosmetics, vegetable oil extraction and soil remediation.