Microemulsion formation and detergency with oily soils: III. Performance and mechanisms

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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: Resultsmentioning

confidence: 99%

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

Upadhyaya¹,

Acosta²,

Sabatini³

2006

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“…However, if the system is operated in a Winsor Type III middle-phase microemulsion region, oil removal in the rinse step can be as high as that in the wash step. In addition, for highly hydrophobic oil such as motor oil, the oil was mostly removed in the rinse step instead of the wash step (12,20). In this present work, similar experiments were performed with the formulations S1 and S2.…”

Section: Figmentioning

confidence: 98%

“…These results suggest that the spreading effect that can be expected to occur when the system is operated at the second detergency maxima (D max2 ) as a result of the ultralow IFT. The mechanism of oily soil removal under the ultralow IFT condition resulting in spreading was explained in detail in a previous study (20).…”

Section: Figmentioning

confidence: 99%

Enhanced triolein removal using microemulsions formulated with mixed surfactants

Tongcumpou

Acosta

Sabatini

et al. 2006

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In previous work, a microemulsion-based formulation approach yielded excellent laundry detergency with hydrophobic oily soils hexadecane and motor oil. In this work, the same approach is used in detergency of triolein, which is a model triglyceride, some of the most difficult oils to be removed from fabric. The linker concept was applied in formulation of the microemulsion system. Three different surfactants were used: (i) dihexyl sulfosuccinate, an ionic surfactant with a moderate hydrophile-lipophile balance (HLB); (ii) secondary alcohol ethoxylate, a lipophilic nonionic surfactant with a very low HLB; and (iii) alkyl diphenyl oxide disulfonate (ADPODS), a hydrophilic anionic surfactant with a very high HLB. The phase behavior and interfacial tension (IFT) of the surfactant systems were determined with different concentrations of ADPODS.The results indicate that as the HLB of the system increases, a higher salinity is required to shift the phase transition from Winsor Type I to Type III to Type II. The three formulations at different salinities were used in detergency experiments to remove triolein from polyester/cotton sample fabric. The results showed that there were two peaks of maximum detergency in the range of salinity from 0.1% to 10% NaCl. The higher the hydrophilicity of the system, the higher the salinity required for maximum detergency. The results of the dynamic IFT and the detergency performance from two rinsing methods lead to the hypothesis that one of these maxima in detergency results from a spreading or wetting effect. The other maximum in detergency is believed to be related to ultralow IFT associated with oil/water middle-phase microemulsion formation. Triolein removal exceeding 80% was attained, validating the microemulsion approach to detergency.Paper no. S1516 in JSD 9, 181-189 (Qtr 2, 2006). KEY WORDS:Alkyl diphenyl oxide disulfonate, dihexyl sulfosuccinate, microemulsion, secondary alcohol ethoxylate, triolein, detergency.Oily soil washing is an important subject of interest in the area of detergency. Most natural oils are considered to be polar oils because of fatty acid or alcohol structures in their compositions. Stained oils on fabric are not only simple hydrocarbon liquids; they can also be polar and nonpolar oils, fatty acids, fatty alcohols, or other substances. Over the last several decades, research has evaluated several types of oils to understand the mechanism of oil removal in the detergency process (1-10). Triolein or glycerol trioleate, a liquid form of triglyceride, is a major component found in most natural fats from both plants and animals. It is present in many food products, such as cooking oil, margarine, and butter. Thus, it is considered a good representative of triglyceride oily soil on clothes and kitchenware in detergency tests. Studies on triolein removal by nonionic surfactants have been reported for decades (1). However, the phase behavior and the detergency mechanism for triolein are not well understood.Triolein has a considerably higher molecular weight tha...

“…Low or ultralow oil/water IFT and high solubilization can result from the presence of microemulsions in the system. The correlation between microemulsion formation and detergency has been noted in a number of studies [1,[7][8][9][10][11][12][13][14][15][16]. It has been shown that the maximum detergency corresponds to the optimum conditions of the system where the minimum oil/water IFT of the microemulsion exists [7,16,17].…”

Section: Introductionmentioning

confidence: 99%

“…In our previous studies [13][14][15], formulation of mixed surfactants based on the linker concept were used to form microemulsions with both motor oil and hexadecane in detergency studies. The three surfactants used, in decreasing order of hydrophilicity, were: alkyldiphenyloxide disulfonate (ADPODS), sodium dioctyl sulfosuccinate (AOT), and sorbitan monooleate (Span 80).…”

Section: Introductionmentioning

confidence: 99%

Microemulsion Formation and Detergency with Oily Soil: IV. Effect of Rinse Cycle Design

Tanthakit

Chavadej

Sabatini

et al. 2008

The objective of this work was to apply a microemulsion-based formulation for the removal of motor oil in laundry detergency at low salinity. To produce the desired phase behavior, three surfactants were used: alkyl diphenyl oxide disulfonate (ADPODS), sodium dioctyl sulfosuccinate (AOT) and sorbitan monooleate (Span 80). The mixed surfactant system of 1.5% ADPODS, 5% AOT and 5% Span 80 (13 parts ADPODS, 43.5 parts AOT, and 43.5 parts Span 80 of the total actives) was found to form a middle phase microemulsion (Type III) at a relatively low salinity of 2.83% NaCl. When this formulation was diluted, detergency performance increased with increasing total surfactant concentration and leveled off above about 0.1% total actives on the three types of fabrics studied (pure cotton, 65/35 polyester/cotton blend, and pure polyester). Detergency was found to improve with increasing hydrophilicity of the fabric with cotton being cleanest after washing and polyester the most difficult to clean. To achieve a specified oil removal, less rinse water can be used if a higher number of lower-volume rinses are employed. An interesting characteristic of microemulsionbased formulations is that a substantial fraction of oil removal occurs during the rinse cycle. In this work, this removal is shown to be due to the low oil/water interfacial tension during initial rinsing and is therefore strongly correlated to residual surfactant concentration in the rinse steps. As a result, the number of rinses and the volume of water per rinse can profoundly affect detergency in these systems.