Surfactant solutions detergent

In detergency, for separation of an oily soil O from a solid fabric S just to occur in an aqueous surfactant solution W, the desired condition is 730 = 7wo+7sw. Use simple empirical surface tension relationships to infer whether the above condition might be met if (a) 73 = 7w. (6) 70 = 7W, or (c) 73 = 70. 

Amphoteric Detergents. These surfactants, also known as ampholytics, have both cationic and anionic charged groups ki thek composition. The cationic groups are usually amino or quaternary forms while the anionic sites consist of carboxylates, sulfates, or sulfonates. Amphoterics have compatibihty with anionics, nonionics, and cationics. The pH of the surfactant solution determines the charge exhibited by the amphoteric under alkaline conditions it behaves anionically while ki an acidic condition it has a cationic behavior. Most amphoterics are derivatives of imidazoline or betaine. Sodium lauroamphoacetate [68647-44-9] has been recommended for use ki non-eye stinging shampoos (12). Combkiations of amphoterics with cationics have provided the basis for conditioning shampoos (13). 

The gravity measurements of the pelobischofite and appropriate compositions detergency showed the essential increase of this parameter for pelobischofite-surfactant mixtures. Thus the washing power of pelobischofite-surfactant solutions with concentration 0,1% was 90%. Erom another hand, similar detergency of bischofite-surfactant mixtures was reached for 1% solutions only. 

Because the reaction of an amine with an acyl chloride is much faster than the hydrolysis of the acyl chloride, the reaction can usually be carried out in an aqueous alkali solution. This is well known as the Schotten-Baumann procedure.6 For example, a number of N-acyl taxol analogs have been prepared under Schotten-Baumann conditions by the reaction of A-debenzoyltaxol with various acid chlorides (Eq. 9.4).7 Highly purified /V-long-chain-acyl neutral amino acids such as potassium AMauroyTy-aminobutyrate, useful as surfactants for detergent... 

From the form of Equation 11, it is clear that the slope, a, will be independent of the aqueous surfactant solution. However, b in the intercept, 1 + (bA sw will not be zero in fact, it will not even be independent of the aqueous surfactant solution, Therefore, the conventional methods of Girifalco-Good plot analysis with an intercept of unity will not work for the detergency systems of interest in this work. The impediment to the Girifalco-Good analysis method is obvious from Figure 9, where no set of data points (3 or more) lies on a line passing... 

Figure 8.7 shows the ternary phase diagram for water, hexanoic acid, and sodium dodecyl sulfate at 25 °C. Seven different areas are shown in the figure, which has been used to describe the solubilization of polar dirt by surfactant solutions in detergency applications. The following comments refer to these seven different regions and explain the labeling used in Figure 8.7 ...

Surfactants. By definition every detergent product contains one or more types of surfactants. Basically, every surfactant is an organic compound consisting of two parts (I) a hydrophobic portion, normally including a long hydrocarbon chain, and (2) a hydrophilic portion, which renders the entire compound sufficiently soluble or dispersible in water or other polar solvent to serve its intended use. Together, these combined hydrophobic and hydrophilic moieties render the compound surface-active—able to concentrate at the interface between a surfactant solution and another phase, such as air. soil, and textile substrate to be cleaned. 

Therefore, Ache and coworkers studied positron interactions in aqueous and nonpolar detergent systems, i.e., DAP in benzene, cyclohexane, n-hexane, and AOT in benzene. They obtained a rather abrupt drop of the intensity I2 which is a remarkably sensitive indication of critical concentration, as compared with the information obtained from spectroscopic or other standard techniques. The method appears particularly promising regarding CMC determinations in nonpolar surfactant solutions. 

Time - resolved spectra of a solid hydrocarbon layer on the surface of an internal reflection element, interacting with an aqueous solution of a nonionic surfactant, can be used to monitor the detergency process. Changes in the intensity and frequency of the CH2 stretching bands, and the appearance of defect bands due to gauche conformers indicate penetration of surfactant into the hydrocaibon layer. Perturbation of the hydrocarbon crystal structure, followed by displacement of solid hydrocaibon from the IRE surface, are important aspects of solid soil removal. Surfactant bath temperature influences detergency through its effects on both the phase behavior of the surfactant solution and its penetration rate into the hydrocaibon layer. 

Solid soils are commonly encountered in hard surface cleaning and continue to become more important in home laundry conditions as wash temperatures decrease. The detergency process is complicated in the case of solid oily soils by the nature of the interfacial interactions of the surfactant solution and the solid soil. An initial soil softening or "liquefaction", due to penetration of surfactant and water molecules was proposed, based on gravimetric data (4). In our initial reports of the application of FT-IR to the study of solid soil detergency, we also found evidence of rapid surfactant penetration, which was correlated with successful detergency (5). In this chapter, we examine the detergency performance of several nonionic surfactants as a function of temperature and type of hydrocarbon "model soil". Performance characteristics are related to the interfacial phase behavior of the ternary surfactant -hydrocarbon - water system. 

The removal of hydrocarbon from the IRE surface can be monitored by the changes in the intensity of the intense CH2 stretching band near 2850 cm 1 in the series of time-resolved spectra recorded during the exposure of the layer to surfactant solution. The absolute intensity of this band varies somewhat from layer to layer. Normalized intensities were obtained by dividing the intensity of the band in the spectrum of the initial, dry layer by the intensity of the band in each of the time-resolved spectra. These normalized intensities are plotted versus time. Values slightly greater than 1.0 occur because of the difference in refractive index between air and water, the media "behind" the thin hydrocarbon layers in the case of the initial and time - resolved spectra, respectively. Normalized intensities in excess of 1.0 can only be detected in detergency runs where little or no removal occurs. 

The characteristic effect of surfactants is their ability to adsorb onto surfaces and to modify the surface properties. Both at gas/liquid and at liquid/liquid interfaces, this leads to a reduction of the surface tension and the interfacial tension, respectively. Generally, nonionic surfactants have a lower surface tension than ionic surfactants for the same alkyl chain length and concentration. The reason for this is the repulsive interaction of ionic surfactants within the charged adsorption layer which leads to a lower surface coverage than for the non-ionic surfactants. In detergent formulations, this repulsive interaction can be reduced by the presence of electrolytes which compress the electrical double layer and therefore increase the adsorption density of the anionic surfactants. Beyond a certain concentration, termed the critical micelle concentration (cmc), the formation of thermodynamically stable micellar aggregates can be observed in the bulk phase. These micelles are thermodynamically stable and in equilibrium with the monomers in the solution. They are characteristic of the ability of surfactants to solubilise hydrophobic substances. 

Structure Formation in Surfactant Solutions. Surfactants, also referred to as soaps, detergents, tensides, or surface active agents, are amphiphilic molecules possessing both hydrophilic and hydrophobic regions. They can be classified as anionic, cationic, zwitterionic, or nonionic (neutral) depending upon the nature of the polar... 

Throughout the discussion, the terms surface active agent, surfactant, and detergent are used interchangeably to refer to amphiphilic substances which form association colloids or micelles in solution. Amphiphilic substances or amphiphiles are molecules possessing distinct regions of hydrophobic and hydrophilic character. 

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