Nonionic surfactants general

J. Cross, in Nonionic Surfactants General Analysis (J. Cross, ed.), Surfactant Science Series, Volume 19, Marcel Dekker, New York, 1987, pp. 137-224. 

In nonionic surfactants generally, the efficiency of adsorption is much greater than in ionic surfactants with the same number of carbon atoms in the hydrophobic group. This is because in the adsorption of ionic surfactants, electrical repulsion between the ionic heads of surfactant ions already at the interface and the similarly charged oncoming surfactant ions increases the positive free energy of transfer of the hydrophilic head from the interior of the bulk phase to the interface. 

Nonionic surfactants generally produce less initial foam and less stable foams than do ionics in aqueous solution. Because such materials must by nature have rather large surface areas per molecule, it becomes difficult for... 

Nonionic surfactants generally have less initial foam and less stability. The large surface area/molecule leads to lower interfacial elasticity, and the big bulky head groups are slow to diffuse to new interfaces. 

Surface-active properties of nonionic surfactants generally result from the average contributions of individual homologs. For some applications a narrower EO distribution can be produced upon request from the suppliers. 

Nonionie Detergents. Nonionic surfactants rarely are used as the primary cleansing additives ia shampoos. They are generally poor foaming, but have value as additives to modify shampoo properties, eg, as viscosity builders, solubilizers, emulsifiers, and conditioning aids. 

To overcome these difficulties, drilling fluids are treated with a variety of mud lubricants available from various suppHers. They are mostly general-purpose, low toxicity, nonfluorescent types that are blends of several anionic or nonionic surfactants and products such as glycols and glycerols, fatty acid esters, synthetic hydrocarbons, and vegetable oil derivatives. Extreme pressure lubricants containing sulfurized or sulfonated derivatives of natural fatty acid products or petroleum-base hydrocarbons can be quite toxic to marine life and are rarely used for environmental reasons. Diesel and mineral oils were once used as lubricants at levels of 3 to 10 vol % but this practice has been curtailed significantly for environmental reasons. 

Finally, some general rules for the amount of surfactant appear to be vaHd (13). For anionic surfactants the average size of droplets is reduced for an increase of surfactant concentration up to the critical micellization concentration, whereas for nonionic surfactants a reduction occurs also for concentrations in excess of this value. The latter case may reflect the solubiHty of the nonionic surfactant in both phases, causing a reduction of interfacial tension at higher concentrations, or may reflect the stabilizing action of the micelles per se. 

Protease performance is strongly influenced by detergent pH and ionic strength. Surfactants influence both protease performance and stabiUty in the wash solution. In general, anionic surfactants are more aggressive than amphoteric surfactants, which again are more aggressive than nonionic surfactants. 

In the framework of the phthalate controversy Wilkinson and Lamb [109] used various in vitro methods in which known amounts of soft PVC materials were shaken, stirred, impacted, or otherwise mechanically agitated in some type of simulated saliva under controlled conditions (T, f), and the saliva extracted into hexane for analysis. Shaking-flask (liquid-liquid) extraction was also used for the solvent extraction of nonionic surfactants of the general type R0(CH2CH20) H (where R... 

Nearly all nonionic surfactants contain the same type of hydrophobes as do anionic and cationic surfactants, with solubilisation and surfactant properties arising from the addition of ethylene oxide to give a product having the general formula 9.40. Usually, depending on the... 

Nowadays, proprietary mixtures of lubricating agents are formulated with ease of removal in scouring very much in mind. Consequently, scouring processes are generally mild, using a nonionic surfactant at about 50-60 °C [11]. 

Surfactants, not surprisingly, exert a highly significant influence on the fluorescence of FBAs in solution. This effect is associated with the critical micelle concentration of the surfactant and may be regarded as a special type of solvent effect. Anionic surfactants have almost no influence on the performance of anionic FBAs on cotton, but nonionic surfactants may exert either positive or negative effects on the whiteness of the treated substrate [33]. Cationic surfactants would be expected to have a negative influence, but this is not always so [34]. No general rule can be formulated and each case has to be considered separately. 

For polyester, the washing-off process to remove unfixed dye and thickening agent is generally a reduction clear as described in section 12.6.6. A simple wash-off with nonionic surfactant must be used on cellulose acetate or triacetate, although a mild reduction clear may be preferable on triacetate. 

It is important to point out that, in general, the micelles composed of nonionic surfactants usually have a lower cmc and higher aggregation numbers than the analogous ionic micelles. This is partly due to the absence of electrostatic repulsion between the heads of the nonionic surfactants. However, in the ionic micelles these repulsion tend to limit the aggregation number and the cmc. 

Nonionic surfactants of general structure 176, used in off-shore drilling (e.g. Nonidet AT 85), are toxic and slowly biodegradable. They can be determined in an FIA system by... 

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