Normalized surfactant concentration

Figure 5. Normalized surfactant concentration from a core flow adsorption test.

Nonionic detergents formulated for use in high turbulence equipment such as jets. Offering efficient oil removal and emulsification properties, KLENZOL 201 is especially useful in processing goods where excessive amounts of oil warrant higher than normal surfactant concentrations without foaming difficulties. 

For normalization of the value of the heat transfer enhancement, we used its magnitude at the maximum for each curve. The result of such normalization is shown in Fig. 2.59. In this figure, C is the solution concentration, Cq is the characteristic concentration, h is the heat transfer coefficient at given values of the solution concentration and the heat flux q, /zmax is the maximum value of the heat transfer coefficient at the same heat flux, and /zw is the heat transfer coefficient for pure water at the same heat flux q. Data from all the sources discussed reach the same value of 1.0 at the magnitude of relative surfactant concentration equal to 1.0. 

Below some critical surfactant concentration, the system is two-phase with excess oil or water depending on the oil/water concentration. On adding more surfactant, the system moves into a one-phase region with normal micelles forming in water-rich systems. The water constitutes the continuous phase, solvating the headgroups of the surfactant whose hydro-phobic tails solubilise oil in the core of the micelle. In oil rich systems, reverse-micelles form. With further increases in surfactant composition. 

Reactions of 2,4-dinitrochloro-benzene and -naphthalene are speeded by DDDAOH and the corresponding chloride -I- NaOH (Cipiciani et at., 1984). The rate/surfactant concentration profiles and the rate constants are very similar to those for reactions in solutions of the corresponding C16 single chain surfactants which form normal micelles. The spontaneous hydrolysis of 2,4-dinitrophenyl phosphate dianion is also speeded by DDDAC1 and rates reach plateau values in very dilute surfactant (Savelli and Si, 1985). 

At equilibrium surfactant concentrations of less than 0.0003 M SDS where the hematite surface is still positively charged, adsorption of surfactant follows its normal pattern due to the electrostatic forces which provide the driving force for adsorption. Sufficient effective surface area must be available for this level of SDS adsorption density. As surfactant adsorption... 

The surfactant concentration range above which micelles are formed is called the critical micelle concentration (CMC). Studies have clearly established that most surfactants aggregate above the critical micelle concentration (CMC) to form normal micelles in polar solvents such as water, while they aggregate to form... 

In dilute aqueous solutions, surfactants have normal electrolyte or solute characteristics and are formed at the interface. As the surfactant concentration increases beyond the well-defined concentrations (i.e., critical micelle concentration, c.m.c.), the surfactant molecules become more organized aggregates and form micelles. At the c.m.c., the physicochemical characteristics of the system (osmotic pressure, turbidity, surface tension, and electrical conductivity) are suddenly changed, as shown in Figure 4.19. 

Reliable Ao(C) isotherms of diluted surfactant solution can be monitored using the very precise (accuracy 0.01 mN m 1) spherotensiometric technique [363]. It is based on determination of the forces emerging when a well wetted sphere is drawn out of a solution. Thus the surface tension of various surfactants such as NaDoS, sodium octyl sulphate [364,365], low molecular fatty acids and normal alcohols [366,367] and acetals, a special kind of nonionic surfactants [368] has been measured. These measurements were performed within a large surfactant concentration range in the presence of different electrolytes and at various temperatures. 

The clinical concentration exceeds the actual intraalveolar concentration that might be expected during therapy, because the material is diluted in situ by the liquid in the air spaces and their surfaces [65]. Other information gives some indication of the surfactant concentration in the normal lungs. The concentration in normal foetal pulmonary liquid [66] and the concentration required to restore alveolar function to immature neonatal infants and lambs [67] change from about 0.5 to 1.8 mg PL cm 3. These concentrations are close but slightly higher than both C, and just above C,. 

When the surfeclant concentration is high relative to the polymer concentration sufRdent sui ctant may be adsorbed on individual polymer molecules to prevent their coalescence to form latex particles or indeed to disperse prdbrmed polymer to form clear solutions in which the solute behaves as a po yelectro yte, But the influence of such effects on tbe course of emulsion polymerization reactions has not been elucidated. Sata and Saito (1952) showed that poly(vinyl acetate) preeptated from acetone solution with water could be solubibzed in sodium dodecyl sulfate solutions after removal of the acetone by dialysis. To obtain a clear solution at 20°C, a wdght of surfactant S-10 times that of pol ner was required. Althou this greatly exceeds the surfactant concentrations normally used in emulsion... 

An excess amount of surfactant can solubilize proteins, presumably by additional adsorption to the surface and generation of a large net charge at the surface of the protein molecule. This is the basis for estimation of protein molecular weight by gel electrophoresis in the presence of sodium dodecyl sulphate (SDS-PAGE). Such effects are usually found only at surfactant concentrations well in excess of those normally found in foods, and have more use in laboratory investigations than in ordinary applications. 

Figure 7. MC data for the normalized local density distribution of the macroions in a slit formed by two uncharged surfaces fixed on a distance H/D = 10. The bulk volume fraction of macroions is / 0.05 (high surfactant concentration) and macroion charge number is fixed...

Figure 9. MC data for the normalized local density distribution of the macroions in a plane-parallel film. (a) The macroion bulk volume fraction, r] = 0.010 (low surfactant concentration) and macroion charge, Z = 30. The film contains two surface monolayers and one middle-film layer, and has the thickness, H/D = 7. (b) The macroion bulk volume fraction r] = 0.045 (high surfactant concentration) and macroion charge, Z = 10. The film contains two surface monolayers and two weak middle-film layers, and has the thickness, H/D = 7.5. The dashed line shows MC data obtained from the simulation without excluded volume forces.

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