Surfactants characteristics

TABLE 18.6 Surfactants Characteristics Surfactant Selected Properties ... 

Niche The section of the environment with which a particular property of the chemical product interacts is referred to as niche. For example, a pesticide can have as the environment the plant, the atmosphere, and the human beings. The pesticide interacts with the environment through its properties. There are different kinds of interaction depending on the niche. For example, some properties such as the contact area depend on the surfactant characteristics and the surface of the leaf. The niche is the surface of the leaf. The absorption of the pesticide depends on the characteristics of the layers, like the cuticle [25], In this case, the niche consists of the layers of the plant s leaves. Also, the diffiisivity of the active product in the layers of the plant leaves corresponds to a property that depends on the environment-product interaction. Some other pesticide properties, such as solubility of the active agent in the solvent, do not depend on the environment. 

In comparison with System A, we thus find that different surfactants would give divergent phase behaviour, due to the dependence of Yow surfactant characteristics. Further, the addition of n-butanol gives rise to a lowering of yow by about 2 mN/m (Fi-... 

The concentrations of PFAs in environments have increased sharply over time (Holmstrom et al., 2005). The sorption/accumulation and fate of PFAs differ from classical chlorinated and brominated POPs in that perfluorinated molecules have surfactant characteristics (i.e., having polar and nonpolar domains) and oleophobic properties. Thus, PFAs is likely to bind to serum protein rather than lipid in tissues (Jones et al., 2003). 

In order to be used as an additive in various types of textile lubricants, surfactants should have high miscibility with base oils as well as the other fundamental surfactant characteristics such as lubricity improving ability and antistatic properties. Table XVI shows the miscibility of C a gAE vari°us lubricant base oils in comparison with that of NPE(IOEO). Good miscibility of SAE can be seen in the Table. Further information, including practical examples, is contained1 in Union Carbide Corp. s booklet on Tergitol 15-S nonionics(20). 

The surfactant characteristics of the product vary depending on its lipophilicity, which is related to the chain length of the n-alkyl moiety attached. The attachment of a C4-C6 n-alkyl ester of L-leucine gives rise to greatly improved whippability as well as to very stable foams, while a potent oil-emulsifying activity results when a longer-chain n-alkyl ester, especially n-dodecyl ester, of L-leucine is attached. This relationship was found with several substrates used (see Table VI). 

For example, alkylbenzene is slightly surface active in nonaqueous media but is insoluble in water, Addition of a single S03H group to the molecule imparts solubility and excellent surfactant characteristics in water but insolubility... 

The potential and the charge of the diffuse electric layer is another important surfactant characteristics. Though these parameters are not directly related to the foam stability, they determine the type of foam films which affect foam stability. Another parameter directly connected to (p0 is the critical electrolyte concentration at which a CBF/NBF transition occurs at a given temperature. It allows to distinguish two equilibrium states of black foam films. The role of (p0 in the CBF/NBF transition permitted to find the value of the critical potential [Pg.532]

Having shown that carboxy terminated polyesters present typical surfactant characteristics after neutralization with amines, it was of interest to examine their application possibilities in emulsion polymerization. Such polymerizations for styrene and for butyl-methacrylate (BMA) have been carried out either by a batch technique or by a semi- continuous procedure. The reaction conditions were the following ... 

The behavior of neutralized polyesters having typical surfactant characteristics, were examined in emulsion polymerization of styrene and BMA. The special features of these polymeric surfactants were shown, especially the fact that the particle size of the latex can be regulated by adjusting the concentration and the polyester molecular weight. 

Snyder LM, Fortier NL, Trainor J, et al Effect of Hydrogen Peroxide Exposure on Normal Human Erythrocyte Deformability, Morphology, Surfact Characteristics, and Spectrin-Hemoglobin Cross-Linking. J. Clin. Invest. 1985 76 1971-1977. 

The characteristic parameter of the surfactant can be estimated by the use of the corresponding correlations (Eqs. (3.3) and (3.4)). For anionic surfactants for instance, salinity scans with a given oil, alcohol type and concentration and temperature, would allow to determine the optimum salinity (S in wt.% NaCl) for each tested surfactant, and thus estimate the value of the surfactant characteristic parameter a from Eq. (3.3). Another way to characterise a surfactant is by using the double-scan technique (see Fig. 3.7). A first scan, e.g. a salinity scan, is carried out with a given set of (not-to-be changed) variables such as oil phase, alcohol type and concentration and temperature. With the first (known) surfactant (subscript 1), the optimum salinity Sj is such that... 

HLD is a generalised formulation yardstick that is some kind of extended HLB, which is function of all formulation variables (surfactant characteristics, co-surfactant type and concentration, temperature, oil nature, salinity. ..) and it may be numerically estimated or measured with a much better accuracy than HLB, roughly equivalent to one-tenth of an HLB unit. From the physical chemistry point of view, it has a strong foundation, since it represents the change in standard chemical potential when a surfactant molecule passes from oil to water in the conditions of experiments. 

A second important surfactant characteristic is its adsorption onto the pore walls of reservoir rock. Perhaps as a consequence of the size of the surfactant molecules, adsorption equilibrium is not immediate but requires appreciable time. The reverse process, desorption into a lower-concentration solution, is even slower. Given a long enough period of contact, surfactant molecules can be expected to adsorb onto, and desorb from, the internal walls of a porous rock according to an equilibrium isotherm resembling the Langmuir curve. However, in many laboratory experiments and at the displacement front in the field such equilibrium may not be attained. 

Charge vessel with ingredients in the order listed using moderate agitation. NOTE Other Avanel products could be used in this formulation to achieve surfactant characteristics. 

Micelle Formation of Natural Organics and Surfactant Characteristes... 

Strongly polar molecules like surfactants can form micelles in solution. Natural organics are amphiphilic molecules (possess both hydrophobic and hydrophilic groups). In a micelle they would arrange to form a hydrophobic core with a hydrophilic outer shell. It has been suggested that FA forms micelles in solution (Clark and Jucker (1993)). Childress and Elimelech (1996) showed evidence of surfactant characteristics of some natural organics where humics make membranes more hydrophilic. Leenheer et al. (1989) reported surface-active properties of aqueous HSs. A difference in mobility was explained by the possible formation of micelles. 

Additional effects can be introduced by variation of surfactant characteristics, like the adsorption and desorption rates on the interface, by measuring the chemical kinetics and the partition coefficient, and by measuring the relative bulk and surface concentrations at equilibrium. 

The nonionic surfactant characteristic is split into its ethylene oxide number tEON). i.e.. the average number of ethylene oxide groups per molecule, and the hydrophobe contribution OC. Only scarce data are available for a, which has a value near 6,6 and 6.1. respectively, for the branched nonyl and octyl phenol... 

Thus RT In K and SAD should exhibit similar (and opposite) variations with respect to the formulation variables. By measuring the partition coefficient with different systems exhibiting a variety of oils, surfactant characteristics, alcohol content, bnne salinity, and temperature. Marquez was able to correlate the term RT In K with the formulation variables in a linear relationship very similar to the correlations. For instance, it was found that (98) ... 

The adempts to rationalize GrifHn s HLB scale from a physicochemical point of view were made in a number of studies. Various correlations were shown to exist between the HLB numbers and the chemical structure or molecular composition of the siufactants. Correlations were also fotmd between the HLB number and physicochemical properties of surfactants and their solutions, for example, stffface and interfacial tension, solubility, and heat of solution, spreading and distribution coefficient, dielectric permittivity of the surfactant, cloud point and phase inversion point, critical micelle concenlration, foaminess, etc. These studies are reviewed in Ref. 262. However, the correlations found are not generally applicable moreover, the concept of the additivity of HLB numbers as such for mixtures of surfactants or oils cannot be proven expermentally when the surfactant characteristics are varied over a wider range (265). 

As one can see, the number of modifications of the simple dodecane molecule that can lead to materials with good surfactant characteristics is limited primarily by the imagination and skill of the organic chemist—and by the time and money available for indulgence in creative molecular architecture. In each example discussed, a solubilizing group has been added to the basic... 

No.18, 2000, p.6741-7 SURFACTANT CHARACTERISTICS OF RANDOM BLOCK POLYELECTROLYTE POLYESTER EMULSIFIER (SMTAPE) IN AQUEOUS SOLUTION AND ON POLYSTYRENE LATEX PARTICLES... 

Table 3 Hydrophilic Group Conlribuiion to the Surfactant Characteristic Parameter...

Once the change or combination of sev cral changes has shifted the firrmula-lioii to optimuni. some accounting is requiied to measure the distance from iipti-muni. The intensity" of each change is calculated according to the correlation expression, and in cases of various concurrent changes they arc summed up. Since both correlations contain the term, ACN with a coefficient that is nearly the same, a comparison in terms of deviation in ACN unit is preferred. Moreover, ACN units arc also used to estimate EPACNUS. the ionic surfactant characteristic parameter. 

Carnitine is at the origin of two types of fluorinated surfactants. The perfluoroalkyl-acylcarnitines (28) (Scheme 24), obtained with satisfactory yields (44-80%), show good surfactant characteristics [60], The synthesis of Ai-perfluoroalkyl carnitine (29) (Scheme 25) is less efficient, and its physicochemical properties have not been evaluated [61]. The betaines of perfluoro-alkyl a,co-amino acids (30) (Scheme 26) are accessible in a similar manner [62]. They are good surface agents [63]. 

Asa-Awukn A, Sullivan AP, Hennigan CJ, Weber RJ, Nenes A (2008) Investigation of molar volume and surfactant characteristics of water-soluble (uganic ctnnponnds in biomass burning aerosol. Atmos Chem Phys 8 799-812... 

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