Surface activation anionic

The direct reaction of 1-alkenes with strong sulfonating agents leads to surface-active anionic mixtures containing both alkenesulfonates and hydroxyalkane sulfonates as major products, together with small amounts of disulfonate components, unreacted material, and miscellaneous minor products (alkanes, branched or internal alkenes, secondary alcohols, sulfonate esters, and sultones). Collectively this final process mixture is called a-olefinsulfonate (AOS). The relative proportions of these components are known to be an important determinant of the physical and chemical properties of the surfactant [2]. 

A review of the preparation, properties, the uses of surface-active anionic phosphate esters prepared by the reactions of alcohols or ethoxylates with tetra-phosphoric acid or P4O10 is given in Ref. 3. The preparation and industrial applications of phosphate esters as anionic surfactants were also discussed in Ref. 31. 

Anodic dissolution reactions of metals typically have rates that depend strongly on solution composition, particularly on the anion type and concentration (Kolotyrkin, 1959). The rates increase upon addition of surface-active anions. It follows that the first step in anodic metal dissolution reactions is that of adsorption of an anion and chemical bond formation with a metal atom. This bonding facilitates subsequent steps in which the metal atom (ion) is tom from the lattice and solvated. The adsorption step may be associated with simultaneous surface migration of the dissolving atom to a more favorable position (e.g., from position 3 to position 1 in Fig. 14.1 la), where the formation of adsorption and solvation bonds is facilitated. 

All factors influencing the potentials of the inner or outer Helmholtz plane will also influence the zeta potential. For instance, when, owing to the adsorption of surface-active anions, a positively charged metal surface will, at constant value of electrode potential, be converted to a negatively charged surface (see Fig. 10.3, curve 2), the zeta potential will also become negative. The zeta potential is zero around the point of zero charge, where an ionic edl is absent. 

As mentioned above, the quantity 0(m) is identified with the shift in the potential of the electrocapillary maximum during adsorption of surface-active anions. For large values of this shift (0(m) RT/F)... 

The analysis of surface-active anions comprises the determination of simple aromatic sulfonic acids, hydrotropes (toluene, cumene, and xylene sulfonates), alkane- and alkene sulfonates, fatty alcohol ether sulfates, alkylbenzene sulfonates, and a-sulfofatty acid methyl esters. Many of these compounds are relevant predominantly in the detergent and cleansing industry. 

Although surface-active anions with aromatic backbone have for sometime been separated by RPIPC and sensitively detected via their UV absorption [41], a chromatographic determination of the other compound classes mentioned above is only feasible by conductivity detection. 

The surface-active anions investigated so far include the class of aryl sulfonates. Fig. 5-37 shows a respective chromatogram with the separation of benzene, toluene, xylene, and cumene sulfonates. They are eluted in this order according to the number of carbon atoms of their substitutents. Tetrabutylammonium hydroxide was used as the ion-pair... 

Silica is not the only surface-active anionic impurity that may be responsible for the abnormally low lEPs reported in the literature. The other impurities are less abundant (see Section 1.11), but they may be more surface-active than silica, and in certain systems the shift in the lEP to a low pH may be chiefly due to anionic impurities other than silica. The silica problem is a specific case of a general problem of surface-active anionic impurities, with silica being the most well-known example of such an impurity. The specific nature of surface-active anionic impurities other than silica is not known. Thus, it is difficult to control and avoid them, and measures undertaken against silica contamination are not necessarily efficient against other surface-active anionic impurities. 

Let us consider first a system consisting only of surface active anions and inorganic cations. Using Eqs (7.12) and (7.13), and the formulas for the ion fluxes, the electric field strength E can be expressed in terms of the concentration gradient c. In this case j is given by... 

If diffusion is the controlling process of adsorption of surface-active anions the boundary condition is,... 

Dissociating in water, anionic surfactants form the surface-active anions and hydrated cations, for example, cations of alkali metals or ammonium ... 

If the ion—metal interaction is completely electrostatic and the squeezing out is absent, the electrolyte is surface-inactive. In the opposite case, specific adsorption takes place, and the corresponding ion is surface-active. Figure 2 shows the electrocapillary curves (dependences of y on electrode potential E) for a mercury electrode in 0.01, 0.1, and 1 M aqueous solutions of a surface-inactive electrolyte (curves 1, 2, and 3) and the corresponding y versus E-curves in solutions containing surface-active anions (1, 2 and 3 ). 

Anionic surfactants are the most commonly used they dissociate in water to form the surface active anion, composed of hydrocarbon radical and hydrophilic group and inactive cation. The substances from this group can be classified further as follows [98] ... 

Experiments were conducted with large concentrations of salts with surface-active anions, I and Br, as supporting electrolytes since they greatly reduce the overpotential of ordinary discharge (e/ri effect) without affecting the barrierless process. Therefore, one would expect a substantial shift, toward higher current densities, of the point of transition from one type of discharge to the other. 

It is most essential that good agreement is observed in the presence of surface-active anions and cations despite the different double-layer structure. The coincidence of corrected curves in the presence of adsorbed anions and such a large cation as tetrabutylammonium is indicative of the fact that, in all cases, the plane of localization of the centers of the discharging ions is the same, just as it should be if they occupy the inner Helmholtz layer. 

Glyceryl ether sulfonates are surface-active anionic surfactants, which utilize a glyceryl backbone in the sulfonated group of the molecule. On the basis of patent literature, the first production of these ethers began with Alfred Kirstahler and Richard Hueter in the 1930s. Since this time, the process for the production of these surfactants has been significantly improved and optimized. 

FAB or LSIMS using a probe inlet does not readily lend itself to quantitative work. Firstly, it is not possible to know how much of the sample has been consumed in the analysis. Secondly, discrimination effects (see section 12.3.3) prevent the comparison of intensities between species of differing surface activity. Semiquantitative results may be readily obtained if discrimination effects are assumed to be constant for the species of interest, for example the determination of homologue distributions in a mixture. For accurate quantitation an internal standard of an isotopically enriched analogue of the analyte should be used. For example, in the determination of cationic surfactants in environmental samples [10], quantitation was achieved by using an internal standard of a trideuterated form of the analyte. In this way the standard will be subject to the same level of discrimination as the analyte. Discrimination effects between different cationic species may also be reduced by adding to the sample an excess of a highly surface-active anionic surfactant. The anionic species will dominate the matrix surface and attract cations into the surface monolayer [10]. 

Due to its solvent compatibility, the selectivity of the lonPac ASH can be altered by adding organic solvents. This effect is demonstrated with the gradient elution of inorganic and organic anions in Fig. 3-40. When eluting with purely aqueous NaOH, a separation of, for example, succinate/malate, malonate/tar-trate, and fumarate/sulfate pairs is not possible. A baseline-resolved separation of these anions can only be achieved by adding 16% (v/v) methanol to the mobile phase. This leads to a shorter retention time of the more surface-active anion, respectively. It is remarkable that in some cases the retention times of the less surface-active anions actually increase. 

Organic solvents not only influence the selectivity for surface-active anions. The retention of polarizable anions, which are retained by ion-exchange and adsorptive interactions, can be reduced significantly by organic solvents. Figure... 

The anion series in the order of their influence on the surface activity of cationic surfactants and on the properties of insoluble monolayers coincide with the lyotropic series. The anion nature is manifested in the specific interaction with cationic surfactants with the formation of ionic pairs or in the anion penetration into the adsorption monolayers. Apparently, charge transfer complexes are frequently formed at the water-air and water-oil interfaces between the adsorbed cations and anions. Mukerjee and Ray estabhshed that these complexes exist in ionic pairs, between Br or J anions and dodecylpyridine ions in chloroform, and also on the micelle surface formed by the same cations in water [84-86]. The data on the ionic pair structure at the interface can be obtained by spectral study of monolayers and solutions of ionogenic surfactants in nonpolar solvents. According to Goddard, the investigation on the mixed monolayers formed by the surface-active anions and quaternary ammonium compounds will enable us to better understand the specific properties of the interaction between the adsorbed ions [72]. 

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