Dodecyl trimethyl ammonium bromide DTAB

FIGURE 7.11 Structure of a common anionic surfactant, sodium dodecyl sulfate (SDS), and, a cationic surfactant, dodecyl trimethyl ammonium bromide (DTAB) (from Refs. 56,57). 

Figure 2.3 illustrates the results of studies on dodecyl trimethyl ammonium bromide (DTAB) at different additions of NaBr [75]. It is seen that with increasing salt concentration the shape of the curve varies and becomes displaced towards lower surfactant concentrations. The... 

A simple analysis of this equation shows that the slope of the isotherm at usual values of P = 0.5 and vz/v - 0.5 should decrease drastically at the transition to the CMC. Eq. (5.144) was used later by Prokhorov and Rusanov for the evaluation of P from the surface tension of aqueous solutions of dodecyl trimethyl ammonium bromide (DTAB) [63]. The obtained value proved to be too high in comparison with the findings of independent methods. A possible reason of this discrepancy can be the assumptions used for the derivation of Eq. (5.144). Namely, the condition i = 1 can hold only at concentrations essentially exceeding the CMC. A... 

Influence of hydrocarbon chain length in 3 types of surfactants dodecyl trimethyl ammonium bromide (DTAB), tetradecyl trimethyl ammonium bromide (TTAB) and cetyl trimethyl ammonium bromide (CTAB)... 

Use of surfactants is an effective way for dispersing CNTs [39]. Reports show that the outer most nanotubes in a bundle are treated more than the innermost tubes and the nanotube remains predominantly btmdled even after surfactant treatment. But mechanical methods like ultrasonication can debundle the nanotubes by steric or electrostatic repulsions [40]. On sonication the high local shear will unravel the outer carbon nanotubes in a bundle and expose other sites for additional surfactant adsorption, thus the surfactant molecules gradually exfoliate the bundle in an unzippering mechanism [41]. Some of the common surfactants used for the dispersion of carbon nanotubes are sodium dodecyl benzene sulfonate (SDBS) [42], dodecyl trimethyl ammonium bromide (DTAB) [43], hexadecyl trimethyl ammonium bromide (CTAB) [44], octylphenol ethoxylate (Triton X-100) [45] and sodium dodecyl sulfate (SDS) [46]. Covalent modification is another way to solubilize the CNTs in different solvents and to improve the interaction with the matrix in composites [47]. 

Fig. 18 Adsorption of paraquat on Ca-bentonite pretreated with cationic surfactant A—a adsorption isotherm of paraquat, displacement of dodecyl trimethyl ammonium bromide (DTAB). (DTAB pretreated 0.73 meq/g) [20]...

CTAB/DTAB = Cetyl/Dodecyl trimethyl ammonium bromide, DSB = Dodecyl sulfo betaine... 

A11 chemicals were commercially available Tetraethyl orthosilicate (TEOS), Metoxy-ethanol NH OH (25%), NaOH, CTAB (Cetyltrimethylammonium bromide), and DTAB (n-dodecyl trimethyl ammonium bromide) (Putz Putz, 2012). 

Fig. 7 Displacement of Na+ and Cd + ions from a layer silicate by cationic surfactant [11] (DTAB = dodecyl trimethyl ammonium bromide, CEC = cation exchange capacity)...

In principle, the adsorption of organic environmental chemicals on layer silicates proceeds extremely slowly so that it may take several weeks to establish an equilibrium state [22]. In contrast, if the layer silicate surface is coated with cationic surfactants in different quantities [22] or of different hydrophobicity, e.g., with DTAB (dodecyl trimethyl ammonium bromide) or DDDMAB (didoceyl dimethyl ammonium bromide) [23] then equilibrium in both systems is reached within 30 min, i.e., a drastic increase in the adsorption rate of organic pollutants results. Their residence time or probability of residence in the soil electrolyte is therefore drastically reduced and their bioavailability thus also drops. 

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