Dodecylammonium acetate

Fig. 9. Correlation of contact angle, flotation recovery, surface coverage by collector, and 2eta potential. Solid, quart2, collector reagent, 4 x 10 Af dodecylammonium acetate. = recovery, % A = zeta potential, mV Q — contact angle, degrees and = surface coverage, % of one monolayer. Ref.

The adsorption of 3ftCl" ions at the air-solution interface of an aqueous solution of dodecylammonium acetate (0.0140 mole/liter) containing a... 

Table I. Relative Adsorbability of Chloride Against Acetate Ions at the Air-Solution Interface of an Aqueous Solution of Dodecylammonium Acetate (0.0140 mole/liter) at 25°C.

Figure 2. Correlation among contact angle. Key O, adsorption density A, flotation response , potential and V, quartz as a function of dodecylammonium acetate (DA A) concentration at pH 6-7.

Figure 10.4 The correlation among collector surface coverage, contact angle, zeta potential, and flotation recovery for the flotation of quartz using dodecylammonium acetate. From Leja [91]. Copyright 1982, Plenum Press.

The value of Qst can be determined from the slope of the plot (log c)r against T. Measurements in the system N-dodecylammonium acetate-quartz showed that -AG increased with increasing temperature over the whole concentration range whereas the adsorption density against temperature showed a minimum over the greatest part of the concentration range. In the range of equilibrium surfactant concentrations of 1 - 9 x 10"4 mol 1" the values of - AG 12.55 to 17.58 kJ/mol were found for temperatures between 5 and 45 °C. 

Regarding other illustrations, the work by Iwasakl and De Bruyn on the adsorption of dodecylammonium acetate on silver sulfide may be mentioned as probably the first attempt to measure a° and F simultaneously and analyze... 

Huang, P, and Fuerstenau, D.W., The effect of hydrophobicity of silicate minerals on the adsorption of dodecylammonium acetate. Mater. Res. Soc. Symp. Proc., 432, 351, 1997,... 

Fig. 3.15. (a) Dependence of flotation of calcite on PZC using dodecylammonium acetate (DDA) and sodium dodecylsulfate (SDS) (b) determination of PZC from species distribution diagram for calcite. 

FIGURE 16,3-10 Comparison of adsoiption of dodecylammonium acetate at different interfaces. (After Somasundaian courtesy of American Institute of Metallurgical Engineers,)... 

FIGURE 16,3 12 Flotation recovery of quartz ai a function of solution pH using dodecylammonium acetate as collector for dotation duration of 5 and 10 s. (After Somasundaran 95 courtesy of Elsevier S.A., Lausanne, Switzerland.)... 

It is difTicult to find in the literature details of experiments that relate contact angle to the efficiency of the dispersion process. A correlation between contact angle and flotation rate for quartz in aqueous solutions of dodecylammonium acetate, with adsorption from solution and electrokinetic (zeta potential) data, was reported by Fuerstenau". In a later review Fuerstenau discussed the relevance of the adsorption process to flotation technology illustrating the direct relationship between the amount of surfactant adsorbed and the contact angle . Numerous values of 0 are published in the literature. Most have been measured on flat surfaces and even with these problems arise due to surface roughness" . For powders the measurement is more difficult, although a number of methods have been reported" and reviewed . 

The relationship between adsorption and interfacial properties such as contact angle, zeta-potential and flotation recovery is illustrated in Figure 39.2 for cationic surfactant dodecylammonium acetate/quartz system (5). The increase in adsorption due to association of surfactants adsorbed at the solid-liquid interface into two dimensional aggregates called solloids (surface colloids) or hemi-micelles occurs at about 10 M DA A. This marked increase in adsorption density is accompanied by concomitant sharp changes in contact angle, zeta-potential and flotation recovery. Thus these interfacial phenomena depend primarily on the adsorption of the surfactant at the solid-liquid interface. The surface phenomena that reflect the conditions at the solid-liquid interface (adsorption density and zeta-potential) can in many cases be correlated directly with the phenomena that reflect the... 

FIGURE 39.2 Correlation of adsorption density, contact angle, flotation response and zeta potential for quartz as a function of dodecylammonium acetate concentration at pH 6 to 7, 20 to 25°C [5]. 

FIGURE 16.3-5 Flotation of calcite with dodecylammonium acetate (DDAA) and sodium dodecyl sulfate (DDSO4) solutions. (After Somasundaran and Agar, courtesy of Academic Press.)... 

TABLE 16.3-2 Calculated and Experimental Values for the Rebdive Effectiveness of Sodium Ions and Barium Ions in Depressing Quartz Dotation at Natural pH Ush% 10 Icmol/m per Dodecylammonium Acetate... 

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