Zeta potential recovery

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.

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.

Figure 15. Plot of oil recoveries versus process aid addition level from the hot water flotation processing of an oil sand in a continuous pilot plant. Also shown is the correspondence with the zeta potentials, measured on-line, of emulsified bitumen droplets in the extraction solution. (Plotted from data in reference 50.)...

In the context of a study of foam flotation of powdered activated carbon (PAC), Zouboulis et al. [143] noted large and different pH effects when an anionic surfactant was used instead of a cationic one. For the cationic surfactant, best recovery (at low surfactant concentration) was achieved at the highest pH, in agreement with electrostatic arguments (see Section IV.B.l) for the anionic surfactant, an intermediate pH was the best. The authors also measured the zeta potential of the carbon in the presence and absence of the surfactants and concluded that the specific chemical nature and the dissociation of each surfactant. 

Fig. 3.14. Dependence of flotation of goethite on surface charge. Upper graph is zeta-potential as a function of pH at different concentrations of sodium chloride lower graph is flotation recovery in 1 x 10 mol/1 solutions of dodecylammonium chloride, sodium dodecyl-sulfate and sodium dodecyl-sulfonate (Iwasaki et al., 1960).

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 18. Correlation between process aid additions for maximum primary bitumen recovery and process aid additions required to attain maximum bitumen/aqueous surface charge (Zeta potential). The data are for continuous pilot plant operation (Hj and laboratory batch extractions (%). (From Schramm and Smith [111].)...

It has been shown [lOJ] that the simple dilution model can be used to fairly accurately predict how to increase slurry water addition levels as well as, for example, to counteract overdosing with NaOH in the slurry. It has also been shown [JOJ] that the correlations between maximum primary bitumen recovery and surface electric charges (Zeta potentials) are also preserved when varying the slurry water addition levels. 

Due to the still negatively charged surfaces, the adsorption of the cationic polymer is only slightly affected by calcium ions in solution. Thus, the zeta potential of calcium carbonate and kaolin at high polymer concentrations is nearly the same in tap water with 286 ppm calcium ions as in distilled water (Fig. 3). Due to the calcium adsorption on the filler surface and the decreasing number of negative surface sites, the charge reversal occurs at five times lower concentrations than in calcium-free solution. The recovery of the fillers isnot influenced by the water hardness, tested from 0 to 1780 ppm calcium ions as CaCOj (not shown here). 

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