Bubble charge

Li, C. and Somasundaran, P, Reversal of bubble charge in multivalent inorganic salt solutions—effect of magnesium.,/. Colloid Interf. Sci., 146, 215, 1991. 

Fig. 10.6. Illustrations of the impracticability of flotation at sufficiently great charges of the same sign of particle and bubble (a), the practicability of flotation in the case of bubble recharging of the bubble charge (b, curve 1). Curves 2 and 1 in (b) illustrate the possibility of flotation at the effective radius of the non electrostatic repulsion forces, which is smaller than the thickness of the double layer (2) and its impracticability in the opposite case (3).

Application of ionic smfactant provides neutralisation of the bubble charge which can be roughly estimated from the surface potential T. From the Gouy-Chapman theory (see Chapter 2) it follows that... 

Means of control differ substantially depending on whether attachment forces are large or small, i.e. the potential well is not deep or is absent. The modes of control of particle and bubble charges should be selected already at the stage of studying the properties of the flotation system. It is advisable to conduct experiments of flotation recovery of particles by bubbles of small and large size, for example, at Re 1 and Re 400. Clearly, opposite charges of particle... 

From the above examples, it is clear that DHBCs themselves can promote the formation of complex crystal morphologies, often involving nanoscopic building units. It is interesting to investigate the influence of an external template on a DHBC-controlled crystaUization system. These foreign external templates include CO2 or air bubbles, charged particles, and air/water interfaces. 

In the flotation device, the flow of charged air bubbles acts as collector and transporter of ionic impurities of treated water. Through the bubble-film extractor, this flow is removed from treated water. So, the mineral composition of treated water can be corrected, and the target mineral impurities can be extracted. The efficiency of demineralization of treated water can be evaluated if the relationship of bubble charge density upon pH and ionic concentration of water is known. An appropriate empiric equation is the following ... 

Berkman and Egloff explain that some additives increase the flexi-bihty or toughness of bubble walls, rather than their viscosity, to render them more durable. They cite as illustrations the addition of small quantities of soap to saponin solutions or of glycerin to soap solution to yield much more stable foam. The increased stability with ionic additives is probably due to elec trostatic repulsion between charged, nearly parallel surfaces of the hquid film, which acts to retard draining and hence rupture. 

For any adsubble method, if the material to be removed (termed the colligend) is not itself surface-active, a suitable surfactant (termed the collector) may be added to unite with it and attach or adsorb it to the bubble surface so that it may be removed (Sebba, Ion Flotation, Elsevier, New York, 1962). The union between colligend and collector may be by chelation or other complex formation. Alternatively, a charged colhgend may be removed through its attraction toward a collector of opposite charge. 

Aeration of liquids not only increases charging due to the large liquid-bubble interfacial area but can also produce hazardous conditions in downstream... 

The effect of physical processes on reactor performance is more complex than for two-phase systems because both gas-liquid and liquid-solid interphase transport effects may be coupled with the intrinsic rate. The most common types of three-phase reactors are the slurry and trickle-bed reactors. These have found wide applications in the petroleum industry. A slurry reactor is a multi-phase flow reactor in which the reactant gas is bubbled through a solution containing solid catalyst particles. The reactor may operate continuously as a steady flow system with respect to both gas and liquid phases. Alternatively, a fixed charge of liquid is initially added to the stirred vessel, and the gas is continuously added such that the reactor is batch with respect to the liquid phase. This method is used in some hydrogenation reactions such as hydrogenation of oils in a slurry of nickel catalyst particles. Figure 4-15 shows a slurry-type reactor used for polymerization of ethylene in a sluiTy of solid catalyst particles in a solvent of cyclohexane. 

A top-quality London hotel was horrified to find that its house champagne, for which it charged 60 per bottle, lost its bubbles a few moments after it was poured. At first the hotel blamed the suppliers, but... 

For lithium metal in 1 Af HC1, the observed facts are that the metal dissolves spontaneously and a gas bubbles out of the solution. From Appendix 3 we select the two half-reactions (notice that the half-reactions are already balanced in both charge and number of atoms) ... 

Foam persistence increases with rise in BW TDS because the bubbles are stabilized by the combined repelling forces of electrical charges at the steam-water interface that result from the high concentration of dissolved salts. The repulsion effect of similar charges prevents bubble thinning, bubble rupture and coalescence mechanisms from taking place. 

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