Bubble separation

Gas bubble separation time of petroleum oils NFT 60-149 ASTM D 3427 Time for air liberation after supersaturation (measurement of density)... 

R. Lemlich, ed.. Adsorptive Bubble Separation Techniques, Academic, New York, 1972. 

D. W. Fuerstenau and T. W. Healy, Adsorptive Bubble Separation Techniques, Academic Press, 1971, p. 92 D. W Fuerstenau, Pure Appl. Chetn., 24, 135 (1970). 

A foam can be considered as a type of emulsion in which the inner phase is a gas, and as with emulsions, it seems necessary to have some surfactant component present to give stability. The resemblance is particularly close in the case of foams consisting of nearly spherical bubbles separated by rather thick liquid films such foams have been given the name kugelschaum by Manegold [175]. 

Interfacial Forces. Neighboring bubbles in a foam interact through a variety of forces which depend on the composition and thickness of Hquid between them, and on the physical chemistry of their Hquid—vapor interfaces. For a foam to be relatively stable, the net interaction must be sufficiently repulsive at short distances to maintain a significant layer of Hquid in between neighboring bubbles. Otherwise two bubbles could approach so closely as to expel all the Hquid and fuse into one larger bubble. Repulsive interactions typically become important only for bubble separations smaller than a few hundredths of a micrometer, a length small in comparison with typical bubble sizes. Thus attention can be restricted to the vapor—Hquid—vapor film stmcture formed between neighboring bubbles, and this stmcture can be considered essentially flat. 

Flexible foams are three-dimensional agglomerations of gas bubbles separated from each other by thin sections of polyurethanes and polyureas. The microstmetures observed in TDI- and MDI-based flexible foams are different. In TDI foams monodentate urea segments form after 40% conversion, foUowed by a bidentate urea phase, which is insoluble in the soft segment. As the foam cures, annealing of the precipitated discontinuous urea phase... 

Robert Lemlich/ Ph.D./ P.E./ Profe.s.sor of Chemical Engineering Emeritus, University of Cincinnati Fellow, American In stitute of Chemical Engineers Member, American Chemical Society, American Society for Engineering Education Fellow, American As.sociation for the Advancement of Science. (Adsorptive-Bubble Separation Methods)... 

Principle The adsorptive-bubble separation methods, or adsub-ble methods for short [Lemlich, Chem. Eng. 73(21), 7 (1966)], are based on the selective adsorption or attachment of material on the surfaces of gas bubbles passing through a solution or suspension. In most of the methods, the bubbles rise to form a foam or froth which carries the material off overhead. Thus the material (desirable or undesirable) is removed from the liquid, and not vice versa as in, say, filtration. Accordingly, the foaming methods appear to be particularly (although not exclusively) suited to the remov of small amounts of material from large volumes of hquid. 

The droplet analogs to the adsubble methods have been termed the adsoplet methods (from adsorptive droplet separation methods) [LeiTilich, Adsorptive Bubble Separation Methods, Ind. E/ig. Chem., 60(10), 16 (1968)]. They are omitted from Fig. 22-41, since they involve adsorption or attachment at liquid-liquid interfaces. Among them are emulsion fractionation [Eldib, Foam and Emulsion Fractionation, in Kobe and McKetta (eds.). Advances in Petroleum Chemistry and Refining, vol. 7, Interscience, New York, 1963, p. 66], which is the analog of foam fractionation and droplet fractionation [Lemlich, loc. cit. and Strain, J. Phys. Chem., 57, 638... 

Excess collector can also reduce the separation by forming micelles in the bulk which adsorb some of the colhgend, thus keeping it from the surface. This effect of the micelles on Ki for the colhgend is given theoretically [Lemhch, Principles of Foam Fractionation, in Periy (ed.). Progress in Separation and Purification, vol. 1, Interscience, New York, 1968, chap. 1] by Eq. (22-44) [Lemlich (ed.). Adsorptive Bubble Separation Techniques, Academic, New York, 1972] if F, is constant when C, > C-... 

By using an anionic collector and external reflux in a combined (enriching and stripping) column of 3.8-cm (1.5-in) diameter with a feed rate of 1.63 ni/n [40 gal/(h ft )] based on column cross section, D/F was reduced to 0.00027 with C JCp for Sr below 0.001 [Shou-feld and Kibbey, Nucl. AppL, 3, 353 (1967)]. Reports of the adsubble separation of 29 heavy metals, radioactive and otheiwise, have been tabulated [Lemlich, The Adsorptive Bubble Separation Techniques, in Sabadell (ed.), Froc. Conf. Traces Heavy Met. Water, 211-223, Princeton University, 1973, EPA 902/9-74-001, U.S. EPA, Reg. 11, 1974). Some separation of N from by foam fractionation has been reported [Hitchcock, Ph.D. dissertation. University of Missouri, RoUa, 1982]. 

Foams are agglomerations of gas bubbles separated from each other by thin films (5). Mainly, the problem is concerned with one class of colloidal systems —gas dispersed in liquid—but liquid dispersed in gas, solids dispersed in liquid (suspensions), and liquids dispersed in liquids (emulsions) cannot be ignored. The dispersion of a gas into a liquid must be studied and observed by the food technologist to improve the contact between the liquid and gas phases, the agitation of the liquid phase, and most important, the production of foam 10). 

Foams consist of bubbles separated from each other by thin—liquid or solid—membranes. The bubbles must have no connection with their neighbors if such a connection exists—i.e., both phases (the gaseous and the condensed) are continuous—the system is a sponge rather than a foam. Bread is the most important kind of food that is chiefly sponge and a little foam. 

General Reeebences Lemlich (ed.). Adsorptive Bubble Separation Techniques, Academic, New York, 1972. Garleson, Adsorptive Buhhle Separation Processes in Scamehom and Harwell (eds.), Surfactant-Based Separation Processes, Marcel Dekker, New York, 1989. 

Other plant-scale applications to pollution control include the flotation of suspended sewage particles by depressurizing so as to release dissolved air [Jenkins, Scherfig, and Eckhoff, Applications of Adsorptive Bubble Separation Techniques to Wastewater Treatment, in Lemlich (ed.). Adsorptive Bubble Separation Techniques, Academic, New York, 1972, chap. 14 and Richter, Internat. Chem. Eng, 16,614 (1976)]. Dissolved-air flotation is also employed in treating waste-water from pulp and paper mills [Coertze, Prog. Water TechnoL, 10, 449(1978) and Severeid, TAPPl 62(2), 61, 1979]. In addition, there is the flotation, with electrolytically released bubbles [Chambers and Cottrell, Chem. Eng, 83(16), 95 (1976)], of oily iron dust [Ellwood, Chem. Eng, 75(16), 82 (1968)] and of a variety of wastes from surface-treatment processes at the maintenance and overhaul base of an airline [Roth and Ferguson, Desalination, 23, 49 (1977)]. 

Wang, L.K., Bubble Dynamics of Adsorptive Bubble Separation Processes, 2007 National Engineers Week Seminar, Practicing Institute of Engineers, Albany, NY, February 2007. 

Wang, L.K., Adsorptive bubble separation and dispersed air flotation, in Advanced Physicochemical Treatment Processes, L.K. Wang, Y.T. Hung, and N.K. Shammas, Eds, Humana Press, Totowa, NJ,... 

Wang, L.K. and Wang, M.H.S., Removal of organic pollutants by adsorptive bubble separation processes, 1974 Earth Environment arid Resources Conference Digest of Technical Papers, Vol. 1, IEEE Cat. No. 74 CH0876-3EQC, pp. 56-57, September 1974. 

Wang, L.K., Kurylko, L., and Wang, M.H.S., Combined Coarse and Fine Bubble Separation SystemA US Patent No. 5257732, Office of Patents and Trademarks, Washington, DC, January 1994. 

Krofta, M. and Wang, L.K., Flotation and Related Adsorptive Bubble Separation Processes, Lenox Institute of Water Technology, Lenox, MA, Report No. LIR-0681/1, 150pp., June 1981. 

Figure 1. Micrograph of foam in a 1.1 pm, two dimensional etched-glass micromodel of a Kuparuk sandstone. Bright areas reflect the solid matrix while grey areas correspond to wetting aqueous surfactant solution next to the pore walls. Pore throats are about 30 to 70 /xm in size. Gas bubbles separated by lamellae (dark lines) are seen as the nonwetting "foam" phase.

Adsorption technology, 13 794-795 Adsorptive air separation, 17 753 Adsorptive bubble separation effluent treatment, 9 432... 

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