Adsorptive bubble separations

Suspended Solids Wood fiber Cotton fiber Activated sludge Free oil Chemical floes Fats 

Titanium dioxide Turbidity Soluble Organics Lignin and tannin Humic acid Protein Soluble oil BOD, COD Color 

Heavy metals (lead, copper, chromium, zinc, etc.) phosphate, sulfate iron, manganese, hardness, etc. 

Volatile Solids Xylene Toluene Ethylbenzene Butylbenzylphthalate Trihalomethanes (chloroform, etc.) 

Adsorptive bubble separation process may be defined as the mass transfer process of a solid from the body of a liquid to the liquid surface by means of bubble attachment (42,75,84). The solids can be in dissolved, suspended, and/or colloidal form. The three basic mechanisms involved are bubble formation, bubble attachment, and solids separation (43,75). 

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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). 

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]. 

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. 

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. 

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

This natural process by which dissolved and/or particulate surface-active materials end up in the atmosphere has been modeled and studied in the laboratory. As summarized by Detwiler and Blanchard (ref. 46), tests in suspensions of bacteria (ref. 76,96,97), latex spheres (ref. 98), dyes (ref. 99), and in sea water and river water (ref. 96,100,101) have demonstrated successful transfer of all manner of surface-active material from the bulk fluid, or the bulk interface, to the droplets ejected when bubbles burst. (This situation can be pictured as an extension of the common industrial adsorptive-bubble-separation process (ref. 102) into a third dimension or phase — the atmosphere.) Further laboratory tests with various tap waters, distilled waters, and salt solutions have shown that no water sample was ever encountered that did not contain at least traces of surface-active material (ref. 46). 

Fuerstenau, D. W., Healy, T. W. Adsorptive Bubble Separation Techniques, Chapter 6, New York Academic Press, (1972) p. 91... 

A few simple differences in the properties of immiscible phases make possible their relative displacement. Most simply, if the phases have different densities they will automatically acquire a relative motion in a gravitational field. Thus in adsorptive bubble separation methods, bubbles injected into a column of liquid rise toward the upper surface. Separation occurs by combining the relative enrichment of components at the bubble interface with the continuous displacement of bubbles through the liquid [33-35]. 

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