Table Of ContentCONTRIBUTOR S
J. AROD
DIBAKAR BHATTACHARYYA
STANLEY E. CHARM
W. DAVIS, Jr.
ALBERT J. de VRIES
DAVID W. ECKHOFF
D. W. FUERSTENAU
ROBERT B. GRIEVES
P. A. HAAS
T. W. HEALY
C. JACOBELLI-TURI
DAVID JENKINS
BARRY L. KARGER
ROBERT LEMLICH
F. MARACCI
A. MARGANI
M. PALM ERA
T. A. PINFOLD
V. V. PUSHKAREV
ALAN J. RUBIN
ELIEZER RUBIN
T. SASAKI
JAN SCHERFIG
adsorptiv e
bubbl e
separatio n
technique s
Rober t Lemlic h
Edited by
Department of Chemical
and Nuclear Engineering
University of Cincinnati
Cincinnati, Ohio
1972
Academi c Pres s
New York and London
COPYRIGHT ' 1972, BY ACADEMI C PRESS, INC.
ALL RIGHTS RESERVED
NO PART OF THIS BOOK MAY BE REPRODUCED IN ANY FORM,
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List of Contributor s
Numbers in parentheses indicate the pages on which the authors’ contributions begin.
J. AROD (243), Service d’Analyse et de Chimie AppliquØe, Centre d’(cid:201)tudes NuclØaires de
Cadarache, France
DIBAKAR BHATTACHARYYA (183), Department of Chemical Engineering, University of
Kentucky, Lexington, Kentucky
STANLEY E. CHARM (157), New England Enzyme Center, Tufts University Medical School,
Boston, Massachusetts
W. DAVIS, Jr. (279), Chemical Technology Division, Oak Ridge National Laboratory,
Oak Ridge, Tennessee
ALBERT J. de VRIES (7), Pechiney-Saint-Gobain, Centre de Recherches de la Croix-de-Berny,
Antony, France
DAVID W. ECKHOFF (219), H. F. Ludwig and Associates, New York, New York
D. W. FUERSTENAU (91), Department of Materials Science and Engineering, University of
California, Berkeley, California
ROBERT B. GRIEVES (175, 183, 191), Department of Chemical Engineering, University of
Kentucky, Lexington, Kentucky
P. A. HAAS (279), Chemical Technology Division, Oak Ridge National Laboratory, Oak Ridge,
Tennessee
T. W. HEALY* (91), Department of Materials Science and Engineering, University of Califor›
nia, Berkeley, California
C. JACOBELLI-TURI (265), Laboratorio di Metodologie Avanzate Inorganiche del Consiglio
Nazionale delle Ricerche, Rome, Italy
DAVID JENKINS (219), Department of Sanitary Engineering, University of California,
Berkeley, California
BARRY L. KARGER (145), Department of Chemistry, Northeastern University, Boston,
Massachusetts
ROBERT LEMLICH (1, 33,133), Department of Chemical and Nuclear Engineering, University
of Cincinnati, Cincinnati, Ohio
F. MARACCI (265), Laboratorio di Metodologie Avanzate Inorganiche del Consiglio Nazionale
delle Ricerche, Rome, Italy
A. MARGANI (265), Laboratorio di Metodologie Avanzate Inorganiche del Consiglio
Nazionale delle Ricerche, Rome, Italy
M. PALMERA (265), Laboratorio di Metodologie Avanzate Inorganiche del Consiglio
Nazionale delle Ricerche, Rome, Italy
T. A. PINFOLD (53, 75), Department of Chemistry including Biochemistry, University of the
Witwatersrand, Johannesburg, South Africa
V. V. PUSHKAREV (299), The Urals Kirov Polytechnical Institute, Sverdlovsk, U.S.S.R.
(cid:149)Present address: Department of Physical Chemistry, University of Melbourne, Parkville,
Victoria, Australia.
(cid:237)
VI LIST OF CONTRIBUTOR S
ALAN J. RUBIN (199), Water Resources Center, College of Engineering, Ohio State Uni›
versity, Columbus, Ohio
ELIEZER RUBIN (249), Department of Chemical Engineering, Technion(cid:151)Israel Institute of
Technology, Haifa, Israel
(cid:212) SASAKI (273), Department of Chemistry, Faculty of Science, Tokyo Metropolitan Univer›
sity, Setagaya, Tokyo, Japan
JAN SCHERFIG (219), Department of Sanitary Engineering, University of California, Irvine,
California
Prefac e
This is the first comprehensive book to cover the various adsorptive
bubble separation techniques. It is a contributed volume, with various
authors for its twenty chapters.
The editor is responsible for defining the scope of the work, and in general
for selecting the topic for each chapter. The authors of the chapters were also
selected by the editor and invited to write on the basis of their specialized
knowledge in their respective areas. However, each author was given wide
latitude to treat his material as he saw fit. The overall result is a highly
authoritative compilation which, it is hoped, will prove to be both informative
and readable.
Chapter 1 introduces the various adsorptive bubble separation techniques.
Chapter 2 deals with certain pertinent properties of foam which are common
to many of them. Then, Chapters 3 through 8 individually discuss several of
these techniques; namely, foam fractionation, ion flotation, precipitate
flotation, mineral flotation, bubble fractionation, and solvent sublation. The
remaining chapters, 9 through 20, summarize the results of numerous
separations, as well as the results of additional investigations into the
mechanisms of the various techniques. As a special feature of interest, the
final six chapters (arranged in alphabetical order by country) comprise a
summary of work, dealing principally with the separation of surfactants and
metallic ions, at several places around the world.
The editor expresses his thanks to the contributors and to the staff of
Academic Press for making this volume possible.
ROBERT LEMLICH
vii
CHAPTER 1 INTRODUCTION
Robert Lemlich
Department of Chemical and Nuclear Engineering
University of Cincinnati
Cincinnati, Ohio
I. Overview
II. Classification of Techniques 2
III. Droplet Analogs 3
References 4
I. OVERVIE W
All techniques or methods of separation, whether physical or chemical, are
based on differences in properties. For example, among the more familiar
techniques, distillation is based on differences in volatility, and liquid ex›
traction is based on differences in solubility.
The adsorptive bubble separation techniques are among the less familiar
methods. This generic name was first proposed by Lemlich (1966), with
adsubble techniques as the convenient contraction. The full generic name has
since been accepted by common consent (Karger et al., 1967).
The adsubble techniques are based on differences in surface activity.
Material, which may be molecular, colloidal, or macroparticulate in size,
is selectively adsorbed or attached at the surfaces of bubbles rising through the
liquid, and is thereby concentrated or separated. A substance which is not
surface active itself can often be made effectively surface active through union
with or adherence to a surface active collector. The substance so removed is
termed the colligend (Sebba, 1962).
Adsubble processes can be found in nature: in sea foam and bubbling
marshes. Among human endeavors, the earliest occurrence is probably
among the culinary arts in such phenomena as the slightly bubble-aided
floating of some constituents in certain boiling soups and other preparations.
Another early example is in the pouring of beer. Certain components of the
beer can concentrate in the foam to a sufficient degree to alter the flavor
(Nissen and Estes, 1940).
In 1878 Gibbs derived the celebrated adsorption equation that bears his
name (Gibbs, republished 1928). About the turn of the century, attempts were
2 ROBERT LEMLICH
begun to test this equation in the laboratory by indirectly measuring the
extent of adsorption of solute on rising bubbles (von Zawidzki, 1900).
Some years later, but much further along the spectrum of particle sizes,
the technique of mineral flotation by air became commercial. Since then,
various adsubble techniques have been employed in a number of industrial
and laboratory separations.
II. CLASSIFICATIO N OF TECHNIQUE S
There are a number of individual adsubble techniques. Figure 1 shows the
accepted scheme of classification (Karger et ai, 1967). It is a compromise
between rational systemization and actual usage of the terms by various
Adsorptive bubble separatio n methods
Foam Nonfoaming
separatio n adsorptive bubble separatio n
Foam Solvent Bubble
fractionation sublation fractionation
(froth)
Flotation
(cid:151)Ø 1 1 ˆ
Ore Macro-
Micro- Precipitate Ion Molecular Adsorbing
flotation flotation
flotation flotation flotation flotation colloid
flotation
FIG. 1. Schematic classification of the adsorptive bubble separation techniques. [From
Karger et al. (1967).]
writers. Accordingly, the reader should not be surprised at the overlap
in the definitions, or when he encounters inconsistencies in terminology
between the works of one author and another(cid:151)or even within the work of a
single author.
As indicated in Fig. 1, the adsubble techniques (or methods) are divided
unequally into two main groups : The larger, called foam separation, requires
the generation of a foam or froth to carry off material. The smaller, which is
termed nonfoaming adsorptive bubble separation, does not.
1 INTRODUCTIO N 3
This smaller division is further divided. Bubble fractionation (Dorman and
Lemlich, 1965) is the transfer of material within a liquid by bubble adsorption
or attachment, followed by deposition at the top of the liquid as the bubbles
exit. Solvent sublation (Sebba, 1962) is the similar transfer to, or to either
interface of, an immiscible liquid placed atop the main liquid.
The larger division is also subdivided. Foam fractionation is the foaming off
of dissolved material from a solution via adsorption at the bubble surfaces.
Froth flotation, or simply flotation (Gaudin, 1957), is the removal of particu›
late material by frothing (foaming).
Froth flotation, in turn, has many subdivisions. Ore flotation (Gaudin,
1957) is the separation of minerals. Macroflotation is the separation of macro›
scopic particles. Microflotation (Dognon and Dumontet, 1941) is the separa›
tion of microscopic particles, especially colloids or microorganisms. (Under
certain conditions, the separation of colloids may sometimes be termed
colloid flotation.)
In precipitate flotation (Baarson and Ray, 1963), a precipitate is formed
and then foamed off. Ion flotation (Sebba, 1959) is the separation of surface
inactive ions by foaming with a collector which yields an insoluble product,
particularly if the product is removed as a scum. Similarly, molecular flotation
is the separation of surface inactive molecules by foaming with a collector
which gives an insoluble product. Finally, adsorbing colloid flotation is the
separation of a solute through adsorption on colloidal particles which are
then removed by flotation.
The overall classification scheme also lends itself to the incorporation of
newly proposed adsubble techniques and others yet to come. For example,
laminae column foaming (Maas, 1969a) is a subdivision of foam fractionation
that utilizes relatively large wall-to-wall bubbles rising up the column.
Booster bubble fractionation (Maas, 1969b) can be viewed as a subdivision of
bubble fractionation that involves the use of certain volatile organic com›
pounds in the gas bubbles in order to improve selectivity of separation.
(cid:201)—. DROPLE T ANALOG S
Before the conclusion of this introductory chapter, it is of interest to point
out that there exist droplet analogs to the adsorptive bubble separation
techniques. These analogs involve adsorption or attachment at a liquid-
liquid interface rather than at a liquid-gas interface. Accordingly, they have
been called, by analogy, the adsorptive droplet separation techniques (Lemlich,
1968), with adsoplet techniques as the corresponding contraction.
The occurrence of adsoplet phenomena also appears to have a long history.
Adsorption on the surfaces of the colloidal particles that rise in milk to
4 ROBERT LEMLICH
form cream comes to mind. Emulsion fractionation is the analog of foam
fractionation, and Eldib (1963) discusses several separations.
Emulsion fractionation, as well as adsorption of solute on a continuous
stream of immiscible droplets, was employed early in the century (Lewis,
1908) in another preliminary attempt to verify the Gibbs adsorption equation.
The latter technique, involving the stream of droplets, has been termed
droplet fractionation (Lemlich, 1968) by analogy with bubble fractionation.
The most significant adsoplet techniques were undoubtedly to be found in
extractive metallurgy. A forerunner is described by T. J. Hoover in his
introduction to the first edition of Gaudin (1932); namely, the report of
Herodotus that the maidens of ancient Gyzantia used to extract gold dust
from mud by means of bird feathers smeared with pitch. Much later, the
Persians of the fifteenth century employed procedures whereby water-wetted
particles were freed under water from an oiled mass (Gaudin, 1957). During
the last century, oil flotation (which may be viewed as the adsoplet analog of
modern ore flotation) was employed in the mineral industries (Taggart, 1927).
However, due to its high oil consumption, oil flotation was supplanted early
in the present century by ore flotation which uses air.
As a whole, the adsoplet techniques have not attracted the measure of
attention accorded to the adsubble techniques. However, the interested
reader may pursue the subject further in the aforementioned references, as
well as in some representative patents and other reports (Elmore, 1902;
Lewis, 1909 ; Rideout, 1925 ; Schutte, 1947 ; Denekas et al, 1951 ; Strain, 1953 ;
Dunning et al, 1954 ; Winkler and Kaulakis, 1955 ; Hardy, 1957).
Further discussion of the adsoplet techniques is beyond the present scope.
The remainder of this book is devoted to the adsubble techniques. 1
REFERENCE S
Baarson, R. E., and Ray, C. L. (1963). Precipitate Flotation, a New Metal Extraction and
Concentration Technique, paper presented at the Amer. Inst. Mining, Metall., Petrol. Eng.
Symp. Dallas, Texas.
Denekas, M. O., Carlson, F. T., Moore, J. W., and Dodd, C. G. (1951). Ind. Eng. Chem. 43,1165.
Dognon, `., and Dumontet, H. (1941). C. R. Acad. Sei., Paris 135, 884.
Dorman, D. C, and Lemlich, R. (1965). Nature 207, 145.
Dunning, ˙. N., Moore, J. W., and Myers, A. T. (1954). Ind. Eng. Chem. 46, 2000.
Eldib, I. A. (1963). In "Advances in Petroleum Chemistry and Refining" (K. A. Kobe and
J. J. McKetta, Jr., eds.), Vol. 7. Wiley (Interscience), New York.
Elmore, E. (1902). U.S. Pat. 692,643.
Certain material of a general nature dealing with the pertinent properties of foam is presented
in the next chapter. The discussion of the separation techniques themselves commences with
Chapter 3.
