358
Ind. Eng. Chem. Process Des. Dev., Vol. 17, No. 3, 1978
Literature Cited Box, M. J., Comput. J., 8, 42 (1965). Brusset, H., Depeyre, D., Proc. €ur. Symp. Comput. Chem. Eng.. 7th. Erlangen. 427 (1974). Brusset, H., Depeyre, D., Boeda, M., Melkior, R., Staedtsbaeder, J. L.. Can. J. Chern. Eng., 49, 786 (1971). Brusset, H.. Luauet. F.. Genie Chim.. 96. 557 11966). Hooke, R., Jeeves, T. A., J. Assoc. Co&ut. hach.,'8, 2 (1961). Lee, K. Y., Aris, R., lnd. Eng. Chem. Process Des. Dev., 2, 300 (1963). Malenge, J. P., C.R. Acad. Sci. Paris, Ser. C,267, 1651 (1968). Malenge, J. P., Villermaux, J., Ind. Eng. Chem. Process Des. Dev., 6, 535
(1967). Malenge, J. P., Vincent, L. M., Ind. Eng. Chem. Process Des. Dev., 11, 465, 468 (1972). Nelder, J. A,, Mead, R.. Comout. J.. 7. 308 11965). Umeda, T., Ichikawa, A., lnd.'€ng. Chem. Pfocess Des. Dev., 10, 229 (1971). Vignes, J., Chim. Ind. Genie Chim., 97, 1264 (1967). Wilde, D. J., "Methodes de recherche d'un optimum", Dunod, Paris, 1966.
Received for review October 10, 1975 Resubmitted January 23,1978 Accepted February 11,1978
Multistage Bubble Fractionator Ralph A. Leonard" and James D. Blacykl Chi-Vit Corporation, A Division of Eagle-Pitcher Industries, Cicero, IIlinois 60650
Bubble fractionation is modified so that higher separation factors are obtained at higher liquid throughputs. This is done by replacing the standard long liquid column with several short columns combined to form a multistage device. This multistage bubble fractionator is effective below feed concentrations of 200 mg/kg (ppm) of surface-active solute in solvent (water). This efficiency increases as feed concentration decreases so that at 1.O mg/kg and a gas to feed ratio of IO3, separation ratios can be as high as lo4. This unit was tested successfully with several organic dyes (Crystal Violet, Rhodamine 6G,and Brilliant Cresyl Blue), a refined oil, blood albumin, and COD (Chemical Oxygen Demand). The short single-stage unit showed surface exclusion of several organic dyes which are sodium salts (Alizarin Red S, Fluorescein Sodium, and Tartrazine).
Introduction Classic bubble fractionation (Lemlich, 1968) uses long narrow columns with low gas flow rates. The bubbles carry surface-active material to the top of the column and leave it there when the bubbles break. This forms a concentration gradient up the column which can be maintained only if liquid mixing is minimized, that is, a t very low gas rates. Since the gas rate is low, the feed rate must also be low so that the surface-active solute concentration in the column does not overwhelm the available interfacial area. These columns, because of their low throughput, have not been widely used. The adsorption of the surface-active solute at the gas-liquid interface increases with the solute concentration c until the surface becomes saturated a t concentration c,. In this region, a reasonable first approximation is to assume that the excess T' of solute a t the gas-liquid interface is proportional to the solute concentration
r =KC
(c1.0
f
-
c ~ / c w Notes
0.2
C
-
-
10
90
0.5
13.0
-
-
-
-
-
2
-
-
-
-
-
4
3c
-
0.2
CD,
mg/kg
1.0 125 100
-
13.5
CFt
mg/kg
9.8 6
2000h
13
>>1.0 154 j j
1140 2 42 11 1460m 13 29 2250 4.5 0.12 2-Mercaptobenzimida~c-~n 6 10 0.1c 0.100 1.2 1.5 a Seven-stage unit with 100 cm2 sparger area. Use human serum in 0.9% NaCl solution, 50% of protein is albumin. Gas is 94.5% N2 and 5.5% COz. This stream is cloudy. Analysis after centrifuging shows high concentrations of active blood albumin. No active
gamma globulin was detected. e This sample isolated from rabbit serum. I' Appears concentrated as this stream is cloudy. Analysis after centrifuging shows no active gamma globulin. g This oil was emulsified in water. Separate oil phase appears here. Supplied by Dr. J. D. Tinkler of Sun Oil Corp. Conditions similar to those for No. 51 oil. A polyether manufactured by BASF Wyandotte. Equivalent to a COD of 3200. A plating bath additive.
j0 103
s-
I02
\
SEVEN STAGES WITH SPARGER I I RHODAMINE 6 G I S SOLUTE FEED IS 6 TO9 M L l M l N GAS I S 5 2 0 0 M L I M I N UNIT ARkA IS 100 CM2
\
V
10
a Figure 3. Effect of feed concentration of separation ratio.
CF
= solute concentration of feed stream, mg/kg
cs
= solute concentration of bulk liquid when the gas-liquid
interface is just saturated with solute, mg/kg cw = solute concentration of W stream, mg/kg d = bubble diameter, cm D = flow rate of the bubble liquid process stream, mL/ min Di = flow rate of bubble liquid removed by the baffle from stage i, mL/min f = fraction of the total liquid feed to the feed stage m which is fed externally, dimensionless F = feed rate, mL/min G = gas rate, mL/min J = operating parameter defined by eq 6, dimensionless K = d r / d c in the linear region below C S , cm m = the feed stage number M = operating parameter for a single stage defined as the square root of the separation ratio, dimensionless n = the total number of stages; the number of the stage from which the D stream is taken W = flow rate of the pool liquid process stream, mL/min r = surface excess of solute, g-mol/cm2
Literature Cited Acknowledgment We appreciate the help of Dr. S. T. Nerenberg, head of the Clinical Laboratory of the University of Illinois at the Medical Center, in making the blood serum tests. Nomenclature A = 1/M, dimensionless Bi = defined by eq 9, dimensionless c = solute concentration, mg/kg or g-mol/cm3 C D = solute concentration of D stream, mg/kg
Adamson, A. W., "Physical Chemistry of Surfaces," 2nd ed, Interscience, New York, N.Y., 1967. Bruin, S., Hudson, J. E., Morgan, A . I., Jr., Ind. Eng. Chern. Fundarn., 11, 175 (1972). Lemlich, R., Ind. Eng. Chem., 60 ( I O ) , 16 (1968). Sebald, J. F., Karassik, I. J., U S . Patent 3 339 345 (1967). Shah, G. N., Lemlich. R., Ind. Eng. Chern. Fundarn., 9, 350 (1970).
Received for review February 22, 1977 Accepted January 12,1978
This paper was presented at the 79th National AIChE Meeting in Houston, Texas, Mar 16-20, 1975.
