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INDUSTRIAL A N D ENGINEERING CHEMISTRY
(78) Rose, H. E., Proc. Inst. Mech. Enprs. (London), 153, 141 (1945). (79) Salisbury, J. K., Power Volume of “Kent’s Mechanical Engineers’ Handbook,” 12th ed., pp. 9-20 to 9-30,12-82 to 12-84, New York, John Wiley & Sons, Inc., 1950. (80) Scheibel, E. G., and Othmer, D. F., Trans. Am. Inst. Chem. Engrs., 38, 339 (1942); IND. ENC.CHEM.,34, 1200 (1942). (81) Schlapfer, P., Audykowski, T., and Bukowiecki, A., Schweiz. Arch. angew. W i s s . u. Tech., 15, 308 (1949). (82) Sherwood, T. K., “Absorption and Extraction,” p. 7, New York, McGraw-Hill Book Co., 1937. (83) Sherwood, T. K., and Holloway, F. A. L., Trans. Am. Inst. Chem. Engrs., 36, 21 (1940). (84) Shulman, H. L., and Molstad, M. C., IND.ENQ.CHEM.,42, 1058 (1950). (85) Simrel, V. R., and Hershberger, A,, Modern Plastics, 27, N o . 10. 97, 98, 100, 102, 150-2, 154, 156, 158 (1950). (86) Stephens, E. J., and Morris, G. A., paper presented at the Montreal meetinn American Institute of Chemical En& =.news, September 1949.
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Stokes, R. H., and Robinson, R. A,, IND. EKC. HEM,, 41, 2013 (1949).
Storrow, 3. A,, J . SOC.Chem. Ind., 66, 41, 73 (1937). Taecker, R. G., and Hougen, 0. A., Chem. Eng. Progress, 45,188 (1949).
Ternovskaya, A. N., and Belopolskii, A. P., Zhur. Fiz. Khim. (U.S.S.R.), 24,43 (1950).
Trevoy, D. J., and Drickamer, H. G., J . Chem. Phys., 17, 1117 (1949).
Vi;ian, J. E., Sc.D. thesis in chemical engineering, Massachusetts Institute of Technology, 1945. Walter. J. F,, and Sherwood, T. K., IND.ESG. C H E X , 33, 493 (1941). Weisman, J., and Bonilla, C. F., Ibid., 42, 1099 (1950). Weller, S., and Steiner, W. A., J . Applied Phys., 21, 279 (1950). White, G. E., Chem. E n g . Progress, 46, 363 (1950). Wilke, C. R., Ibid., 46, 95 (1950). Winter, E. R. S., Trans. Faraday Soc., 46, 81 (1950). Yang, L. M.,Proc. Rou. SOC.(London), A198, 94, 471 (1949). RECH~IV November ~D 6, 1950.
ADSORPTION HOPKINS UNlVERSlM,~BALTlMORE18, MD.
The Field of adsorption has been a very active one in all aspects. The trend toward increased interest in the use of this tool for separation which was evidenced in previous years has continued and expanded. Lewis and co-workers have applied the concepts of relative volatility to reparation of hydrocarbons in binary and ternary gaseous separation. The reiative volatility of any two compounds was found to be the same for a ternary system as for the binary system of those components. Estimation of x y diagrams from pure gas isotherms is allowable for many systems. Chromatographic techniques have been utilized for separation of liquid mixtures of gasoliner and gas oils, but no approach similar to that for the gases has been attempted. Liquid phase studies are considerably more difficult of interpretation than gas phase studies and as yet there i s no method of correlating adsorption in the liquid phase which is as applicable for nonspecific systems as the B.E.T. equation is for gases. Some few attempts to correlate liquid studies b y this equation have not met with great success. The adsorption of high polymers has been previously studied and presents about the same picture as other liquid phase work. This has been extended by Tiselius and others to adsorption of colloidal particulates. A very large number of studies have been made on specific systems and preparation of adsorbants,
T
HERE has been a great deal more activity in the field of adsorption this year than in previous years, as attested by the large number of references. The vast bulk of this work has been, as usual, in physicochemical equilibrium studies and interpretations of these by the standard isotherm equations, the Brunauer-Emmett-Teller, Freundlich, and others. A large percentage of this work has been liquid phase studies of removing dyes or decolorizing liquids, as discussed below. However, several articles this year are concerned with studies of a more strictly unit operations type and: in particular, the resolution of mixtures. Some few have been concerned with the resolution of gaseous mixtures. The most fundamental approach to this subject has been made by Lewis and his eo-workers (181-186),who were concerned with hydrocarbon mixtures and the resolution of these over activated carbon and silica gel. They first determined the pure gas isotherm and found that for most of the gases there was good reversibility and no hysteresis evident. Utilizing the various adsorption equilibria, they studied the xy diagrams (vapor-adsorba t e equilibria) of binary gaseous mixtures of compounds of the same number of carbon atoms as well as of some ternary systems. The factors of molecular weight, molecular structure, and liquid boiling point were found to be involved in the phenomenon of
preferential adsorption. Molecular structure was more important over silica gel than over carbon, and, in general, the greater the boiling point difference of two liquids the greater was the relative volatility difference over both adsorbants. The data v, ere correlated by the equation
-&=1 hr‘ 1
where the h7 values refer t o the moles of each component adsorbed from the mixture and the primed value refers to the capacities for the pure components. An empirical method was developed for prediction of the adsorptive relative volatility over silica gel. For multicomponent mixtures the relative volatilities of any two components appear to be equal to the values obtained for the binary mixture of these components. I n many cases, the N 1 us. Nz correlation coupled with t,he assumption of constant relative volatility yields satisfactory zy diagrams, allowing estimation of mixture data from pure gas isotherms. Carbons of different adsorptive capacities were found to yield essentially the same equilibrium diagram for a given mixture. A review by Eagle and Scott on cyclic adsorption processes (88) underlines the great usefulness of the cyclic adsorption method for almost quantitative separation of aromatics and olefins from other compounds of varying feed stock. The optimum number and size of adsorption columns were stated to be determined by the character of the feed, the desired purity of raffinates and extracts, and economic considerations and construction. Studies were made in a pilot plant on various charged stocks. Two patents were issued to Brandt (36)and to Gilliland (111) for separation by adsorption in countercurrent flow using various adsorbants, such as charcoal, activated alumina, and silica gel. These closely parallel previous studies on the hypersorption method.
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The only other article on adsorption from binary mixtures of hydrocarbons concerns a study by two Russian authors (263)on the separation of carbon dioxide, ethylene, or propene from air over activated carbon. This is primarily a stripping operation rather than a true separation of materials, both of which might be adsorbed. Gases other than hydrocarbons are represented by two studies. White and Schneider (606)studied the physical adsorption of oxygen-argon mixtures on silica gel a t 0". At this relatively high temperature, neither of the gases is adsorbed appreciably and the adsorption is essentially a linear function of the partial pressure. With the total adsorption so low, neither component is inhibited by the presence of the other, so that equilibrium is obtained for both gases a t their respective relative partial pressures, no matter which of the gases &st came in contact with the surface. The quantitative separation of argon from small quantities of krypton and xenon by multiple adsorption and desorption was measured by Gerling and Baranovskaya (110). The work described by them was more truly separation of binary mixtures, in that the study was conducted from -80" to -120" C. The adsorption of the gases was stated to conform to the Freundlich equation and the adsorption conformed to Henry's law. Krypton was desorbed with greater difficulty than argon; a method was worked out, based on calculation and conbmed by experiment to separate argon from small quantities of krypton. The mixture was adsorbed a t - 100"C. and the adsorbed gases were desorbed and readsorbed in stepwise adsorbers. By this procedure, the argon was recovered and the bulk of the krypton remained adsorbed. Any xenon present remained with the krypton. Selective adsorption, particularly in the liquid phase, by chromatographic techniques was proposed by Hibshman (138)for the separation of is0 and normal paraffins, by Hansen and co-workers (127)for the separation of zirconium and hafnium, and by Hopf (143) for Separation and purification of quinidine and quinine. The utilization of this adsorptive technique for recovery of nitrogen oxides by silica gel (98)and for separation of cracked gasolines (96) was discussed, as well as the separation of hydrocarbons b y selective adsorption (116)and the analysis of distillates by fractionation (18). Several reviews on the hypersorption process have appeared, in1 particular one by the early experimenters in this field, Berg and co-workers (23). The removal of sulfur compounds from gas. streams by hypersorption was discussed by Kehde and Chapin (169). A number of tools and mathematical correlations have appeared during the past year, which have not been applied to the practical problems involved in designing adsorbers but which it seems will be applied in the future. These concern the theoretical principles of adsorption of gases by activated charcoal (114) for the hypersorption of olefins, where in a physical mathematical study the phenomena of the adsorption and capillary condensation in porous media are reviewed. Theoretical analysis of the fractionating process of adsorption has been approached by Mair and co-workers (201). The mathematics of adsorption in fluidized beds has been discussed by Kasten and Amundson (166). As in the case of previous mathematical studies, this theory applies only to equilibrium isotherms and to nonequilibrium cases that are linear and reversible. I n general, the more complicated cases are not solvable by direct mathematical approach. The redistribution of the adsorbate by diffusion within the bed has been discussed by Ledoux (179) in terms of the usual dimensionless variables, so that it is possible t o use these data to determine the diffusivities in other systems. The flow of gases through porous media has been studied by Takagi (279) and correlated with the temperature rise of active charcoal on adsorption of various organic solvent vapors. The heat of adsorption, as related to the relative adsorbability of gaseous hydrocarbons, was studied over silica gel and carbon
42
black by Smith and Beebe (279). Separation of propene and butane was attempted but not obtained. Selective adsorption of the two components was indicated. SURFACE AREA STUDIES
Adsorption has been used for numerous studies of surface area, in line with the developments over the past several years. Carbon black, silica gel, organic materials, salts, pigments, crystalline carbon, and carbide powders, as well as many other materials, have been studied by various authors (16,16, 43, 168,266,313). The use of adsorption as a tool for measuring surface area has been compared by Arne11 (7) with the well known permeability method. Good agreement was found for the modified Kozeny equation. The estimation of the surface area of powders from the temperature dependence of the adsorption from solution has been investigated by Hirst and Lancaster (140). Rideal and Trapnelt. (248)utilized chemisorption of oxygen to estimate the surface area of tungsten used in catalytic study. This was found to ghe good agreement with the catalytic activity of the surface. Joyner and eo-workers (160)have compared the pore volume distributions between the nitrogen adsorption isotherm and the mercury porosimeter. They have con6rmed their previous studies, indicating that the pore volume distributions are in complete agreement with the Brunauer-Emmett-Teller areas. Work on the adsorption of krypton on paint films has extended the technique of adsorption to smaller total surface areas (309). A rather large amount of work has been done on determining the surface coverage of various molecules. The adsorption of nitrogen has been used in the past as a standard method of surface area determination by the adsorption technique, and this gas is utilized wherever possible. For very small surfaces, krypton adsorption has been used, and numerous articles have appeared at various times, attempting t o correlate the adsorption of different gases on the same surface. To date, this has been not too successful and recent studies do not change the picture appreciably. A rather complete study was made by Livingston (188)on the cross-sectional areas of various gas molecules for adsorption a t temperatures ranging from -252 O C. t o room temperature. Correlations between studies on various surfaces by different molecular species do not always agree with the data given by Livingston, but indicate rather that either the Harkins and Jura k value or the surface area coverage assigned to a given molecular species will vary with the surface upon which it is adsorbed (129,
286). Studies on alumina by Russell and Cochran indicate better agreement for stearic acid adsorption than for adsorption of either nitrogen or butane (266, 266). A review by Dunaca has compared the Harkins and Jura approach to the Brunauer-Emmett-Teller approach, according to the Anderson modification (84). He found that the Harkins constant, k , could be estimated approximately from the Anderson constant and a given value for the area occupied by an adsorbed molecule. A good method of determining the surface areas of a large number of solids to about 20% accuracy was given, based on the assumption of a value for the Anderson constant and the linearity of the P/P,vs. l / V plot over the range of P / P , from 0.25 to 0.75. Studies of the anomalous adsorption of helium a t liquid helium temperatures (10) by Band indicate that the high value of the volume of gas that will just fill the first monolayer a t its saturation density yielded by the ordinary Brunauer-Emmett-Teller plot are real and indicate that the Brunauer-Emmett-Teller theory only requires generalization. A study of the adsorption of nonpolar gases and of water vapor on proteins by Benson and Ellis (29) indicated that reasonable and fairly consistent values of surface areas and heats of adsorption were found, depending only on the state of subdivision of the protein powders. Adsorption of water, however, was immeas-
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INDUSTRIAL AND ENGINEERING CHEMISTRY
urably fast and the value of adsorption was independent of surface area. A study by Komarov, Drozdova, and Chernikova (166) on the adsorption of nitrogen and butane on various solids indicated that the nitrogen adsorption was in all cases larger, as might be expected, and that, in general, three fractions of the total surfaces exist: that rapidly accessible to butane, that slowly acceaible to butane, and that accessible to nitrogen but not to butane. Numerous studies have been made on the utilization of liquid phase adsorption to surface area determination and, according t o the published accounts, with considerably greater success than that previously observed. The use of the iodine number (or amount of iodine adsorbed) was found in two studies (21, 186) to yield surface area values in complete agreement to those obtained using the low temperature adsorption of nitrogen or area calculations from electron micrograph of carbon blacks. Stearic acid adsorption from solution was found to be simpler and to give good agreement with nitrogen when the nitrogen molecular area was calculated as 17.8sq. A If the nitrogen value is taken as 16.2 sq. A., a linear correlation in the results obtained gave 16.7 sq. A. for the molecular coverage of the stearic acid molecule (25’5,266). The equilibrium and kinetics of liquid phase adsorption have been discussed by Eagle and Scott (87). An approach to the use of soap molecules from aqueous solutions was made, using surfaces of graphite and polystyrene (60). Reviews of the use of surface area determinations by adsorption techniques have been published by Emmett (89), Prettre (,941),and Taylor (184). CHROMATOGRAPHY
Chromatographic techniques are interesting from a unit operations point of view, in that most of the work on separation of liquid phase components would be so indexed. There have been numerous studies on practical problems, particularly in the petroleum field, for both the separation and the analysis of complex mixtures. The separation of cracked gasolines by this technique was studied by Fink and co-workers (94, 96). Factors affecting the efficiency of the adsorption and the characteristics of the adsorbant and regeneration techniques were discussed recently. The finer silica gels are found to give more efficient separations; the disadvantages of the h e r silica gels are obviously those of greater pressure drop and greater difficulty in separating from the fluid stream. In general, the adsorbing capacity of silica gel for olefins in the same range of molecular xeights decreases in the order: cyclic. > branched-chain > straightchain olefins. The chromatographic analysis of gas oils was investigated by other Shell Oil chemists (63)and chromatographic analysis was extended to several other applications, including estimation of the hydrocarbons in primary tars by hot chromatography by Vahrman (298), separation of chlorophylls by Wendel ( S o d ) , and analysis of hexachlorocyclohexane (104). A review of chromatographic analysis was published by Descamps (78). Improvements in the art of chromatography were mentioned in many of the studies, but several developments merit individual mention. A capillary-ascent test tube method was developed by Rockland and Dunn (261). An apparatus which records, on photographic paper, the changes in refractive power of a solution leaving a filter us. the amount of solution was developed by Hellstrom and Borgiel (132), who further indicated that difficulties which arose in work using a commercial model were overcome and discussed the methods for so doing. A single apparatus for applying pressure and suction regulation to chromatographic columns was developed by Booth ($8). The term LLpartography” was proposed by Rockland and Dunn (&52) for paper partition chromatography. A device for rapid and accurate reading of the separation values in paper chroma-
Vol. 43, No. 1
tography was described by them, involving a proportional divider, which they have suggested be called “partogrid.” The met’hod involves a simple mechanical device for evaluating t,he separation coefficient. Various uses for the separation of one material from another have been dkcussed for bot’h inorganic and ionic systems (3,33, 105, 107, 178, 281, 311) and organic systems (8, 38, 5’7, 63, i&, 189,228,866,278,319). The adsorption of particulates and proteins has been carried out. by this technique. Shepard and Tiselius (867) have discussed t’he rhromatography of proteins as affected by salt concentration and pH when adsorbed on silica gel. The problem of separat,ing subcellular part,iculates from the cytoplasm of cells was developed by Riley, Woods, and Burk (849). The use of chroniatography to obtain adsorption isotherms was attempted by Nestler and Cassidy (WM), using the frontal-analysis technique in binary mixtures of fatty acid of low molecular weight,. The Freundlich isotherm Fvas found to hold for these materials over the range studied. The effect of the structure of the adsorhte on the adsorption was investigated by several workers. Hydrogen bonding was found to be a factor, giving some rather anonxilous results for certain hydroxy substituted compounds in preference to others with slightly different structure (f44,%@). The adsorption on carbon of ketones with varying side chains was found to follow the rule that a decrease in the rate of movcment of the ketone zone occurred with increasing mass of the side chain. On silica gel and similar adsorbants, the reverse was found to be true (271). Similar relationships were found for the effect of the side chain on the strength of adsorption with some primary aliphatic alcohols and amines by Monaghan, Moseley, and LeRosen (214). This latter study also indicated irregularities in the effect of side chain on adsorption affinity. Naturally occurring phenolic substances showed similar irregularities, although in general a straight line was obtained for the plot of the log of the function of the separation coefficient against the number of subst,ituent groups of any one kind (870). Several articles appeared on the use of paper chromatography. General articlcs were published by Gordon (116)and Clegg ( 5 2 ) , and general considerations were discussed by Jones (149). An interesting innovation was the use of alumina-impregnated filter paper by some British authors (69). Automatic paper chroniatography was proposed by Muller and Clegg (216)and the kinetics of paper chromatogram development was investigated, in which the square of the radius of the colored zone on a paper disk chromatogram was found to be proportional to the development time for a given solvent or solute. Paper chromatography of several substances was investigated, including a complete study on phenolic substances (93). The improvement and various discussions of the characteristics of different chromatographic adsorbants were mentioned in these studies and specifically by several other authors (154,156,867,196). General review articles on chromatography in several languages were published (148, 167, 194, 208, 277, 689, 508). A plan was described for chromatographic separations on an industrial scale, utilizing a stationary radial chromatographic separator with an exchangeable inner container, containing the adsorbant. The general plant layout for this system was provided (195). LIQUID PHASE ADSORPTION
The adsorption from liquid phase, either by the liquid surface itself or by solid surfaces, has been the subject of numerous investigations. Previous work of Hansen, Fu, and Bartell (116),more completely published now, indicated that for sparingly soluble organic materials in aqueous solution the Brunauer-EmmettTeller equation of multimolecular adsorption holds fairly well. The adsorption of electrolytes and the heats involved therein have been measured by numerous investigators. The
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49
adsorption of nickel and cobalt from aqueous solutions by manganese dioxide was measured, using the chloride and nitrate solution. The adsorption was found to be cationic and reversible and the anion was not adsorbed. This was advanced as an explanation of the greater percenbge of nickel oxide than of cobalt oxide in the ores (98). The percentage of adsorbed ions of z i w and copper on calcium carbonate was found to decrease as the concentration increased. The adsorption followed t h e formula of Langmuir-Terrin. Each adsorbed ion neutralized various active centers of the absorbant. I n mixed solutions of copper and zinc, the c o p per diminishes the adsorption of zinc to a degree to make it negligible (42). The specific adsorption isotherm of thiocyanate ion was estimated by comparison with the adsorption of potassium chloride a t the free surface of solution (193). The specific adsorpAdsorptive Dryer of 500-Cubic Foot Capacity ion a t the tion of hydrogen free surface of solutions was calculated by the same author and found to be nearly linear. ethyl stearate on various metal surfaces. No orientation was Other studies were made on calcium hydroxide (85), numerous found on platinum, but on reactive metals, such as cadmium and compounds of sodium (209), and many other materials (106, zinc, the diffraction pattern showed a change well above the melt119,968). ing point of stearic acid. Methyl stearate behaved similarly Tiaelius and other authors have studied the adsorption of col(260). Various other similar studies were made on both polar loidal materials or the adsorption on colloidal materials in numerand nonpolar organic compounds (%4,61,117,124). QUS instances. The adsorption of sulfanilamide on silk fibroin The adsorption by clays and soil as related to the exchange has been measured by Coulombre and Moore (W),and the encapacity thereof has been rather thoroughly studied (70,106,108, tropies of adsorption were found to be negligible. Sorption 119,197,,969)and applied to an interesting practical use wherein isotherms of substantive dyes and humic acids by various gels inthe clay is mixed with a small amount of comminuted cellulosic dicated the presence of sharp minima and maxima; depending material, such an wood flour; this material is extruded into upon the water content of the adsorbant (165). small cylinders, and calcined to a content of low residual volatile Passivation of iron was achieved with protein layers, particumatter. The product is an adsorbant for oil, grease, water, and larly solutions of gelatin, resulting in decreased attack of the iron other materials (197). Suggestions as to the use of clays for the by sulfuric acid. Adsorptive passivation was found to be suadsorption of vitamin B1 have been made by Sakurai and Hori perior to parkerization (168). (259). In particular an approach has been made by Capon and The adsorption of glutamic acid on aluminum oxide indicated co-workers (106)to the elucidation of the activity of the soil by t h a t aluminum chloride is useful in increasing the adsorptive adsorptive technique involving exchange activities of chernopower (24'4.6). The Nobel lecture of Tiselius (288), on the use of zems. adsorption analysis as a means for study of substances of high Of the numerous studies of adsorption of dyes, the effect of admolecular weight and their decomposition products, has now been sorption on the rate of diffusion in gels merits mention because of published (287). the postulate that there are active centers in the gel which immoThere have been a large number of studies of adsorption from bilize the diffusion in the gel. The result is that Fick's law is not solution by various substrates. It would be impossible to survey exactly valid, but the deviation could be related to pH (39). these exhaustively, but mention of a few fields may be of interest. The adsorption of acid dyes on cellulose has been thermodpThe adsorption on metal or mineral surfaces of specifically adnamically evaluated by Peters and Vickerstaff (234). sorbed materials has been the subject of increasing interest. The In an interesting piece of work by Dickey (74) a method has theory of water-repellant films on solids formed by adsorption been reported for obtaining silica gels having specific adsorption was suggested by Cook and Nixon (68) for use in flotation studies. afEnities for certain azo dyes. The silica gel is prepared in the Physical and chemical adsorption of long-chain compounds on presence of a particular dye and then as much of the dye as pracmetals was studied by radioactive technique and no reaction was tical is removed by prolonged extraction. Gels prepared in this observed in any case of adsorption of high molecular weight alcoway were very much more powerful adsorbants for the particular hols on zinc, cadmium, copper, platjnuni, and gold. With stearic dye used in their preparation than control gels. acid, however, the film reacted with zinc, cadmium, and copper As usual, there has been a great deal of activity in the adsorpW). Electron diffraction observations were made on adsorbed tion a t liquid-liquid and liquid-air interfaces. There is compara-
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I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
tively little practical significance to this work, but a great deal of theoretical interest. When a dry powder is wetted by a liquid, a gas is evolved. This was quantitatively studied by KrasnovskiI and Gurevich (170), using various oxide samples for the adsorption of palmitic acids in toluene solutions. They stated the volume desorbed can be used for characterizing the powder. One interesting technique in the study of adsorption from the liquid phase mentioned above-the use of radioactive tracer methods for determining adsorption of very small quantities of high molecular weight materials at interfaces-was further discussed (109, 145). P R E P A R A T I O N AND PROPERTIES OF V A R I O U S A D S O R B A N T S
Chemically inert gel bas been prepared by Biget (28)by coagulating acetone solutions of cellulose acetate with aqueous solutions of metallic perchlorates. Gels containing as little as 2y0 acetate were obtained. These were inert to solutions of p H 0 to 9, and were unaffected by many organic substances. Those materials which caused dehydration, hardening, or plasticizing of the gels rapidly destroyed them. Barrer ( I S ) has prepared crystalline hydrogen zeolites by heating the corresponding ammonium zeolites in oxygen. The hydrogen zeolites of mordenite and chabazite were found to be excellent adsorbants and to take u p propane more rapidly than the natural zeolites. The decolorizing efficiency of fuller's earth (196) was improved by extruding the earth mixed with a small concentration of aqueous sodium hydroxide and neutralizing the extruded material by sufficient mineral acid to react with the alkaline reagent. The earths so treated were stable after repeated regeneration. Montmorillonite was activated by treatment with sulfuric acid. The specific surface tended toward a maximum and then decreased as increasing amounts of aluminum, iron, and magnesium oxides were removed from the siliceous material. The surface areas were studied by both x-ray and gaseous adsorption techniques. When sodium montmorillonite was dried a t successively higher temperatures, the sample increased to a maximum area of 90 square meters per gram when approximately half the water had been removed. The area and water content then decreased to approximately 0 as the sample was dried a t successively higher temperatures, in the range of from 300' t o 900" C. Calcium montmorillonite reacted similarly, except that two maxima were observed (191, 192). Activation of bentonite and other clays containing montmorillonite was reported by Hickey (134) to result in catalysts for hydrocarbon conversion, or in contact adsorbants for aqueous or organic impurities in oils and fats, or as decolorizing agent for oils, sugar, and process waters. The use of hydrochloric acid or sulfuric acid was found to be preferable to mineral acid for activation. The maximum level of activation was achieved by removal of 20 to 45% of the lattice aluminum. For use as a catalyst, the treated clay was calcined a t 400' to 600" C. Bentonite and similar materials can be activated to remove considerably more of the water content by partial drying and then extraction with a water-soluble liquid such as ethyl alcohol (49). When bentonites are heated, the exchange capacity to lithium ions is lost (141). Spherical particles of highly acid treated bentonites were prepared by mixing a finely powdered bentonite with alumina sol, dispersing the mixture in butanol, and agitating the dispersion until the sol sets to the hydrogel, forming spherical particles of alumina hydrogel and bentonite. The well known preparation of activated carbon by impregnation of the starting material with zinc chloride and subsequent calcination has been studied by several authors (2, 78, 81). The yield, homogeneity and activity of the product were found to depend on the uniformity of contact between the steam used for activation and the carbon and on the temperature of the steam. The yield of carbon activated by zinc chloride was found to be considerably greater than that obtained in activation by carbon diox-
Vol. 43, No. 1
ide. For birch charcoal the adsorption of dyes indicated that when large excesses of zinc chloride compared to organic material were used the resultant pores in the charcoal were accessible to colloidal particles. Activation of sugar carbon by heat treatment from 500" to 1100' C. was found to result in maximum adsorption at about 800" for organic acid of low molecular weight (186). When activated carbon was oxidized by boiling in nitric acid, a high adsorption for hydrogen sulfide was obtained, in contrast to unoxidized charcoal which did not adsorb the gas. The 10% nitric acid treatment was better in this respect than more concentrated solutions. Preliminary adsorption of hydrogen sulfide on the oxidized carbon was found to raise its adsorption capacity for benzene (291). Electron microscope studies (S42) of active carbon indicated that the material was not uniform, as would be expected, and that the dimensions of the visible pores increased when the total pore volume was increased by longer heating. Electron microscope studies of silica gels indicated that, in general, they belong to one of three classes: a transparent gel which bad no pores and was similar to quartz fragments, gels consisting of crystals 500 to 1000 A. in size with pores between the particles of 160 to 600 A., and intermediate structures. These data agreed with adsorption data (248). The elastic properties of silica gels were examined by Munro (618), who found that Young's modulus was not independent of load and increased with the age of the gel, as well as the concentration. Increased temperature increased the modulus of acid gels, whereas alkali gels showed a higher modulus a t room temperature and a lower elastic recovery. Modifications and production of silica and other gels have been the subject of numerous studies. A process and apparatus for continuous manufacture were described by Weir (303). Silicaalumina catalysts were prepared by mixing alumina trihydrate with silica sol containing an excess of sulfuric acid. The gel was soaked in ammonia to precipitate alumina in the body of the silica matrix (55). A similar catalyst was prepared by depositing on activated alumina an organic compound capable of producing hydrated silica when subjected t o heat (2.9'7). If the silica-alumina sol has incorporated in it a small percentage of powder under 50 microns in size and is fusible at 1000" F., a catalyst of greater particle strength isobtained ($IS),which can be subjected to more severe drying conditions. Preparation of gels by spraying tbe sodium silicate solution into a n agitated sulfuric acid solution a t relatively low temperatures was developed by Archer and Dunn (6). In this method the gel was allowed to age for some time before washing. Other methods involving aging of the gel were developed by Ashley and Jaeger (9) and Higuchi (135). High speed agitation of the sulfuric acid solution used for precipitation o l the silica-alumina gel resulted in controlled particle size (6). Hydration of gels which decrepitate in contact with liquid water can be accomplished by an addition of ice, allowing the mixture to stand for extended periods of time (4). Other general improvements in silica and other gels have been put forth in production (112, 17'7, 629), washing (66), drying (172, 394), and heat treatment (997). Production of spherical gel materials has been the subject of a number of publications (191,203, 904, 836-,998). Forming of viscous inorganic sols into any desired shape-rods, disks, or spheres-and hardening the resultant shapes by immersion in liquid ammonia or exposure to gaseous ammonia were developed by Marisic and Griest (804). Molded active materials were prepared by coating pieces of refractory inert solids with wax and applying a layer of the wet, workable mass. On drying, a hard shell of the adsorptive material developed with a hard inner core (91). KINETICS OF A D S O R P T I O N
The kinetics of hydrogen adsorption on nickel was utilized b y Sadek and Taylor (868)in the study of nickel catalyBt prepara-
INDUSTRIAL AND ENGINEERING CHEMISTRY
January 1951
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tions. Both physical adsorption and chemisorption were observed and the different preparations adsorbed different relative amounts by the two types. The data did not support an interpretation based either on solubility of hydrogen in the lattice or on a n exothermic entry of hydrogen into the nickel lattice a t low temperatures. The kinetics of desorption of hydrogen was studied by Cornault and by Keier and Roginskii (59, 160). If desorption was stopped before complete degassing and more hydrogen was added, this was adsorbed more rapidly than during the primary adsorption, indicating that desorption does not appear to start from patches least active in adsorption on sugar charcoal, The adsorption of hydrogen on reduced copper was found to be very slow and equilibrium was not reached after 66 hours (174). Methane was chemisorbed on a composite nickel-alumina-manganese-kieselguhr catalyst and found to obey a simple Langmuir rate equation with desorption neglected (294). The desorption of the methane was not observed, but instead the evolved gas was hydrogen. Tbe rate of the hydrogen desorption did not result in a simple Langmuir equation, indicating surface heterogeneity. Chemisorption of oxygen was used by Rideal and Trapne11 (248) to estimate the surface area of tungsten used for chemisorption studies of hydrogen. The equilibrium adsorption of hydrogen was found to change very slowly with temperature and pressure and to fit a Freundlich isotherm. The heats of adsorption were calculated by the Clausius-Clapeyron equation. The observed decrease of heat of adsorption with coverage could not be accounted for on the basis of simple electrostatic dipole-dipole repulsion. The thermodynamics of an adsorbate on an adsorba n t is discussed by Hill (133, giving particular attention to the heat of adsorption. It was found that the true equilibrium of adAH sorbate was given by -fi = with fi as the two-dimen-
Surface diffusion of adsorbed molecules of organic materials in silica gel and active carbons a t low temperature waa reported by Haul (ISO), utilizing a direct weighing method to measure the diffusion. The ink bottle mechanism for hysteresis was stated a s being confirmed by a theoretical paper by Katz (157). A determination of the pore size distribution, by applying the ink bottle theory to previous data, yielded results compatible with expected values by statistical consideration. Todes and Bondareva (290), making the assumption that experimental deviations from Langmuir’s adsorption isotherm are determined by heterogeneity of the surface and with disregarded interaction between adsorbed molecules, established integral equations for the distribution function of portions of the surface with values of adsorption coefficient. Solutions of these integral equations were sought by choosing empirical functions which agreed best with experimental values. After a thorough-going discussion of mathematical techniques for solving this type of equation, they stated a preference for Roginskii’s approximation, and use of Taylor’s series after the first term. The Langmuir isotherm for localized unimolecular adsorption was generalized by Hill (iS7-169), using statistical methods in order to discuss adsorption on a heterogeneous surface, with and without interactions between adsorbed molecules. The configurational entropy and the nature of the phase changes on a random heterogeneous surface were discussed. The theory predicted, a t least for one special case, that condensation would occur in two steps. The application of the thermodynamic methods enabled thermodynamic functions to be calculated from the BrunauerEmmett-Teller statistical model.
sional spreading pressure. Hansen (125) derived the Clapeyron equation thermodynamically as applied to calculation of heats of adsorption from adsorption isosteres and came to the conclusion that the derivation should be evaluated a t a constant number of adsorbed molecules per unit surface area of the solid rather than the usual isosteric evaluation. Cremer (64) explained deviations from the Langmuir a d s o r p tion formula on the hypothesis that the surface had centers with different heats of adsorption. Adsorption begins a t centers of high energy and the number of adsorption centers having a given heat has an exponential dependence upon the heat. This theory takes into account a factor characteristic of the disorder of the surface and the degree of adsorbability of the substances adsorbed. The number of active catalytic centers was found to increase exponentially with the heat of adsorption. Beebe and co-workers (16.9) measured the differential heats of adsorption of nitrogen and oxygen on titanium dioxide and calculated the partial molal entropy of the adsorbed gas. The results show that the partial molal entropy of the adsorbed gas is less than the partial molal entropy of the bulk three-dimensional liquid or solid phases a t coverages less than a monolayer, as defined by the Brunauer-Emmett-Teller equation, for all the systems investigated; a t coverages greater than a monolayer, the value a p proached the entropy of the three-dimensional liquid or solid. The entropy requirements of the Brunauer-Emmett-Teller theory were shown to be incompatible with the experimental evidence a t coverages lesa than a monolayer. Other heat of adsorption studies were made on silica gel (86, 872), on carbon (17,19,21012S1,2S2, 2S5,264, 261, B O ) , and on miscellaneous other solids (14, 62,178-176,198,211, SOi? 81s) for various adsorbates. The adsorption of dissolved substances and vapors on liquid surfaces was examined by Gyani (18s). Systems were chosen so as to have ideally homogeneous adsorbing surfaces. I n many ca6es a very good agreement was found. The transitory motion of the adsorbed molecules was confined rigidly to one plane. Adsorption among some adsorbed molecules was indicated on the adsorption of some polar molecules on mercury.
The large number of references published during the past year preclude complete discussion of individual studies of equilibrium data. For the convenience of persons interested in such studies, a cross-index reference list follows.
(
ri
51
”)
m2
INDIVIDUAL STUDIES OF EOUILIBRIUM DATA
Adsorbants of Major Interest. CHARCOAL.( 2 , 17, S6, 46, 48, 76-79,81, 82, 88,1OS, 111, lis, 1S0, 161-165,181-186, 210, 220, 2S1, 2.92, 242,246, 2624 264, 271, 272,276,879, 280,286,295, SOO, 306). CARBON (other than charcoal). (9.8.15. 16. 19. 2i. SO. 76. 80. 82, 88, 103,‘126, 151, 152, 160, 164,18h1186, $09; 810, 8i8,h 4 ; 2S5, 246,247, 261, 27S1291, 298, 896).
GELSOTHERTHAN SILICA.(4,5,15,28,S6, S9,66,85, 87, 112, 1S1,164,165, 172, 177, IOS, 204, 211,815,227, 829, 236,255,266, 268, SOS). CLAYS. (@, 70,108,119,1S4,1.61,191,192, 190,197,199, $00, 259, 274, 286). OXIDESOTHERTHAN GELS. (S8, 4 4 92, 99,109,140,155,164, 165,167,171,187,19O12S0, 244, 255-267,276,281, SOO, S14). METALS. (46, 90,117, 124, 128,129,152,162, i66,169,17S176, 198, 216, 2SS,848, 258,260,864). Adsorbates of Interest. NITROGEN. (15, 16, 9 2 , 43, 90, 97, 129, 150, 158, 16S, 166,188, 192, 210, 233, 246,263, 255, 26‘1, 286, so9, Sf s, S14). RAREGASES. (10, 97,99,110,158,188,190,210,J05, SO9, 818, 314). WATERVAPOR. (22, 40,41, 67, 77,97,129,142,164, 188,811, 226, WSS,2S8, 2@, 254,26S, 265, S06,515). HYDROCARBONS AND NONPOLAR ORGANIC VAPORS. (15,18,19, %2,S8,89,51, 5.3, 59, 61, 6S, 69, 70, 78, 79, 85,87, 88, 95, IOS, 114, 122,124, 126,129, 1S0, 1S5, 144, 162, 166,170,181, 182, 18s-185, 188,201 , 21 9,225, 251,245, 25S, 255,256, 961,263,270, 272, 276, 279,280, 286, 291, 294). POLAR ORGANIC VAPORS. (1, 25, S5, 58,51, 58, 60, 69, 80, 86, 91, 102, 1 W , 109, 117, 122, 124, 126, 129, 1S0, 144,168, 164, 165, 187, 188, 210, 225, 2S1, 236, 244,250, 254, 261, 26S, 270, 276,280, 291, 298).
INDUSTRIAL AND E N G I N E E R I N G CHEMISTRY
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General Subdivisions of the Field. HEATSOF ADSORPTION AND THERMODYNAMIC CONSTANTS.( I S , 17, 19,22, 69, 62, 64,86, 106, 166, 136, 163, 173-175, 198, 810, 211, 231, 232, 235, 248, 254, 281, 272, 273, 279, 280, 295, 301, 513). SURFACE AREA. ( 7 , 10, 15, 16, 21, 22, 40, 43, 60, 84,89, 124, 126, 129, 140, 147, 150, 158,166, 175, 175, 186, 188,191, 192, 241, 247, 848, 266, 256, 261, 265, 273, 279, 284, 286, 509, 313). CHROMATOGRAPHY. (3, 8, 39, 33, 38, 52, 53, 57, 63, 69, 72, 95, 94, 95, 104, 10.5, 107, 116, 132, 145, 144, 148, 149, 154, 155, 167, 178, 189, 194, 196, 208, $14,216, 217, 220, 228, 249, 251, 252, 257, 262, 666, 267,270, 271, 277, 278, 281, 289, 296, 298, 304, 308, 31 1 , 312. Reviews Dealing with Adsorption. (11, 13, 23, 34, 37, 38, 57, 72, 73, 76, 79, 86, 88, 89, 101, 106, 207, 113-116, 118, 132, 135, 148, 149, 164, 167, 180, 194, 199, 206, 214, 230, 241,266, 273, 277, 282-284, 287-289, 508, 310 ) BIBLIOGRAPHY
(1) .4ddison, C. C., and Elliott, T. A , , J . Chem. Soc., 1949, 3395-
403.
(2) Alexa, G., and RBdulescu, F. D., B u l . Inst. S o t l . CercStarz Technol., 3, 177-222 (1948) (in French). 13) Alexander, G. B., J . Am. Chem. SOC.,71, 3043-6 (1949).
Allen, 0. W., U. S.Patent 2,505,079 (April 25, 1950). American Cyanamid Co., Brit. Patent 626,455 (July 15, 1949). Archer, J. R., and Dunn, G., U. S. Patent 2,483,868 (Oct. 4, 1 a4a) Arnell, J. C., Can. J . Research, 27A, 207-12 (1949). honoff, S.,Science, 110, 590-1 (1949). Ashley, K. D., and Jaeger, .4.O., U. S. Patent 2,478,519 (-4ug 9, 1949). Band, W,, Phys. Rev., 76, 441-2 (1949). Barrer, R. M., J . chim. phys., 47, 82-94 (1950). Barrer, R. M., Nature, 164, 112-13 (1949). Barrer, K. M., Quart. Revs. (London), 3, 293-320 (1949). Barrer, R. hl., and Woodhead, AT., Trans. Faraday Soc., 44, 1001-7 (1948). Bartell, F. E., and Dodd, C. G., J . P h y s . & Colloid Chein., 54, 115-28 (1950). Bartell, F. E., and Dodd, C. G., “Surface rlreas of Crystalline Carbon and Carbide Powers as Measured by Adsorption of Nitrogen,” 23rd Colloid Symposium. Bastick, J., Compt. rend., 230, 1163-5 (1950). Beaven, G. H., Foster, L. F., and Thompson, C. N., J . Inst. Petroleum. 36. 89-104 11950). Beebe, R. A., Kington, G.’L., Polley, M. H., and Smith, IT. R., J . Am. Chem. SOC., 72, 40-2 (1950). Beeck, O., Givens, J. W., and Ritchie, A. W., J . Colloid Sci., 5, 141-7 (1950). Beneon, P., and Sanlaville, J., J . chin&.phys., 47, 108-12 (1950). Beneon, S. W., and Ellis, D. A., J . Am. Che772. Soc., 72, 2095102, 2102-5 (1950). Berg, C., Fairfield, R. G., Imhoff, D. H., and Rlulter, H. J., Petroleum Refiner, 28, No. 11, 113-20 (1949). Bernard, R., and Hirtz, J., Compt. rend., 228, 1859-61 (1949). Bernard, R., and Hirts, J., J . chim. phys., 47, 96-8 (1950). Bersin, T., and Loheyde, I., 2. phusiol. Chent., 283, 275--6 (1948). Bhatnagar, M . S.,J . Sci. I n d . Reseaich ( I n d i a ) , 6B, No. 12, 18&8 (1947). Biget. A. M.. Ann. chin?., (12) 5 , 66-195 (1950) Bishop, J. A., J . Phys. & Collozd Chem., 54, 697-702 (1950). Boer, J. H. de, and Ormondt, J. Tan, LT. S. Patent 2,478,166, (Aug. 2, 1949). Bond, G. R., Ibid., 2,507,496 (May 16, 1950). Booth, V. H., Analyst, 75, 109-11 (1950). Bourdon, D., and Cotte, J., Bull. soc. chim. France, 1949, 429. Boutaric, A., Scientia ( I t a l y ) ,84, 159-65 (1949) (in French). Bowden, F. P., and Moore, A. C., Research (London),2, 585-6 (1949). Brandt, P. L., U. S. Patent 2,493,911 (Jan. 10, 1950). Brdicka, R., Chenz. Lasty, 38, 252-9 (1944). Brockmann, H., and Volpers, F., Chem. Ber., 82, 95-104 (1949). Bromberg, A. V., and Mal’tseva, 0. S., Kolloid. Zhur., 12, 9-16 (1950). Brown, C., and Savage, R. H., “Adsorption of Water Vapor by Carbon Wear Dust,” 117th Meeting AM. CHEX. SOC., Houston, Tex., 1950. Camposortega, Afonoada, and Rowen, J . SOC. Chem. I n d . (LOndO?L), 68, 118-19 (1949). Canals, E., htarignan, R., and Cordier, S., Ann. pharnt. franc., 7,502-9 (1949). Carman, P. C., and Malherbe, P. le R., J . Soc. Chem. I n d . (London), 69, 134-43 (1950). Carroll, B., J. Am. Chem. Soc., 72, 27634 (1950). Chamie and Filcakova, J . chim. phys., 46, 174-5 (1949).
VOl. 43, No. li
(46) Charonnat, R., and Leclerc, J., Ann. phurm. franc., 7, 625-7 (1949). (47) Chirkov and Vereshchinskii, Doklady Akad. Nauk S.S.S.R., 67, 317-20 I194R). (48) Chmutov, K. V., and Alekseev, N. G., Ibid., 67, 321-3 (1949). (49) Christiansen, A., Dan. Patent 68,670 (March 7, 1949). (50) Chu, J. C-H., Microfilm Abstracts, 9, No. 2 , 31-2 (1949). (51) Clark, C. R., Degont, J., Denard, L., and Dervichian, D. G., Research (London), S u p p l . , Surface Chemistry 1949, 173--9 (in French). (52) Clegg, D. L., Anal. Chem., 22, 742 (1950). (53) Clerc, K. J., Kincannon, C. H.,and Wier, T. P., h d . , 22, 864--7 (1950). (,54) Colin-Russ, A., Proc. Intern. Co?lgr. Pure and Applied Chem. (London),11,381-9 (1947) (in English). (55) Connolly, G. C., U. S. Patent 2,474,888 (July 5, 1949). (56) Ibid., 2,481,825 (Sept. 13, 1949). (57) Cook, A. H., Nature, 164, 30&1 (1949). (58) Cook, M. A., and Nixon, J. C., J . Phys. & Colloid Chem., 54, 445-59 (1950). (59) Cornuault, P., J. chin?. phys., 47, 157-64 (1950). (60) Corrin, M. L., Lind, E. L., Roginsky, d.,and Harkins, W.D., J . Colloid Sci., 4, 485-95 (1949). (61) Cotton, P., Research (London), Suppl., Surface Chemistry 1949,233-8 (in French). (62) Coulomhre, J., and Moore, J. RI., J . P h y s . & Colloid Che7i~.,54 6 6 1 4 (1950). -~ , (63) Goutier, L., Andre, H., and Prat, J., Chim. anal., 31, 201-3 ~~
\_.__,_
~~
~
11Q4Q). ~-”-~,.
(64) Cremer, E., J . china. p h y s . , 46, 411-19 (1949). (65) Crisp, D. J., Research (London), Suppl., Surface Chemistry 1949. 65-78. (66) Cumper, C. W. N., and Alexander, A. E., T r a m . Faraday Soc., 46,235-43 (1950). (67) Cutler, J. A., and McLaren, A. D., J . Polymer Sci., 3, 792-4 (1948)(68) D’Alcontres, G. S., Gazz. chim. ztal., 79, 609-13 (1949). (69) Datta, S. P., Overell, B. G., and Stack-Dunne, M., Nature, 164, 673-4 (1949). (70) Davydov, A. T., and Lisouina, G. hl., Kolloid. Zhur., 11, 30810 (1949). (71) Dean, R. B., and Li, F-S., “Sorption of Vapors by Monolayers. Organic Vapors on Stearic Acid Monolayers,” 117th Meeting AM.CHEW,Soc., Houston, Tex., 1950. (72) Descamps, M., Bull. assoc. anciens Btud. brass. univ. Louvain, 44, 125-444, 171-90 (1948). (73) Devaux, H., Research (London), Suppl., Surface Chemistry 1949, 3-5 (in French) 5 8 (in English). (74) Dickey, F. H., “Preparation of Specific Adsorbants,” 117th Meeting AX,CHEM.SOC., Houston, Tex., 1950. (75) Dubinin, M. A!., Vestnik A k a d . Xauk S.S.S.R., 19, No. 3, 19-36 (1949). (76) Dubinin, M. M., Chmutov, K. V., and Alekseev, N. G., Doklady A k a d . h’auk S.S.S.R., 66,875-8 (1949). (77) Dubinin, M. )I., and Zaveiina, E. D., Ibid., 56, 715-18 (1947); Chem. Zentr. (Russian Zone Ed.), 1948, 11, 171. (78) Ibid., 68, 91-4 (1949). (79) Ibld., 72, 319-22 (1950). (80) Dubinin, M. hf., and Zaveriiia, E. D., Zhur. Fiz. Khsm., 23, 993-1004 (1949). (81) Ibid.. 24. 470-8 11950). , , (82) Dubinin; h/I.?vI., Zaverina, E. D., and Timofeeva, D. P., Ibid., 23, 1129-40 (1949). (83) Duhinin, M. M., and Zuev, ,4. G., Dolclady Akad. Xadc S.S.S.R., 69, 209-12 (1949). (84) Dunaca. J. F..Trans. Faradau SOC..45.879-91 (1949). (85) Dzhigit, 0. hi., Kiselev, A. k., and Krasil’nikov, K.G., Doklady Akad. N a u k S.S.S.R., 71, 77-9 (1950). (86) Dshigit, 0. M., Kiselev, A. V., Mikos-Avgul, N. N., and Shcherhakova, K. D., Ibid., 70, 441-4 (1950). (87) Eagle, S., and Scott, J. W., IND. ENG.CHEM.,42, 1287-94 (1950). ( 8 8 ) Eagle, S., and Scott, J . W., Petrotacm Processing, 4, 881-4 (1949). (89) Emmett, P. H., Advances in Catalysis, 1, 65-90 (1948). (90) Emmett, P. H.. and Kummer, J. T., J. chim. phys., 47, 67-73 (1950). (91) Epstein, H. T., Microfilm Abstracts, 9, No. 2, 46-7 (1949). (92) Eristavi, D. I., Kolloid. Zhur., 10, 322-8 (1949). (93) Evans, R. A,, Parr,W. H., and Evans, W. C., Nature, 164, 6745 (1949). (94) Fink, D. F., Lewis, R. W.,and Weiss, F. T., Anal. Chem., 22, 850-7 (1950). (95) Ibid., pp. 858-63. (96) Forestier, Hubert, and Kiehl, J. P., Compt. rend., 229, 47-9 (1949).
January 1951
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INDUSTRIAL AND ENGINEERING CHEMISTRY
Forestier, Hubert, and Kiehl, J. P., J . chim. phys., 47, 165-73 (1950). Foster, E. G., “Recovery of Nitrogen Oxides by Silica Gel,” E. I. du Pont de Nemours & Co., Wilmington, Del. Frederikse, H. P. R., Physica, 15,860-2 (1949) (in English). Freytag, H., Z.Naturforsch., 5b, 123 (1950). Frumkin, A. N., Uspekhi K h i m . , 18,9-21 (1949). Fu, Y.,and Bartell, F. E., J . Phys. & Colloid Chem., 54,537-46 (1950). Fu, Y., Hansen, R. S., and Bartell, F. E., Ibid., 53, 1141-52 (1949). Fuks, N. A., and Chetverikova, L. S., Zhur. Anal. K h i m . , 3, 220-5 (1948). Gapon, E. N., and Gapon, T. B., J . Gen. Chem. U.S.S.R., 19, No. 9, a49-57 (1949). Gapon, E. N., and Zuev, L. A., Kolloid. Zhur., 10,83-93(1948). Gapon, T. B., and Gapon, E. N., Zhur. Anal. Khim., 3,203-12 (1948). Garcia, F. G., Anales real SOC. espafi. As. y quim., 45B, 1067-74 (1949). Gaudin, A. M., and Bloesher, F. *W., Trans. Am. Inst. Mining Met. Engrs., 187,Tech. Pub. 2813-B ( M i n i n g Eng., 187,499505) (1950). Gerling, E. K., and Baranovskaya, N. V., Zhur. Anal. Khim., 5, 131-8 (1950). Gilliland, E.R., U. S. Patent 2,495,842(Jan. 31, 1950). Glassbrook, C. I., and Hansford, R. C., Ibid., 2,484,284(Oct. 11, 1949). Godlewicz, M., Nature, 164,1132-3 (1949). Goggi, G., Riv. combustibili, 3, 157-69 (1949). Gordon, A. H., Angew. Chem., 61,367-9 (1949). Gorter, C. J., and Frederikse, H. P. R., Physica, 15, 891-6 (1949)(in English). Greenhill, E. G., Trans. Faradav SOC.,45,625-31 (1949). Gregg, S. J., Research (London), Suppl., Surface Chemistry 1949,205-16. Gruner, E., and Vogel, R. E., Kolloid-Z., 116,89-99 (1950). Guastalla, J . Research (London), Suppl., Surface Chemistry 1949,145-51 (in French, English summary). Guastalla, J., and Mibashan-Saraga, L., Ibid., pp. 103-8 (in French, English summary). Gyani, B. P., J . I n d i a n Chem. Soc., 26, 307-12 (1949). Gyani, B. P., J . Phys. & Colloid Chem., 53,1091-1101 (1949). Hackerman, N.,and Glenn, E. E., Ibid., 54,497-505 (1950). Hansen, R. S.,Ibid., 54,411-15 (1950). Hansen, R. S., Fu, Ying, and Bartell, F, E., Ibid., 53, 769-85 (1949). Hanaen, R. S., Gunnar, Keith, Jacobs, Alfred, and Simmons, C. R., “Adsorption Separation of Zirconium and Hafnium,” Iowa State College, Ames, Iowa, 1950. Harashima, Akira, Tanaka, Tomoyasu, and Sakaoku, J . Phys. SOC.J a p a n , 3,208-13 (1948)(in English). Harris, B. L., and Emmett, P. H., J . Phys. & Colloid Chem., 53, 811-25 (1949). Haul, R., Angew. Chem., 62, 10-16 (1950). Heard, L., U.S. Patent 2,505,895(May 2, 1950). Hellstrom, N.,and Borgiel, H., Acta Chem. Scand., 3, 401-7 (1949)(in English). Hibshman, H. J., IND.ENG.CHEM.,42, 1310-14 (1950). Hickey, J. H., U. S. Patent 2,484,828(Oct. 18,1949). Higuchi, Bull. Inst. Phys. Chem. Research (Tokyo), Chem. Ed., 23,40-6(1944). Hill, T. L., J . Chem. Phys., 17,520-35 (1949). Ibid., p. 590. Ibid., pp. 668-9. Ibid., PP. 762-71. Hirst, W., and Lancaster, J. K., Research, 3,336-7 (1950). Hofmann, U., and Klemen, R., 2. anorg. Chem., 262, 95-9 (1950). Hoover, S. R.,and Mellon, Edward F., J . Am. Chem. SOC.,72, 2562-6 (1950). Hopf, P.P,. Lynam, C. G., and Weil, H., Brit. Patent 585,224 (Feb. 3,1947). Hoyer, H., Kolloid-Z., 116, 121 (1950). Hutchinson, Eric, J. Colloid Sci., 4,599-601 (1949). Hutchinson, Eric, Trans. N . Y . Acad. Sci., 11, 266-70 (1949). Innes, W. B.,“Rapid Automatic Surface Area and Pore Volume Determination by a New Adsorption Method,” 117th Meeting AM. CHEM.SOC., Houston, Tex., 1950. Jacobs, Ph. (Utrecht, The Netherlands), Pharm. Weekblad, 84, 717-25, 734-9 (1949). Jones, T. S. G., Chemist & Druggist, 153,247-9 (1950). Joyner, L. G., Barrett, E. P., and Skold, R. V., “Comparison of Pore Volume Distributions Determined from Nitrogen Adsorption Isotherms and by Mercury Porosimeter.” 117th Meeting AM. CHEM.SOC., Houston, Tex., 1950.
53
(151)Juza, R., Chem.-Ztg., 74, 55-7 (1950). (152) Juza, R., and Grasenick, F., 2. Elektrochem., 54,145-52 (1950). (153)Juza, R.,and Tentschert, H., Z. anorg. C h m . , 262, 165-74 (1 950). (154)Kaplan, S.,and Meller, F., J . Gen. Chem. U.S.S.R., 19,No. 11, a507-12 (1949)(English translation). (155)Kaplan, S., and Meller, F., Zhur. Obschchei K h i m . ( J . Geu,. Chern.), 19, 2038-44 (1949). (156)Kasten, P. R.,and Amundson, N. R., IND.ENG.CHEM.,42, 1341-6 (1950). (157)Kats. S. M..J . Phws. & Colloid Chem.. 53. 1166-86 (1940). (158j Keenan, A. G., a n i Holmes, J. M., J . Phys. & Colhid-Chem. 53, 1309-20 (1949). (159)Kehde, Howard, and Chapin, E. €I., “Removal of Sulfur Compounds from Gas Streams by Hypersorption,” 117th Meeting AM.CHEM.SOC., Houston, Tex , 1950. (160) Keier, N. P., and Roginskiy, S. Z.,Dokladu A k a d . .Vauk S.S.S.R. 57, 157-9 (1947); Chem. Zentr. (Russian Zone E d . ) , 1948, 11, 471. (161)Keier, N.P., and Roginskii, S.Z., Zhur. Fiz. Khzm., 23,897-916 (1949). (162)Kemball, C.,Proc. R o y SOC.(London), A201,377-91 (1950). (163) Kington, G. L., Beebe, R. A., Polley, A t . H., and Smith, W. R., 6.Am. Chem. Soc., 72, 1775-81 (1950). (164)Kiselev, A. V., and Smirnova, I. V., Zhur. F i z . K h i m . , 23,101824 (1949). (165) KoganovshiI, A.M., Kolloid. Zhur., 11, 237-43 (1949). (166) Xomarov, V. A,, Drozdova, V. M., and Chernikova, E. A,, Zhur. Fiz. Khim., 23, 1141-51 (1949). (167)Konstantinova-Shlezinger, M. A., and Gorbacheva, N. 4., Zhur. Anal. K h i m . , 3,213-19 (1948). (168) Koshurnikov, G.S.,Zhur. Priklad. K h i m . ( J . A p p l i e d Chem.), 22, 698-702 (1949). (169)Kozakevitch, P.,J . Chem. Phus., 47,24-32 (1950). (170) Krasnovski:, A. A., and Gurevich, T. N., Kolloid. Zhur., 11, 172-5 (1949). (171) Krishnamoorthy, C., and Overstreet, R., Science, 111, 231-2 (1950). (172)Kumberlin, C. N., and Pierce, J. A., U. S. Patent 2,503,913 (-4pril 11, 1950). (173) Kwan, T., J . Research Inst. Catalysis (Hokkaido Univ.) 1,81-94 (1949). (174)Ibid., pp. 95-9. (175)Ihid., pp. 100-9. (176)Ibid., pp. 110-16. (177)Layng, E. T.,U. S. Patent 2,487,564(Nov. 8, 1949). (178) Lederer, M., Science, 110, 115-16 (1949). (179) Ledoux, Edward, J . Phys. & Colloid Chem., 53,960-6 (1949). (180)Leenheer, L., Bull. soc. belge geol. paleontol. hydrol., 57,299-320 (1948). (181)Lewis, W.K., Gilliland, E. R., Chertow, B., and Cadogan, W. P., IND. ENG.CHEM.,42,1319-26 (1950). (182)Ibid., pp. 1326-32. (183)Lewis, W.K., Gilliland, E. R., Chertow, B., and Hoffman, W. H., J. Am. Chem. SOC.,72, 1153-7 (1950). (184)Lewis, W.K.,et al., Ibid., 72, 1157-9 (1950). (185)Ibid. pp. 1160-3. (186)Linner, E. R., and Williams, A. P., J . Phys. & Colloid Chem., 54,605-18 (1950). (187)Lipets, M. E., and Trapeznikov, A. A , , Zhur. Fiz. K h i m . , 23, 981-92 (1949). (188) Livingston, H.K., J . Colloid Sci., 4,447-58 (1949). (189)Loeb, C., and Lichtenberger, J., Bull. 8oc. chim. France, 1950, 362-3. (190) Long, E. A., and Meyer, L., Phys. Rev., 76,440-1 (1949). (191)Longuet-Escard, J., J . Chim. phys., 47, 113-17 (1950). (192) Longuet-Escard, J., Mering, J., and Perrin-Bonnet, I., Ibid., 47, 234-7 (1950). (193)Lorenz, P. B., J . Phys. & Colloid Chem., 54,685-90 (1950). (194) Lynam, C. G., and Weil, H., Brit. Patent 635,271 (April 5, 1950). (195) Lynam, C. G., and Weil, H., Mfg. Chemist, 21, 1959, 205 (1950). (196) McCarter, W.S. W., U. S. Patent 2,477,386(July 26, 1949). (197) Ibid., 2,480,753(Aug. 30, 1949). (198) McClellan, A. L., and Hackerman, Norman, “Sorption of Gases on Metals a t Room Temperature,” 117th Meeting AM.CHEM.SOC., Houston,Tex., 1950. (199) MacEwan, D. M. C., Nature, 162,No. 4128,935-6 (1948). (200) McLaughlin, R. R.,and Azis, D., J . Chem. Education, 26,325-6 (1949). ENG. (201) Mair, B. J., Westhaver, J. W., and Rossini, F. D., IND. CHEM.,42, 1279-86 (1950). (202) Marcelin, A., Research (London), Suppl., Surface Chemistry 1949,223-31(in French, English summary).
INDUSTRIAL AND ENGINEERING CHEMISTRY Marisic, M. M., and Griest, E. M., U. S. Patent 2,492,167 (Dec. 27,1949). Ibid., 2,492,808 (Dec. 27, 1949). Matsunaga, Yoshiaki, Bull. Nagoya Inst. Technol., 1, 260-70 (1949). Maxted, E. B., J . Chem. SOC.,1949, 1987-91. Meister, H., Swiss Patent 237,380 (Aug. 1, 1945). Meng. K. H., E. S. Patent 2.487.574 (Nov. 8. 1949). Merrill, R. C., and Getty, R., J . P h i s . & Colloid‘Chem., 54, 489097 (1950). _. .. --, Millard, Ben, Cynarski, Jeanette, and Beebe, R. A,, “Calorimetric Heats of Adsorption of Nitrogen, Argon, and Methanol on Several Carbon Pigments of Widely Different Physical Characteristics,” 117th Meeting Ax. CHEM.SOC., Houston, Tex., 1950. Milligan, W. O., and Morgan, C. S., Jr., “Adsorption of Water Vapor on Ferric Oxide-Chromic Oxide Gels,” 117th Meeting Ani. Cmm. SOC., Houston, Tex., 1950 Milligan, W. O., and Morgan, C. S.,Jr., “High Temperature -4dsorption Apparatus,” 117th Meeting AM. CHEM. SOC., Houston, Tex., 1950. Milliken, T. H., U. S. Patent 2,487,065 (Sov. 8, 1949). -Monaghan, P. H., Moseley, P. B., and LeRosen, A. L., “Effect of the Side Chain on the Strength of Adsorption of Some Primary Aliphatic Alcohols and Amines,” 117th Meeting - 4 ~CHEM. . Sac., Houston, Tex., 1950. Mostovetch, Nicolas, Compt. rend., 228, 1702-4 (1949). Mtiller, R. H., and Clegg, D. L., Anal. Chem., 21, 1123-5 (1949). Ibid., pp. 1429-30. hIunro, L. A., McNab, J. G., and Ott, W. L., Can. J . Research, 27B, 781-90 (1949). Murphree, E. V., U. S. Patent 2,515,134 (July 11, 1950). Nestler, F. H. M., and Cassidy, H. G., J . Am. Chem. Soc., 72, 680-9 (1950). Ono, Syu,J. Chem. Phys., 18, 397 (1950). Ono, Syu, M e m . Faculty Eng., K y u s h u Univ., 12, 1-8 (1950). Ibid., pp. 9-19. Owen, J. J., U. S. Patent 2,475,984 (July 12, 1949). Pal’velev, V. T., Doklady A k a d . N a u k S.S.S.R., 65, 875-8 (1949). Pamfilov, A. V., Devyatyhk, G. G., and Shirshova, L. V., Zhur. Fiz. K h i m . , 24, 292-8 (1950). Pardee, W. A., and Elliott, G. E., U. S. Patent 2,493,896 (Jan. 10, 1950). Partridgc, S. M., and Westall, R. G., Biochem. J., 44, 418-28 (1949). Patrick, W. A., U. 8. Patent 2,503,168 (April 4,1950). Perchet, R., Genie civil, 126, 208-9 (1949). Perreu, Jean, Compt. rend., 229, 195-7 (1949); 228, 1427-9 (1949). Tbid., 230, 642-4 (1950). Perrot, M., and Arcaix, S., Ibid., 229, 1139-42 (1949). Peters. R. H.. and Vickerstaff.. T... Proc. Rou. SOC.(London). A192, 292-308 (1948). Pierce, C., and Smith, R. N., J . Phys. & Colloid Chem., 54, 35464 (1950). Pierce, J. A., U. S. Patent 2,506,316 (May 2, 1950). Pierce. J. A.. and Kimberlin, C. N.. Jr. (to Standard Oil Development Co.), U. s. Patent 2,474,910 (July 5 , 1949). Plank, C. J., Ibid., 2,499,680 (March 7, 1950) Polak, Feliks, Roczniki Chem., 22, 181-90 (1948). Pouradier, J., and iibribat, M., Research (London), Suppl., Surface Chemistry 1949, 135-44 (in French, English summary). Prettre, Marcel, J . chim. phgs., 47, 99-103 (1950). Radushkevich, L. V., and Lukyanovich, V. M., Zhur. Fiz. Khim., 24, 21-42 (1950). Rao, K. S., Rao, M. B., Vasudevamurthy, A. R., and Rao B. S., Proc. Nall. Inst. Sci. India, 16, 1-4 (1950). Rauen, H. M., and Wolf, L., Z . physiol. Chem., 283, 233-42 (1948). ENG.CHEM.,42, 1315-18 Ray, G. C., and Box, E. O., Jr., IND. (1950). Reyerson, L. H., and Wertz, J. E., “Sorption of the Oxides of Nitrogen on Carbon Surfaces,” 23rd Colloid Symposium. Reyerson, L. H., and Wertz, J. E., “Sorption Studies on the Bromine-Graphite System,” 23rd Colloid Symposium. Rideal. E. K., and Trapnell, B. M. W., J . chim. phys., 47, 12638 (1950). Riley, Vernon, Woods, M. W., and Burk, Dean, “Chromatographyas an Approach to the Problemof Separating Subcellular Particulates,” 117th Meeting AM. CHEW SOC., Houston, Tex., 1950. Robinson, D. A., and Mills, G. F., IND.ENG.CHEM.,41,22214 (1949).
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Vol. 43, No. 1
Rockland, L. B., and Dunn, M. S., Science, 109,539-40 (1949). I b X , 111,332-3 (1950). Roginskii, S. Z., and Yanovskii, hl. I., Zhur. Fiz. Khim., 24, 137-43 (1950). Runov, A. D., Kiselev, A. V., Kiselev, V. F., and Alekseev, S. N., Ibid., 23, 1005-17 (1949). Russell, A. S.,and Cochran, c. N., IND. ENG.Cmbr., 42,1332-5 (1950). Ibid., PP. 1336-40. Sacconi, Luigi, Xature, 164, 70-1 (1949). Sadek, H., and Taylor, H. S., J . Am. Chem. SOC.,72, 1168-75 (1950). Sakurai and Hori, Bull. Inst. Phys. Chem. Research (Tokyo), 22, 760-8 (1943). Sanders, J. V., Research (London), 2, 586-7 (1949). Schaeffer, T.V. D., Polley, M. H., and Smith, W. R., J . Phys. & Colloid Chem., 54, 227-39 (1950). Schroeder, W. A,, “Hydrogen Bonding and Relative Adsorption Affinities of Certain Derivatives of Diphenylamine and N Ethylaniline on Salicylic Acid,” 117th Meeting AM. CHEM. SOC., Houston, Tex. Seelioh, F., Monatsh., 79, 338-47 (1948). Shafrin, E. G., and Zisman, W. A., J . Colloid Sci., 4, 571-90 (1949). Shapiro, I., and Kolthoff, I. M., J . Am. Chem. Soc., 72, 776-82 (1950). Shemyakin, F. A I . , and Mitselovskil, E. S.,Zhur. Anal. K h i m . , 3, 349-53 (1948). Shepard, C . C., and Tiselius, A., Discussions Faraday SOC.,No. 7, 275-85 (1949). Shishniashviy, M. E., Isvest. A k a d . N a u k S.S.S.R., 1950, 16977. Sierra, F., and Monllor, E., Anales As. y quim. (Madrid), 41, 234-48 (1945). Smith, E. C. B., and Westall, R. G., Biochim. et Biophys. Acta, 4, 427-40 (1950) (in English). Smith, E. D., and LeRosen, A. L., “Effect of Side Chain on Chromatographie Adsorption of Some Ketones on Carbon,” 117th Meeting AM. CHEM.SOC., Houston, Tex., 1950. Smith, W. R., and Beebe, R. A., IND.ENQ.C H E ~ 41, . , 1431-5 (1949). Smith, W. R., and Schaeffer, W. D., Proc. 2nd Rubber Technol. Conf. (London) 1948,403-13. Standard Oil Development Co., Brit. Patent 590,252 (July 11, 1947). Starodubstev, S. V., Zhur. Eksptl. Teoret. Fiz., 19, 215-24 (1949). Stengler, G., and Krenkler, K., Erdol u. Kohle, 3, 120-4 (1950). Strain, H. H., Frontiers in Chem. 8, (Frontiers in Colloid Chemistry) 29-63 (1950). Strain, H. H., IND.ENG.CHEM.,42, 1307-10 (1950). Takagi, Sadashige, J . Chem. SOC.J a p a n , 68, 5-6 (1947). Tamaru, S., and Sato, K., Rev. Phys. Chem. J a p a n , Shinkichi Horiba Commem. Vol., 1946, 1-5, Tanaka, M., Ashizawa, T., and Shibata, M., Chem. Researches ( J a p a n ) , 5, Inorg. and Anal. Chem., 35-52 (1949). Taylor, H. S., Adaances in Catalysis, 1, 1-26 (1948). Taylor, H. S., Frontiers in Chem. 8, (Frontiers in Colloid Chemistrv). 1-28 (1950). Taylor,”. S., i.ch&. p h w . , 47, 74-81 (1950). Teichner, S., Ibid., 47, 118-21 (1950). Tendeloo, H. J. C., Mans, A. E., and deHoogh, G., V I I Congr. intern. inds. agr., Paris, 2, 182-8 (1948) (in English). Tiselius, Arne, Naturwissenschaften, 37, 25-33 (1950). Tiselius, Arne, Prix Nobel, 1948, 102-21. Titov, E. M., Zavodskaya Lab., 13, 1359-64 (1947). Todes, 0. &I.,and Bondareva, A. K., Zhur. Priklad. K h i m . ( J . Applied Chem.), 21, 693-707 (1948). Toropov, S. A., and Pylaev, A. V., Ibid., 22, 568-71 (1949). Trapeznikov, A. A., Kolloid. Zhur., 12, 67-80 (1950). Trillat, J. J., and Millet, J., J . recherches centre natl. recherche sci. (Paris), 1950, No. 10, 32-5. Troesch, A., J . chim. phys., 47, 145-7 (1950). Ibid., pp. 148-56. Trueblood, K. N., and Malmberg, E. W.,Anal. Chem., 21, 1055-8 (1949). Utterback and Bergstrom, U. S. Patent 2,477,019 (July 26, 1949). Vahrman, hl., Nature, 165, 404-5 (1950). Vinogradov, G . V., and Borodulina, L. P., Zhur. Priklad. Khim. ( J . Applied Chem.), 21, 249-50 (1948). Vogt, H., Pharm. Zentralhalle, 87, 38-44 (1948). Vol’kenshtein, F. F., Zhur. Fio. Khirn., 23, 917-30 (1949). Weatherburn, A. S., Rose, G. R. F., and Bayley, C. H., Can. J . Research, 27F, 179-93 (1949).
INDUSTRIAL AND ENGINEERING CHEMISTRY
January 1951
(303)Weir, H. M., U. S. Patent 2,485,249(Oct. 18, 1949). (304) Wendel, K.,Planta, 37, 604-11 (1950). (305) White, L.,and Schneider, C. H., J . Am. Chem. SOC.,71,2945-6 (1949). (306)Wiig, E. O.,and Juhola, A. J., Ibid., 71,561-8 (1949). (307) Wilga, J., Mindler, A. G., and Gilwood, M. E., “Decolorieing Solutions by a Granular Synthetic Resin,” 117th Meeting AM. CHEM.SOC., Houston, Tex., 1950. (308) Williams, T.I., Anal. Chim. Acta, 2,635-48 (1948)(in English). (309) Wolock, I., and Harris, B. L., IND. ENG.C H ~ M42, . , 1347-9 (1950). (310) Wustefeld, H., Arch. Metallcunde, 3, 223-4 (1949).
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(311) Yang, J. T., and Haissinsky, M., Bull. SOC. chim. France, 1949, 540-7. (312) Zafir, M., Folia Pharm. ( T u r k e y ) , 1, No. 3, 29-31 (1949) (in German). (313) Zettlemoyer, A. C., Chand, A., and Gamble, E., J. Am. Chem. Soc., 72, 2752-7 (1950). (314) zettlemoyer, A. c.9Healey, F. H., and Fetsko, J. M., “Adsorption of Gases on Cadmium Oxide,” 117th Meeting Ana. CHEM.SOC., Houston, Tex., 1950. (315)zhdanovg s* Dokl&J Ahad* S*S-S*R*v681 99-102 (1949). RECEIVED November 13, 1950.
CENTRIFUGATION ~ - - _ _ _ _
JAMES 0.MALONEY
UNIVERSITY OF K A N S A S , LAWRENCE, K A N .
A
flow relationships in a basket centrifuge has been presented by Burak and Storrow (17). They pointed out t h e limitations of the equation suggested by Maloney (479, and developed others suitable for experimental verification. I n their experimental study they suspended maize starch particles of about 12 microns in diameter in water and centrifuged them in a perforated basket fitted with a fabric medium. A comparison of data on cakes of various thicknesses showed t h a t the starch was uniformly packed. The rate of passage of water through various thicknesses of previously deposited cake was not proportional to the square of the speed of rotation, as predicted by the theoretical equations. The authors attempted, without success, to correlate the data by putting the deviations into the permeability term. Then they made filtration studies on deposited filter cakes and also on cakes first formed in the centrifuge and then carefully inserted into the filter cell. Their results were somewhat confusing and bear out the results of Wilcox (81),who was forced t o conclude that his filter-cell experiments did not give results comparable with those obtained in a centrifuge. I n such a study, some simplification might have been obtained by the employment of carefully sized and incompressible materials, such as silica. German workers (14) reported descriptions and performance data on several centrifuges that were used for separating gaseous isotopes. Studies were conducted on xenon, krypton, selenium, and uranium isotopes. The rotors were of the tubular variety subdivided into from 1 to 10 chambers. The rotor diameters were as great as 12 cm. and the lengths were as great as 67 cm. Speeds u p to 60,000 revolutions per minute were employed. In the separation of UFc isotopes, the separation factors ranged from 1.01 to 1.06. An extensive study of the variables affecting the clarification of sulfate liquors in a Bird continuous centrifuge has been reported (68). The main value of this investigation to readers outside the paper industry lies in the proof that the performance of this machine is qualitatively predictable from theoretical considerations. Conclusions of general interest include: The percentage of solids in the liquor in the centrifuge increased rapidly above a certain feed rate; a decrease in the operating temperature of the feed liquor from 195’ to 165” F. roughly doubled the percentage of solids in the effluent; a marked increase in the percentage of solids in the effluent occurred if the feed liquor contained more than 10% of solids. Richardson and Lyons (60)have obtained operating information on the dewatering of coal in a Bird continuous unit (Figure 1). Because of the
marked improvement in the material available on centrifugation i s noted. Several investigations obtained sufficient data to permit a comparison of theory-with practice (77, 58). A new textbook (76) on unit operations provides an improved treatrnent,of centrifugation. Continuous centrifuges for handling solids and liquids have been combined with mixers to extract castor oil, linseed oil, and soya oil from the ground seeds continuously (6). The First unclassified information on the separation of uranium isotopes using centrifuges has appeared (74).
D
N
URING the past year several books appeared containing sections on centrifugation. The most voluminous treatment occurs in Perry’s third edition of the “Chemical Engineers’ Handbook” (SO). -Only minor changes have been made in this material since the first edition of 1934. The section might have been improved by providing a bibliography on the subjeot, by including descriptions and performance data on the units for continuously handling slurries, and by bringing the cost information up to date. All of the information necessary is readily available (27, 47-61, 68, 81). The discussion by Brown et al. (16) represents a marked improvement over those in earlier texts. These authors give, for the first time, an illustrated description of modern equipment, a discussion of the theoretical aspects of the subject, a bibliography, and some problems. But this discussion, like those in all the other standard texts, might be improved by the inclusion of illustrative examples and a comparison of calculated results with actual performance data. Such examples and comparisons are furnished in relation to other operations b u t not for centrifugation. Golding (35) has published an adequate treatment of centrifuges for laboratory use. His discussion includes a number of illustrative examples exhibiting the method for calculating; the time required for certain particles to be separated by centrifugal action; the relative centrifugal force in test tube units; and the pressures developed in the centrifuging tubes. The account could serve.as an introduction to the field. Nichols and Bailey ( 6 4 ) have written extensively on the ultracentrifuge as a laboratory device. Review articles on the subject have continued t o appear. They include a description of lubricating oil centrifuges together with operating instructions ( I O ) ; a review of applications of the ultracentrifuge in research and practice (45); and a review (in German) of American centrifugal practice and its developments (63). F U N D A M E N T A L STUDIES
Noteworthy progress is being made in the development of fundamental information in this field. Investigators are beginning t o study the variables affecting the performance of centrifugal machines. One of the few theoretical treatments of the
