2102
INDUSTRIAL AND ENGINEERING CHEMISTRY
flattened globules, and reduction of the base attachment of the globules until the oil is released as such. It has been observed that the stages in this process are identical for oils with or without free fatty acid, as well as those containing sulfonates, except that the process occurs more rapidly with those oils containing free fatty acid or sulfonate. Another observation that is pertinent was made in dropspreading experiments. A drop of mineral oil cont,aining 10% oleic acid was placed next to a drop of alkaline silicate solution plus surface active agent. When the drops met there was a reaction of almost explosive violence in which the oil was displaced from the metal surface. This did not occur TTith mineral oil without free fatty acid, I n each of these experiments soap formation, as evidenced by formation of turbidity, occurred as a secondary action but was apparently not a major factor in the improved cleaning. ACKNOWLEDGMENT
~ c, c. F ~ ~E. R. Rechel, to ~~ and ~ J. IT’. LIitchell of Frankford Arsenal Ordnance Laboratory for ~
~is
Vol. 40, No. 11
their encouragement; to the Ordnance Department for permission to publish this paper; and to Adele Goldstein for performing a considerable part of the experimental work. LITERziTURE CITED
Bennett (Hsde) Ltd., Brit. Patent 516,218 (Dec. 28, 1939). ( 2 ) Harris, J. C., Am. SOC.Testing Materials Bull. 136 (Oct. 31, 1945). (3) Lyons, E. H., Trans. Electrochem. Soc., 80, 367 (1941). (4) Mitchell, R. W., Proc. Am. Electrochem. Soc., 1938,p. 238 (5) Robinson, Conmar, “Mechanism of Detergent Action,” p. 148, New York, N. Y . ,Chemical Pub. Co., 1939. (6) Spring, S., Forman, H. I., and Peale, L. F., IND.EXG.CHEM., ANAL.ED., 18, 201 (1946). (7) Spring, S., and Peale, L. F., IXD.ENG.CHEM.,38, 1063 (1946). (8) Spring, S., and Peale, L. F., MetaE PTogrcss, 51, 102 (1947).
(1)
y 13, 1947. Presented before t h e ~ RECEIVED ~ ~ ~M aiChemistry ~ at ~ Engineering t h,e 11th Meeting of
Division of Industrial and i ~ the AYBRICANCHEMICAL
Atlantic City, s.J,
SOCIETY,
CA GEL PERCOLATI Application to Synthol
BUELL O’CONSOR Stanolind Oil and Gus Compuny, Tulsa, Okla.
Silica gel percolation may be used as a laboratory tool in the study of synthol-like materials. First, i t offers a quick means of determining the classes of compounds contained in synthol to an accuracy of *2Yce Secondly, i t offers a convenient, ready method for the separation of small batches of material for further study, and thirdly, when supplemented by the use of an azo dye, i t offers a method of determining hydrocarbons and oxygenated materials to an accuracy of *lyo. This greater accuracy results not only from having a more sensitive break point, but also from making summation volume readings only.
obtained from the IIavison Chemical Corporation. The columns were packed with the aid of a tamping rod and fresh gel was used each time. With this column nitrogen pressure of 35 pounds per square inch gage was used to increase the rate through the column. n-Heptane was employed as the diluent and methanol as the eluant. The effluent material passed int,o siphon receiver, Figure 2, which drained int.0 a refractometer every time it filled. A plot was then made of refractive index against sample number (Figures 3 t o
T
HIS work on silica gel percolation was undertaken originally to develop a method for the rapid quantitative determination of compound types found in synthol, a product of a modified Fisher-Tropsch synthesis. A discussion of Twsett’s original work in chromatographic analysis plus later developments which relate to the work to be described, may be found in the literature (1-6).
3
APPLICATION TO SYNTHOL
It was believed that silica gel technique could be applied succedsfully to a more complex mixture, namely synthol. This belief was based on the hypothesis that adsorption affinities differ more as to classes of compounds than as to molecular size. If this hypothesis was correct, then two applications were immediately evident, first, a ready analytical tool and secondly, a separation method for types of compounds. As a n analytical tool, besides the obvious advantage of speed. the one-step process eliminated an accumulation of errors resulting from multihandling of the same solution. Further, with regard to olefins, existing methods of unsaturation determination were unsatisfactory in the case of synthol where olefins exist in such a conglomeration. The importance of the second function lies largely as an adjunct to purification by distillation since distillation of the original sohtion affords poor resolution due to azeotropes caused by eoexisting classes of compounds. Figure 1 shows the type of percolation colunin used in the analysis. I n all cases the silica gel employed had a particle size of 75% held by 325 mesh and 25% through 325 mesh; i t was
4
Figure 1. Percolation Column
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November 1948 n
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INDUSTRIAL AND ENGINEERING CHEMISTRY
rial into smaller size volumes were made to permit the isolation of the transitional fluid. The main limitation of the procedure so far described is the complete elution of the alcohols. Were the alcohols properly eluted the chief source of error would be limited t o variations in the volume (dispensed by the siphon receiver) which varies somewhat with the changes in viscosity. It is apparent that the accuracy of analysis would be improved if it were possible to measure summation volumes only, t h s t is, to take volume readings a t the break points only. A
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