November 1948
INDUSTRIAL AND ENGINEERING CHEMISTRY
(5) Grosse, A. V., Morrell, J. C., and Mattox, W. J., Ibid., 32, 530 (1940). (6) Hoop, H.,Smittenberg, J., and Visser, G. H., Cong. m o n d i a l petrole, $me Cong., Paris 1937, Vol. 11,p. 489. (7) Hurd, C. D., and Eilers, L. K., IND. ENG.CHEM.,26,776(1934). (8) Lebedev, S. V., and Kobliansky, G. G.,Ber., 63B,1932 (1930). (9) McMillan, W. A., IND.ENG.CHEM.,ANAL.ED., 9, 511 (1937). (10) Marshall, C. E., and Caldwell, 0. G., J . Phya. Colloid Chem., 51, 311 (1947). (11) iMelpolder,F.W., andBrown, R. A., Anal. C h m . , 20,139 (1948). (12) Moore, V. G., and Shilyaeva, L. V., J . Oen. Chem. (U.S.S.R.), 7 , 1779 (1937). (13) Nasarow, I. N., Ber., 69B,18 (1936). I (14)I b d , 69B,21 (1936). (16) Ramser, J., Atlantic Refining Co., unpublished data. (16) Robertson, A. E., U. S. Patent 2,196,363(April 9,1940).
2099
(17) Roetheli, B.E.,and Conn, M. E., U. S. Patent 2,314,457(Nov. 23, 1943). (18) Thacker, C. M.,Folkins, H. O., and Miller, E. L., IND.ENQ. CHEM.,33,584 (1941). (19) Tropsch, H., and Mattox, W. J., Zbid., 26,1338 (1934). (20) Whitmore, F.C., I b i d . , 26,94 (1934). (21) Whitmore, F. C.,Laughlin, K. C., Matusreski, J. T., and Surmatis, J. O., J. Am. Chem. Soc., 63, 756 (1941). (22) Whitmore, F.C., and Mosher, W. A.,Ibid., 68,281 (1946). (23) Whitmore, F.C..and S t a h l y , E. E., Ibid., 55,4153(1933). (24) Ibid., 67, 2168 (1945). RECEIVED June 4, 1947. Presented before the Division of Petroleum CHEMICAL SOCIETY, AtChemistry a t the 111th Meeting of the AMERICAN lantic City, N. J.
Oil Composition in Alkaline Cleaning SAMUEL SPRING' AND LOUISE F. PEALE Frankford Arsenal, Philadelphia, Pa. Free fatty acid, present normally or as an additive in oil, facilitates the removal of oils from pickled steel surfaces. High free fatty acid content in the neighborhood of 10% reduces the ease of removal of sulfurized fatty or fatty oils from unpickled steel. Addition of oil-soluble sodium sulfonate soaps to mineral oils or lard oil results in improved cleaning, whereas its addition to sulfurized oils usually makes cleaning more difficult. The presence of considerable quantities of free fatty acid or oil-soluble sulfonate soap in oils, where effective in improving cleaning, reduces the differences normally found in cleaning pickled and unpiclrled steel or in the use of various alkaline cleaners. At nearly equivalent viscosities and free fatty acid content, the ease of removal of oils follows the series: mineral oil > sulfurized mineral oil > lard oil > sulfurized lard oil. In industrial processing, the addition of free fatty acid or oil-soluble soap to oils will facilitate cleaning provided these materials do not interfere with the functional application of the oils.
I
T HAS frequently been reported (2, S) that the type of soilin-
volved in a cleaning process determines the ease of its removal to a great extent. This paper presents data on this factor for a variety of oils in industrial use. I n addition, it concerns the process of addition of a component t o an oil before its application for the purpose of facilitating subsequent cleaning. This is in contrast with previous processes in which, prior to alkaline cleaning, parts are immersed in a solution of fatty acid in organic solvent (I) or in a solvent emulsion containing oil-soluble soap (4). This bears some relation t o the work of Speakman (6)who showed that the ease with which an oil can be removed may be modified by dissolving in it a few per cent of a polar substance. EXPERIMENTAL METHOD
The procedure used for evaluating the cleaners was similar to that reported previously (6). I n general, this consists of coating metal panels by immersion in the oil, followed b y drainage under standard conditions, particularly with regard to temperature. The panels are cleaned by a procedure in which time, concentra1 Present address, Whitemarsh Research Laboratories, Pennsylvania Salt Manufacturing Company, Wyndmoor, Pa.
tion, agitation, and temperature are controlled. After a prescribed rinsing operation, the panels are sprayed with water. This results in a uniform water film over the cleaned areas, whereas discrete droplets condense over the areas that have not been cleaned thoroughly. These delineated areas are sketched on graph paper having 100 squares, and the percentage of the panel area that has been cleaned is thus estimated. The cleaning index is the average value obtained for ten observations-that is, both sides of five panels. The reproducibility of the data has been indicated previously (6, 7 ) . I n the experimental work reported here, the tests were run at 60" C. for 5 minutes with agitation at 10 r.p.m. Except where otherwise stated, the cleaner was a solution of 1.5% sodium orthosilicate and 0.15% of an alkyl sulfonate type surface active agent. I n carrying out this investigation, care was taken to consider the factors found to be important in previous work. Thus, data were accumulated for cold-worked, oxide-covered surfaces both before and after pickling. The importance of the viscosity of the oil (Figure 1) required that comparisons be made at equivalent viscosities. I n addition, studies were made with mineral oils of different viscosity. RESULTS
EFFECT OF FREEFATTY ACIDCONTENT.The removal of lard oil from steel surfaces is dependent on the free fatty acid which is normally present in this oil. This i8 shown in Table I. Thus, removal of almost all of the free fatty acid from lard oil b y treatment with aqueous sodium hydroxide, fbllowed by thorough washing and drying, results in a considerable decrease in cleaning value. There is no difference between the effect of the naturally occurring free fatty acids and oleic acid since, after removal of the former, replacement with the latter gives similar cleaning performance. Increase of the free fatty acid content of prime lard oil b y addition of 1%oleic acid improves cleaning to a level of good performance but further increase t o 10% does not result in perfect cleaning. A lower grade of lard oil of normally higher free fatty acid content (4%) also gives this good level of cleaning. In addition to this, the presence of 3 or 4% free fatty acid lessens the difference between the results obtained with unpickled and pickled steel surfaces; this is normally large for lard oil containing 0.1 or 1.8% free fatty acid.
2100
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 40, No. 11
The role of the free fatty acid found normally in sulfurFree Pickled Steel Unpickled Steel ized fatty oil is important as St. Cleaning St. F a t t y licid. Cleaning removal of this free fatty acid Oil % Source of Free F a t t y Acid index, % dev. index, 70 dev. caused a great reduction in Lard, Prime 0.1 Free f a t t y acid removed from lard oil with N a O H 20 5 30 6 Prjme 1.8 As received 44 6 88 5 cleaning value for pickled steel, Prime 1.8 Oleic acid added to lard oil minus free f a t t y acid 47 6 92 6 but had little effect with unPrime 2.8 1% oleic acid added t o prime lard oil 86 3 .. .. No. 2 4. 1 9 s received 81 5 83 6 pickled steel. On the other 10.0 8% oleic acid added t o prime lard oil 92 5 78 5 Prime hand, addition of 10% oleic acid caused no improvement OF ADDITIONOF OLEICh 7 I D TO MINERAL TABLE 11. EFFECT for the pickled condition but a O I L S ON REMOVAL FROX STEEL great decrease in cleaning value for the unpickled condition. This Pickled Steel Unpickled Steel Viscosity, Sec. % Free is in accord with the hypothesis that the free fatty acid makes oil (looo F . / p y - F a t t y Cleaning St. Cleaning St. bolt C.\.) Acid index, yo dev. index, yo dev. removal difficult from cold-worked., unDickled metal surfaces. . 170 0 66 6 94 3 probably because of reaction with the oxide-covered surface to 10 89 6 98 2 170 form a heavy metal soap ( 7 ) . This action of free fatty acid was 86 6 470 0 47 6 470 2 88 2 91 5 observed to a lesser extent (Table I ) for lard oil containing 10% 91 5 470 10 91 5 970 0 19 G 30 5 oleic acid. It is not apparent readily except where the free fatty 31 6 970 2 39 G 56 6 50 6 acid content is rather high and 970 10 it tends to be obscure; with a mineral oil base (Table 11) OB FREEFATTY ACIDCONTENT OF SULFURIZED FATTYOIL ON REMOVAL TARLITJ 111. EFFECT because the aci.ion of free fatty FROM STEEL Free Pickled Steel Unpickled Steel acid caused a yeiieral improveFatty Acid, Cleaning St. ment in the level of cleaning. Type of Oil % Source of Free F a t t y Acid %: $ % index, % dev. One of the characteristics of Sulfurized fatty in mineral 0 . 1 Free f a t t y acid removed with S a O H 0 0 47 5 the addition of free fatty acid 2 . 0 As received 69 G 45 6 12 .O 10% oleic acid added to sulfurized f a t t y oil 72 6 0 0 t o oil to obtain improved cleanSulfurized f a t t y in toluol 0 . 1 Free fatty acid removed wlth Ca(OH)z 9 3 63 6 10.0 As received 52 G 38 3 ing is that it tends t o reduce thc differences that have been found previously for various operating conditions. It has been pointed out that the differences normally found in 60 cleaning pickled and unpickled surfaces are obscured when oleic acid is added to the oil being removed. I n addition, thc diffcr50 ences in cleaning value for alkaline salts used in conjunction with a r" w surface active agent (Table IV) are obscured to a considerable ex5 40 tent by the presence of a high free fatty acid content in the oil. 2 The improvement due to the addition of oleic acid to the oil brings w d 30 the results to a level of fairly good performance for both good and poor cleaners but where the performance is alreadv at a high level, 20 the combination of factors does not operate additively in a way that is discernible by the method used in this investigation. IO L 200 300 400 500 600 700 800 900 1000 EFPECT OF GLYCERIDES AND SULFUR.An adequate comparison among oils to determine the influence of their composition on easr OF FREE FATTY ACID CONTENT IX REXOVAL OF LARDOILFROM STEEL TABLE I. EFFECT '
2.:
TABLEIv. REDUCTION OF DIFFERENCES AMONG ALKALINE CLEANERS DUE TO PRESEKCE OF FREEFATTY ACID IN OILS (Alkaline salts plus 0.15% of an alkyl aryl sulfonate) 1.6% Sodium 1.5% Sodium 1.5% Trisodum Orthosilicate, LIetasilicate, Phosphate, PI1 12.2 P H 134P H 12.5 Free Cleaning Cleaning Cleaning Fatty index, St. index, St. index, St. Oils Acid, 70 % dev. % dev. % dev. Lard, prime 1.8
TABLE \'. EASPI O F RE:aroV.%IJ O F OILSO F 1r.4R10~-SCO\~POSIWONS (Viscosity of oils equivalent) Pickled Steel pree F a t t y Cleaning St. Oil Acid, index, % dev. 5 Lard, prime 0.1 Mineral 0.0 2o 66 6 Sulfurized fatty in mineral 0 . 1 0 0 Sulfurized mineral 0.0 38 6
Unpicklcd Steel Gleaning St. index, % dev. 30 6 94 3 47 5 81 6
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
November 1948
TABLEVI.
EFFECTOF
%
Treatment Lard (prime) As received Free fattv acid removed by sodium hydroxide (aqueous) Free fattv acid removed bv calcium hvdroxide (solid) Free fatty acid removed by sodium hydroxide 1.870 oleic acid Free fatty acid removed b y calcium hydroxide 1.8% oleic.acid Plus 2y0 calcium oleate Free fatty acid removed b y sodium hydroxide 10% oleic acid Free fatty acid removed b y oalcium hydroxide 10% oleic acid Plus 2% calciurn,oleate 8% oleic acid Plus 5% oleic acid
+ + + +
+
28;
TABLE VIII.
Sodium Oleate,
%
0.0 0.2 0.0 0.1 0.0
0.1
Pickled Steel Cleaning index, St. % dev. 5 44 5 31 56 6 6 76 47 6 3 75
S.U.V.)
st.
dev.
1.8
42
6
85
22
6
30
6
0.1
4
3
31
6
1.8
47
6
92
6
1.8 1.8
3 6 6
59 61 83
6
10
6 14 84
10 10 10
41 23 91
6 5 5
75
6 5 5
Unpickled Steel: Cleaning index, St. % dev. 6 54 84 6 2 94 6 88 4 86 3 88
EFFECTON CLEANING OF ADDITION OF SOLUBLE OIL TO OILS Soluble Pickled Steel Oil, Cleaning St. 5% index, % dev.
iCbdee&,:in#
0.1
EFFECT ON CLEANING OF ADDITION OF SODIUM OLEATETO OILS
Viscosity, Sec. (looo F./ Saybolt U.V.) Lard, prime 200 200 Mineral 170 170 470 470
Unpickled Steel
Pickled Steel Cleaning index, % d ::
of removal requires that the free fatty acid content as well as viscosity be similar. Data for lard, mineral, sulfurized fatty oil blend, and sulfurized mineral oil, thus adjusted, are given in Table V. I t appears that the glycerides which constitute the fatty oil act t o increase the difficulty of removal, as lard and sulfurized lard oils are removed with greater difficulty than mineral and sulfurized mineral oils, respectively. I n addition, sulfurization results in increased difficulty of removal as sulfurized lard and mineral oils have lower cleaning values than lard and mineral oil, respectively. EFFECTOF ADDITIONOF SOAPSTO OILS. In performing the experiments on the influence of free fatty acid in lard oil, the fatty acids naturally present were removed by treatment with calcium hydroxide or by aqueous sodium hydroxide. Both treatments resulted in an oil, with 0.1% free fatty acid, which gave low values In the cleaning test. However, addition of oleic acid to the oil treated with sodium hydroxide gave results similar t o those obtained with untreated lard oil of equivalent free fatty acid content, whereas addition of oleic acid to the oil treated with calcium hydroxide gave little improvement. (See Table VI.) These results were explained when it was found that addition of calciuni Boaps to lard oil caused a considerable reduction in cleaning values and, moreover, the presence of 2% calcium oleate prevented the improvement normally obtained on addition of 8y0 oleic acid to lard oil. The low solubility of sodium oleate in oils prohibited investigation of the effect of addition of this material. The presence of
TABLE VII.
0.2y0 neutral sodium oleate (Merck U.S.P.)in lard oil caused a slight reduction (Table VII) in cleaning for pickled steel but had no effect on unpickled steel. However, addition of 0.1 yosodium oleate to mineral oil caused an appreciable improvement in cleaning performance with pickled steel. T o investigate the influence of dissolved soaps, an oilsoluble sulfonate soap (soluble oil) was added t o various oils. The data obtained are pre-
CALCIUM SOAPS IN OILS IN REDUCINQ CLEANINQ Free Fatty Acid
Unpickled Bteel Cleaning St. index, yo dev.
58
78
2101
6
6
5
material used was a commercial sulfonated soluble oil, but the same results have been obtained with Aerosol OT (sodium sulfonate of dioctyl succinic acid) dissolved in the oils. Addition of 1% of this soluble oil to lard oil caused a substantial improvement in the cleaning of pickled steel but had no effecton unpickled steel. However, under more severe conditions where a lower concentration of cleaner was used, the,values for unpickled steel were 33y0 for lard oil and 83% for lard oil containing l’j&soluble ail. Thus, some effects are obscured a t a high level of cleaning but manifest themselves as conditions become more severe. Addition of 1% of soluble oil to mineral oil of light and medium viscosity gave a similar result to that obtained with lard oil. Moreover, addition of this soluble oil to a heavy mineral oil caused a considerable improvement in cleaning pickled steel while addition of 3y0of soluble oil to heavy mineral oil gave a greater improvement in removal from unpickled steel.
TABLE IX. Type of 0 1 1 Sulfurized fatty in mineral Sulfurized mineral
EFFECT ON CLEANING OF ADDITIONOF SOLUBLE OIL TO OILS
Viscosity, set. Soluble (loooF./ Oil,
9.U.V.) 170 170 170 170 170 170
% 0 1 3
0 1 3
Pickled Steel Cleaning St. index, % dev. 6 70 6 26 42 6 6 45 38 6 25 6
Unpiokled Steel Cleaning St. index, % dev 45 6
..
51 95
16
6 6 3
91
5
There appears to be some adverse action between the sulfonate and sulfurized oils. Frequently, there is a considerable reduction in cleaning performance in removal of the latter from pickled steel on addition of 1 or 3% of soluble oil, as shown in Table I X . Just as in the case of the addition of free fatty acid to oils, the presence of soluble oil has the effect of reducing the cleaning differences normally obtained for pickled and unpickled surfaces and various alkaline cleaners. DISCUSSION
A knowledge of the effect of composition factors on cleaning
should materially assist in setting up cleaning rocedures because , and data on viscosity, as well as free fatty acid, s u k ~ r glyceride, soap content can be obtained readily. The process of addition of free fatty acid or an oil-soluble sodium sulfonate to certain oils, before functional application, in order to facilitate subsequent removal may offer considerable advantage in industrial cleaning; particularly for high viscosity oils that are difficult t o remove. ID many instances these additions will not interfere with the performance of the oils. Moreover, the observation that these additions result in reduction of the differences normally found among alkaline cleaners widens the scope of industrial application of this process. For example, it may permit removal of oils from surfaces that are sensitive to strong alkali by the use of weakly alkaline cleaners. I n a previous paper (8)the process of oil removal was described as consisting of shrinkage of the oil film, formation of
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
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)
before t h e ~to c, c. F ~ ~E. R. Rechel, ~ RECEIVED ~ ~~ and ~ ~ ~M ia y 13,~1947. ~Presented , Engineering Chemistry at t h e 11th Meeting of J. IT’. LIitchell of Frankford Arsenal Ordnance Laboratory for SOCIETY, Atlantic City, s.J,
~
~is
Division of Industrial and i ~ the AYBRICANCHEMICAL
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 effluentmaterial 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
%~~~~~ to afford cn-
fzaci“’o;f irhT A r
A&!!?
f:iyn; @ in. in.
d~z
bora to ~
Ti”,”$; ~
of brass 0.39-
tubing, B , 17
&k*
Of
,:I,
tubing; (4) support packing.for
~
~
e
Figure 2. Siphon Receiver (1) Vent; (2) oblique surface to ensure liquid running down walls) (3) constriction to in-
crease
sensitivity point.
of
siphon
