Alkyl Aryl ulfonateJ
e
d
ixtures DETERGENT PROPERTIES REYNOLD C. MERRILL AND RAYMOND GETTY Philadelphia Quartz Company, Philadelphia, Pa. Measurements of the ability of alkaline builders to prevent the deposition of iron oxide, ilmenite black, and raw umber on cotton cloth show that sodium silicates and phosphates are more effective than sodium carbonate or hydroxide for this purpose. Dodecyl benzene sodium sulfonate suspended more iron oxide than the builders, less ilmenite than the silicates or phosphates but usually more than sodium carbonate o r hydroxide, and less raw umber than almost any builder. Some silicate-phosphate mixtures appeared to show synergism in preventing deposition. The amount of soil removed by synthetic detergentalkaline builder mixtures and their relative efficiency varied considerably for three types of “standard” soiled cloth. For a variety of soils, synthetic detergent-alkaline builder mixtures give as good or better detergency than synthetic detergents alonc and a t lower cost. Synthetic detergent, tetrasodium pyrophosphate, or sodium metaor sesquisilicate mixtures showed large synergistic effects for one kind of soil.
after washing in a mixture of 40% dodecyl benzene sodium sulfonate, 20% sodium sulfate, and 40% sodium metasilicate as after rashing in the usual commercial detergent containing 40% dodecyl benzene sodium sulfonate and 60% sodium sulfate Under the same conditions mixtures with trisodium phosphate and tetrasodium pyrophosphate removed more soil than the commercial detergent, whereas mixtures with sodium carbonate removed less. In fact, more soil TWS removed at detergent concentrations of 0.1 % or less by these alkaline builders alone than was removed by the 40% dodecyl benzene sodium sulfonate-60% sodium sulfate mixture. Siinilirily, the phosphates and metasilicate were more efficient in suspending burned umber than was the commercial dodecyl benzene sodium sulfonate-sodium sulfatr inixtuie or sodium carbonate Vaughn and Smith report ( I O ) that substantial qumtities of a commercial detergent containing 40% sodium alkyl aryl sultonate--60% inorganic salts can be replaced by sodium carbonate. metasilicate, a carbonate-bicarbonate mixture, or a sodium 5111-
T
HE manufactui e of synthetic detergents has now attained the status of a major chemical industry. During 1948, around 268 million pounds of 1 0 0 ~active o organic detergent were produced and the amount is still increasing rapidly. The synthetic detergents nox heing produced in largest amounts are the alkyl aryl sulfonates. Practically all commercial products of this type contain sodium sulfate formed by neutralization of the excess sulfuric acid used for sulfonation. For practical application3 most of them are used with an inorganic builder to give improved detergency at lower cost. The purpose of this paper is to report experimental data on the detergent properties of two typical alkyl aryl sulfonate detergents with the widely used inorganic builders, sodium carbonate, trisodium phosphate, tetrasodium pyrophosphate, and sodium silicates with silica to alkali (NalO) ratios by weight of 0.98 (metasilicate), 2.0, 2.8, and 3.2. Data on the effect of builders on alkyl aryl sulfonate deteigents were reviewed by Harris in 1946 (4). The addition of moderate amounts of sodium sulfate and magnesium chlor.ide to low concentrations of dodecyl benzene sodium sulfonate somewhat increased the amount of a carbon black, mineral and vegetable oil soil removed in washing tests. The addition of trisodium phosphate, tetrasodium pyrophosphate, and sodium carbonate produced larger increases in the amount of soil removed and apparently more of the phosphates than of chloride or sulfate could be added before the soil removal mas decreased (4,5 ) . A later paper by Harlis and Brown (6) showed that replacement of one fourth to one third of the commercial detergent containing 40% dodecyl benzene sodium sulfonate with sodium carbonate, metasilicate, trisodium phosphate, and tetrasodium pyrophosphate greatly increased the aniount of soil removed by 0.075 and 0.1% detergent solutions in a synthetic hard water containing 300 parts per million (p.p.m.) calcium and magnesium hardness. For example, the reflectance of soiled cloth was about twice as great
7ot
I
I
0 IO
I
I
I
0 20 0 30 0 40 % ANHYDSOUS ELECTROLYTE
I
0 50
Figure 1. Prevertion of Deposition of Iron Oxide by Detergent Solutions (above) and Alkaline Electrolyte Solutions (below) a t 60” 6. Naz0.2.98102; A’, NazO. Above. 0 ,KazSiOs; 0 , Sa20.2.1SiOz; 0, 3.3Si02;
Below.
A,dodeoyl benrone sodium sulfonate
0 , NaaPzOi; 0 , N a s P 0 1 ; A , NanCOs; A, NaOH
INDUSTRIAL AND ENGINEERING CHEMISTRY
May 1950
5d 90
857
--I
I
I P
. /O
! ? O'
r
-
-
-
""
70r ' I I
50
I
0 10 X
I
I
020 030 040 A M Y D R O U S ELECTROLYTE
I
050
Figure 2. Prevention of Deposition of Raw Umber by Detergent Solutions (above, below) and Alkaline Electrolyte Solutions (middle)a t 60" C . Above. 0, NaaSiOa; 0 , Naz0.2.1SiOz; A, dodeoyl benzene sodium sulfonate
0,NarPzOr; 0 ,NaaPOA, A, NazCOa; A,NaOH Below. 0, 60% dodeoyl benzene sodium sulfonate-40% NaaSOa,
# 30#
0.10
0.20
0.N
0.40
0.50
Mrddle.
0 60% dodeoyl benzene sodium sulfonate-40% NarSiOs;
dodecyl benzene sodium siilfonate-40% Na0.2.1SiOz
SILICATES TABLE I. ANALYSESOF SODIUM
(C)
N a
b
% NazOO
% SiOaa
29.2 14.6 13.8 9.02
28.2 29.7 31.7 29 2
Remaining component is HzO. NazSiOs, 5Hz0. Not a commercial product. No trade name.
W t Ratio Si0z:Nazd 0.97 2.03 2.81 3.20
ELECTROLYTE
A , 60%
cate-carbonate mixture without decreasing the ability of 0.25% solutions to remove a carbon black soil from cotton cloth. Morrisroe and Newhall (7) found that replacing as much as three fourths of a commercial 40% sodium alkyl aryl suIfonate-60% sodium sulfate with trisodium phosphate or tetrasodium pyrophosphate increased the removal of a carbon black by 0.2% solutions in 300 p.p.m. hard water. Mixtures containing equal weights of pyrophosphate and alkyl aryl sulfonate removed considerably more soil than the same amount of either constituent alone. About 40% of the commercial organic detergent-sodium sulfate mixture could be replaced with sodium carbonate, bicarbonate, or metasilicate before detergent effectiveness was decreased. Substituting borax for any part of the synthetic detergent reduced detergency. The addition of relatively small amounts of inorganic salts such as sodium, magnesium or aluminum chloride to long chain alkyl sulfate detergents also somewhat increased their ability t o clean soiled cloth or remove oil, although the addition of still larger
Trade Name Metso Granular5 D
% ANHYDROUS
Mole Ratio, Si0a:NazO 1.00 2.09 2.91 3.30
Figure 3. Prevention of Deposition of Ilmenite by Detergent Solutions (above, below) a n d Alkaline Electrolyte Solutions (middle)at 60" C. .4boue. 0 NazSiOa. 0 Naz0.2.1SiOz. 0 Naz0.2.9SiOz. Solutions of Naz0.3.bSiO~ga;e
reiults similar t o 'thos'e obtained with Naz0.2.9Si02 solutions Middle. 0, NarPzOi; 0 , NaaPO4; A * NazCOa; A, NaOH Below. A dodeoyl benzene sodium sulfonate. A 6 0 7 dodeovl beneene sodiuh sulfonate-40% Naz0.2.1SiO~; 0: 60% dtdecyl bknzene sodium eulfonate-40% NazSiOa. 0 60% dodeoyl benzene sodium sulfonate;40% NarSO4
amounts decreased it (3, 8). However, i t appears that the increases in detergency are considerably greater with builders such as the phosphates and silicates, and much larger amounts can be added before a reduction in efficiency occurs. MATERIALS
Analyses of the Philadelphia Quartz Company's silicates used for all the work reported in this paper are summarized in Table I. The sodium phosphates, carbonate, and hydroxide were Baker's analyzed reagent grade chemicals. Although the inorganic builders contained water, all results are calculated on an anhydrous basis. The Monsanto Chemical Company's Santomerse No. 3 which is 99+% dodecyl benzene sodium sulfonate ( 4 ) was used for the work on prevention of deposition. Nacconol HG made by the National Aniline Division of the Allied Chemical & Dye Corporation was used in the soil removal teats. It contains 60% alkyl aryl sulfonate and 40% sodium sulfate. The ilmenite was air-floated ilmenite black produced by British Titan Products Company, Billingham, Stockton on Tees, England. A crocus martis obtained from the Charles A. Wagner Company was used as the iron oxide pigment. The raw umber was obtained from the E. E. Nice Company and was the identical sample used by Carter and Stericker in their work on the prevention of deposition in soap-silicate solutions ( 2 ) .
INDUSTRIAL AND E N G I N E E R I N G CHEMISTRY
858
w
"I
I
401
0
I
I
I
25
50
75
9,
COMPONENT
and 3.2 ratio silicates are not shown in Figure 2, above, since they were similar to those obtained with the 2.0 ratio silicate. Sodium carbonate was the next most effective, whereas sodium hydroxide and dodecyl benzene sodium sulfonate were least effective. Figure 2, below, shows that mixtures containing 60% dodecyl benzene sodium sulfonate with 4001, metasilicate or 2.0 ratio silicate (anhydrous basis) prevent the deposition of raw umber more than does the usual commerciai mixture containing 40% sodium sulfate. The order of decreasing effectiveness for preventing the deposition of ilmenite black was: tetrasodium pyrophosphate; 2.0, 2.8, and 3.2 ratio sodium silicates; sodium metasilicate; anti trisodium phosphate (Figure 3, above and middle). Sodium carbonate had little effect. The deposition of ilmenite on the fabric in sodium hydroxide scilutjicinsw a s greater than that in dist,illed water.
J
DO
A
Figure 4. Prevention of Deposition of Iron Oxide (above)and Raw Umber (below) by 0.1% Solutions of Alkaline Electrolyte Mixtures at 60" C. Above
Below
Component A NarPz07 NaaSiOa NarPaOi NazSiOa
Vol. 42, No. 5
Component B Naa0.3.3SiOz NazCOs NazSiO: NazCOa
50
0
40
0
8 30
PREVENTION OF DEPOSITION 50 2,
soil from depositing or redepositing on the fabric. This property is referred to as "prevention of deposition or redeposition," or "whiteness retention.'' Therefore, the ability of the alkaline builders and dodecyl benzene sodium sulfonate to prevent the d e position of three types of soil, iron oxide, raw umber, and ilrnrnite black, on a cotton fabric was measured. One gram of either of these pigments was uniformly suqwnded in 100 ml. of a solution of the detergent in distilled water in a pint jar. A 3-inch square of desized Indianhead cloth and ten 0.25inch steel balls were then added. The jars mere sealed, placed in a Launder-0-Meter ( I ) , and rotated a t 48 revolutions per minute (r,p.m.) for 30 minutes at 60" C. The soil suspension was then removed and replaced by 200 ml of distilled water brioye rotating for 10 minutes at 60" C. in the Launder-0-Meter This rinsing with distilled water was repeated and the cloth allowed to air dry. The reflectance of the cloth after ironing was compard in at least 3 different places with that of the original unsoiled cloth with a Lumetron hotoelectric colorimeter equipped with a device for measuring relectances (Figures 1 to 3, inclusive). The reflectance data on prevention of deposition by mixtures of alkaline electrolytes, summarized in Figures 4 and 5, were obtained using the Hunter Multipurpose reflectometer; therefore, thev are not directly comparable to Figures 1 to 3, inclusive. Replicate tests agreed within 5%.
25
0
An important factor in detergent action is the ablllty to keep
COMPONENT
75
100
A
Figure 5. Prevention of Deposition of Ilmenite b y 0.1% Solutions of Alkaline Electrolyte Mixtures a t 60° c. Component B
Component A
The ability of dodecgi benzene sodium sulfonate to prevent the deposition if ilmenite io maximum a t a concentration of 0.05% (Figure 3, below). A mixture of 60% dodecyl benzene sodium sulfonate40% sodium sulfate reaches about the same maximum a t a total detergent concent,ration of approximately 0.1yo but is less effective a t most ot>herconcent.rationsstudied. Similar mis-
12 I/
Under the experimental conditions, the deposition of the iron oxide on cotton cloth was prevented most efficiently by dodec1.1 benzene sodium sulfonate, tetrasodium pyrophosphate, and sodium silicates with silica to alkali ("azo) ratios of 2.0, 2.8, and 3 2 (Figure 1). Trisodium phosphate and sodium metasilicate ~ r r e less effective in these tests. Tests on the deposition of the iron oxide on the cloth from distilled water were, as was expected, much more difficult to reproduce but gave cloths with reflectances in A range around 65%. It appears then, that the sodium hydroxide and probably to a much lesser extent the sodium carbonate actually increased the deposition of iron oxide. Khen raw umber was used as the pigment, the tetrasodium pyrophosphate was most efficient in preventing deposition (Figure 2, above and middle). The trisodium phosphate and sodium silicates were about equally efficient. Data on the 2.8
10
P" 9
8
7 6
8 10
50
25
9e
75
90
WILDER
Figure 6 . pH a t 23" C,. of 0.2% Synthetic DetergentBuilder Mixtures in 50 P.P.M. Hard Water 0, Naz0.3.3Si02; 0 , Naz0.2 PSI@$ 0 , NazSiOa; 0 , SarPx07; A nNaOH
May 1950
INDUSTRIAL AND ENGINEERING CHEMISTRY
859
crease resulted (Figure 5). Some of the data siiggested B synergistic effect of silicate-phosphate mixtures. pH OF SOLUTIONS
The pH of detergent solutions is of considerable interest, particularly for use in contact with human skin. Accordingly, the pH’s of 0.2y0 solutions of mixtures of Nacconol HG with sodium hydroxide, carbonate, pyrophosphate, metasilicate, and 2.0 and 3.3 ratio silicates in a hard water containing 50 p.p.m. calcium carbonate hardness were measured with a Beckman Model G pH meter a t 25” C. The results (Figure 6) show the expected increase in pH in the order pyrophosphate, 3.3 and 2.0 ratio dicates, carbonate, metasilicate, and hydroxide. Mixtures of the detergent with sodium carbonate had pH’s about the same as those of the 2.0 ratio silicate so the values were omitted from Figure 6. SOIL REMOVAL
The ability of 0.2% solutions of mixtures of Nac’conol HG and the builders to remove soil from three commercially available “standard” soiled cotton fabrics was studied using a Launder-0Meter.
I
I
25
50 4. BUILDER
I
I
75
90
I
Figure 7. Soil Removal with 0.2% Synthetic DetergentBuilder Mixtures in 50 P.P.M. Hard Water Above. A, NazCOa; A, Pr’aOH, a. NaaPzOi Below.
0,Naz0.3 3SiOr
0 . Nn20.2 OSiOz, 0 NaaBO,
tures containing metasilicate and 2.0 ratio silicate in place of the sodium sulfate are equally effective below 0.1% detergent and more effective above this concentration. Except for the behavior of dodecyl benzene sodium sulfate mixtures with ilmenite, the ability of the detergents studied to prevent the deposition of iron oxide, raw umber, or ilmenite does not vary greatly over the range of concentrations from 0.05 to 0.50%. With the three soils the effectiveness decreased in the order: pyrophosphate, sodium silicates, trisodium phosphate, carbonate, and hydroxide. The latter alkali, and to a lesser extent sodium carbonate, increased the deposition of iron oxide and ilmenite over that obtained in distilled water. Powney and Noad (9) also found that sodium carbonate and hydroxide increase deposition of ilmenite under somewhat different experimental conditions. It is interesting that the 2.0 ratio sodium silicate prevented the deposition of all three pigments to a greater extent than did the 2.8 and 3.2 ratio silicates or the metasilicate. Dodecyl benzene sodium sulfonate was about the best suspending agent for the iron oxide, intermediate for ilmenite, and almost the poorest for raw umber. Probably the comparative effectiveness of inorganic alkaline and organic detergents varies with the type of soil. MIXTURES, The ability of mixtures containing varying proportions of alkaline detergents to prevent deposition was studied under the same conditions at a total detergent concentration of 0.1%. Mixtures containing about 25% pyrophosphate and 75% metasilicate or 3.3 ratio silicate were as good or better than the same weight of pyrophosphate alone in preventing the deposition of the three soils on cotton cloth (Figures 4 and 5). Mixtures of sodium carbonate and silicates had to contain about 40% silicate before becoming as effective as the silicate alone. Replacement of more than about 30% of pyrophosphate with sodium carbonate decreased the ability of the mixture to prevent deposition of ilmenite; 75 to 85% could be replaced with silicates before a de-
A 4.25 X 5 inch piece of the standard soiled cloth was placed in a pint jar with 200 ml. of a 0.2% solution of the detergent in water of 50 p.p.m. hardness (calcium carbonate equivalent) and twenty 0.25-inch steel balls were added. The water was prepared by adding sufficient calcium chloride and magnesium sulfate to distilled water to give a stock solution containing the desired hardness, two thirds of which was due to calcium ions. The pint jars were rotated at about 48 r.p.m. at 60” C. in the Launder-0-Meter for 20 minutes. The solution was then drained off and replaced with 200 ml. of fresh detergent for another 20-minute wash under the same conditions. This procedure was repeated twice again to give a total of four 20-minute washes, each with 200 ml. of fresh detergent solution. The cloth was then rinsed in two successive 300-ml. portions of the 50 p.p.m. water by rotating a t 60’ C. with the steel balls for 10 minutes. After the second rinse, the cloth was allowed to dry in air and then ironed. The total increase in per cent reflectance was determined by measuring, with a Hunter Multipurpose reflectometer using the green filter, the reflectance of each piece before and after washing. All tests were made in duplicate or triplicate. Most Launder-0-Meter loads of 20 jars contained a test jar of 0.2% Nacconol HG to test reproducibility of the technique and to guard against possible changes in the soiled cloth. The standard soiled cotton cloth obtained from the U. S. Testing Company, Inc., was made by impregnating permanent finish Indianhead cloth with graphite in a heavy mineral oil (Oildag) and a refined cottonseed (Wesson) oil. The soiled cloth had a reflectance of 27% with a maximum deviation from the
\
15 I
I
I
I
I
10
25
60
75
90
%
BUILDER
Figure 8. Soil Removal with 0.2% Synthetic DetergentBuilder Mixtures in 50 P.P.M. Hard Water
0,Nez0.3.3SiO1; 0 , Naz0.2.0SiOe: n, NazSiOa
INDUSTRIAL AND ENGINEERING CHEMISTRY
860
IO
25
75
50
90
% BUILDER
Figure 9. Soil Removal with 0.2970 Synthetic DetergentBuilder Mixtures in 50 P.P.M. Hard Water B,KaaPzOi, A, SazC08. A ,3NazO.ZSiOz
average of less than *1% as measured by a Hunter Multipurposc reflectometer using the green filter. Its oil content was about 1 gram per square yard and consisted of about 0.66 mineral oil and 0.33 cottonseed oil. Results with this cloth are shown in Figure 7. Only:-the mixture of 10% 3.3 ratio silicate with the synthet,ic detergent showed improved soil removal as compared with the synthetic detergent alone. Equal parts of the 3.3 ratio silicate and the synthetic detergent removed as much soil as the same total weight of detergent alone. Mixtures containing 10 to 50% builder showed decreased soil removal in the order 3.3 ratio silicate, 2.0 ratio silicate, sodium hydroxide, sodium metasilicate, tetrasodium pyrophosphate. Results with the metasilicate and hydroxide were so nearly the same that no real choice in relative position could be made. Sodium carbonate mixtures removed about as much soil as the 2.0 ratio silicate mixtures at 10% builder but much less than any of the silicat'es a t 50%. Within this range 3.3 ratio silicate mixtures caused about txice as much increase in reflectance of this particular soiled cloth as tetrasodium pyrophosphate. hrlixt'ures containing less than 50% synthetic detergent showed smaller differences among the builders. Results obtained by the same technique using a soiled cotton test cloth obtained from Testfabrics Inc. are summarized in Figures 8 and 9. This soiled cloth is printed on a cotton sheeting
W
e 9
2 c z6 ln W
9 0
!23
1 0
25
50
75
90
% BUILDER
Figure 10. Prevention of Redeposition during Washing by Synthetic Detergent-Builder Mixtures in 50 P.P.M. Hard Water
0,Naz0.3.3SiOa;
0 , NazSiOa;
,.
Na4PgOi; A , NagCOa
Vol. 42, No. 5
in accordance with Specification 318-47 (International) of ttic: U. S.Bureau of Ships. The soil is a paste of 1.0 part ethylcellulose, 14.0 parts naphtha, 0..5 part butyl alcohol, 2.0 parts lampblack, 2.5 parts hydrogenated vegetable oil, 20.0 parts mineral oil, 0.8 part sodium alginate, 57.1 part>scold water, 1.3 parts corn starch, 0.5 part oleic acid, and 0.3 part morpholine. Mixtures of the synthet'ic detergent, with all builders removed more soil than the synthetic detergent aloiic, in contrast to the results with the U.S.Testing Company's soiled clot'li. The order of effectiveness of the silicates in mixtures containing 10 to 59% builder w a ~the opposite of thpir order n.ith Ihe ot,her soiled cloth. iLIixtures con-. t,aining tetrasodium pyrophosphatc, and sodium sesqui- and metasilicate removed more soil than those with the 2.0 or 3.3 ratio sodium silicates or sodium carbonatc. The free fat,ty acid in the: soil is not necessarily responsible for better soil removal by tho meta- and sesquisilicate a,s compared with the more siliceous products. Tetrasodium pyrophosphate mixtures, which are less alkaline than any of the silicates, :ilso remove more soil from this soiled cloth than do mixtures with t h e siliceous silicates, whereas they too removed less soil than 2.0 or 3.3 ratio silicate mixtures from the U. S.Testing Company's soiled cloth.
1
I
10
I
25
I
50
I
75
I
90
I
% BUILDER
Figure 11. Soil Removal by 0.29% Synthetic DetergentBuilder Mixtures in 50 P.P.M. Hard Water
The ability of the various d.eteryent-builder mixtures to prcvent the redeposition of soil from the Testfabrics Inc. soiled cloth was determined by measuring tho reflectance of the unsoiled pertion of the cloth before and after washing. The results, most of which are shoxn in Figure 10, demonstrated that mixtures of the synthetic detergent with various silicates and tetrasodium pyrophosphate were more efficient than the same weight of either constituent alone in preventing redeposition of this soil. Substituting sodium carbonate for synthetic detergent resulted in incrcttsed redeposition. The third type of soiled cotton cloth used was developed at t,hc Pennsylvania State College by Pauline B. Nack and associates, and obtained from F. D. Snell, Inc. It is made by soiling a yard of Indianhead muslin with 1 gallon of Stoddard solvent, 40 grams of hydrogenated cottonseed oil, 20 ml. of heavy lubricating oil, arid 12 grams of Norit C carbon black. The increases in reflectance of this cloth after washing in 0.2%solutions of Nacconol HG-sodium metasilicate mixtures are shown in Figure 11. Mixtures of Kacconol HG and metasilicate containing up to about 75% metasilicate remove about as much of this particular type of soil as the synthetic detergent alone. Soil removal by mixtures of metasilicate with Nacconol HG to which sufficient sodium sulfate had been added to reduce the alkyl aryl sulfonate content from 60% to 40% is also illustrated in Figure 11. Replacement of synthetic detergent with sodium sulfate lowered soil removal considerably.
May 1950
INDUSTRIAL AND ENGINEERING CHEMISTRY DISCUSSION
The foregoing data show that as good or better detergent action may be obtained in many cases for a variety of soils by replacing pmt of the relatively expensive synthetic detergent by an inexpensive alkaline builder. Silicates and tetrasodium pyrophosphate are preferred to sodium carbonate, largely because of their ability to prevent the deposition or redeposition of soils on cloth. Most economical results can probably be obtained with mixtures of synthetic detergent, pyrophosphate, a sodium silicate, and some sodium carbonate. Such a mixture should contain the most efficient detergent for any one of the wide variety of soils found in practical applications. The effectiveness of such mixtures is frequently greater than expected on the basis of the efficiency of each constituent taken separately. In the present work this synergistic effect is most clearly demonstrated in the much greater increase in reflectance of the Testfabric's soiled cloth and lower decrease in brightness of the unsoiled portion after washing in mixtures of synthetic detergent with pyrophosphate or metaor sesquisilicate than after washing in either alone. Perhaps part of the synergism is due to one or more of the soil constituents being preferably removed by one component of the mixture. Such an explanation is in agreement with the greater complexity of the soiling mixture showing the largest synergistic effects but probably does not explain all cases of synergism in detergent studies. An important result of this work is the demonstration that the relative effectiveness of the synthetic detergent and builders varies with the type of soil. Thus, the dodecyl benzene sodium sulfonate was the best suspending agent for iron oxide, poorer than the pyrophosphate or silicates but better than sodium carboriate or hydroxide a t most concentrations for ilmenite, and al-
861
most the poorest for raw umber. The relative order of efficiency of soil removal by mixtures containing up to 50% of 3 silicates and pyrophosphate for the U. 8. Testing Company's soiled fabric was almost the inverse of that obtained with the Testfabrics Inc. cloth. A mixture of equal weights of synthetic detergent and sodium metasilicate removed definitely less soil from the cloth obtained from the U. S. Testing Company than did the detergent alone. The same mixture removed about the same amount of soil from the cloth soiled with the Pennsylvania State College mixture as did the detergent by itself, but removed considerably more soil from the soiled cloth obtained from Testfabrics Inc. The best detergent for a particular application varies with the type of soil. Results based on only one type of soil can be misleading. For practical studies the soil and testing technique used for evaluating detergent mixtures should closely approximate the conditions under which the product is to be used. LITERATURE CITED
(1) Carter, J. D.,IND. ENG.CHEM.,23, 1389 (1931). (2) Carter, J. D., and Stericker, W., Zba'd., 26, 277 (1934). (3) Dreger, E. E., Keim, G. I., Miles, G. D., Shedlovsky, Leo, arid Ross, John, Ibid., 36,610 (1944). (4) Harris, J. C.,OiE & Soup, 23, 101 (1946). (5) Harris, J. C.,Soap Sanit. Chemicals, 19, 21 (1943); A.S.T.M. Bull. 125, 27 (1943). (6) Harris, J. C., and Brown, E. L., Oil & Soap, 22,1 (1945). (7) Morrisroe, J. J., and Newhall, R. G., IND.ENG.CHEM.,41,423 (1949). ( 8 ) Palmer, R. C., J. SOC.Chem. I n d . , 60,56 (1941). (9) Powney, J., and Noad, R. W., J . Textile Inst., 30, TI57 (1939). (10)Vaughn, T.H., and Smith, C. E., J. Am. Oil Chemists Soc., 25, 44 (1948). RECEIVED September 29, 1949.
Hydrogenation of Coal in a
Fluidized Bed E. L. CLARK, M. G. PELIPETZ, H. €1. STORCH, SOL WELLER, AND STANLEY SCHREIBER Central Experiment Station, U.S. Bureau of Mines, Pittsburgh, Pa. Undesirable features of the Bergius-I.G. process, which include difficult handling of a residue-oil slurry, reaction space used for recycle oil, and deleterious effect of recycle oil on hydrogenation of coal, suggest the desirability of developing a dry-coal hydrogenation process. Bench-scale hydrogenation tests of a Wyoming bituminous coal in an agitated or fluidized bed produce oil yields of 20 to 27Yo and hydrocarbon gas yields of 20 to 279$ of moisture- and ash-free coal a t hydrogen pressures of 1000 pounds per square inch and less. Hydrogenation of coal using a fluidized coal bed thus offers a possible means of dry coal processing a t pressures well below those used in European plants. Products of the fluidized bed hydrogenation are oil, hydrocarbon gases, and a char residue suitable for use as fuel or feed for gas production.
G
ERMAN practices in the high-pressure hydrogenation of coal by the Bergius-I.G. process have been disclosed by many published accounts. These German hydrogenation plants, produced the bulk of the aviation fuel and part of the motor gasoline, Diesel fuel, fuel oil, paraffin wax, and lubricating oil
required by the German war machine (6). Many features of this Bergius-I.G. process indicate potential advantages in effecting,a reaction between dry coal and hydrogen: The equipment required to condition heavy oil-let-down for use as a pasting or injection oil with coal feed could be eliminated. Reaction space used by the oil portion of the coal-oil feed mixture could be used for the reaction of additional coal. The removal of unreacted coal as a dry material instead of a mixture with oil would materially decrease the capital and maintenance cost of the hydrogenation plant. I n addition, work in batch autoclaves where coal was hydrogenated in both the presence and absence of a heavy oil vehicle indicated that the heavy oil exercises a deleterious effect on the reaction ( 7 ) . Unpublished data obtained in batch autoclaves by Donath indicated the possibility of obtaining good liquid yields a t moderate pressures with dry coal ( I ) . The experimental work presented herein represents a possible means of carrying out the hydrogenation of dry coal. Additional experimentation is in progress, and the data presented here are being expanded to cover additional coals and to investigate other problems leading to the development of a usable dry-coal hydrogenation process.
