SOME STUDIES OF SOAP SOLUTIONS.
I1
BY VICTOR LENHER AND GEORGE M. BISHOP
'
It has been shown1 that the same amount of soap will not necessarily be sufficient to emulsify the same quantity of different kinds of oils. I n the previous experiments, where quantitative emulsifications were made, the temperature was The results herewith controlled for the most part to 25'. reported have been obtained by studying the emulsifying action of soap solutions on certain of the more common oils and water at 100'. Conditions of Experivnen's.-The total volume of mixture was always IOO cc, the difference between the amount of oil and soap solution added being made up with distilled water, The emulsions were stirred five minutes, and if at the end of another five minutes neither constituent had separated, the emulsion was considered satisfactory. At first sight, these conditions may seem rather arbitrary, but actually they are fairly standard. Practically all laundry washing is done in boiling water, and the suds or emulsions when once formed are usually washed away within five minutes, thus obviating the necessity for an emulsion remaining permanent for a longer time. Furthermore, most of the emulsions break within the first two or three minutes, or else they remain permanent for hours. The same type of stirring apparatus was used in these experiments as we have heretofore2 used. Materials Used.-The sodium oleate used was prepared from very pure sodium hydroxide and very pure oleic acid. The oils used were high grade commercial oils. Procedure.-Ten cc of the oil were measured into the glass jar. All measurements of oils were made with pipettes. Three cc of N/IOsodium oleate solution and 87 cc of water were added to the oil. The total volume of oil, soap and water was IOO cc in all cases. The water bath around the jar was brought Lenher and Buell: Jour. Ind. Eng. Chem., 8, 701 (1916). Ibid., 8, 701 (1916).
Some Studies of Soap Solutions. 11
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' 0.25
0.50
0.75
1.00
I
I
Fig. I I
I
I
Fig.
2
Fig. 3
1
Victor Lenher and George M . Bishop
70
to boiling and the contents of the jar were allowed to come to the temperature of the bath. The motor was then started and continued at high speed for exactly five minutes. The bath was removed, the jar was removed and allowed to stand for five minutes. If oil separated, an insufficient amount of emulsifying agent was present. The operation was then repeated with more sodium oleate and less water. Ten cc of the oil were again measured out, 3.5 cc of N / I O sodium oleate and 86.5 cc of water were added. The temperature was again raised to 100’and the mixture stirred five minutes. If there still appeared unemulsified oil at the end of five minutes, the operation was repeated with the addition of 4 cc of N/IO sodium oleate. If this amount of sodium oleate produced an emulsion it was apparent that at least enough had been added, but i t may have been more than was necessary to accomplish emulsification. Therefore the experiment was repeated with 3.8 cc, etc., until the minimum amount of soap necessary to produce emulsification was ascertained. The data are shown graphically in Figs. 1-3. TABLE I Emulsification of Cottonseed Oil with Sodium Oleate cc Oil
I
cc Oleate Sol’n
30 40
4.0 5.2 6.8 7.5
50 60
40.0
IO 20
cc
oil
IO 20
30 40
50
60
1
cc Oleate
12.3
86.0 74.8 63.2 52.5 37.7
cc Oleate Sol’n
cc water
6.0 6.0 6.0
84.0 74.0 64.0 48 .o 25 .o
I2
.o
25.0 40.0
1
0.I22
0.158 0.207 0.228 0.374 I .216 (No emul.)
-
-
gm Na Oleate
1
gm Na Oleate
0.182 0.182 0.182 0 * 365 0.760 I . 216 (No emul.)
Some Studies o j Soap Solutions.
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cc oil
cc Oleate Sol’n
cc Water
IO 20
30 40 50 60
4.5 4.8 5.3 8.0 9.6 40.0
85.5 75.2 64.7 52 .o 40.4 -
0.146 0.161 0.243 0.292 I . 2 16 (No emul.)
cc Oil
cc Oleate Sol’n
cc Water
gm Na Oleate
IO
30 40 50 60
5 .o 7.5 9.2 13 .o 19.0 40.0
85.0 72.5 60.8 47 .o 30.7
0.152 0.228 0.280 0.395 0.587 I . 216 ( N o emul.)
cc Oil
cc Oleate Sol’n
cc Water
20
-
5.2 7.8 10.3 14.0
IO 20
30 40 50 60
84.8 72.2
59.7 46.0 29.8 5.2
20.2
34.8
gm Na Oleate 0 . I37
.
gm Na Oleate
0.158 0.237 0.313 0.426 0.614 I .058
,
Emulsification of Rape Seed Oil with Sodium Oleate cc Oil IO 20
30 40
50 60
cc Oleate Sol’n
3.0 5.3 7.5 9.0
I 1 .o
40.0
I
cc Water
87.0 74.7 62.5 51 .o
39.0
-
gm Na Oleate
0.091 0.161
0.228 0.274 0.334 I . 216
(No emul.)
Victor Lenher avld George M . Bishop
72
TABLEVI1 :or Oil with E bdium Oleate cc oil
cc Oleate Sol’n
cc Water
gm Na Oleate
IO 20
5.3 9.8 12.5
84.7
0.161 0.298 0.380 0.365 0 * 374 I . 2 16 (No emul.)
30 40 50 60
12.0
12.3 40.0
70.2
57.5 48 .o 37.7
-
TABLEVI11 Emulsification of Sesame Oil with Sodium Oleate cc oil
cc Oleate Sol’n
cc Water
gm Na Oleate
IO 20
4.8 4.8 6.8 7.8 8.3 40.0
85.2 75.2 63.2 52.2 41.7
0.146 0.146 0.207 0.237 0.252 I .216 (No emul.)
30 40
50 60
-
8
E1 ulsification of Spl m Oil with Sodium Oleate cc Oil
cc Oleate Sol’n
cc Water
IO 20
15 .o 18.0
75.0 62 .o
30 40 50 60
20.0 2 2 .o 22 .o
38.0 28.0
40.0
50.0
-
I
’
gm Na Oleate
0.456 0.547 0.608 0.669 0.669 I ,216 (No emul.)
The results obtained with the various oils are in general the same for each oil. With small amounts of oil, each I O cc increase in the oil requires but slight increase in the amount of soap required for emulsification, but above 40 cc the amount of soap required for emulsification increases rapidly. The ‘fdirt” that the laundryman has to deal with is in large part oils from one source or another. The present data seem to be added information that emulsification is at least one of the most important factors in the detergent action of soap.
