818
INDCSTRIAL A N D ENGINEERING C H E M I S T R Y
Vol. 17, No. 8
A Test for Relative Decolorizing Efficiencies of Clays' By J. B. Hill, L. W. Nichols, a n d H. C. Cowles, Jr. THEATLANTIC REPININGCo., PHILADELPHIA, PA.
I
N T H E revivification by burning of spent fuller's earth or clay, resulting from the filtration of heavy petroleum oils, proper control of the clay kilns has been difficult because no easy means of comparing the relative activities of the burned clays has been at hand. The activity of the clay is commonly tested by percolating through a sample of it an oil similar to that which it is desired to clay-treat in plant practice, and obtaining a rough idea of the yield of proper color oil. The tediousness and inaccuracy of this method, coupled with the fact that the variation of the oil used for this test makes it only very roughly reproducible, has led to a search for a quick and reasonably accurate test on burned clays which could be applied as a check on the clay kilns. Preliminary Experiments
Several methods were given preliminary trials, among them, the decolorizing effect of the clay on a standard solution of a pure dye in a highly purified and definite oil of about the kerosene range, and decolorizing action of the clay on a vegetable oil, such as soy bean oil, which could be obtained as a fairly standard article. An aqueous solution of methylene blue has been used with some success to test clays in the ceramic industry. This solution when applied to the present problem showed such promise and seemed so simple that it was finally adopted and the method described developed on the basis of it. The general method was to shake a definite weight of the clay with a definite volume of a standard solution of the dye under certain standard conditions, and to compare the resultant partially decolorized solution with standards made up from the original methylene blue solution by dilution with water in various proportions and numbered according to the percentage of the original solution in the dilution. A reported number, therefore, represents the percentage of dye in the original solution not adsorbed by the clay. A concentration of about 0.25 gram dye per liter was found convenient for the original solution. A considerable number of variables enter into the method and these were separately investigated and standardized. VARIATION IN SAMPLES-The variations between lots of methylene blue from different sources and the reproducibility of the standard solution were naturally of prime importance. Samples of methylene blue were obtained from two reliable distributors and compared. One product was apparently about 15 per cent stronger than the other-i. e., 15 per cent more of one dye was necessary to give a solution of the same color intensity than of the other. In order to avoid this difficulty, a solution of a n inorganic salt was made up .as a standard, and the dye solution was made up roughly by weight and adjusted to match this standard. Solutions of these two blues gave identical results on the clay test. SOLUTION ACID-It developed very early in the course of the work that i t would not be possible to use a neutral solution of the methylene blue on account of an apparent alkalinity of the clay. I n order t o make sure that the solution remained acid, the origiNI sulfuric acid. nal methylene blue solutions were made up in & I n acid much more dilute than this, especially with fresh clays, low readings are obtained. REMOVAL OF SUSPENDED CLAY-It was also necessary, before reading, t o remove the suspended clay from the solution by centrifuging rather than by filtration, on account .6f adsorption of the color by the filtering medium. 1 Presented before the Division of Petroleum Chemistry at the 69th Meeting of the American Chemical Society, Baltimore, Md , April 6 to 10, 1925.
WEIGHTOF CLAY-The weight of the clay to be used with 100 cc. of the standard solutions was investigated with the idea of setting one weight which would give readable results for clays over the entire range from a light-burned, unused clay to a clay used and burned so often that it is ready for the dump. Table I shows the differences obtained by using various weights of the clays. Inasmuch as comparisons with the standards are most easily made within the range of Numbers 1 to 30, the 4-gram sample was considered the most satisfactory and adopted as standard.
-
Table I-Effect
of Various Weights of Clay on the Methylene Blue Number
----METHYLENE BLUENTJMBER5 grams 3.5 grams 4 grams Claya 2 grams .A 9 0.9 0.5 1.3 B 24 8.0 4.5 2.0 C 9.0 6.0 3.0 28 D 30 10.0 6.5 3.0 7.5 4.0 34 12.0 E 7.0 F 44 20.0 11.0 11.0 22.0 15.0 G 50 16.0 N 52 26.0 22.0 a Sample A is a burned, unused clay. Samples B to H have been used and reburned one or more times.
TIMEOF SHAKING-The effect of normal variations in the shaking of the clay with the solution was found to be unimportant. The time of shaking is, however, a serious factor and must be kept constant. Table I1 shows the results obtained on two different samples of clay, shaking for various lengths of time. Althoug the 10-minute shaking does not by any means produce the ma imum adsorption of dye, a longer time was considered cumbersome, and since the results a t 10 minutes could be duplicated this time was adopted.
s
Table 11-Effect of Time of Shaking on the Methylene Blue Number Time of shaking METHYLENE BLUENUMBER Minutes 5 10 20
Clay C 22
9
3.2
Clay H 40 26 12
TEMPERATURE-The temperature a t which the test is carried out is also shown to be important, as indicated in Table 111. A temperature of 32.2' C. (90" F.) was set in order to approximate maximum normal laboratory temperature. Judging from the rate of change of the result with temperature, this should be held to 90' * 3' F. Table 111-Effect
of Temperature on the Methylene Blue Number Temperpre Methylene O C. F. blue number C 15.6 60 15 32.2 90 9
Clay
57.2
135
4
Final Method
A solution of a reagent grade of methylene blue is made up in a strength of approximately 0.25 gram per liter in approximately 0.1 N sulfuric acid. The solution is adjusted so that a dilution with nine parts of water compared in a 113cc. (4-OZ.) oil sample bottle matches a standard cobalt solution in a similar container in intensity of color. The standard cobalt solution is a solution of cobaltous chloride in 95 per cent alcohol containing 2.5 volume per cent of 32 per cent hydrochloric acid and 0.4700 gram cobalt per 100 cc. a t 15.6' C. (60" F.). Several standards are h a d e up in 4-ounce (113-cc.) oil sample bottles from the standard methylene blue solutions by dilution with various proportions of water and marked with a number corresponding to the per cent of the original solutions in the diluted standard. A convenient set of standards is 1, 2, 3, 5, 7, lo, 13, 16, 19, 22, 25, and 30. Standards below 1, of course, can also be prepared. These standards,
ilugust, 1925
INDUSTRIAL AND ENGINEERING CHEMISTRY
819
Effect of Moisture
Experience on this method of testing clays indicates that it is limited to burned clays. Clays revivified by other mean? do not line up a t all with the percolation data. The effect of water in the clay on the test is also interesting. Although it is general experience that the presence of moisture in clay very materially lowers its decolorizing activity on percolation a t temperatures below the boiling point of water, the methylene blue test is not affected. This is, of course, as would be expected, but the results-as exemplified in the data in Table Ti-are rather striking. Apparently, the methylene blue test indicates the value which the clay would have if it were dry. Inasmuch as samples of clay are much more likely to have an opportunity to absorb moisture than the large bulk of clay from the kilns, this point offers a decided advantage for the methylene blue test, hilice precautions to insure the avoidance of moisture absorption are eliminated. Table V-Effect
of Moisture on M e t h y l e n e B l u e N u m b e r a n d Filter Yield
Clay A
B 1 He#rylubOilfi t e r r a fo'6'iJACoiot
2
--..
800
\
.
io r ; L r i O i i Frltcred to
'2
VPlF
Co1 0 1
1
I
Per cent moisture 0.0 0.18 0.90 3.70
Methylene blue number 0:i 0.8 0.9
0.0 0.12 0.35 7.40
7.0 8.0 8.0 9.0
Filter yields, grams per 600 grams light !ubricating oil filtered to 1 N. P. A. 2 N. P. A. 1130 200 880 160 850 180 475 50 820 100 720 I J 0 510 0 310
Destruction of Muscle Shoals Ammonium Nitrate b y Fire and Explosion' By C.
E. Munroe
SATIOSAL RESEARCH COUNCIL, WASHINGTON. D. C.
R O carloads of ammonium nitrate from Muscle Shoals
IC
Y
5
IO
I
/S
I ZO
J
/ycthyJPne B h c Numbers Variatlon i n Filter Y i e l d s w i t h M e t h y l e n e B l u e Color
the points lie along the same genera1 direction, although they do not conform to any expected form of curve. The curves have been drawn as straight lines only as an approximation to the recorded data. The points on the unused clay are somewhat out of line and if these are taken out amuch smoother curve is possible. T a b l e IV-Comparison
Clay
Methylene blue number
A
0.8
C
E F G I
6.0 7.5 11 15 22
'/2
of Filter Yields w i t h M e t h y l e n e B l u e N u m b e r -FILTER YIELDS(GRAMSPER 600 GRAMS)? Heavy lubricating Light lubricating oil filtered to oil filtered to N. P. A. 1 N. P. A. 2 N. P. A. 6 N. P. A. 1350 2100 75 225 1380 25 112 800 1000 0 69 660 480 620 0 69 435 0 0 365 280 0 0 230
were destroyed by fire while in transportation. One of these fires occurred on Bpril 4 and the other on Mag 3, 1925. Each car contained 220 barrels of the material, it having been packed in new flour barrels lined with manila paper some six years previously. As these barrels, with their contents, had been standing in the warehouses for some six years, and therefore exposed to varying changes in humidity, the barrel staves had become well impregnated with ammonium nitrate, and it is thought that the fires may hal-e been caused by the friction of these niter-impregnated staves upon one another. Other shipments came through successfully, among them two carloads made up elsewhere in the train drawing the car which was destroyed on May 3. On hlay 7 an explosion occurred in the nitrate of ammonia emporating pan of the Hercules Powder Plant, a t Emporium, Pa., whereby one man was killed, another one slightly iiijured, and the shed in which the operation was being conducted demolished. The explosion occurred during the reprocessing of Muscle Shoals ammonium nitrate, while the solution was being evaporated in an open cast-iron pan, fitted with steam coils. Some of the nitrate that was being reworked had been coated and it was thought that sufficient organic matter had accumulated from this source to form a. mixture, which was explosive a t the crystallizing temperature, 276" to 278" F., then being used. It is estimated that from 400 to 500 Bounds of nitrate were involved in the explosion, and that the explosion originated in the "heel" left in the pan. 1
Recei\ ed June 19, 1928.
