Dec., 1919
T H E JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
one expeller will handle 400 tons. Therefore, six expellers are necessary. A charge of $9 per ton of raw material is allowed for drying and handling from cars t o storage bins preliminary t o expelling, while $ 1 5 per ton of dry seed is allowed for expelling t h e oil and handling from t h e seed storage t o t h e oil in tanks. These include all overhead a n d management charges, except rent of property or interest on real estate investment. The oils made by t h e above methods have been refined and deodorized and fabricated into edible products with splendid results. Experiments on animals have demonstrated the feeding value of t h e residues. The Cobwell system of grease recovery from garbage was also investigated from this standpoint. Since it involves only one handling and yields the finished fertilizer and crude oil a t once, i t has the advantage of leaving t h e plant unencumbered for operating on other products during t h e remainder of t h e year. Based on large-scale operation of existing plants, a charge of $4.75 per ton of raw material is allowed. No work t o make oil in large enough amounts t o study industrially has been done by this method.
1-
The return from fabricated tomato cyclone waste is $116,000while the cost is $118,000, which renders utilization of t h e whole waste impracticable. I n t h e case of t h e Cobwell system, t h e loss is even greater. However, if t h e seed alone are shipped in, there is B profit in drying and expelling of about $54,000, while in the Cobwell system i t is about $60,000. I have figured expeller oil at $0.14 per lb., solvent oil at $0.13, press cake at $40 per ton and dry skins a t $ I O per ton. With grapes, there is only $5,000 profit using t h e entire pomace, while in the Cobwell system there is a profit of $26,000. With seed alone, b y drying and pressing one clears $15,000, while in extracting by t h e Cobwell system there is a profit of $33,000. I allowed $0.14 for expeller oil, $0.13 per lb. for extracted oil, $ 1 2 per ton for seed cake and $17 per ton for dried skins. Thus using the drying and pressing method on t h e waste of tomatoes and grapes there is a profit of $69,000, while by using t h e Cobwell system of extraction i t is $93,000. BUREAU OF U.
s.
P L A N T INDUSTRY
DEPARTMENT OF AGRICULTURE WASHINGTON, D. C.
LABORATORY AND PLANT
THE APPLICATION OF ROTATING REDUCTORS IN THE DETERMINATION OF IRON B y WALTERSCOTT Received May 23, 1919 INTRODUCTION
I n a former article' t h e efficiency a n d rapidity of rotating metallic cylinders in t h e reduction of vanadic acid have been described. It is t h e purpose of this paper t o give an account of t h e results obtained in applying a similar method of reduction in t h e case of ferric sulfate. R E D U C T I O N O F F E R R I C S U L F A T E B Y T H E R O T A T I N G ZINC CYLINDER
I n t h e first series of experiments, t h e results of which are shown in Table I, A and B, t h e reduction was brought about by a small hollow zinc cylinder into which was fitted a rubber stopper holding an iron spindle, this being attached t o t h e shaft of a small motor which was run by t h e ordinary city current. The motor was fixed t o a wooden stand in such a way t h a t i t could be raised and lowered, thus partly immersing t h e zinc cylinder in the solution t o be reduced which was contained in a tall narrow beaker. A split glass cover, in which a hole had been made slightly larger t h a n t h e iron spindle, was placed over the top of t h e beaker. The conditions of action were as follows: Total volume of solution reduced, 8 ; cc.; concentrated sulfuric acid, 5 cc.; surface of zinc in contact with solution, 2 5 sq. cm.; source of iron, ferrous ammonium sulfate, t h e iron content of which had been determined by titration with permanganate, standardized against sodium oxalate; t h e iron solution containing sulfuric 1
113 5
Gooch and Scott, A m . Jour. S C L ,46 (1918), 427.
acid was oxidized previously t o reduction b y chlorine gas, t h e chlorine boiled off, and t h e iron solution reduced while hot. A correction factor of 0.08 cc. of permanganate was obtained under t h e same conditions as in t h e experiment, and applied. Dilution was made with boiled water. TABLEI A-PRELIMIN ARY
Iron
Taken Gram 0,0713 0,0713 0,0712 0,0713 0,0712 0.0713 0.0712 0,0713 0.0712
-APPCOX.Time Temp. Temp. Vol. No. of End of at at of Iron Reduc- Reduc- T!tra- Titra- Rev. Found Error tion tion tion tion per Gram Gram Min. Deg. C. Deg. C. Cc. Min. 1 83 35 300 1000 0.0364 -0,0349 2 83 35 300 1000 0.0581 -0.0132 37 300 1000 -0,0063 3 82 0,0649 1000 4 77 36 300 0,0701 -0.0012 5 76 35 300 1000 0.0710 -0.0002 B-QUANTITATIVE DETERMINATIONS 35 300 1000 0.0712 -0.0001 6 72 37 300 1000 +O,OOOl 6 75 0.0713 34 300 1000 6 75 0,0715 +0.0002 37 300 1000 +O.OOOl 6 75 0,0713
These results indicate t h a t the reduction of the small amounts of iron taken is completed regularly under t h e given conditions within a period of 6 min.
. INCREASE
I N REDUCING SURFACE
For t h e experiments in Table 11, A, B, and C, a larger cylinder was made and the iron spindle fixed directly in t h e zinc. This same type of zinc cylinder has been used in all t h e experiments which follow. The conditions under which t h e results in Table I1 were obtained were the following: Total volume of solution reduced, 60 cc.; concentrated sulfuric acid, 5 cc.; surface of zinc in contact with solution, about 45 sq. cm.; source of iron, its content, reduction, and oxidation the same as in Table I. A correction factor of 0.10 cc. of permanganate was obtained
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
1136
and applied. Dilution was made with ordinary distilled water in A, a n d with boiled distilled water in B and C. The iron content was only approximate in t h e preliminary experiments of Table 11, A and B, and all others which follow.
Iron Taken Gram
TABLEI1 A-PRELIMINARYDETERMINATIONS (Dilution made with distilled water) Approx Temp. at Temp. Vol. Approx. Time at at of No. of End of Reduc- Reduc- Tjtra- Titra- Rev. Iron tion tion tion tion Error Found pe.r M1n. Gram Min. Deg. C. Deg.C. Cc. Gram
0.0713 0.0713 0.0713 0.0713 0.0713
0.0595 0.0700 0.0675 0.0705 0.0704
0.0713 0.0713 0,0713 0.0713
010716 0,0710 0,0708 0,0710
0.0705 0.0706 0.0705 0,0705 0.0706 0.0706 0,0706
0,0707 0,0704 0,0701 0,0702 0.0704 0,0706 0.0704
-0.0118 -0.0013 -0.0038 -0,0008 -0.0009
L
2.5 2.5
67 78 73 76 72
32 33 31 30 32
300 300 300 300 300
800 800 800 800 800
€3-PRELIMINARYDETERMINATIONS (Dilution made with boiled distilled water) +0.0003 -0.0003 -0.0005 -0.0003
2.5 2.5 2.5 2.5
71 75 74 73
31 33 28 31
300 300 300 300
800 800 800 800
C-QUANTITATIVEDJ~TERMINATIONS (Dilution made with boiled distilled water) 4-0.0002 -0.0002 -0.0004 -0.0003 -0.0002 0.0000 -0.0002
2.5 2.5 2.5 2.5 2.5 2.5 2.5
.. . ..
.. ,. ,
.
..
31 30 30 32 32 30 28
300 300 300 300 300 300 300
800 800 800 800 800 800 800
The results of Table I1 indicate plainly t h e increased rapidity of the reduction when t h e surface of t h e reducing cylinder of zinc is increased. REDUCTION B Y ROTATING ZINC ANODE
I n t h e experiments of Table I11 t h e reductions were made b y using t h e zinc as t h e rotating anode and a piece of sheet platinum as t h e stationary cathode. The time of reduction for these small amounts of iron was practically t h e same as when no electrolytic current was used. The electrolytic current in these experiments, as well as in all others which follow, was furnished b y eight storage cells, so arranged t h a t t h e current was controlled by a rheostat. T h e conditions were as follows: Zinc in contact with solution, 45 sq. cm.; platinum cathode, 5 cm. X I O cm.; number of amperes used, 6; all other conditions-source and amount of iron; content, oxidation, reduction, volume, and temperature a t beginning of reduction; amount of concentrated sulfuric acid used; dilution and volume titrated--were exactly the same as in Table 11, B or C.
Iron Taken Gram
TABLEI11 A-PRELIMINARYDETERMINATIONS (Reductiou at room temperature) Approx. Approx. Temp. Time Temp. No. Vol. at of at of at End of Iron Reduc- Titra- Rev. Titra- ReducFound Error tion tion per tion tion Gram Gram Min. Deg. C . Min. Cc. Deg. C.
0.0707 0.0707 0.0707
0.0425 0.0677 0.0708
-0.0282 -0.0030
1 3
0.0707 0.0707 0.0707
0.0579 0,0701 0.0714
-0.0128 -0.0006 +0.0007
2 3
20.5 19.5
800 800
300 300
28 30
800 800 800
300 300 300
4-0.0001 5 20.0 800 300 B-PRELIMINARYDETERMINATIONS (Reduction started at boilinn. temperature) . 1
29
C-QUANTITATIVEDETERMINATIONS (Reduction started at boiling temperature) 0.0705 0.0706 0.0705 0.0706 0.0705
0.0707 0.0705 0.0701 0,0705 0.0701
+0.0002 -0.0001 -0.0004 -0.0001 -0.0004
2.5 2.5 2.5 2.5 2.5
25 32 31 31 33
800 800 800 800 800
300 300 300 300 300
21.2 24.0 26.0
.. .. ..
.. ..
Vol.
11,
No.
12
The results of these experiments show t h a t there is no advantage in t h e use of t h e rotating anode as compared with t h a t of the unelectrified zinc cylinder for small amounts of iron. REDUCTION O F LARGE AMOUNTS O F IRON BY ROTATING ZINC CYLINDER
I n t h e experiments of Tables I V and V, iron corresponding t o I g. of ore (containing 7 0 per cent iron) has been determined quantitatively. I n order t o obviate a correction factor and t h e use of boiled water, t h e value of I cc. of a solution of potassium permanganate (approximately N/IOX 1.4)in terms of iron was determined. I n making this standardization about 5 g. (weighed t o t h e fourth decimal place) of ferrous ammonium sulfate (the iron content of which had been previously determined) was dissolved in ordinary distilled water in a 1500-cc. evaporating dish. Then 7.5 cc. of concentrated sulfuric acid, and also t h e same amount of concentrated hydrochloric acid as would be introduced by t h e oxidation of iron with chlorine, were added. T o t h e solution thus obtained was added a solution made b y rotating t h e zinc cylinder for t h e same length of time in a boiling solution of water of t h e same volume and sulfuric acid content as was used in t h e reduction of iron. This mixture was diluted in t h e evaporating dish t o I liter with ordinary distilled water and titrated with t h e permanganate t o color This method of determining t h e iron equivalent of I cc. of t h e permanganate assumes t h a t no ferric iron is present, and such was found t o be true.
Iron Taken Gram 0.7065 0.7065 0.7065 0.7065 0,7065 0.7065
0.7065 0.7065 0.7065 0.7065
TABLEI V A-PRELIMINARYDETERMINATIONS (Reduction started a t room temperature) Approx. Approx. Temperature Time Temp. No. Vol. Deg. C. of at of at RrIron Reduc- T%a- Rev. Titia- fore After Found Error tion tion per tion Reduc- ReducGram Gram Min. D e s . C . Min. Cc. tion tion 0.3385 0.5494 0.6069 0.6456 0.6978 0.7072
-0.3380 -0.1571 -0.0996 -0,0609 -0.0087 +0.0007
1 2 3 4 6 8
19.5 19.5 19.0 20.5 23.0 25.0
700 700 700 700 700 700
1000
1000
1000 1000 1000 1000
B-PRELIMINARYDETERMINATIONS (Reduction started at boiling temperature) 0.5511 -0.1554 1 23 700 1000 0.6689 0.7009 0.7107
-0.0376 -0.0056 +0.0042
2 3 4
21 23 24
700 700 700
1000
1000
1000
19 20 20 20 20 20
22 24.5 27 29.8 33 36
..
.. .. ..
.. .. ..
..
.. ..
..
C-QUANTITATIVEDETERMINATIONS (Reduction started at boiling temperature) 0.7065 0.7065 0.7065 0,7065 0.7066 0.7066
0.7058 0.7060 0.7056 0.7057 0.7062 0.7060
-0.0007 -0.0005 -0.0009 -0.0008 -0.0004 -0.0006
4
4 4 4 4 4
24 24 24 28 28 25
700 700 700 700 700 700
1000 1000 1000 1000 I000 1000
I
.
T o determine whether hydrochloric acid at the. concentration and temperature of this experiment would vitiate t h e results (without using a manganous salt), experiments with and without t h e hydrochloric acid were carried out and no change could be detected. Since t h e procedure of t h e preceding reductions was somewhat modified in obtaining t h e results o f Table IV, t h e conditions are given as follows: An exact weight of ferrous ammonium sulfate was dissolved in 45 cc. of water, and 4 cc. of concentrated sulfuric acid added; this solution was heated t o boiling and chlorine gas passed through it while still hot;.
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
Dec., 1919
after oxidation t h e excess of chlorine was boiled off. While t h e solution was still a t t h e boiling temperature the zinc cylinder was lowered into it and rotated for the periods indicated. The reduced solution was poured into a 1500-cc. evaporating dish, 7 . 5 cc. concentrated sulfuric acid added, the volume made up t o a liter with ordinary distilled water, and titrated. The permanganate was made of such strength as t o obtain complete oxidation with less t h a n IOO cc. t o avoid refilling t h e burette. The zinc cylinder was of such dimensions as t o get a contact surface of about 7 5 sq. cm. REDUCTION
OF
LARGE
AMOUNTS
OF
IRON
USING
RO-
TATIXG ZINC ANODE
The equivalent value of
I
cc. of permanganate
(N/Iox 1.4 approximately) in terms of iron was determined in a similar way t o t h a t used in Table IV. The zinc was made t h e rotating anode a n d a piece of platinum foil, j cm. X I O cm., was t h e stationary cathode. The current used measured 6 amperes. Other conditions were t h e same as in the experiments of Table IV.
Iron Taken Gram 0.7065 0.7065 0,7065
0.7065 0,7065
n 7066
0,7066 0.7065 0.7066
TABLEV A-PRELIXINARY DETERMINATIONS (Reduction started a t boiling temperature) Time of Approx. Iron Reduc- Temp. a t No. of Found Error tion Titration Rev. Gram Gram Min. Deg. C. per Min. 1 26 0.6452 -0,0613 700 -0.0019 2 26 700 0.7046 3 26 0.7055 -0.0010 700 B-QUANTITATIVE DETERMINATIONS (Reduction started a t boiling temperature) 24 -0.0005 3 700 0.7060 22 +O.OOOl 3 700 0.7066 22 700 3 0.7060 -0.0006 21 3 -0.0008 700 0.7058 21 -0,0004 700 3 0.7061 22 3 700 +O,OOOl 0.7067
R E D U C T I O N O F SMALL AND LARGE AMOUNTS O F F E R R I C BY
ROTATING
ALUMINUM
The conditions of the experiments in B and C were t h e same as in t h e experiments in Table 111, excepting t h a t t h e amount of concentrated sulfuric acid was 4 cc., t h e total volume reduced j 2 cc., and t h e surface of contact with the aluminum 7 0 sq. cm. The conditions of t h e experiments in D were exactly t h e same as in A except t h a t large amounts of ferric sulfate were used. TABLEV I A-PRELIXINARY (Reduction started a t boiling temperature without the electrolytic current) Time Temp. No. Vol. of at of at Iron Iron Reduc- Titra- Rev, Titra- AmTaken Found Error tion tion per tion peres Gram Gram Gram Min. Deg. C. Mip. Cc. Used -0.0301 1 29 700 300 0 0,0716 0.0145 -0,0059 3 29 0,0716 0,0657 700 300 0 4 30 0.0706 -0.0010 700 300 0 0,0716 5 26 0.0716 0.0000 0.0716 700 3,OO 0 B-PRELIMINARY (Reduction started a t boiling temperature with the electrolytic current) 0.0716 0,0559 -0.0157 1 31 700 300 6 0.0716 0,0715 -0.0001 2 28 700 300 6 C-QUANTITATIVE (Reduction started a t boiling temperature with the electrolytic current) 2.5 30 800 300 6 0.0716 0.0000 0.0716 2.5 28 800 300 6 0.0716 0.0000 0.0716 2.5 30 800 0.0716 0.0000 300 6 0.0716 2.5 27 800 300 6 0,0716 +O.OOOl 0,0715 2.5 32 800 300 6 0,0715 -0.0001 0.0716 D-PRELIMINARY FOR LARGEAMOUNTS (Reduction started a t boiling temperature without the electrolytic current) -0.0580 1 24 800 1000 0 0,6570 0.7150 -0.0155 2 23 800 1000 0 0.6995 0.7150 -0.0069 3 26 800 1000 0 0.7091 0.7150 ~~
Approx. Vol. a t Titration Cc. 1000 1000 1000
The results of Tables I V and V show t h a t large amounts of iron as ferric sulfate in dilute sulfuric acid solution, and also containing small amounts of hydrochloric acid, are rapidly reduced both with and withoul t h e electrolytic current, the time of reduction being slightly less when t h e electrolytic current is used. The correction factor and t h e use of boiled water were eliminated in this set of experiments b y t h e method described above for t h e standardization of permanganate. SULFATE
1137
T U B E AND
BY
R O T A T I S G A L U I l I N U M ANODE
I n the experiments of Table VI a good grade of aluminum pipe was substituted for the zinc cylinder. The hollow tube of aluminum was attached t o t h e shaft of t h e motor b y an iron spindle which was inserted into a rubber cork, and the cork into the tube. When t h e electrolytic current was used, connection between t h e spindle and tube was made by means of a small piece of sheet platinum. A correction factor of 0 . 2 0 cc. of permanganate was obtained and was used in t h e quantitative determinations. The conditions of t h e experiments in A were t h e same a:; in t h e experiments of Table 11, except t h a t the amount of concentrated sulfuric acid added was 4 cc., the total volume reduced was 5 2 cc., and t h e surface of contact with the aluminum was 7 0 sq. cm.
The experiments made with aluminum seemed t o indicate t h a t t h e reduction brought about by this metal is somewhat more rapid t h a n t h a t by zinc, either with or without the aid of the electrolytic current. The difficulty in obtaining aluminum of t h e necessary degree of purity has, however, prevented, for t h e time a t least, the quantitative study of t h e use of aluminum in the reduction of larger amounts of ferric sulfate. CONCLUSION
The results show t h a t ferric sulfate, in either small or large amounts, may be rapidly and efficiently reduced b y rapidly rotating reductors of zinc or aluminum, either without or with the aid of the electrolytic current; and t h a t quantitative results may be obtained by titration of the reduced ferrous salts with potassium permanganate. The reducing action of the rotating zinc cylinder exposing a considerable area of action ( 7 5 sq. cm.) t o solutions of ferric salts of suitable volume (50 cc.) affords a rapid and exact alternative to reduction b y t h e amalgamated zinc column of t h e Jones reductor, the rapidity of reduction depending largely upon t h e area of the reducing surface of t h e zinc, the temperature, and t h e volume of t h e solution. By this method i t should be possible t o determine with rapidity, convenience and exactness t h e total content of iron in sulfate or chloride solutions of ferric salts obtained by any of the usual processes from t h e metal or an ore. A C K N 0 W L E D G ME NT
This work was done a t t h e Kent Chemical Laboratory of Yale University in 1918, and t h e writer wishes t o t h a n k Prof. F. A. Gooch, who suggested t h e problem, and whose advice a t all times has been most helpful. AKRON,0x10
