1436
INDUSTRIAL AND ENGINEERING CHEMISTRY
reflux ratio of 1000, Equation 9 calls for 105plates for the given separation. As a check the same calculation was made by the McCabe-Thiele method, and the same result was obtained.
Subscripts:
++
n, n 1 = plates above feed level m, m 1 = plates below feed level c = overhead product
w = bottoms or tail product
Nomenclature mole fraction of more volatile component in liquid y = mole fraction of more volatile component in vapor z’ = mole fraction of less volatile component in liquid y’ = mole fraction of less volatile component in vapor 0 = overflow or reflux in section of column above feed level, moles P = overhead product, moles W = tail product, moles R = reflux ratio for the rectifying section = O / P R’ = reflux ratio for the stripping section = ( F $- O)/(F - P) or F/W for a stripping column alone F = feed. moles n = num’ber of plates Q! = ratio of vapor pressure of the more volatile component of a binary solution to that of the less volatile component, at the same temperature Q!’ = reciprocal of a z
VOL. 29, NO. 12
f
= feed
=
Literature Cited (1) Fenske, M. R., Tongberg, C. O., Quiggle, D., a n d Cryder, D. S., IND.ENQ.CEEM.,28, 644 (1936). (2) Huffman, J. R., a n d Urey, H. C., Ibid., 29, 531-5 (1937). (3) Lewis, W. K., Ibid., 14, 492-7 (1922). (4) McCabe, W. L., a n d Thiele, E. W., Ibid., 17, 605-11 (1925). ( 5 ) Peters, W. A., Jr., Ibid., 15, 402-3 (1923). (6) Underwood, A. J. V., Trans. Inst. Chem. Engrs. (London), 10, 112-62 (1932).
(7) Walker, W. H., Lewis, W. K., a n d McAdams, W. H., “Principles of Chemical Engineering,” 1st ed., New York, McGrawHill Book Co., 1923. RECEIVED August 16, 1937.
Production of from Water MOHD. SHAFEE A N D J. L. SARIN Government Industrial Research Laboratory, P. 0.Shahdara Mills, Lahore, India
ATER caltrop or water chestnut (Trapa bispinosa) is an aquatic plant which has been grown in India from the most ancient times. It yields a nut whose kernel is used locally in bilious troubles and diarrhea, as a general article of food, and in the preparation of poultices ( I ) . No statistics are available as to the tptal production of the nut, but it has been roughly estimated to be more than 10,000 tons a year a t present and is gradually decreasing (6). Economic utilization of this crop would be important to areas of the country where it is grown extensively and is available a t a low cost. The caltrop nut is triangular in shape and about 0.75 inch long (3). It is covered with a tough brown skin whose thickness varies with the species of plant. I n certain cases the shell is very thick and has long projected horns. The kernel is white and of a fine fibrous texture. Usually a thinskinned nut is composed of two-thirds kernel and one-third shell. The nut is collected from underneath the surface of the water where i t grows, and the skin is removed by specially designed knives. The kernel is spread in the open for drying.
The following practical procedure was developed for starch production:
Production of Starch For the preparation of starch the sun-dried broken kernel was used. The percentage composition of the dried kernel was as follows: Oil Gums, sugar, eto. Starch
A method has been worked out for the preparation of water caltrop starch (sangara). Its preparation in northern India would imply a more extensive utilization of an economic crop than at present. The determination of its physical properties and actual factory tests seem to show that the starch can be used with advantage for sizing cotton and rayon y a r n s , f o r finishing and printing cotton cloth, and for preparing ice cream and milk powders.
0.07 7.92 72.55
The dried kernels were washed with water to remove dust and dirt. They were then steeped in 0.25 per cent sodium hydroxide solution for 24 hours, preferably at a temperature of 40’ to 4 5 O C . This removes most of the coloring matter and softens the kernel for further treatment. The kernels were washed to remove as much of the alkali as possible and were flnally immersed in a 0.25 per cent hydrochloric acid solution to neutralize the re-
DECEMBER, 1937
INDUSTRIAL AND ENGINEERING CHEMISTRY
1437
TABLE I. GELATINIZATION TEMPERATURE FROM ~ / & ~ E C OVISCOSITY ND MEASUREMENTS 3% Starch Paste Sangara Farina Maize Wheat
60'C. 62'C. 64OC. 66'C. 68°C. 7OOC. 72'C. 74'c. 33 33 33 33 33 33 33 41 45 50 56 33 (%) 33 33 33 33 33 33 )::( 33 33 33 33 33 33 33
(3336)
76'C. 78OC. 80°C. 82OC. 84'C. 35 36 38 38 39 62 72 81 90 97 37 41 44 48 52 33 33 33 33 (34)
HEATINQ AT 90" C. TABLE11. EFFECTOF CONTINUED IN VISCOSITY(IN SECONDS) 3% Starch Paste
10 Min. 48 265 57 45
Sangara Farina Maine Wheat
15 Min. 51 305 52 46
20 Min. 52 421 51 46
25 Min. 50 374 51 43
30 Min. 50 358 51 43
120 Min. 45
60
Min. 47 226 49 39
116
45 37
CHANGE
ON
180
86OC. 88OC. 90'C. 92'C. 94OC. 96OC. 40 42 42 44 45 46 109 120 138 150 186 225 64 54 52 50 50 49 35 35 36 36 37 39
Min. 43 78 41 36
240 Min. 41 53 39 35
TABLE111. VISCOSITYOF CONSTANTLY AQITATEDSTARCH PASTES(IN s',1 3% Starch Paste
5 Min.
Sangara Potato Maize Wheat
1800
72
58 45
10 Min. 16 Min.
20 Min.
25 Min.
30 Min.
60 Min.
90 hlin.
73 454
72 290 49 45
70 243 49 45
55 158 47 43
51 81 45 43
82 514 51 47
82 750 55 46
44 50
maining alkali. The washed and softened kernels were pulped in a coconut shredder under a regulated constant stream of water, the pulp was strained through a sieve (120 mesh per inch), and the residue was ground in an edge runner, washed, and passed through a series of shaking sieves. The residue which did not pass through the sieves was thoroughly stirred with water and again passed through sieves to remove all possible starch. The washings were collected and again passed through a fmer sieve (200 mesh per inch). The liquors passing through the sieve were concentrated to the desired consistency by deposition and then allowed to settle in a series of tanks or a set of tables where the starch was deposited. The liquor containing fibrous suspended matter was allowed to flow away. The starch was further purified by washing with slightly dilute sodium hydroxide and retabling. It was dried in the open OR in an air oven at a temperature not exceeding 30' C. (86''F.). The starch obtained was white and had the following percentage composition: Moisture Starch Ash
9.83 89.92 0.13
Nitrogen Fatty matter
Trace &o'ne
By-Products of Water Caltrop Starch Process
360 Min. 40 46 37 34
SECONDS)
120 Min. 180 Min. 240 &Min.300 Min. 360 Min, 45
43 47 41 38
60
43 41
...
40
.. ..
.. ...
...
36
39
.. ..
35
approximate percentage composition of the suspended airdried pulp was as follows: Water Starch Crude fiber
6.75 54.48 33.60
Ash Protein
3.44 1.52
It can be satisfactorily used as a cattle feed.
Properties of Water Caltrop Starch Water caltrop starch (sangara) granules are of medium size. One hundred twenty granules were measured and found to range in size from 10 to 48p. The average diameter was 20p. To measure the starch granule, the micrometer ocular ( X 10) was used on the microscope, together with a 0.65-mm. (x 40) objective. The microscopic examination showed that the starch consisted of simple oval or round granules. On the whole, the granule resembled that of potato starch in shape.
The waste material from the production of water caltrop starch consists of the residual pulp (36 per cent) and the water from the various starch operations and purifications. The
L .
c
B
Y
I 6 6 TEMP€RATUR 74 k E,h'C ~
26
$0 $2 24 Jk 28
7!6
O E!
I
$9 $6 $8 $0 d2 d4 36
TIME, MlNUTES
FIGURE 1. GELATINIZATION TEMPERATURE FROM 1 / 6 - S VISCOSITY ~ ~ ~ ~ MEASUREMENTS ~ A . Sangara
B . Farina
C. Maire
D . Wheat
F I G W R2.~ EFFECTOF CONTINUED HEATING AT 90' C. ON VISCOSITYCHANGES (IN l / ~SECONDS) A . Sangara
E . Farina
C. Maize
D . Wheat
INDUSTRIAL AND ENGINEERING CHEMISTRY
1438
For viscosity determinations, a 3 per cent starch paste was prepared. The required amount of starch was first suspended in 10 cc. of cold water, and then the remaining water was added from a pipet, allowance being made for the moisture content of the starch. For all measurements this water was maiiitained a t 99” C., except for the determination of gelati-
VOL. 29, NO. 12
and this also served as a measkre of the point a t which complete gelatinization occurs. Readings were taken a t 2” C. intervals. The effect of continuous heating with and without constant agitation was also investigated. For comparison, determinations of viscosity were also made of potato, maize, and wheat starches. The results are given in Tables I, 11, and I11 and in Figures 1, 2, and 3. Water caltrop starch behaves similarly to maize and wheat starches.
Proposed Uses
TIME,MINUTES
FIQURE 3. VISCOSITYOF CONSTANTLY AGITATEDSTARCH PASTES (IN 1/5 SECONDS) A . Sangara B. Potato
C. Maize
D. Wheat
nization temperature when it was held at 50” C. Paste uniformity was ensured by agitating with a stream of water from the pipet. A Stormer viscometer was used for all viscosity determinations (4). A series of measurements was made of the temperature at which the starch begins to swell for gelatinization The maximum viscosity was determined by continuous heating
Sangara starch can apparently be used for textile sizing, since its viscosity varies little over a wide temperature range. Its suitability as a sizing and finishing material can be judged when the experimental work on the chemical properties and penetrating and coating power of the starch on cotton yarn is finished. Actual sizing and finishing tests carried out in the Government Finishing and Dyeing Factory, Shahdara, show that the water caltrop starch possesses satisfactory coating and penetrating qualities and is suitable for sizing cotton and rayon yarns, for finishing cloth, and as a thicken ing material in calico printing. Another use appears to be in the manufacture of ice cream [‘improvers” and powders (intended for boiling milk and sugar mixes) and as a constituent of dried milk powders. Analysis of a number of ice cream powders showed that they contain an appreciable percentage of cornstarch (9). When water caltrop starch was substituted for cornstarch in these powders, it gave better results in making the ice cream more creamy and in improving and smoothing its texture and body.
Literature Cited (1) Badel, Powel, “ P u n j a b R a w Materials,” 1868. (2) Food, 6,40 (1936). (3) Kashyap, S. R.,“Lahore District Flora,” 1936. (4) T h u r b e r , F.H., IND. ENQ.CHEW,25, 565-8 (1933). ( 5 ) Watt, G., “Commeroial Products of India,” 1908. RECEIVED August
4 , 1937.
Treatment of Rayon Waste FOSTER DEE gNELL Foster Dee Snell, Inc.,Brooklyn, N. Y.
T
HE plant under discussion is a knitting mill operating solely on rayon. Some rayon contains as low as 6.5 per cent of oil, but a t least 25 per cent of production is from rayons containing up to 18‘per cent. This rayon is knit, boiled off, and dyed in the production of underwear. The boil-off process is carried out with low-titer soap and soda ash. Some of the product receives a hypochlorite bleach treatment before dyeing. Operations in this mill were previously described in detail ( 2 ) . The volumes and methods have altered since that time, and the method of waste treatment then in use has been abandoned. The city of Sparta, Ill., has an activated sludge plant with a capacity approaching 400,000 gallons per day. The dye wastes can be satisfactorily handled by this plant along with the normal sewage. The problem is therefore only the treatment of the minor amount of boil-off waste. This has been as low as 15,000 gallons per day and is at present esti-
mated a t 60,000 gallons per day. A temporary expedient of discharging this waste into a near-by stream proved unsatisfactory because of damage to riparian rights of downstream landowners. The former method of treatment has been included (1) in a recent survey (9) of textile waste treatment. Therefore this paper is intended to bring up to date the information as to methods of treatment used. The original plant now serves only as a temporary impounding basin. By acidifying the boil-off and putting it through a centrifugal separator, satisfactory results were obtained. The cost of treatment was not excessive but the cost of equipment would be large for handling such a small volume of waste. Methods of treatment with ferrous sulfate and lime or aluminum salts and lime were tried. Although the waste could be clarified, the cost was substantial and the finished effluent was strongly alkaline. Precipitation by lime was tried and was even more objectionable because of alkalinity.
