1438 INDUSTRIAL AND ENGINEERING CHEMISTRY VOL. 29, NO. 12

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-

TIME,MINUTES

FIQURE 3. VISCOSITY OF CONSTANTLY AGITATED STARCH 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

and this also served as a measkre of the point a t which com- plete 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 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, “Punjab Raw Materials,” 1868. (2) Food, 6, 40 (1936). (3) Kashyap, S. R., “Lahore District Flora,” 1936. (4) Thurber, 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.

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 aban- doned.

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-

T mated a t 60,000 gallons per day. A temporary expedient of discharging this waste into a near-by stream proved unsatis- factory 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 cen- trifugal 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 alu- minum 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.

DECEMBER, 1937 INDUSTRIAL AND ENGINEERING CHEMISTRY 1439

The ingredients of the waste are mainly sodium carbonate, alkali metal soaps, and emulsified mineral oil. Such an emulsion would be decomposed by conversion of the soap to an insoluble form. Experimental work indicated that addition of calcium chloride will convert the soap to insoluble calcium soaps which will entrain all of the emulsified oil to give it a clear and colorless effluent.

In laboratory experiments 2 and 4 cc. of 12 per cent calcium chloride solution per 100 cc. of boil-off gave the finished effluents shown in Table I. These factor weights correspond to treatment with 2 and 4 pounds of calcium chloride per 100 gallons, respectively, the calcium chloride being the com- mercial 75 per cent grade. For practical use a solution of calcium chloride containing about 3 pounds to the gallon would be suitable.

T+4BLE I. RESCLTS O F TRADE WASTE TREATMENT (IN PARTS PER ~ ~ 0 , 0 0 0 )

Treatment Raw 2 Lb. 4 Lb. Filtered Liquor CaCh CaC12 through

per per Bed of 100 Gal. 100 Gal. Ashes

nH i n fi 7 6 7 2 7 0 - _ .,_ . . _ %tal solids a t 110’ C. 668 394 739 i 4 i Inorganic solids (by loss on ignition) 308 333 509 216 Organic solids (by difference) 360 61 130 25

method) 376 U a 66 Oz-consumed (permanganate

Not significant because chlorides are present.

The amount of calcium chloride required is substantial be- cause the sodium carbonate must be converted to sodium chloride and calcium carbonate as well as the alkali soaps to calcium soaps. The pH of the finished effluents indicates that the reaction takes place smoothly since they are nearly neutral. Laboratory results such as these are only an indi- cation, and for practical results it is highly probable that further reduction could be made. The process was tried out on a plant scale and operated satisfactorily with a pilot plant. The development of a simpler process rendered its complete installation unnecessary.

The removal of such sludge in a relatively concentrated condition is satisfactorily carried out by filtration on a light cotton fabric. The rate of filtration is about 1 gallon per 90 square inches of filtering area per minute so that commer- cially about 1.25 square feet of filter area would be required per 1000 gallons per day. If it stands for several hours, it becomes oily. It was expected that the sludge would need to be filtered before it became oily but experience shows that such was not the case. A tank of calcium chloride solution was expected to feed the solution to the waste to be treated while passing through a suitable calender for mixing. As indicated by the analyses of Table I, the finished effluent is clear and transparent and harmless to fish and vegetable life. Pilot plant operation indicated a cost for materials of 20 cents per 1000 gallons. The indicated labor cost is low.

The use of ashes as a filter bed was developed with the cooperation of the State of Illinois Sanitary Water Board and proved to be simpler and less expensive. The effluent was found acceptable, and analysis of a representative sample is included in Table I. The results reported with addition of calcium chloride cannot be directly compared because of the in- crease in solids due to the salts resulting from treatment. The effluent from the ashes contains considerable suspended mat- ter a t times but is much clarified from the original condition.

The ashes can be expected to contain substantial amounts of soluble heavy metal compounds, mainly lime. Probably the reaction of these with the soaD is similar to the reac-

The sludge is curdy in nature.

stroyed by this treatment, the emulsion is broken and pre- cipitation of the oil results.

In practice the bed used is 3 feet deep and contains 1440 cubic feet or 30 tons of ashes. It is roughly divided into three sections, and the oldest section is replaced each week. The used ashes are hauled away by local people because their oily condition makes them excellent material for building secondary roads. Each charge of 30 tons of ashes treats about 1,000,000 gallons of boil-off. It is estimated that this volume of boil-off contains 6500 pounds of oils and 1500 pounds of soap, soda ash, etc. Although this treatment has been in use for only about a year, satisfactory results have been obtained.

Acknowledgment This paper is published by permission of the Weil-Kalter

Company of St. Louis, Mo., and Sparta, Ill. The coopera- tion of Paul Weil and A. S. Barnard is acknowledged particu- larly.

Literature Cited (1) Geyer, J. C., and Perry, W. A., “Textile Waste Treatment

and Recovery,” p. 93, Textile Foundation, Inc., 1936. (2) Turpin, U. F., Eng. hrews-Record, 109, No. 26, 7-8 (1932).

RECEIVEID September 11, 1937. Presented before the Division of Water, Sewage, and Sanitation Chemistry at the 94th Meeting of the American Chemical Society, Rochester, N. Y., September 6 to 10, 1937.

Life of Shellacs after Heating

ARTHUR A. VERNON AND ROLAND E. GILL Rhode Island State College, Kingston, R. I.

ESTS were made to determine how long various samples T of shellac would stand heating without losing their tacki- ness. The samples were aged in an electric oven for varying periods and tested on an electric hot plate maintained a t 275” F. The table gives the time in seconds, after the shellac had melted, necessary for the samples to lose all tackiness when tested with a spatula.

The specifications are given in the A. 8. T. M. Standards (Designations D237-33 and D207-55) :

After Heating at 140’ F. Time of Heating-----

Shellac 0 1 hr. 2 hr. 3 hr. 4 hr. A. Refined dry bleached 0 0 0 0 0

Regular dry bleached 94 50 0 0 0

C. Regular dry bleached 137 36 30 0 0 Refined dry bleached 570 462 394 366 17

D. Grade A, orange shellac 1415 1395 1365 1137 1047 After Heating a t 180’ F.

A. Refined dry bleached 0 0 0 0 0 Regular dry bleached 94 0 0 0 0

B. Refined dry bleached 183 0 0 0 0 512 290 217 0 0

Grade A, orange shellac 1636 891 836 122 0 1153 708 633 0 0

90 0 866 470 365 C. Regular dry bleached 137 0 0 0 0

Refined dry bleached 570 206 174 0 0 D. Grade A, orange shellac 1415 984 930 0 0

Each group represents a product of a different manufac- The samples were furnished through the courtesy of turer.

George Lawson. tion of calcium chloride. Since the stabilizing agent is de- RECEIVED J ~ I ~ 23, 1937.