December, 1933
INDUSTRIAL AND ENG INEERING CHEMISTRY
1403
by using solutions in which the p H could be controlled over curve a t about pH 4.2; therefore it is to be expected that a a considerable range of p H values. It was found that t'he buffer solution with a p H around 5.0 would not cause a phosphate buffers described by Clark ( 2 ) were the most complete flocculation of the copper salt. logical to use. Table I1 indicates that when the residual p H of the buffer solution is 6.3 or above, there is a complet'e removal of the The buffer solutions were prepared in 50-cc. volumes at a definite pH, to which were added in order the copper sulfate copper ions by the aluminum floc. It also indicates that a t solution with stirring, and then the alum solution rrith stirring. a residual p H of about 6.0 to 6.4 there is an average of almost The copper sulfate and alum solutions are described above. 90 per cent removal, and that from a p H of 5 to 6 there is These solutions were allowed to stand until the floc had settled. This required from 4 to 15 hours. Then the supernatant liquid better than 50 per cent removal of the copper ions. The conclusions which must be drawn from these data are was filtered by decantation so that only about 35 cc. ran through, and very little of the floc came on to the filter paper. Of these that, so long as the p H of filtered water remains above 6.3, 35 cc., 25 cc. were used for the determination of the copper a very heavy dose of copper sulfate may be used without any by the ferrocyanide method, and 10 cc. were used for the coloridanger of the copper salt getting through the filters in a water metric determination of the pH. filtration plant which is using the alum treat'ment method. The results of these experiments are given in Table 11. The LITERATURE CITED composition of the floc was not determined in any case. In tests 2 , 7, 21, 33, 37, 40, 41, and 44 no alum solution (1) Buswell, A. M.,et al., IllinoisState Water Survey, Bull. 22 (1926). was added after the copper solution. These tests show that (2) Clark, W. M., "Determination of Hydrogen Ions," 2nd ed., p. 114, Williams & Wilkins, 1927. the copper is flocced out more at' the higher p H values than at (3) Hopkins, 4.J.,and Beebe, R. rl., J. Phys. Chem., 34, 570 (1930). the lower, and that even a t a p H of 5.0 half the copper ions (4) Miller, L. B., Public Health R e p l s . , 38, 1995 (1923); 40, 351 are removed in the floc. This is in accord with the potentio(1925); 40, 1413 (1925). metric titration curve for copper sulfate with sodium hydrox- (5) Theriault, E. J.,and Clark, W. M., Ibid., 38, 181 (1923). ide (S), which is similar to that for aluminum sulfate with (6) Yoe, "Photometric Chemical Analysis," Vol. I, p. 182 (1928). sodium hydroxide ( 5 ) . However, the copper curve is dis- RECEIVED September 19, 1933. Presented before the Division of Water. placed upwards in p H with respect t o the aluminum curve. Sewage, and Sanitation Chemistry a t the 86th Meeting of t h e .-lmerican The copper curve bends a t about pH 5.0 and the aluminum Chemical Society, Chicago, Ill., September 10 t o 15, 1933.
Effect of Previous Starching upon Ease of Washing Cotton Fabrics LAWRENCE E. STOUT AND KR'APELF. SCHIERMEIER, Washington University, St. Louis, Mo. Starching prerious to soiling aids in the redressing formulas will be used. HE value of s t a r c h as of the dirt f r o m material by washing. ?vIoreover, any factor which an aid in the removal tends t o facilitate the washing of dirt from fabrics has Boiled wheat and rice starch is superior to a n y of operation w i t h o u t decreasing b e e n recognized qualitatively for a long t i m e . H o w e v e r , the other grades sfudied. Soluble ulheatand rice the life of the fabrics treated is few if any quantitative studies starch ranks second, and the boiled corn starch of major chemical engineering have been c a r r i e d out on the third. Quantitative data give definite compariimportance t o the industry. subject. Guernsey ( l )states sons of the values of the different types and quantithat the addition Of EXPERIMENTAL PROCEDURE ties of starch as a washing aid f o r the removal of such as starch to an a l k a l i n e .. . solution lessens the destructive dzrt* Test s t r i p s of c l o t h w e r e action of the a l k a l i p r e s e n t washed free from all starch or and increases the cleansing power of the detergent. Harvey dressing materials, dried, and ironed. These test pieces ( 2 ) also points out that the removal of old starch or previous were then starched in a definite manner, dried, ironed, and starch effectively removes much of the mechanically held soiled in a standard soiling solution. The dry soiled samples dirt and makes subsequent washing processes easier. These were washed repeatedly, and the cleansing effected by each men have recognized some effects of prestarching in washing washing was measured quantitatively, operations, but no quantitative data have been published. CHEMICALS AND MATERIALS USED. Tests were made upon The modern power laundry is interested in ease of washing two grades of white cotton sheeting. The first weighed 2.2 and uniformity of the washed articles. Moreover, it is con- grams per sq. cm., had twenty threads per cm., and in this fronted with the problem of washing heavily dressed fabrics report is designated as the coarse grade. The second weighed and returning them t o the owner with their original appear- 1.6 grams per sq. cm., had 26 threads per crn., and is desigance. Heavily starched materials contain from 4 t o 5 per nated as the fine grade. Three commercial grades of starch cent, white shirts and collars about 9 per cent starch. Imita- were used: (1) a soluble starch consisting of about 80 per tion linens are heavily dressed, and starch is a n essential cent rice and 20 per cent wheat, ( 2 ) a boiled starch of approxiconstituent in the dressing used. Therefore, it was felt that mately 50 per cent rice and 50 per cent wheat, and (3) a these quantitative data on the effect of previous starchings boiled corn starch. The soiling solution consisted of a upon the ease of washing of cotton fabrics might justify suspension of lampblack in water as described by Vail ( 3 ) . heavy starching. The higher starch concentrations studied PREPARATION OF SOILEDSAMPLE.The starch solutions can serve as a basis for the interpretation of furthm work on used were made up to various concentrations. Test strips the washing of dressed fabrics in which the more complicated were saturated with the starch solution in question and then
T
'
allowed to dry. T h o illcrease in weight. of the test strij) representcd tlie quantity of stnrcli lield hy the cloth and KLLS cxpresscd as prr cent b y w e i g h t on the basis of the unstarclied sample. Thedriedstarclied test strips were retted wit,li water, stirred in the soiling solution, and tlicn tightly wrung. This operation was repeated until tile samples acquired a maxiinuin black. The soiled s a i n p l e s were rinsed in clear water until no free carbon washed off, and were then allowed t,o dry. WASHING OF sb\LI'LEd. All washing o p e r a t i o n s were carried o u t i n a Ftouwe 1 s e i e n t if i c a l 1y operated c o m m e r c i a l l a u n d r "v .: each wash was identical in all respects. The iietted samples, along with sulccient other "flat work" to make a charge of 110 pounds (49.9 kg.) of dry netted materials, were placed in a 42 x 84 inch (106.8 X 213.4 cm.) nmnel nietal washer (Figure 1) and subjected to the washing cycle outlined in Figure 2. After washing, the sarnples were centrifugalized and dried, i ~ n da specimen of each strip cut off to be evaluated. The degree of black of each ISSPECTION AND TESTING. test portion was read by a Weston Illunlination Meter, model G03. This instrunient consist8 of two photosensitive disks set in a paddle and registers their effect upon a microammeter calibrated in foot candles. A light of constant intensity was cast upon the sample from which it was reflected t o the disks as shown in Figure 3. This enabled quick and accurate reading3 on the samples. The intensity of illumination upon the sample under meaalreinerrt mas adjustcd by insert-
i~ b t x n d a r d p i e c e of rriiitc p q m i i i plnce of the s ~ m p l cand adjusting tlie distance of the lamp irntil the meter reading -,as 24.8. Readings were taken from both sides of each sainple and the average calculated as per c e n t w h i t e , based upon tlie soiled sample as 0 per cent and the unsoiled as 100 per cent white.
ing
RESULTSOF TESTS Witli t,Iie conditiuns a s outlined, a s e r i e s of lireliminary tests indicated in Table I was nin upon the coarse sample of cloth. A study of these data points out several generalizations. In every case s t a r c h i n g p r e v i o i i s to s o i l i n g and washing facilitated the renioval of dirt. Cloth treated with boiled wheat and rice starch washed cleaner than cloth treated with the other two grades of starch investigated. This was the case not only after the first wash but after six washes. For example, on tile first wash 36 per cent of the soil was removed froni the unstarcliod sample, 53 per cent from the boiled corn starch sample, 65 per cent from the soluble wheat and rice sample, and 71 per cent from the boiled wheat and rice sample. Furthennore, the unstarclied sample reqnired
t i m e washings before it eouid approximate tlie degree of cleanliness obtained by a single washing of the sample treated with 20 per cent wheat-rice boiled starch. Likewise, tlie specimen dressed with boiled corn starch required two washings to become as elcan :is did the cloth t.reated with tlie boiled wlrcnt-rice starch after a singlc msliing.
-
20% boxlea
wlleat-rLee starch 71.B 87.6 91.2
98.4 99.0 99.0
Ii'lcunE 2.
WAsHINc; CYCLE FOR FL.4T W O H K
Flow is downward unless otherwise indicated.
-No
etarrh 35.8
69.0 70.0 74.5 78.2 80.8
These dat.a are plotted in Figure 4 to indicate the approximate rate of washing under the four conditions stated. These preliminary measurements indicated that further investigations might be confined t o a st.udy of tlie two wheatrice starches and eliminate the inferior corn starch. The fine-Fade cloth was prepared for testing as previously described, and the data listed in Table I1 indicate the effect of varying the starch content upon the rate of washing.
I N D U S T R I A I. -4S D E N G I N E E R I N G C H E hl I S T R Y
Decemher, 1933
1405
TABLE11. EFFECTOF VARYIXGSTARCH CONTENTUPON RATE which had lower starch OF WASHIKG content did not assume a PER CENT WHITE AFTER:l i n e a r function as rap1st 2nd 3rd 4th 5th 6th STARCH wash wash wash wash wash wash idly, but appeared al% most to reach a constant BOILED WHEAT-RICE STARCH brightness as the curve 0.0 28.5 30.0 41.0 45.0 47.0 48.0 8.3 42.5 52.0 54.0 57.0 58.0 57.5 became horizontal. This 12.7 46.5 50.0 54.5 59.0 61.5 63.0 14.0 49.5 53.0 60.0 64.5 66.0 56.0 shows that the soil was 15.9 52.5 57.5 62.0 63.0 62.5 61.0 removed from the sam24.6 59.0 62.5 64.5 68.0 69.0 69.5 26.0 60.0 62.5 67.5 69.0 70.0 65.5 ples of greater s t a r c h 44.5 58.5 62.5 64.0 67.0 74.0 65.5 54.7 62.5 64.5 68.5 73.0 74.5 68.0 content not only more 10 2 0 30 40 50 BOLUBLB WHEAT-RICE STARCH effectively b y t h e first 0.0 28.5 30.0 41.0 45.0 47.0 48.0 P E R CENT STARCH 33.0 5.5 46.0 wash, but that the highly 36.5 41.0 45.0 45.5 38.0 51.0 52.5 7.5 45.0 49.0 52.5 s t a r c h e d samples con- FIGURE 5. EFFECTOF STARCH 8.9 40.5 52.0 55.5 54.5 46.5 47.0 CONTESTON RATE OF WASHING 10.3 43.5 48.0 50.5 53.5 58.0 57.0 tinued to give up more 15.7 49.5 53.5 57.5 59.5 62.5 63.0 27.4 54.5 58.5 62.0 69.0 64.0 dirt than those of less 59.6 starch as the number of washings increased until the conThese data are plotted in Figure 5 to show the effect of stant brightness condition was reached. In other words, constarch concentration upon the per cent white after each wash- stant brightness was reached sooner for those samples having ing. I n Figure 6 these same data are plotted to illustrate less starch; consequently they did not become as clean. The results show that each coarse cloth gave up its soil the effect of the number of washings upon the per cent white, more readily than did a corresponding fine cloth. I n the each curve showing a different starch content. first wash the former retained an average of 10 per cent less soil. An average of about 15 per cent of the total soil was reDISCUSSION OF RESULTS m o v e d b y the second wash, Figure 5 indicates little advantage in starching to an exw h i l e o n l y 3 p e r cent was tent greater than 30 per cent. The curves become almost WIwashed from the finer sample. horizontal for the higher percentages. It would seem, there- ZB ? The coarse material r e a c h e d fore, that a t this starch content the cloth is densely saturated 98 per cent white in the sixth 5 6 with the starch and a protective coating has been formed on Y0 washing while the cleanest fine the fibers. A thicker coating of starch fails to prevent more sample reached o n l y 74 p e r dirt from entering. When given the same soiling treatment, g 5 c e n t white. The slower rates 4 of washing of the fine cloth the starched cloths become a deep black more readily than t h e unstarched o n e s . NO OF W A S H E S made it a-better material for However, upon close ex- FIGURE 6. EFFECTOF T~~~ such studies, and it is thereamination it was noted AND CONTESTOF STARCHOS fore recommended for similar 90 that the former held the E4SE OF WASHING washing tests. soil on the surface while 80 ACKXOWLEDGMENT in the case of the un70 starched cloths the soil The authors are indebted to Killiam M. Perry of the Perrypenetrated deeper, leav60 ing the soiled s u r f a c e Higgins Laundry, St. Louis, Mo., for extending the facilities of his plant for this study. Acknowledgment is also made to fibers lighter in color. 50 Furthermore, a com- H. G. Hake, professor of Electrical Engineering, Washington parison of the curves in University, for the loan of the illumination meter and advice 40 F i g u r e 5 f o r t h e two On arranging its set-up* 30 grades of starch indicates LITERATURE CITED that for a 30 per cent 20 (1) Guernsey, Am. Duestuf Reptr., 12, 766 (1923). starch content 6 per cent (2) Harvey, “Laundry Chemistry,” p. 85, C. Lockwood & Son, soil was removed 10 London, 1926. in the first wash from the (3) Vail, Oil & Fat Ind., 8,414 (1931). 0 s a m p l e s treated w i t h I 2 3 4 5 6 boiled than from RECEIVED July 13, 1933. Presented before the Division of Industrial and Chemistry a t the 86th Meeting of the American Chemical NO O F WASHINGS samples treated with the Engineering Society, Chicago, Ill., September 10 to 15, 1933. FIGURE4. EFFECT OF STARCHESsoluble starch, and 33 per OS EASEOF WASHING c e n t m o r e soil was removed from the boiled INDUSTRIAL GCM INDUSTRYAT MARSEILLE.The kernel of starch sample than from the unstarched one. As the starch the locust bean (St. John’s bread), which grows on the carob in the countries bordering on the Mediterranean Sea, is, content was decreased, the curves of the two types of starch tree according to the best information available, the raw material more nearly approached each other. Even for a starch con- from which industrial gum is made. Industrial gum is manutent of 10 per cent the average starched sample washed 16 factured principally in France and in England. There are two per cent cleaner than the unstarched sample, and a 5 per cent important factories in the city of Marseille, the names and adof which are available upon application t o the Bureau sample washed 8 per cent cleaner. After five washings the dresses of Foreign and Domestic Commerce, Washington, D. C. There 30 per cent boiled starch sample was 71 per cent white, the is also a small factory, producing a negligible quantity, located 30 per cent soluble was 63 per cent white, while the un- at Rouen. The principal factory in England, located at Birkenhead, near starched was only 47 per cent white. is known under the name of Etablissements Tragasol The washing of fine cloth samples that had been heavily Liverpool, Co., Ltd. Unsuccessful attempts have been made t o manuimpregnated with starch appeared to follow a linear function facture this product in Spain and Italy, but only an inferior after the first washing. However, washing of those samples quality has been produced.
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