January, 1931
INDUSTRIAL AND ENGINEERING CHEMISTRY
EFFECT OF TIMEOF YEARON PHYSICAL COXSTAKTS OF TURPENTINE The time of the year a t which the oleoresin was collected seems to have exerted little Or no effect upon any Of the physical constants of the turpentine obtained, provided that fairly large samples only are considered. %ark isnow inprogress having for its object the determination of the physical and chemical characteristics of the samples of rosin obtained during the investigation. ACKXOTVLEDGMENT This investigation is being carried out in cooperation with the Industrial-Farm Products Division, Bureau of Chemistry and Soils, United States Department of Agriculture, Washington, and is under the immediate supervision of F. P. Veitch. is made to him for many suggestions’ The authors are indebted also to c. F- SPeh, secretarymanager of the Pine Institute of America, for assistance and
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suggestions. They desired to express especial appreciation to Lenthall Wyman, in charge of the Southern Forest Experiment Station a t Starke, and to Harper, Busch, Pease,-and have made the individual tree Olsen, of the station staff, studies, photographed the trees,and performed all field work in connection with the project. LITERATURE CITED Bull. 116 (1922), (1) Betts, u. s. Forest (2) Herty, C. H., Ibid., 90 (1911). (3) Hertv. C. H..unmblished work. (4j Herty’and Diekinson, J. ISD. E m . CHEM., 4 , 495 (1912). ( 5 ) Hitch, A. R., Ibid., 23, 1135 (1931). (6) Otte, B. J., Master’s Thesis, University of Florida, 1930. (7) Schorper. A. W.. Forest Products Lab.. R e p t s . 2489.2491 (1913). (8) Schorger; A. W:, J. IND.ENQ.CHEM.,5,-971-73 (1913); (9) Ibid., 7, 321 (1915). (10) Veitch and Grotlisch, U. S. Dept. Agr., Bull. 898,5 (1920).
RECEIVED June 20, 1933. Presented before the Division of Agricultural and Food Chemistry a t the 85th Meeting of the Amencan Chemical Society, Washington, D. c., March 26 to 31, 1933.
Removal of Fluorides from Drinking Waters C. S. BORTJFF, State Water Survey, Urbana, Ill. An a v e r a g e a n a l y s i s of the ECENTLY it has been Removal of injurious quantities of soluble stock water follows (wells 7, 8, established that mottled fluorides f r o m drinking waters can be accomand 9): t e e t h a r e caused by plished by dosing with alum, with subsequent d r i n k i n g waters c o n t a i n i n g P . v. m. removal of the floc by sedimentation and filtrafluorides. T h is condition deFe+++ 0.7 tion. Under certain conditions contact beds of velops during childhood w hi1 e Si02 18.0 67.8 Ca++ the teeth are being formed (1, activated alumina or some other aluminum Mg++ 29.6 1.5 NH: 4-8). Surveys conducted by compound that may be developed f o r this purpose 24.9 Na state and national public health so,-23.6 m a y prove feasible. Household drinking sup0.6 NO*organizations are calling atten2.7 c1the water with plies could be treated by shaking 330 cos tion to the importance of this activated alumina in suitable containers. The problem and to the high inciA control fluoride a n a l y s i s dence of distrophy found in those decanted waters would be clear. Softening, with was made of each batch of prelocalities where fluoride-containthe addition of excess lime, causes the co-precipipared water. ing waters are consumed. Two tation of considerable fluoride. The extent of the cities-namely, Bauxite, Ark., above treafmenls will depend on the fluoride conand O a k l e y , Idaho-have disUSE O F -4LUMINUM COMPOUNDS centration in the’raw water and the amount of carded abundant water supplies in favor of those containing less As aluminum forms a soluble fluorides which will ultimately be established as fluorides, Other cities are seribut slightly ionized salt with the toxic limit allowable in water supplies. A ously considering similar action. f l u o r i d e s , the writer investipractical demonstration of fluoride removal at In some localities it seems imgated the use of aluminum sulsome water treatment plant equipped with settling possible to find water supplies fate, sodium aluminate, zeolite, basins and jlters would be of great value. f r e e f r o m f l u o r i d e s (1, 8 ) . activated alumina, and bauxite Numerous methods have been as DreciDitants and adsorbents proposed for the determination of the small quantities of of fluorides. Some of these suistanles are at present used fluorides found in waters (W),but no one has proposed a method in the treatment of water but are not recognized as fluoride for the removal of this injurious ion. This paper is a report removers. of studies made to ascertain the possibilities of treating poAluminum sulfate in dosages of 0.5 grain (8.5 p. p. m.) to table waters to remove fluorides. 10 grains per gallon (171 p. p. m.)1 was added to 2-3 liters of In all of the following studies the quantitative analyses for stock water containing various known quantities of fluorides fluorides were made in accordance with the procedure re- The coagulant and waters were mixed for 30 minutes by a cently recommended by the writer (thorium titration) except mechanical stirrer and then permitted to stand 18 to 24 that 250 cc. of the fluosilicic acid distillate were collected. hours before filtering off the floc. Duplicate analyses were This distillate was then made alkaline with 1.0 cc. of 5 N always made of the treated as well as the original, fluoridesodium hydroxide before being slowly concentrated to 25 cc. containing waters. Periodically analyses were made of on the hot plate. Sodium alizarin sulfonate without zir- alum-treated samples which were not filtered. These latter conium was used as the indicator. The fluoride waters used samples served as checks on the analytical procedure. Rein these tests were prepared by treating the University of coveries within 0.2 p. p. m. of the amount of fluoride added Illinois supply with various amounts of sodium fluoride. 1 All aluminum sulfate dats are in terms of anhydroua salt.
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IYDUSTRIAL AND ENGINEERING CHEMISTRY
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were always obtained. Figure 1 shows that increasing dosages of aluminum sulfat,e gave proportionately greater removals of fluorides. In Illinois and many other localities the fluoride content of the waters which are causing mottled teeth lies between 2.0 and 3.0 p. p. m. To reduce this to 1.0 p. p. m., or slightly less, would require the t r e a t m e n t of these waters with about 2.0 grains (34 p.p.m.) per g a l l o n of aluminum sulfate. For waters that contain as much a s 5 . 0 p . p . m . of fluorides, single treatment with 10 grains (170 p.p.m.) o r d ou b 1e coagulation with 5 and 3 grains, respectively, would 0' I I I 17 34 51 68 r e d u c e t h e fluoride content to 1.0 p. p. m. FIGURE1. REMOVAL OF FLUORIDES WITH ALUMINUM SULFATE or less, a concentraOriginal pH, 7.2 to 7.4 tion which seems to produce no mottling (2, 8). These dosages are a little in excess of amounts normally required for removal of color and turbidity from waters. Good mixing and good flocculation have been found necessary for maximum removal of fluorides with aluminum sulfate. Various types of waters containing identical quantities of fluorides, when given the same aluminum sulfate treatment, resulted in the same removal of fluorides. Chloride and sulfate concentrations as high as 1000 p. p. m. had no effect on the removal of fluorides. The curves of Figure 2 show that the optimum pH range for the removal of fluorides with aluminum sulfate lies between 6.25 and 7.5 with some slight advantage shown for a pH of 6.7. The original fluoride content was 5 p.p.m.; the aluminum sulfate dosage, 86 p.p.m. These data are in line with the well-recognized fact that in the slightly acid range the alum floc is largely basic aluminum sulfate, and carries in its constitution and adsorbed to it large quantities of other negative ions (3). Whether the fluorides are removed as a basic aluminum fluoride complex or are merely adsorbed on the floc remains a question. SODIUM ALUMINATE.Na&lzOa (c.P.) affected small removals of fluorides when used as a coagulant. A dosage of 24 and 41 p. p. m. reduced the fluoride content of a 5 p. p. m. water to 4.8 and 4.4 p.p.m., respectively. ZEOLITE. In the tests made on the removal of fluorides by zeolite, a miniature contact filter was set up in a 55-mm. glass tube into which were added 490 grams of synthetic zeolite. Through this filter were passed 6 liters of stock water (University of Illinois) containing 5.0 p. p. m. of fluorides, a t the rate of 300 cc. per minute. A composite of the fourth and fifth liter contained only 0.6 p. p. m. of fluorides. The zeolite was backwashed, regenerated with 5 per cent sodium chloride, and washed free of salt with fluoride-free water. Fifty liters of stock water containing 5.0 p. p. m. of fluorides were then passed through this filter at the rate of 234 cc. (at start) to 165 (at finish) per minute. The 4- to 6-liter fraction of effluent collected contained only 0.9 p. p. m. of fluorides. This, however, increased to 2.5 in the 11- to 14-liter fraction, 3.4 in the 20- to 23-liter fraction, 3.6 in the 27- to 30-liter fraction, 3.7 in the 36- to 39-liter portion, and 4.0 p. p. m. in the 44 to 47-liter fraction. A second regeneration of the zeolite with 5 per cent salt was followed by passing a 40-liter portion of stock water containing 5.0 p. p. m. through the filter. The 3t o 5-liter portion passed through contained 2.9 p. p. m. of Al,(Q)s
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Vol. 26, No. 1
fluorides while the 6- to 9-liter fraction contained 3.8 p. p. m. Subsequent portions collected showed no removal of fluorides. The zeolite was next backwashed, treated for 30 minutes with 2 per cent sodium hydroxide, and washed free of the alkali with fluoride-free water. Again the filter was treated with the stock water containing 5.0 p. p. m. of fluorides, and again it showed small removals for only the first 8 liters of water passed. The 3- to 5-liter portion contained 3.7 p. p. m.: while the 6- to 8-liter fraction contained 4.7 p. p. m. Subsequent samples collected showed no removal. From the above data it is apparent that fresh synthetic zeolite is capable of removing fluorides from waters but that the capacity is small. The fact that small removals were noted for short periods following regeneration with salt or sodium hydroxide can be explained on the basis of preferential adsorption. TABLEI. REMOVAL OF FLUORIDES BY CONTACT FILTERO F ACTIVATED ALUMINA~ ORIQINALFLUORIDE CONTENT OF FILTER EFFLUENT REQENERAFLUORIDE 3-5 9-11 19-21 28-30 38-40 48-50 TION CONTENT litera liters litera litera litera litera 7 Parts Der million 1 Original 1.4 5.0 1.6 1.9 2.0 2.0 2.3 2 0.6 5.0 2 % NaOH 1.4 1.6 1.6 1.2b 3 0.9 0.6 1.2 2 % NaOH 3.0 2.0 ... 1.0 0.7 2.1 4 3.0 1.1 0.9 1.3 3.0 1.4 5 0.6 0.9 1.0 1.0 1.1 1.4 1.9 2.1 6 3.0 1.6 2.0 2.0 9$2v&I 1.0 1.5 7 1.3 1.5 2.2 3.0 .I. 0.7 0.7 0.9 3.0 8 e 2 N HC1 0.5 ... 1.5 9 2 N HC1 0.5 0.7 0.9 ... 5.0 ... a A filter 35 mm. in diameter and 305 mm. deep, containing 300 grama of activated alumina. was used: filtration rate was 200 cc. Der minute exceut a8 noted. b Filtration rate 50 cc. per minute. c Filtration rate 120 cc. per minute.
RUN
... ...
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ALUMISA. Another contact filter was prepared by using 35-mm. glass tubing into which were placed 300 grams of activated alumina classified so as to be retained on a 40-mesh sieve. This gave a contact bed 305 mm. deep. Fifty liters of stock water containing 5.0 p. p. m. of fluorides were passed through this filter a t the rate of 200 to 250 cc. per minute. As noted in Table I, the fluoride content of tke first 21 liters passed through this filter was reduced to less than 2.0 p. p, m. while the forty-eighth to fiftieth liters contained 2.3 p, p. m. The activated alumina was then backwashed, regenerated with 500 cc. of 2 per cent sodium hydroxide for 30 minutes, washed free of phenolphthalein alkalinity, and again treated with water containing 5.0 p. p. m. of fluorides a t the rate of 200 cc. per minute (0.08 gallon per pound or about 4 gallons per cubic foot per minute). As noted in Table I, the first 30 liters of water passed contained a m a x i m u m of 1.6 p. p. m. of fluorides. The thirty8 eighth to fortieth liters were col1 I 1 1 leked a t the rate of 50 cc. per zi ~ o W , U " , * ; I & eo minute instead of 200 and showed 2. EFFECT OF an additional removal of fluorides P~ ON F~~~~~~~ REowing to thelonger contact period. M O V A L SULFATE BY ALUMINUM Run 8 was also made at a slower rate-namely, 120 c c . p e r minute-and, as noted in Table I, gave somewhat lower residual fluoride concentrations in the effluent waters. Regeneration with 500-cc. portions of 5 per cent aodium chloride (commercial salt) and 2 N hydrochloric acid (30 minutes) gave results which are approximately the same as noted in the sodium hydroxide regeneration runs. Treatment with 2 N hydrochloric acid caused some loss in weight in the activated alumina. Sodium chloride would seem to be the logical regenerant to use.
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January, 1934
INDUSTRIAL AND ENGINEERING CHEMISTRY
In another test two samples of stock water containing 5.0 p. p. m. of fluorides were mixed for 30 minutes with 1.5 and 50 p. p. m., respectively, of fresh powdered activated alumina. The waters were filtered and found to contain 4.2 and 2.0 p. p. m. of fluorides, respectively. The activated alumina settled rapidly; hence the waters could have been decanted instead of filtered from the alumina. BAUXITE. A bauxite (commercial grade) contact filter operated in the same manner as the activated alumina filter gave small removal of fluorides. SILICA GEL,SODlUM SILICATE, A44ND F E R R ~ SALTS C A contact filter containing 498 grams of silica gel reduced the first 6 liters of a 5.0 p. pam. fluoride water to 4.0 p. p. m. (filtering rate, 350 cc. per minute). Treatment of waters with sodium silicate (256 p. p. m.) and aluminum sulfate or sodium aluminate gave removals of less magnitude than that given by the same treatment without the sodium silicate. It is known that the ferric fluoride complex is only slightly ionized. Therefore there was a chance that fluorides might be removed by this coagulant. Treatments of 2 to 5 grains per gallon (34 to 85 p. p. m.) on waters containing from 1.8 t o 5.0 p. p. m. of fluorides at a pH of 7.2 gave small removals. When the treatment was accompanied by 10 to 20 grains per gallon of lime (170 to 340 p. p. ma),waters containing 1.8 and 5.0 p. p. m. of fluorides were reduced to 1.6 and 4.7 p. p. m., respectively.
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LIMETREATMENT Treatment of stock waters with sufficient calcium hydroxide to cause precipitation of the carbonate and magnesium hardness and produce a phenolphthalein alkalinity which was equal to or slightly greater than half the total, brought about co-precipitation of part of the fluorides present. In one test a water containing 5.0 p, p. m. of fluorides was reduced to 3.0 p. p. m. while another containing 3.0 p. p. m. was reduced to 2.1 p. p. m. ACKNOWLEDGMENT The activated alumina, silica gel, and synthetic zeolite used in this investigation were furnished through the courtesy of International Filter Company, Chicago, Ill. LITERATURE CITED (1) Boissevan. Colorado Medicine (April, 1933). (2) Boruff and Abbott, IND.ENO.CHEM.,Anal. Ed., 5 , 236 (1933). (3) Buswell, “Chemistry of Water and Sewage Treatment,” p. 164, Chemical Catalog, 1928. (4) Dean, J. Am. Dental Assoc., 20, 319 (1933). ( 5 ) Dean, Pub. Health Repts., 48, 703 (1933). (6) Sebrell, Dean, Elvove, and Breaux, Ibid., 48, 437 (1933). (7) Smith, Lantz, and Smith, Ariz. Expt. Sta., Tech. Bull. 32, 253 (1931). (8) Smith and Smith, Ibid., 43, 213 (1932).
RECEIVED September 12, 1933. Presented before t h e Division of Water, Sewage, and Sanitation Chemistry st the 86th Meeting of t h e American Chemical Society, Chicago, Ill., September 10 to 15, 1933.
Effect of Water Vapor on Ignition Temperatures of Methane-Air Mixtures G. W. JONES
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HENRY SEAMAN, U. S. Bureau of Mines Experiment Station, Pittsburgh, Pa.
If the presence of water vapor Water vapor, in amounts above 5 mm. vapor has an appreciable effect on the the Bureau of Mines for deraisesthe ignition temperatures ease of ignition of natural gastermining the permissibility of methane-air mixtures. The maximum inair mixtures by explosives when of explosives, natural gas-air crease in ignition temperature is 11’ and ocmixturesof uncontrolled humidithe hot products of detonation ties -axe used. Objections have curs f o r a saturated mixture containing approxiare discharged into the mixtures, then, since natural gas consists been raised to these tests on the mately 4 per cent methane. Water vapor has no largely of methane, differences grounds that the moisture conappreciableeffect upon the lag on ignition f o r tent of the mixtures may affect should be found in the ignition methane-air mixfures. the ease of ignition which is detemperature of methane-air mixtermined largely by the ignition tures, or in the lag at the ignition temperature and the lag at the ignition temperature. The temperatures, when the percentages of water vapor present ignition temperature may be defmed as that temperature at in methane-air mixtures are changed. Tests are made with which rapid combustion becomes independent of external s u p this end in view. plies of heat. The lag is the time required at the given temPREVIOUS WORKON RELATION OF MOISTURE TO IGNITION perature to cause ignition of the mixture. TENPERATURES Ignition temperatures are affected by a number of variables; the most important, in addition to lag, are the percentage Although the specific effect of small traces of water vapor of combustible in the mixture, the oxygen concentration, the on gaseous reactions has been known since Dixon’s historic size and form of the apparatus used and the material of which report in 1880 ( 2 ) , few determinations of the effect of water it is composed, the pressure on the mixture when ignition vapor on ignition temperatures have been reported. Prettre occurs, and the presence of catalysts and small amounts of and Laffitte (4) studied the effects of “burnt residual gases” impurities in the mixtures. on the ignition temperatures of carbon monoxide. They By using an apparatus of a definite size and structure, and found that the ignition temperature of one mixture was lowan oxygen supply of constant proportions (normal air), by ered 30’ C. by 7.6 per cent of water vapor. This corresponds conducting the experiments a t atmospheric pressures, and with the reports of Bone and Weston (1) who found that the by eliminating impurities in the mixtures, the effect of water ignitibility by condenser discharge sparks of a 2CO 0 2 mixvapor on the ignition temperature of a combustible-air mis- ture rapidly diminishes as the water vapor is removed, the ture can be determined. minimum spark energy required to ignite it increasing until X THE gallery tests used by
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