INDUSTRIAL AND ElYGI.VEERI.VG CHE*MISTRY
August, 1927 Table V-Imports YEAR 1917 191s 1919 1920 1921 1922 1923 1924 1925 1926
of P h e n o l i n t o t h e U n i t e d S t a t e s CRYSTAL Pounds 30,700 148,300
... ...
250 349,500 126,600 176,100 256,100 2 18,400
LIQUID Pounds 3 14,600 134,400 2,100 1,000 147,'ioo 2,800 44 1,600 QS,700
25,900
Since the war phenol imports have come very largely from England. The raw material from which it is obtained in that country is derived from coke ovens, gas houses, and blast furnaces. The coke ovens, operated in connection with coal mine:: or steel mills, have been undergoing the same change as in this country, and a recent official statement gave the proportion of by-product ovens in 1924, as disclosed by a census survey, as about 75 per cent of the total. I n the gas houses the coal gas process largely prevails, in contrast to the practice in this country where water gas has for the most part taken the place of coal gas. Tar from coal gas is much richer in the tar acids than that from water gas, and England can produce much more of them than she needs. The 1924 census showed an output of coke-oven and blastfurnace tar of some 500,000 tons, from which more than 3 million pounds of carbolic acid were obtained. KO figures are to be had which would show what proportion of the total output in England is represented by these amounts. British raw-material costs in making phenol are somewhat lower than in this country, and labor and other costs are very much lower. An investigation made in 1923 showed t h a t the American cost of production, including that of both natural and synthetic phenol, was 142.5 per cent of that of the largest producer of refined phenol in England. Cresylic Acid
Although in synthetic resin manufacture cresylic acid is practically interchangeable with phenol, conditions of production and trade are materially different. It is not made synthetically, the whole supply coming from tar distillation. As commercial production in this country is in the hands of a single large concern, with twenty or twenty-five plants, annual figures of output cannot be given. There has, however, been a marked increase within the last two or three years.
919
Prior to the passage of the Tariff Act of 1922 all cresylic acid entered free. The normal importation was heavy, averaging some 8 or 9 million pounds a year. In 1920 the trade reached its peak with a total of 10,600,000 pounds, including cresol and distillates of tar containing a considerable proportion of cresol, the whole being valued a t $957,000. The use of war-time phenol greatly reduced the import trade. The 1922 Tariff Act put a heavy duty on refined cresylic acid but pemitted the crude still to come in free. The line was drawn by assuming that crude cresylic acid would fall in that class of tar products distilling less than 5 per cent tar acids below 190"C. Foreign manufacturers apparently have been able to control their processes so that grades of cresylic acid can be produced which will fall in that class but which can be easily refined to higher grades. Although domestic production has considerably increased since 1922, imports have continued to come in to the extent of some 2 million pounds a year, nearly all free of duty. Within the last year cresylic acid imports have shown a big gain, the 1926 trade being nearly three times that of the year before. Imports of cresylic acid were not separately classified under that name before 1924. For the last three years crude cresylic acid imports and those of distillates yielding less than 5 per cent tar acids under 190' C., all of which are admitted free, have been as shown in Table VI. of Crude Cresylic Acid, Etc. TARDISTILLATES YIELDING LESS THAN 5 PER CENTT A R CRESYLIC ACID ACIDSUNDER 190' C. Pounds Value Pounds Value 2,327,500 $157,600 2,440,400 $151,900 2,163,600 122,700 5,994,800 367,700 5,802,900 331,600 3,136,800 197,000
Table VI-Imports YEAR 1924 1925 1926
Refined cresylic acids subject to duty are classified as tar distillates yielding 75 per cent or more of tar acids below 215' C. Imports for the three years have been as follows: YEAR 1924 1925 1926
POUNDS 378,400 135,800 7,200
VALUE $38,800 29,000 4,200
Cresylic acid can be produced in England a t much lower cost than in this country. A recent inquiry revealed a n average cost about one-half that of American manufacture.
Estimation of Organic Matter in Sewage and Effluent' Modification of Adeney's Acid Dichromate Method By W. E. Abbott LABORATORY OF CHIEFSANITATION CHEXIST,SHANGHAI MUNICIPAL COUNCIL, CHINA
RGANIC substances can be oxidized rapidly and almost completely to carbon dioxide by a mixture of potassium dichromate and sulfuric acid a t a high temperature. Several methods have been described for estimating the carbon in organic substances by the use of this oxidizing mixture, the carbon dioxide evolved being absorbed and weighed. Small amounts of carbon monoxide are produced, however, and must be oxidized either by passing the mixed gases with air over heated platinized asbestos or by some other means. Several years ago Adeney found that many organic substances were completely oxidized by prolonged digestion
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Received March 28, 1927
with a concentrated mixture of sulfuric acid and potassium dichromate a t the temperature of the water bath. Moreover, a t this temperature there was no appreciable spontaneous loss of oxygen from the dichromate such as occurred a t higher temperatures. It was thus possible to use a measured amount of potassium dichromate and to titrate the excess a t the conclusion of the digestion. The loss represented the oxygen required to oxidize the organic matter to carbon dioxide and water. I n other words, the method promised to be the means of estimating the oxygen which a polluted liquid would consume during the complete conversion of its organic matter to carbon dioxide, water, and ammonia. Unfortunately, this reaction could not be
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INDUSTRIAL A N D ENGINEERING CHEMISTRY
directly applied to polluted liquids, owing to the chloride which they contained in solution. The chloride reacted with the dichromate to form chromyl chloride and chlorine, thereby causing a very large error. It was necessary either to find some means of correcting for this chloride error or to displace the chloride before performing the test. The second method was found most feasible, evaporation with sulfuric acid being adopted to drive off hydrochloric acid. These facts were disclosed by Adeney to the writer several years ago. Three years ago the test was adapted for use in this laboratory, a very large number of tests being performed from time to time to investigate possible limitations. The results obtained in these tests and the experience gained in the use of the method as a routine determination are discussed in this paper. Conditions for Successful Chloride Removal
Vol. 19, No. 8
or 3 cc. of 10 per cent sulfuric acid added. The top of the basin is covered with a filter paper laid between two solidglass triangles to ward off smuts and dust. Evaporation on the water bath is continued with occasional stirring until about 0.7 cc. of liquid remains, when the sample is vigorously stirred a t intervals during 3 or 4 minutes to remove the chloride. Twenty-five cubic centimeters of 0.125 N dichromate solution are added and evaporation is resumed until about 1 cc. remains. Five to ten cubic centimeters of concentrated sulfuric acid are added, and the basin is left on the water bath for 2 hours. The liquid is then diluted with distilled water, and the residual dichromate is titrated with ferrous sulfate, using potassium ferricyanide as external indicator. The greatest care failed to eliminate the necessity for blank determinations. The liquid in the basins undergoing digestion must be maintained above 94' C.
Application to Known Organic Substances Many series of tests were carried out both with chloride solutions and effluent samples to determine the most satisI n the procedure finally adopted the conditions for maxifactory procedure. It was mum oxidation are not invariably found necessary m a i n t a i n e d throughout, to evaporate until the sulThe oxygen absorbed from A modification of Adeney's acid dichromate method furic acid became concendichromate by various orfor the determination of organic matter in sewage trated to about 50 per cent ganic substances when suband effluent is described, together with the principal by volume before there was jected to the modified direasons for its adoption. much chloride loss. The chromate test was therefore Experimental evidence is summarized to show that addition of 3 cc. of 10 per determined. The o x y g e n the oxygen absorption i n the method is of the same cent sulfuric acid to 25-100 actually absorbed was exmagnitude as the oxygen absorption which would cc. of a liquid containing pressed as a percentage of occur during the complete conversion of the organic 100 to 200p.p.m.of chlorine the oxygen calculated as matter to carbon dioxide, water, and ammonia. gave the most satisfactory The new method is shown t o possess very marked n e c e s s a r y to convert the results. advantages over the permanganate absorption test. substance into carbon dioxide, water, and ammonia. I n every case there was T h i s p e r c e n t a g e usually some darkening of the liauid during this evaporation, and considerable charring was varied slightly from day to day. The results are summarized observed in certain cases when the liquid had reached a low in Table I. These figures are all lower than they would have bulk. Observations were therefore carried out to determine been had not the procedure for chloride removal been necessary. the minimum time for which the liquid must be maintained Table I-Percentage Oxidation at low bulk with the certainty of chloride removal. It DIGESTION WITH EXCESS SULFURIC ACID was found that occasional stirring during 3 minutes after SUBSTANCE None 1 hour 2 hours 3 hours Rochelle salt 90 the liquid had attained a bulk of about 0.7 cc. left in the Lactose 89 to 93 98 9s worst case only an insignificant, trace of chloride. Main- Sodium oxalate Succinic acid 93 99 99 tenance on the water bath for 10 minutes after the attain- Asparagine 90 to 95 acid 78 to 80 80 ment of this bulk gave a loss of from 0 to 5 per cent of the Sulfanilic Cellulose (filter paper) 83 t o 84 84 85 to 90 60 65 to 70 total oxidizability. Use of the test as a routine deter- Peptone (Difco) (Witte) 66 mination has shown that some trials are necessary before Peptone Egg albumin 61 Gelatin 62 66 the point at which chloride removal is complete can be Stearic acid 44 73 74 judged satisfactorily. Until this skill is attained it is best to allow an excessive contact with acid, as the loss of oxidizaThis causes losses due to the decomposition by the acid bility is not great, whereas the presence of residual chloride during the evaporation to drive off chloride and also because would produce a large error. for some time after the addition of dichromate solution a Relation between Acid-Dichromate Concentration and weak acid and dichromate solution is acting on the organic matter. The last-mentioned loss can be eliminated by Oxidation Effected neutralizing the acid with sodium carbonate before adding Working with pure substances, it was found that the the dichromate. With certain substances the percentage amount of oxidation depended primarily on the concen- oxidation was increased-e. g., with sulfanilic acid from 80 tration of sulfuric acid in the solution. The percentage to 99 per cent. I n actual practice with raw sewage samples oxidation increased rapidly a t first and then more slowly the increase in oxidizability was slight. Apart from direct with increase in the concentration of acid. The maximum losses, the low values recorded may in certain cases be due oxidation was always obtained when solid dichromate, dry either to the formation of stable compounds which resist organic matter, and concentrated sulfuric acid interacted. further oxidation under the given conditions or to the evoluThe dichromate concentration in solution was of compara- tion of volatile compounds such as carbon monoxide which tive unimportance. escape further oxidation. Method Adopted Comparison of Acid-Dichromate Absorption and Oxygen Absorbed during Carbonaceous Fermentation Twenty-five cubic centimeters of a raw sewage or a n A sample of raw sewage previously freed from suspended equivalent volume of other liquid are placed in a small evaporating basin, and 0.3 cc. concentrated sulfuric acid matter by centrifugation was diluted suitably with water
INDUSTRIAL A N D ENGINEERING CHEMISTRY
August, 1927
and incubated a t 21 O C. The dissolved-oxygen absorption and the various nitrogen compounds were estimated daily until nitrification commenced. The dissolved oxygen absorbed by the sample during the purely carbonaceous fermentation was obtained from these figures after making the appropriate corrections for the dissolved-oxygen absorption of the diluting water. Table I1 shows the results obtained during three such series of tests. The dissolved-oxygen absorption is on the average 80 per cent of the dichromate absorption in these experiments. Table I1 DISSOLVEDOXYGENABSORBED REFORE hTITRIFICATION STARTS P. P. m.
ACID-DICHROMATE ABSORPTION P. 9.m. 120 101 107
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Relation between Acid-Dichromate Absorption a n d 5 Days’ Dissolved-Oxygen Absorption The relation for any class of liquid varies considerably, no doubt mainly because of the sensitiveness of the dissolved oxygen test to the quantity and quality of the suspended matter in the sample. Table I11 shows the variation of ratio between these two tests with time as a raw sewage is changed by aeration with activated sludge. T o avoid the fluctuations in the dissolvedoxygen absorption due to suspended matter, the analyses were performed after the liquids had been centrifuged and decanted from the suspended matter. Table 111
AERATION
Hours Raw sewage 1 2 4 5 6
OXYGEN ABSORPTION Acid 5 Days dichromate dissolved oxygen P. p . m. P. Q. m. TEST 1 206 130 106 80 86 55
RATIO
Acid dichromate 5 Days dissolved oxygen 1.58 1.32 1.56
...
1.63 1.44 1.55 1.82 4.00
7
8 22 TEST 2
Raw sewage
1 2 4 5 6 7 8
22
158 78.5 65 50 42.8 44.3 37.2 33.6 20.7
residual permanganate is then titrated. Kitrite is destroyed with urea before permanganate addition. With crude sewage the dichromate absorption is on the average 5.1 times greater than the permanganate absorption. The individual ratios vary between 4.6 and 6.3. For raw sewage from which the suspended solids have been removed by centrifuging and decanting, the average ratio is 4.5. For well-purified activated-sludge effluents the average ratio is 2.5. Again the individual ratios vary within narrow limits-namely, 2.2 and 3.0. The variation of the ratio as the liquid changes from crude sewage to purified effluent is shown in Table IV, which records the changes in a sewage sample on aerating with 21 per cent activated sludge. All samples were separated from suspended matter by centrifuging and decanting before analysis.
100 88
Since Adeney has shown that 70 to 80 per cent of the organic matter is oxidized to carbon dioxide, water, and ammonia before nitrification commences, it would appear that in the examples given the dichromate absorption figure approximates the oxygen required to convert all the organic matter into carbon dioxide, water, and ammonia.
112 53.6 39.7 28.2 21.1 22.0 17.5 17.3 3.2
1.41 1.46 1.63 1.77 2.02 2.01 2.12 1.94 6.46
Relation between Acid-Dichromate Absorption and Oxygen Absorption from Permanganate This varies with each sample, but for any class of liquids the ratio does not vary much from a constant average value. The ratios depend on the type of permanganate absorption test used. The modification employed in these determinations, and which gives results which are on the average only 66 per cent of the absorption when using the A.P.H.A. 1923 procedure, is performed as follows: 100 cc. of an effluent (or a smaller volume of a stronger liquid diluted t o 100 cc. with distilled water) are mixed with 50 cc. of 0.0125 N potassium permanganate and 10 cc. of 30 per cent sulfuric acid, and placed in a 37” C. incubator for 4 hours. The
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AERATION
Hours
Table I V OXYGEN ABSORPTION FROM: Acid dichromate Permanganate P. p . m. P. p . m.
RATIO Dichromate Permanganate
It is apparent that the dichromate absorption test affords a more sensitive index of the course of purification than the permanganate absorption test. For instance, as a result of aeration from the sixth to seventh hour the dichromate method records in the example 16.5 per cent purification while the permanganate absorption only records 5.4 per cent Likewise, the percentage purification measured in terms of acid-dichromate absorption is always greater than in terms of the 4 hours’ permanganate absorption-e. g., after 22 hours’ aeration 86.4 per cent against 67.7 per cent. The two alternative modifications published by Adeneyz last year give in actual practice results of the same magnitude as the local modification, the hot-plate procedure giving rather higher and the water-bath procedure rather lowei percentage oxidation. The resulting scientific advantage of the hot-plate procedure appeared to be offset for routine purposes by the extra attention required for careful temperature regulation on the hot plate. As a result the procedure has not been changed for the present. *Adeney and Dawson, Sci. Proc. R o y . Dublin (1926).
SOC., 18 (N S ) , 199
Contamination of Soil Source of Oil “Discoveries” The Geological Survey has announced that contamination of the soils from filling stations or other sources of refinery products is probably responsible for most of the reports regarding the finding of gasoline or kerosene-like material in wells, springs, basements, and other excavations. The reports come from various parts of the United States, said George Otis Smith, the director, and often lead to local excitement. His further comments upon the situation follow: I n a large number of cases, these reports lead t o local excitement and the hope t h a t the material indicates natural occurrences of crude oil which can be developed commercially. These reports come from all sorts of geologically impossible locations. They may be in regions where the underlying rocks are Archean or granites a s well as in regions where the underlying rocks are sediments not intrinsically hopeless as sources of oils. We believe t h a t in practically all such cases the reported occurrences are due to contamination of the soils from filling stations or other sources of refinery products. Of course, there are a few occurrences of particularly high-grade natural petroleums which contain as much a s 80 or even 85 per cent gasoline, b u t even these highest grade crudes do not possess “the chemical and physical properties of gasoline.” They are likely to have a notable difference in distillation range. No cases have come t o our attention in which the laboratory technician is not able t o determine whether the material submitted is a fugitive distilled product or a mixture of products, on the one hand, or a natural product on t h e other.
