I S D U S T R 1-4 L I S 1) E N G I N E E R I S G C H E \l I S T R Y
J a n u a r ? , 1933
Judging from these results, higher paraffins can be expected to show higher extents of dissociation a t equilibrium by reason of the formation of olefins containing two or more substituent groups attached to the ethylene group. In addition, the increasing number of independent dehydrogenation reactions which a paraffin can undergo increases with molecular weight, and the extent to which the paraffin dissociates should increase accordingly.
ACKXO WLEDGMENT The authors are indebted to G. G. Oberfell and R. C. Alden for their generous support, and to L. H. Fitch and H. J. Hepp for assistance in the analysis of complex mixtures. LITERATURE CITED (1) Burrell, Seibert, and Jones, Bur. Mines, Bull. 197,41 (1925). (2) Dillon, Young, and Lucas, J . Am. Chem. SOC.,52, 1953 (1930).
59
(3) Egloff,Schaad, and Lowry, J . Phys. Chem., 34, 1617 (1930). (4) Francis, IXD.ESG. CHEW, 20,227 (1928); Francis and KleinSchmidt, h m . Petroleum Inst., Proc. lOlh Ann. M e e t i n g , 11, Sect. 111. 93-9 (1930). (5) Frey and \’ant, IXD.EBG.CHEx, 19,492 (1927). (6) Giauque, J . Am. Chem. SOC.,52,4816 (1930). (7) I. G. Farbenindustrie Akt.-Ges., French Patent 637,410 (July 11, 1927); British Patent 301,402 (June 27, 1927). (8) Lewis and Randall, “Thermodynamics,” p. 173, McGraw-Hill, 1923. (9) Oberfell and Alden, Oil Gas J., 27,142 (1928). (10) Parks and Huffman, J. Am. Chem. SOC.,52,4381 (1930). (11) Pease, Ibid., 45,2296 (1923). (12) Pease, Ibid., 50,2715 (1928). (13) Pease and Stewart, Ibid., 49,2783 (1927). (14) Podbielniak, Oil Gas J., 28,38 (1929); 29,235 (1930). (15) Shepherd and Porter, ISD.ESG.CHEM.,15, 1143 (1923). (16) Tausz and Putnoky, Ber., 52B,1573 (1919). (17) Van Wartenburg, Z.physik. Chem., 61,366 (1908). RECEIVED July 43, 1832.
Behavior of Activated Carbon with Metallic Water-Purification Equipment A.
s. BEHRMAN
AND
H. GUSTIFSON,International Filter co., Chicago, 111.
for installation; there was no I t has been found that a relaticely high por e a s o n t o e x p e c t fate to be the w r i t e r s ’ organization tential difference is set up between a bed of kinder in those situations than it began actively the commeractivated carbon and the metallic water-purijicahad been in Chicago. cial development in this country tion equipment in which the carbon is used. of the use of granular highly acCARBON-hTETdL TESTS T h i s behavior is not exhibited by wood charcoal tivated carbon for water purificaO p e r a t i n g on o n e of the tion, primarily for the removal or other carbons previously employed in water “hunches” that is frequently the of objectionable tastes and odors. purification. A dielectric lining is now prosalvation of any research laboraIt was natural that the first comcided f o r such metallic equipment in order to tory, a short section of steel pipe mercial units designed for the avoid injury to the carbon, contamination of the was filled with granular Hydropurpose should follow the design water, and eventual destruction of the metallic darco (the a c t i v a t e d carbon and construction of the convenused by the writers’ organizaequipment. Typical comparative data are given tional pressure sand filter, with tion) and covered with Chicago the sand replaced by granular showing Ihe potenfial differences set up between city water. Electrical connecactivated carbon. various types of carbons and a number of metals. tions were then made from the Two weeks after the first inThe suggestion is made that there m a y be a steel and from the carbon to a stallation of this sort mas made in relationship between the potential differences set sensitive millivoltmeter. The Chicago, it was reported that the needle was deflected v i o l e n t l y u p under certain conditions and the activity of effluent water from the activated across the entire scale. carbon purifier contained an apcarbons in some types of adsorption phenomena. Tests with o t h e r c o m m o n preciable quantity of ferric hymetals and allovs showed the droxide. Although this report was somewhat annoying, no special concern was felt a t the time, same effect, though to a varying degree f n all cases the since it was believed that the source of ferric hydroxide could activated carbon was found to be cathodic to the metallic probably be accounted for by the corrosive effects of the oxygen element of the couple, thus accounting for disintegration and in Lake Michigan water on the new steel tank of the purifier; eventual disappearance of the metal. Other highly activated carbons were next tried, with similar and, since this water is characteristically slightly supersaturated with calcium carbonate, it was confidently felt that a results. With relatively inactive forms of carbon, however, protective coating would be deposited on tkle steel fairly such as the -wood charcoal and bone black previously employed in water purification, no potential difference could rapidly, thus arresting further corrosion. Accordingly, a second examination was made a few weeks be detected. In Table I are shown the potential differences observed later. The situation was fully as bad as before, if not worse. Not only was the amount of ferric hydroxide in the effluent between various types of carbons and a number of different water decidedly objectionable in itself, but it was plainly only metals and alloys. The apparatus used in making these a question of time before the carbon would be definitely measurements consisted of a specially prepared electrode of injured by the coating of ferric hydroxide, and before serious the carbon being tested, a plate or rod of the metal, and a disintegration of the steel shell would result. sensitive voltmeter. The carbon electrode comprised a The problem was one which obviously required a quick slotted hard-rubber tube (taken from the positive element of solution. To make matters worse, several similar pieces of an Exide Ironclad storage battery) filled with particles of the equipment were on their way to various parts of the country carbon, thoroughly washed, and screened uniformly through
S THE early part of 1929
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INDUSTRIAL AND E N G I N E E R I N G CHEMISTRY
10 to 14 mesh (screen openings 1.65 and 1.29 mm., respectively). These tubes are inch (0.79 cm.) inside diameter and were used in 5-inch (12.7-cm.) lengths. After stoppering the bottom end of a tube, the tube was filled within a half inch (1.27 cm.) of the top by adding successive small portions of the dry granular carbon, lightly tapping the tube after each addition. The electrode was then immersed in water to a depth of 1.5 inches (3.81 cm.), and allowed to become thoroughly saturated. The metal electrode, likewise submerged in the water to a depth of 1.5 inches (3.81 cm.), was placed 1 inch (2.54 cm.) from the carbon electrode and connected to one side of the voltmeter. Just before making a reading, the half inch of free space in the upper portion of the carbon electrode tube was quickly filled with dry carbon, and the tube was tapped to compact the carbon and to remove any air bubbles. The circuit was then completed by means of a brass rod, one end of which was placed in contact with the carbon, the other end being connected to the voltmeter. The purpose of these precautions was obviously to insure a dry contact between the carbon and the brass connector, and so avoid the danger of the deceptive readings which would have been obtained if the brass had come in contact with the electrolyte. The wood charcoal and bone black used in these experiments were good commercial grades of these materials. Of the activated carbons employed, Hydrodarco is prepared by processing certain Texas lignites; and Xuchar is made from certain cellulosic residues in the paper industry. Minchar is prepared by the destructive distillation of a carbonaceous shale. Only these carbons are included in the accompanying tables, as certain comparative data concerning them have already appeared in the literature (2); but other carbons have been similarly studied.
Vol. 25, No. 1
contact with water or stronger electrolyte. Here again the procedure followed was one chosen for its convenience and rapidity in giving results of relative value, rather than the cumbersome (and in this case not so practical) method ordinarily followed in plotting the so-called adsorption isotherm ( I ) , The method employed consisted essentially in allowing a solution containing an excess of phenol to percolate through a bed of granular carbon under carefully controlled conditions, and then in determining the residual phenol in the effluent. The aqueous solution of phenol used contained 250 mg. per liter. The carbon bed had a depth of 6 cm. and a volume of 32 cc. As before, the carbon was screened through 10 to 14 mesh, and was thoroughly washed before use. One liter of the phenol solution was passed through the carbon bed in just 30 minutes, the flow being controlled by means of a calibrated orifice. The adsorption capacities of the various carbons tested are given in Table 11. TABLE11. CARBON
PHENOL
-4DSORPTION CAPACITP
PHENOL REMOVED BY 32 cc. CARBOX
CARBON
PHENOL REMOVED BY 32 cc. CARBON
MQ. Hydrodarco Nuohar Bone black
195 127 43
Minchar Wood charcoal
M g. 12 9
DISCUSSION OF RESULTS
It is evident that there is a striking parallelism between the
magnitude of the potential difference set up by a carbon with a metal, and the adsorption capacity of that carbon for phenol. If the behavior of carbons in other respects exhibits a consistent relationship of this sort, the thought suggests itself that the magnitude of the potential difference set up under certain control conditions might be taken as a crude measure of, or index to the activity of a given carbon. Not enough TABLEI. VOLTAGESOF VARIOUSCARBON-METAL COUPLES data are available a t this time to do more than suggest this possibility. ELECCARBONTROLYTEMETAL Based on the work described in the foregoing and upon Stainother related investigations, a patent application was filed Cast less Steel Brass Monel iron Cu Zn A1 Pb steel covering metallic water-purification equipment, employing a 1” 0 . 1 2 0.06 0 . 0 9 Hydrobed of activated carbon in which a nonconducting lining is darco 2 b 0.14 0.06 0 . 1 0 1 0 . 0 8 0.04 0.05 Nuchar inserted between the carbon and the metal. Shortly after 2 0.08 0 . 0 4 0.06 Minchar 1 0.00 0.00 0.00 this application was filed, a patent on the same subject was 2 0.00 0.00 0.00 issued to Brandt (3) of the Darco Corporation. It is all too 1 0.00 0.00 0.00 Bone black 2 0.00 0 . 0 0 0 . 0 0 common, in industrial research and development, to find Wood (maple) 1 0.00 0 . 0 0 0.00 0 . 0 0 0 . 0 0 0 . 0 0 0.00 0 . 0 0 0 . 0 0 work and results anticipated by some other investigator. one’s charcoal 2 0.00 0.00 0.00 0.00 0.00 0 . 0 0 0 . 0 0 0.00 0.00 The present case is unusual in that Brandt’s organization was a Chicago city water (total solids, 150 p. p. m.; pH 7.9). b Chicago city water plua 350 p. p. m. NaCl (pH 7.8). already associated with that of the writers’, so that the fruits of both investigations could be combined commercially, even The values of the potential differences given in Table I though there had been unknowingly and unintentionally an are relative rather than absolute; it is entirely possible that appreciable duplication of effort and expense. Another method of overcoming the destructive galvanic refinement of the procedure employed would slightly modify these results. For the purpose of the inquiry a t hand, how- action described in the foregoing is to apply a small counterever, it is felt that these data are amply accurate. electromotive force. A description of this method (which is covered by a pending patent application) and results obtained with its use are reserved for presentation in a future paper. PHENOL ADSORPTIVECAPACITYOF CARBONS The question then arose as to a possible connection between the potential difference developed in galvanic couples of the sort described and the activity of the various carbons as measured in other ways. Since one of the most useful characteristics of activated carbon in water purification is its ability to remove phenols, chlorophenols, and other phenolic derivatives, the effort was made to determine whether or not the phenol adsorption capacity of a carbon could be related to the potential difference set up between itself and a metal in
LITERATURE CITED (1) Bancroft, “Applied Colloidal Chemistry,” p. 28, McGraw-Hill, 1921
J. Am. mater W o r k s Assoc., 21, 789 (1929); Norcom and Dodd, Ibid, 22,1415 (1930). (3) Brandt, U.S.Patent 1,781,314(Nov. 11, 1930). (2) Baylis,
RDCEIVED June 2, 1932. Presented before the Division of Water, Sewage, and Sanitation Chemistry a t the 83rd meeting of the American Chemical Society, New Orleans, La., March 28 to April 1, 1932.
