A. C. ANDREWS, B. L. MICKEL, and K. C. KLASSEN Kansas State College, Manhattan, Kansas
IN
TRE construction of laboratory ozonizers employing consists of a 4-mm. Pyrex tube filled with mercury the Berthelot tube ( I ) , extensive glasswork involving and connected to a high-voltage transformer a t D. large-diameter tuhing is necessary. Furthermore, it Electrical contact with the mercury is obtained by is customary t o immerse these units in an external means of a removable cork stopper through which water bath which serves as one high-voltage electrode a small bolt or other suitable conductor has beeu and also cools the appamtus. Where extensive use passed. The electroded tube is filled with merrury and justifies their permanent location, such large units the stopper is then inserted into its open end in such give excellent service. However, for laboratories need- a manner that no air bubbles are trapped in the mering ozone infrequently, a smaller, self-contained, and cury column. The other high-voltage terminal leads more easily constructed ozonizer might he more de- into the water-jacket by means of a soft-glass connection E, into which a platinum wire has been sealed. sirable. Cooling water enters the apparatus at F and exits a t E. The ozonizer is supported upon a wooden stand. A 110-volt neon-sign transformer whose secondary (center-grounded) delivers 30 milliamps a t a potential of 12,000 volts was employed to produce the silent discharge. General Operation. All glassware in contact with ozone was cleaned prior to operation. Ground-glass fittings were sealed with small amounts of silicone grease applied only at the outside extremities of each fitting so that a minimum amount could contaminate End Aeembliaa of th. Ononiz.. the inside of the ozonizer. Water was allowed to flow Simpler types of ozonizers have been described through the condenser until a constant temperature (5, 6), but in these no provisions for electrode cooling had been attained, meanwhile passing oxygen through have been made. Henne and Perilstein (92) describe the apparatus in order to displace all air; the transa successful Pyrex ozonizer featuring an integral water- former circuit then was closed and ozone was collected. Calculation of Yield. I n the estimation of perjacket electrode and a recycling of the oxygen a second time through the region of electrical excitation. Their centage yields a t various rates of oxygen input, flow ozonizer is fabricated from Pyrex tuhing and, as is the rates were indicated by a conventional differential case in the construction of Berthelot tubes, consider- manometer. For each flow rate the time necessary to introduce 200 rnl. of oxygen into the apparatus was able glasswork is necessary in its assembly. We have employed an ordinary Pyrex West con- calculated; during this time the ozone was bubbled denser and Pyrex tubing in the construction of an oz- through a 5 per cent XI solution, contained in two onizer of the Henne-Perilstein type. This unit, shown collection flasks connected in series. The solutions in the figure, is simply constructed from stock ma- from both receivers were then combined, acidified terials, may he mounted in any position, is compact, with 5 per cent H2S04, and titrated with 0.01 M sturdy, and provides controlled amounts of ozone for Na2S203. Linear starch indicator solution (3, 4) was used. Duplicate titrations were run a t each flow many laboratory operations. Oxygen, dried by bubbling through a sulfuric acid rate, and the average yield of ozone in each pair was tower and regulated by means of a needle valve, is used in the calculations. The average variation from metered through a flowmeter and enters the ozonizer the mean of these ozone yields in these duplicate a t A, passing the length of the water jacket through titrations was *3.7 per cent. At 25'C. and a t a flow the tube connected to the fitting A. The mixture of rate of 2 1. per hour, approximately 2 per cent of the oxygen and ozone formed in the first pass then re- entering oxygen was converted to ozone. At flow verses its direction of flow through the electrode area rateslower than this, a yieldof 4per cent was approached and is emitted a t B. The ozone may he passed into as a limiting value, while a t higher flow rates, cona collection assembly orreleased into a hood or ozone version was less complete. Optimum yield, in terms destroyer. By means of a simple hall-and-socket of moles ozone delivered per unit time, was achieved joint or standard taper connection, the collector may a t flow rates in the vicinity of 8 to 10 1. of oxygen he coupled to the ozonizer. The central electrode C per hour. 34
MARCH, 1955 ACKNOWLEDGMENT
The authors wish to thank the Research Corporation for financial support of the work leading to this paper. Credit is also due to Dr. Ronald F. Cotts of the zonolite company, E ~ lllinois,~ for pre-~ liminary work involving several other types of ozonizers.
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LITERATURE CITED (1) HARRIES, C.,Ann., 343, 339, 343, 376 (1905). (2) HENNE,A. L., AN^ W. L. PERILSTEIN, J. Am. C h m . SOC., 65, 2183 (1943). (3) LAMBEET, J. L.,Anal. Chem., 2% 981 (1953). (4) SCHOCH, T. J . , J . Am. Chem. Sac., 64, 2957 (1942). ~ ~ ~ ~I d . Eng. ,Chem., Anal. W., AND W. CARMODY, (5) SHEERAN, Ed., 9, 8 (1937). (6) UHRIG, K., J. CHEM. EDUC., 22, 582 (1945).
