ENRICHMENT OF OXYGEN-18 BY THE CHEMICAL EXCHANGE OF NITRIC OXIDE WITH NITRIC ACID SOLUTIONS
The rapid exchange of O/sup 18/ between nitric oxide and nitric acid solutions occurs with a single stage enrichment factor of 1.020 plus or minus 0.002 in approximate agreement with calculations from spectroscopic data. Since O/sup 18/ concentrates in the gas phase, the use of the system required the conversion of nitric oxide to water and nitric acid. This was accomplished by partial decomposition of the nitric oxide in an arc, and reaction of the remainder with hydrogen to form wafer. The water extracted NO/sub 2/ from the gas stream to form nitric acid of the desired concentration. Some of the characteristics of the exchange reaction were investigated during the operation of exchange columns for the concentration of O/sup 18/. For 8 M nitric acid, the height equivalent to a theoretical plate (R.E.T.P.) increases approximately linearly with flow rates above 80 mg atoms of O/min-cm/sup 2/. At 25 deg and a flow rate of 85 mg atoms of O/min-cm/sup 2/, the maximum over-all separation was obtained for 6 M HNO/sub 3/. Although the rate of the exchange reaction increases with increasing acid concentration, the value of ( alpha -- 1) decreases so that ( alpha --1)/H.E.T.P. is msximum for 6 M HNO/sub 3/. The over- all separation was not greatly affected when the temperature was increased from 25 to 80 deg , indicating that the product of the transfer coefficient and ( alpha -- 1) is approximately constant. With a decrease in temperature, the decrease in the transfer coefficient was not compensated by and increase in ( alpha - 1), so that the over-all separation decreased with the temperature was lowered to 0 deg . Cohen's theoretical equations for the increase in isotope concentration with time were used to analyze the operation of the exchange column and to determine the ratio of hold-up at the reflux end to the hold-up in the column. The optimum operating conditions for the system were selected and a comparison was made with other methods of concentrating O/sup 18/. The exchange system described appears to be somewhat more favorable than the distillation of water, but not as promising as the low temperature distillation of nitric oxide. (auth)
- Research Organization:
- Columbia Univ., New York
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-18-000531
- OSTI ID:
- 4158897
- Journal Information:
- Journal of Physical Chemistry (U.S.), Journal Name: Journal of Physical Chemistry (U.S.) Vol. Vol: 66; ISSN JPCHA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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