I. The Rate and Mechanism of the Air Oxidation of Parts-Per-Million Concentrations of Nitric Oxide. II. The Quantitative Determination of Parts-per-Million Quantities of Nitrogen Dioxide in Nitrogen, Oxygen, and up to 75 p.p.m. of Nitric Oxide by Electron-Capture Detection in Gas Chromatography

Citation

Morrison, Milton Edward (1965) I. The Rate and Mechanism of the Air Oxidation of Parts-Per-Million Concentrations of Nitric Oxide. II. The Quantitative Determination of Parts-per-Million Quantities of Nitrogen Dioxide in Nitrogen, Oxygen, and up to 75 p.p.m. of Nitric Oxide by Electron-Capture Detection in Gas Chromatography. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/12M9-RH51. https://resolver.caltech.edu/CaltechETD:etd-01232004-114631

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Part I A study of the air oxidation of parts-per-million (p.p.m.) concentrations of nitric oxide was carried out in a constant-volume, batch reactor. The initial concentration of nitric oxide was varied from 2 to 75 p.p.m. while the oxygen concentration ranged from 3 x 10[^4] to 25 x 10[^4] p.p.m. The rate of the reaction was measured in the ambient temperature region from 17 to 37[degrees]C and at a pressure of one atmosphere. Gas analyses were made by means of chromatography. The initial order of the oxidation reaction in the absence of nitrogen dioxide was 2.00 [plus or minus] 0.09 for nitric oxide and 0.97 [plus or minus] 0.11 for oxygen. From initial rate data at 26.5[degrees]C, a third-order rate constant of (1.297 [plus or minus] 0.051) x [...] was obtained. There were no measurable surface effects due to the Pyrex reaction vessel, but the addition of nitrogen dioxide did increase the initial oxidation rate. The initial third-order rate constant in the absence of nitrogen dioxide exhibited a small negative activation energy. A mechanism was proposed which involved six reactions with NO3, N2O3, and N2O5 as intermediates. When the rate equation which resulted from that mechanism for the oxidation of nitric oxide was integrated, the standard deviation of the predicted concentration of nitric oxide from the experimental data in the range from 2 to 75 p.p.m. of nitric oxide was 1.6 p.p.m. Part II A gas chromatograph was developed for the quantitative analysis of gas mixtures containing nitrogen dioxide at concentrations from 0.5 to 75 p.p.m. in nitrogen, less than 25 x 10[^4] p.p.m. of oxygen, and up to 75 p.p.m. of nitric oxide. The chromatography column consisted of powdered Teflon, Fluoropak 80, which had been coated with a methyl silicone oil, SF-96. A parallel-plane electron-capture detector when operated in the pulse mode was found to be the most sensitive chromatography device available for the detection of nitrogen dioxide. The analysis was accurate to an absolute deviation of 3.4 percent, with a standard deviation of 1.3 p.p.m. in the concentration range from 3 to 75 p.p.m. of nitrogen dioxide when oxygen was present to the extent of 25 percent by volume in nitrogen. The detection limit for the method was 0.5 p.p.m. of nitrogen dioxide. Studies were carried out to determine the optimum properties and operating conditions for the chromatography column. The parameters that affected the sensitivity of the electron-capture detector were examined. These included temperature, flow rate, cell geometry, size of tritium source, voltage, and the means of applying this potential to the cell. Photographic materials on pp. 87, 88, 154, 155, 157, 158, 159 are essential and will not reproduce clearly on Xerox copies. Photographic copies should be ordered.

Thesis Files