An experimental comparison of a kinetic model for the reaction of alpha-pinene and Delta(3)-carene with ozone and nitrogen oxides.

Unlabelled: A kinetic model was compiled to simulate reactions of the monoterpenes, alpha-pinene and Delta(3)-carene, with O(3), NO(2) and NO. The influence of different initial settings of O(3), NO(2) and NO on the monoterpene reaction was evaluated. At initial levels of 75 p.p.b. of O(3), NO(2) and NO each, 1.5% of alpha-pinene and 1.1% of Delta(3)-carene were calculated to react after 215 s. The corresponding experimental results showed that 9.3-12.2% of alpha-pinene and 9.9-11.7% of Delta(3)-carene reacted. The calculated levels of O(3), NO(2) and NO were compared to experimental measurements and were shown to correspond well. However, comparison of the amount of monoterpene reacted between calculated and experimental results, demonstrated that the calculations underestimated the amount of monoterpene reacted in the experimental chamber. The difference between experimental and calculated results could, e.g., be the effect of surfaces and the presence of water, which are parameters not included in the kinetic model known to have influence on these reactions.

Practical Implications: A compiled kinetic model could be used to predict concentrations of O(3), NO(2), NO and to predict the effects on the monoterpene reaction in a Teflon reaction chamber when changing the initial concentrations of O(3), NO(2). However, the results in the present work show that surface and moisture effects have to be settled and the effects included in future models.