E. C. Tuazon, S. M. Aschmann, R. Atkinson
Apr 5, 2000
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39
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Journal
Environmental Science & Technology
Abstract
The current widespread use of poly(dimethylsiloxane)s (PDMS) in a broad range of applications leads to their release into soil environments where they degrade to monomeric products, primarily dimethylsilanediol, most of which enter the atmosphere by volatilization. The major degradation pathway of volatile organosilicon compounds in the atmosphere is expected to be a reaction with hydroxyl (OH) radicals. In this work, the kinetics of the gas-phase reactions of dimethylsilanediol, trimethylsilanol, and tetramethylsilane with the OH radical were measured using a relative rate method which employed the N2H4 + O3 reaction as a nonphotolytic source of OH radicals, with analysis by Fourier transform infrared (FT-IR) spectroscopy in a 5870 L chamber. The measured values of the OH radical reaction rate constants (cm3 molecule-1 s-1) at 298 ± 2 K are as follows: dimethylsilanediol, (8.1 ± 1.0) × 10-13; trimethylsilanol, (7.2 ± 0.8) × 10-13; and tetramethylsilane, (8.5 ± 0.9) × 10-13. These values lead to an estim...