Inhibition of the S(IV) Autoxidation in the Atmosphere by Secondary Terpenic Compounds

Authors: Pasiuk-Bronikowska W.¹; Bronikowski T.²; Ulejczyk M.²

Source: Journal of Atmospheric Chemistry, Volume 44, Number 1, January 2003 , pp. 97-111(15)

Publisher: Springer

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Abstract:

To better understand the role of terpenic compounds in atmospheric chemistry the influence of sobrerol, a water-soluble product of photochemical autoxidation or ozonolysis of alpha -pinene, on the rate of S(IV) autoxidation was studied. Laboratory experiments were performed under heterogeneous conditions, at constant supply with S(IV) by dissolution of CaSO₃.1/2 H₂O fine particles and with air oxygen by diffusion through a planar gas-liquid interface. The progress of S(IV) autoxidation, uncatalysed or catalysed by Fe₂(SO₄)₃ or CoSO₄, was followed conductometrically. The inhibiting effect of sobrerol was discussed in terms of the chain reaction terminated in a step linear with respect to sulphoxy radicals. A method was proposed for quantification of the inhibiting effect and the rate constant (2.0–3.8)10⁸M^-1s^-1 was given for the step eliminating sulphate radicals. Further consequences of the inhibition: shifting the reaction locus from the gas-liquid (droplet) interface to the liquid (droplet) bulk and strong oscillations in the rate of S(IV) autoxidation resulting of the activity of sobrerol-derived radicals were also shown.

Keywords: aqueous phase; cloud chemistry; heterogeneous reaction; inhibition by terpenes; sobrerol; sulphur oxidation

Language: English

Document Type: Research article

Affiliations: 1: Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, Pl-01-224 Warsaw, Poland, E-mail: wpb@ichf.edu.pl 2: Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, Pl-01-224 Warsaw, Poland

Publication date: 2003-01-01