Experimental simulation of stratospheric ozone reactions with chloroalkane organic pollutants

Abstract

Environmental contextChlorinated organic atmospheric pollutants, which can be produced naturally or anthropogenically, are considered as a factor responsible for stratospheric ozone depletion. Based on experimental simulations and low temperature vibrational spectroscopy, this work reports a mechanism for the reaction of chloroalkanes with ozone. This reaction leads to the formation of the photochemically reactive chlorine oxide species. Kinetics and implications of the reactions are discussed. AbstractThe present work deals with the important problem of stratospheric ozone depletion and an investigation of the atmospheric decay of organic pollutants. The products of the heterogeneous reactions of ozone with chloroethane and 1-chloropropane in a flow-through vacuum electric discharge unit under conditions similar those observed in the stratosphere are studied by low-temperature infrared (IR) absorption spectroscopy. Taking into account the literature data, a scheme for the interaction of ozone with halogen-substituted alkanes at low temperatures is proposed, which shows the formation of chlorine oxides that have high photochemical activity and can cause damage to the ozone layer even when present in small concentrations. The conversion of chloroalkanes over time demonstrates the first-order-decay behaviour of the investigated processes.