Study on photodissociation and photoconversion characteristics of CS2 in O2/O3 environment using real-time conversion products obtained by UV-DOAS
Jie Gao, Mu Li, Huan Zhao, Yongqi Wu, Qiang Gao, Xijun Wu, Yucun Zhang, Yucun Zhang, Yungang Zhang, Yungang Zhang
Abstract
Carbon disulfide (CS 2 ) is extremely susceptible to decomposition by ultraviolet radiation , and its decomposition products affect the concentration of trace gases in the atmosphere, which disrupts the balance of atmospheric chemistry . It is essential to elucidate the photochemical reaction characteristics of CS 2 for more in-depth study of the complex chemical and physical changes in the atmosphere. Therefore, this paper firstly provides a clear visualization of the evolution process of CS 2 and conversion products by UV differential optical absorption spectroscopy combined with multi-wavelength least squares method, and then the photodissociation and photoconversion characteristics of CS 2 under trace-oxygen, additional-oxygen and additional-ozone conditions are explained. The results show that the generation of SO 2 from CS 2 is about 100 ppm when only trace-oxygen is present, and the main channels of the reaction are CS 2 + h v → CS + S and CS + 4O → SO 2 + CO 2 . The SO 2 concentration increased from 138 ppm to 150 ppm as the oxygen concentration increased with the main reaction channels CS 2 + 6O → 2 SO 2 + CO 2 and CS + 4O → SO 2 + CO 2 . However, in the additional-ozone environment, the main reaction channels CS 2 + 2O 3 → 2SO 2 + CO 2 and CS + 4 / 3 O 3 → SO 2 + CO 2 gradually dominate as the ozone concentration increases, at which point the SO 2 concentration decreases from 140 ppm to 125 ppm. The results indicate that in the photochemical reaction of CS 2 , the unstable products O atoms and CS directly affect the photochemical reaction rate and the concentration of SO 2 . This study not only enables real-time monitoring of the evolution process and conversion products of CS 2 , but also lays the foundation for future studies on the conversion properties of CS 2 in photochemical reactions.