Spontaneous ChlorineGeneration via Interfacial Oxidationof Chloride by O2 on Acidic Microdroplets
Abstract
Abstract Reactive chlorine species significantly influence atmospheric chemistry, yet their sources remain inadequately defined. We have discovered a spontaneous formation pathway for substantial molecular chlorine (Cl2) from the oxidation of chloride (Cl–) through interfacial oxidation by O2 on acidic microdroplets. This efficient interfacial reaction is facilitated by protons (H+), which enrich Cl– at the gas–liquid interface and mediate the electron-transfer process, concurrently releasing gaseous Cl2 and hydroxyl radicals (OH). Given the prevalence of acidic, chloride-containing droplets in marine and polluted urban environments, this formation mechanism constitutes a substantial and previously unaccounted tropospheric chlorine source. Unlike established mechanisms, this pathway generates active halogens without consuming gaseous oxidants like O3 or OH, instead producing particulate reactive oxygen species (ROS). Consequently, current atmospheric models likely underestimate the contribution of reactive halogens to atmospheric oxidation capacity.
// Source
Authors: Shuying Li, Zhuo Wang, Yiqun Cao, Wei Ma, Hao Li, Tianzeng Chen, Yonghong Wang, Peng Zhang, Pengfei Liu, Biwu Chu, Chang Liu, Yongchun Liu, Yujing Mu, Xiuhui Zhang, Tao Wang, Qingxin Ma, Joseph S. Francisco, Hong He
Institutions: University of Pennsylvania, Hong Kong Polytechnic University, University of Chinese Academy of Sciences, Beijing University of Chemical Technology, California University of Pennsylvania, Chinese Research Academy of Environmental Sciences, Chinese Academy of Meteorological Sciences, Beijing Institute of Technology, Research Center for Eco-Environmental Sciences, Beijing Electronic Science and Technology Institute, Beijing Research Institute of Mechanical and Electrical Technology, Institute of Urban Environment