Open AccessModeling Cl 2 formation from aqueous NaCl particles: Evidence for interfacial reactions and importance of Cl 2 decomposition in alkaline solution
Author(s) -
Knipping Eladio M.,
Dabdub Donald
Publication year - 2002
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2001jd000867
Subject(s) - chlorine , aqueous solution , decomposition , chemistry , chloride , hydroxide , inorganic chemistry , reaction rate constant , hydrogen peroxide , reaction mechanism , reaction rate , yield (engineering) , chemical reaction , sodium hydroxide , hydrogen chloride , chemical decomposition , kinetics , thermodynamics , organic chemistry , catalysis , physics , quantum mechanics
A series of experiments have demonstrated that a significant yield of chlorine gas is produced when mixtures of ozone and sodium chloride particles above their deliquescence point are irradiated at 254 nm. In order to obtain expressions for future modeling studies, a comprehensive model is used to analyze the system and to determine its sensitivity. This work reexamines and expands previous studies [ Knipping et al. , 2000]. The enhanced model, described in detail herein, reaffirms that current known physical and chemical processes fail to reproduce the observed Cl 2 formation in the experiments. A methodological analysis, proposed as a framework for similar studies, of the physicochemical system supports the accountability of an overall mechanism initiated by the formation of a relatively stable complex of the hydroxyl radical and chloride ions at the gas–liquid interface for the observed chlorine generation. Different potential fates of the OH•••Cl surface •− intermediate are discussed. A rate expression and kinetic parameters are presented for the overall reaction of the interfacial mechanism. In addition, sensitivity studies underscore the importance of accurately modeling chlorine decomposition processes in alkaline solution—in particular, the reactions of chlorine with hydroxide, carbonate, and basic hydrogen peroxide. Recommended aqueous‐phase rate constants for these reactions are drawn from a literature evaluation illustrating the limited availability and lack of agreement of related kinetic data.