Formation of molecular chlorine in dark condition: Heterogeneous reaction of ozone with sea salt in the presence of ferric ion

Abstract

Uptake coefficients of O3 on NaCl and synthetic sea salt (SSS) were found to be enhanced from < 10−5 to ∼ 3.5 × 10−2 in the presence of water‐soluble Fe3+ in the Fe/Na weight ratio larger than 0.1%. Cl2 release was observed without radiation in the reaction of O3 and a FeCl3/NaCl mixture with surface adsorbed water at the yields of 0.48 and 0.28 for Fe/Na ratio of 1.0 and 0.5 weight %, respectively. Only Br2 release was observed for a FeCl3/SSS sample. These results imply that when bromide is deficient in sea salt, Cl2 would be released from the sea salt with the coexistence of Fe3+. The estimate was made to show that the Cl2 releasing rate can be high enough to explain sporadically observed Cl2 at nighttime in a coastal area.