Influence of water surface properties on the heterogeneous reaction between O3(g) and I(aq)−

The production of molecular iodine via the interfacial reaction between aqueous iodide and gas-phase ozone in the presence of octanol films was studied as a function of reactant and octanol concentrations using absorption spectroscopy. The total production of iodine displayed a Langmuir–Hinshelwood dependence on the concentrations of bulk aqueous iodide and gas-phase ozone, in agreement with earlier studies. The amount of iodine released into the gas phase relative to that remaining in solution depended on the concentrations of iodide and octanol. The amount of gas-phase I2 was smaller for higher iodide concentrations, while the amount remaining in solution increased. The total amount of I2 product increased somewhat on octanol-coated surfaces. However, the more striking result is that the release of I2 into the gas phase was diminished by ∼50%, and the amount retained in solution increased correspondingly in the presence of an octanol monolayer.

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► The O3(g)/I(aq)− reaction was studied as a function of I− and octanol monolayers.
► As I− increases I2 product remaining in solution increases via sequestration by I−.
► An organic coating influences the gas – solution partitioning of the I2 product.
► Laboratory studies of the O3/I− reaction may not relate to the “real” sea surface.