Determination of ozone solubility in polymeric materials

The transport of a gas or vapour through a dense, nonporous membrane can be described in terms of a solution-diffusion mechanism, which states that the permeability is determined by its diffusivity and solubility. The solubility of many different molecules in many different polymers has been measured and can be found in the literature. However, very little information can be found about the solubility of ozone in polymers. Therefore, a dynamic frontal chromatography method to determine the ozone solubility was developed and was successfully applied to three different polymers: Teflon 65 N (S = 0.088 ± 0.080 mole O3/m3 polymer per mole O3/m3 air at T = 296.95 K, n = 3), “reaction exhausted” polydimethylsiloxane (PDMS) (S = 1.005 ± 0.077 mole O3/m3 polymer per mole O3/m3 air at T = 298.85 K, n = 5) and Hyflon AD80 (S = 3.549 ± 0.147 mole O3/m3 polymer per mole O3/m3 air at T = 298.15 K, n = 4). The term “reaction exhausted” PDMS polymer is used, because initially a reaction was observed and sorption values could only be determined after this reaction was exhausted. Experiments were performed at different temperatures; sorption proved to be strongly temperature dependent, for “reaction exhausted” PDMS a ΔHs value of −11.05 ± 0.98 (standard deviation) kJ/mole was measured (n = 8); for Hyflon AD80 a ΔHs value of −17.24 ± 1.17 (standard deviation) kJ/mole was measured (n = 8). The quantitative ozone solubility data presented here are of high relevance to polymeric membrane-assisted processes, which make use of ozone as an oxidant, for example, advanced oxidation processes (AOP's).