Adsorption and decomposition of water-dissolved ozone on high silica zeolites

The adsorption properties of water-dissolved ozone on high silica zeolites were investigated. Adsorbed ozone was desorbed almost reversibly. The adsorption equilibrium relations were described by a linear expression written as q=βC, where q is the amount adsorbed, C is the equilibrium concentration and β is the equilibrium constant. Also, the β values were strongly dependent on the SiO2/Al2O3 ratio (mol/mol) and on the pore structure of the high silica zeolites. The larger the SiO2/Al2O3 ratio, the larger the value of β. ZSM-5 (SiO2/Al2O3 ratio: 3000), which gave the highest adsorption capacity of water-dissolved ozone, was able to highly concentrate water-dissolved ozone on the adsorbent. The decomposition behavior of adsorbed ozone was also investigated. Ozone adsorbed on high silica zeolite was observed to be a little more stable than ozone existing in bulk water. The decomposition rate was independent of SiO2/Al2O3 ratios in the range of 30–3000 or a solution pH in the range of 4–6.