Kinetics of Estrone Ozone/Hydrogen Peroxide Advanced Oxidation Treatment

Abstract

Ozone/hydrogen peroxide batch treatment was utilized to study the degradation of the steroidal hormone estrone (E1). The competition kinetics method was used to determine the rate constants of reaction for direct ozone and E1, and for hydroxyl radicals and E1 at three pH levels (4, 7, and 8.5), three different molar O3/H2O2 ratios (1:2, 2:1, and 4:1) and a temperature about 20°C. The average second-order rate constants for direct ozone-E1 reaction were determined as 6.2 × 103 ± 3.2 × 103 M−1s−1, 9.4 × 105 ± 2.7 × 105 M−1s−1, and 2.1 × 107 ± 3.1 × 106 M−1s−1 at pH 4, 7, and 8.5, respectively. It was found that pH had the greatest influence on the reaction rate, whereas O3/H2O2 ratio was found to be slightly statistically significant. For the hydroxyl radical-E1 reaction, apparent rate constants ranged from 1.1 × 1010 M−1s−1 to 7.0 × 1010 M−1s−1 with an average value of 2.6 × 1010 M−1s−1. Overall, O3/H2O2 is shown to be an effective treatment for E1.