Ozonation characteristics of bisphenol A in water

Ozonation characteristics of bisphenol A were investigated as a function of gaseous ozone dose, initial concentration of bisphenol A, pH, radical scavenger (tert-butanol), and radical initiator (hydrogen peroxide). The ozonation led to a complete removal of bisphenol A in water within a certain period of time. The overall rate of the ozonation linearly increased with the ozone dose. The stoichiometry in the ozonation of bisphenol A was found to be 1.5 - 1.8 mole of ozone per mole of bisphenol A. The direct reaction rate constants were 1.3 x 10(4) M(-1)s(-1) for bisphenol A (at pH = 2) and 1.6 x 10(9) M(-1)s(-1) for dissociated bisphenol A (at pH = 12). Bisphenol A degraded via the direct reaction with molecular ozone in the pH range from 2 to 12. Degradation by OH radical was minor even at pH = 12. The overall degradation rate in heterogeneous conditions was independent of pH as it was limited by ozone mass transfer rate. Use of hydrogen peroxide did not alter the main degradation route and the molecular ozone remained a principal oxidant as a substantial portion of the OH radical is scavenged by hydrogen peroxide. Effective ozone mass transfer may appear essential to enhance the ozonation kinetics of bisphenol A.