MODELING OF CHLOROPHENOL TREATMENT IN AQUEOUS-SOLUTIONS - 2 - OZONATION UNDER BASIC CONDITIONS

Ozonation of 2-chlorophenol (2-CP), 4-chlorophenol (4-CP) and 2,4-dich lorophenol (2,4-DCP) in basic aqueous solutions is discussed. In such conditions (pH=9.5), ozonation of chlorophenols proceeds rapidly due t o the presence of the dissociated form of the phenolic compound. No oz one occurs in the bulk of the liquid and, in modelling, it becomes nec essary to account for the reactions in the liquid film. Two approaches were tested: 1) the film and bulk balances were solved sequentially, and the diffusional fluxes coupling the balances were obtained by solv ing numerically the concentration profiles in the film; 2) the bulk ma ss balances were solved without the film mass balances by applying the enhancement factor calculated from existing correlations. The results of both approaches are compared with experimental data. The formation mechanism of an aromatic quinone, hydrogen peroxide and chloride ions during the ozonation appeared to differ under basic conditions from t hat under acidic conditions. Hydroxyl radical reactions did not, howev er, have any effect on the chlorophenol decomposition.