A REFINED MODEL FOR OZONE MASS-TRANSFER IN A BUBBLE-COLUMN

The mathematical model proposed by Marinas et ai. (1993) for a bubble column gas-liquid contactor is refined to described the mass transfer of ozone absorption and decomposition in the aqueous solution with the decomposition rate expression of general reaction orders (not necessa rily integers). Three system equations are employed to describe the oz one concentrations in the bulk liquid (C-ALb), the hold-up gas (C-AGb) , and the superficial gas rise velocity (u(G)), respectively. The vari ation of u(G) and the effect of ozone decomposition on the mass transf er, which is reflected by the enhancement factor (E-r) defined as the ratio of chemical to pure physical mass fluxes according to the film m odel of gas liquid absorption, are considered in the refined model. Th is analysis thus extends the applicability of the model of Marinas et al. (1993) and is of special importance for the ozone mass transfer in the cases of basic solutions and of low mass transfer coefficients, i n which the effect of decomposition on absorption is significant. An e xample of such case is the cyanide wastewater treatment in the strong basic condition.