A steady-state wetted wall reactor model was developed taking into account the mass transfer between the phases (N), the reaction between ozone and 2,4-xylidine (R), the 2,4-xylidine vaporization, as well as the stoichiometric ratio of the consumed ozone to the reacted 2,4-xylidine.
The mass balances for the ith (i = 1 for ozone and i = 2 for 2,4-xylidine) component in the jth stage are:
for the gas phase, where F is the cross-sectional area of the reactor, l is the height of the stage (l = L/n = 0.1 m, where L is the total length of the reactor and n is the number of stages), [H.sup.i] is Henry's dimensionless coefficient calculated for ozone according to [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] at 20[degrees]C) and for 2,4-xylidine obtained from the literature ([H.sup.xyl] = 0.27 ).
It can be noted that both models predict satisfactory 2,4-xylidine degradation in the CWO process.
It assumes an irreversible surface reaction between the absorbed reactants (2,4-xylidine and oxygen).
where k is the reaction rate coefficient, and [K.sup.xyl] and [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] are the adsorption coefficients of 2,4-xylidine and oxygen, respectively.
The values of parameters in the 2,4-xylidine adsorption coefficient (Eq.
The reaction kinetics is presented formally through a direct oxidation reaction in the liquid phase, including oxygen and 2,4-xylidine concentrations in the liquid phase.
where k is the reaction rate constant, [c.sup.xyl] and [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] are the concentrations of 2,4-xylidine and dissolved oxygen in the liquid phase, and superscripts x and y are reaction orders.
On the basis of the 2,4-xylidine decay, the apparent activation energies and pre-exponential constants were determined for the reactions of the CWO and the WAO, with and without catalyst, using a parameter estimation program.
As can be seen from Table 4, the reaction between 2,4-xylidine and oxygen is formally a typical second-order reaction, first-order in respect to both reactants.
The effect of temperature on the 2,4-xylidine degradation under constant oxygen pressure, [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], is presented in Fig.