Determination of fast ozone oxidation rate for textile dyes by using a continuous quench-flow system

Ozone oxidation kinetics of Reactive Blue 19 anthraquinone dye in a tubular in situ ozone generator and reactor: Modeling and sensitivity analyses

“…Gomes et al, [26], in a previous study using a quench-flow system, obtained a value of 3.4 Â 10 À2 L mg À1 s À1 for AO7 dye at a pH of 2.5. The rate constant value of 1.6 Â 10 À2 L mg À1 s À1 obtained in our work for RB-19 dye at a pH of 2 is consistent with the above data.…”

“…The values of E and D become the input to the set of mass balance equations (Eqs. (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)) for the bulk liquid whose solution calculates the value of concentrations of dye, dissolved ozone, primary products (P1) and secondary products (P2) at the next time step (t = 0 + Dt). Then, the program goes back to calculate the new values of Ha, E inst , and R based on this new value of dye concentration in bulk.…”

“…An implicit solution for stiff problems available in MATLAB software (ode23tb) was used to solve the set of equations (Eqs. (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)) in the bulk liquid. The solutions of the equations for the film calculates the values of E and D at time t and these values are used in the mass balance equation for bulk liquid and the reactor system (Eqs.…”

“…With the value of k 1 being known, the value of k 2 was determined by fitting the model (Eqs. (3)(4)(5)(6) and (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)) output for COD concentration to the experimental data. The value of k 2 was varied during the model execution until the model output fitted the experimental data satisfying the minimum value of the objective function given by Eq.…”

“…Hence the second order kinetics rate constant obtained in this research cannot be compared to the reported results of the literature for RB-19 dye ozonation. There have been some attempts recently to fit a second order rate equation to the primary decolorization reaction for other anthraquinone and azo dyes [25][26][27]. Gomes et al, [25] attempted to fit rate data from a 15-min time period to a second-order rate model without considering diffusion effects.…”