J.R. Portela Miguélez

Kinetics of wet air oxidation of phenol

Abstract Aqueous solutions of phenol were oxidized in a batch reactor at temperatures between 150 and 300 °C and pressures from 100 to 200 bar. The initial phenol concentrations were between 460 and 1650 ppm and the initial oxygen concentration was always above 800% excess. The oxidation experiments covered essentially the entire range of phenol conversions and included all temperature ranges studied by previous workers. The reduction of COD during oxidation was also measured. Furthermore, pyrolysis experiments were carried out to verify that phenol is not degraded by this mechanism in the conditions studied. Due to disagreement in the previous published data about the activation energy, an effort has been made to obtain reliable kinetic data, assuring great oxygen excess and minimum disturbance in the sampling procedure. The oxidation reaction was found to be pseudo-first order with respect to phenol, with an activation energy of 34.4 kJ mol −1 . The influence of pressure and temperature on the induction time was also studied.

Wet air oxidation of oily wastes generated aboard ships : kinetic modeling

Ships are floating industrial plants which generate great amounts of toxic and hazardous wastes. Nevertheless, a feasible model for the management of such wastes has not been developed yet. This work studies the feasibility of treating those wastes aboard the ship by means of aqueous oxidation at high pressures and temperatures. Wet air oxidation has proved to be a very efficient technology for the treatment of those residual currents, resulting in destruction efficiencies of greater than 90% of initial COD and 99.9% of oil/greases content. A kinetic model for the oxidation process, based on a series-parallel reaction pathway, is proposed and is shown to fit the experimental results.