Study on Catalytic Wet Air Oxidation Process for Phenol Degradation in Synthetic Wastewater Using Trickle Bed Reactor

The present work aims to study the feasibility of utilizing a trickle bed reactor, packed with activated carbon catalyst, for phenol degradation in synthetic wastewater. Effect of operating variables (e.g., pH, pressure, temperature, gas flow rate, liquid flow rate, and flow mode) on the performance of the trickle bed reactor was investigated and optimized. Results showed that phenol degradation would be enhanced by increasing temperature, pressure, and gas flow rate, while initial concentration of phenol and liquid flow rate give a different trend. It was found that down-flow mode exhibits better performance than up-flow mode. High degradation rate of phenol of about 97 % was obtained at optimum conditions (liquid space time = 0.143 h, temperature = 160 °C, oxygen partial pressure = 0.9 MPa, and phenol concentration = 5 mg/l). Reaction kinetics including effects of catalyst deactivation on the oxidation process was investigated. Results showed that the oxidation process behaves as pseudo-first-order reaction with respect to phenol concentration, and 0.6 with respect to oxygen solubility. Activation energy is 77.7 kJ/mol. and reaction rate constant is equal to 1.826×109l/kgcat\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${1.826 \times 10^{9}{l}/{kg}_{\rm cat}}$$\end{document} h. However, when catalyst deactivation was taken into account, the reaction rate constant and activation energy were 2.9×1011l/kgcat\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${2.9 \times 10^{11} {l}/{kg}_{\rm cat}}$$\end{document} h and 114.43 kJ/mol, respectively, and the oxygen order was equal to 1.4. The calculated kinetic parameters were compared with the data reported in the literature.