Catalytic wet oxidation of phenol by hydrogen peroxide over pillared clay catalyst

Extrudates of Al-Fe pillared clay catalyst suitable for packed-bed operations are evaluated for wastewater treatment via a wet oxidation process employing hydrogen peroxide as the oxidant. The reaction was carried out in a semibatch basket reactor under rather mild conditions. Operational parameters were studied under the following conditions: temperature from 25 to 90 degreesC, atmospheric pressure, initial phenol concentration from 100 to 2000 ppm of the liquid phase, catalyst loading from 0 to 10 g/L, and input H2O2 concentration from 0.15 to 0.6 mol/L. Under these conditions, the Al-Fe pillared clay catalyst achieves a total elimination of phenol and significant total organic carbon (TOC) removal. This catalyst can be used several times without any change in its catalytic properties, and hence, it would be a promising catalyst for industrial wastewater treatment. The reaction takes place to a significant extent both in the liquid phase and on the catalyst surface. Hence, apparent kinetic models were developed by formulating the reaction rate in two kinetic expressions that separately consider the homogeneous and heterogeneous contributions. Using the second-order approach for the homogeneous reaction and the Langmuir-Hinshelwood approach for the heterogeneous reaction, the developed kinetic models describe well the removal of phenol and the formed intermediate carbon over the entire range of the variables studied.