Decomposition of 2-Chlorophenol Employing Goethite as Fenton Catalyst at pH 3. The Iron Dissolution Steps as well as Temperature, Catalyst Loading and Iron Concentration Effects

GUADALUPE B. ORTIZ DE LA PLATA; ORLANDO M. ALFANO; ALBERTO E. CASSANO

CHEMOSPHERE

Elsevier

Año: 2008

0045-6535

The decomposition of 2-chlorophenol (2-CP) employing the Fenton heterogeneous reaction at pH 3 and using Goethite as a source of iron was studied. The main explored variables were: temperature, catalyst loading and the molar ratio of hydrogen peroxide to 2-CP. The results were interpreted considering that, excluding the transfer of iron from the solid to the solution and the hydrogen peroxide decomposition promoted by the oxide surface, the rest of the reaction was taking place in the homogeneous phase. The presence of iron in the solution was essential to initiate the reaction by proton dissolution, but detected chorobenzoquinone and chlorohydroquinone catalyzed the reductive dissolution of ferrous ions into de solution. At low catalyst concentration (CCat = 0.5 × 10-3 g cm-3), a molar ratio of H2O2 to 2-CP = 50 and 50 ºC, after 3 h of reaction time 98.7% of 2-CP and 74.6% of TOC conversions were obtained. Operating conditions can be adjusted such as the total iron contained in the solution could be kept below 1.5 ppm. Increasing catalyst concentration and temperature produced very important hydrogen peroxide decomposition. All observed effects were explained with the proposal of a comprehensive reaction sequence.