Intensification of the Fenton Process by Increasing the Temperature

The effect of temperature on the Fenton process has been studied within the range of 25-130 degrees C using phenol (100 mg/L) as target compound, 10 mg/L Fe(2+), and a dose of H(2)O(2) corresponding to the theoretical stoichiometric amount (500 mg/L) for mineralization. The TOC reduction was considerably improved as temperature increased. Whereas at 25 degrees C the TOC decreased less than 28%, a reduction of almost 80% was achieved at 90 degrees C. Beyond this temperature no significant improvement of mineralization was observed, although the rate of the process was considerably enhanced. Increasing the temperature leads to a more efficient consumption of H(2)O(2) which indicates an enhanced iron-catalyzed H(2)O(2) decomposition into radicals as temperature increases rather than the generally accepted thermal breakdown of H(2)O(2) into O(2) and H(2)O. Therefore, working at a temperature well above the ambient provides a way of intensifying the Fenton process since it allows a significant improvement of the oxidation rate and the mineralization percentage with reduced H(2)O(2) and Fe(2+) doses. Furthermore it would not represent a serious drawback in the case of many industrial wastewaters which may be already at that temperature. Besides, partial recovery of heat from the treated off-stream would always allow saving energy. The TOC time-evolution was well described by a kinetic model based on TOC lumps with apparent activation energy values in the range of 30-50 kJ/mol.