Article

Intensification of the Fenton Process by Increasing the Temperature

Industrial & Engineering Chemistry Research (Impact Factor: 2.24). 12/2010; 50(2). DOI: 10.1021/ie101963k

ABSTRACT The effect of temperature on the Fenton process has been studied within the range of 25−130 °C using phenol (100 mg/L) as target compound, 10 mg/L Fe2+, and a dose of H2O2 corresponding to the theoretical stoichiometric amount (500 mg/L) for mineralization. The TOC reduction was considerably improved as temperature increased. Whereas at 25 °C the TOC decreased less than 28%, a reduction of almost 80% was achieved at 90 °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 H2O2 which indicates an enhanced iron-catalyzed H2O2 decomposition into radicals as temperature increases rather than the generally accepted thermal breakdown of H2O2 into O2 and H2O. 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 H2O2 and Fe2+ 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.

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    • "In this context, the in situ generation of H 2 O 2 has been employed in numerous electro-Fenton degradation reactions [31] [32] [33] carried out under diverse experimental conditions [34] [35] [36] [37] [38], in which H 2 O 2 can to produce hydroxyl radicals ( "
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    • "However, Hermosilla et al. (2009), claims that there was no significant increase in the COD removal when the temperature was increased from 298 to 318 K and COD removal results were constant at about 64%. Zazo et al. (2011) reported that increasing operating temperature had possitive effect on the TOC reduction. They found that TOC reduction of almost 80% was achieved at 363 K. Beyond this temperature no significant improvement was observed, although the rate of the process was considerably enhanced. "
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    • "Hence, the design of photo-Fenton reactors should also take into account the necessity of facile integration with other effluent decontamination technologies. A final point that has only recently been considered in a more systematic context is the intensification of Fenton processes by increasing the temperature (Zazo et al., 2011), particularly attractive in the case of photo-Fenton reactions where a substantial part of the absorbed light energy is dissipated as heat in the solution. "
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