Effects of Temperature and Ultraviolet Solar Radiation on Degradation of Formic Acid using the Fenton Reactions

ROSSETTI, G.E.; ALBIZZATI, E.D.; ALFANO, O.M.

Río de Janeiro, Brasil

Congreso; 2º Congreso de Ingeniería Química del Mercosur y 4º Congreso del Mercosur de Ingeniería de Sistemas y Procesos - ENPROMER 2005; 2005

Universidade Federal do Rio de Janeiro, Brazil

The effect of the reaction temperature on the degradation rate of formic acid, using the Fenton and photo-Fenton processes, is investigated. First, a stirred tank laboratory photoreactor irradiated from the bottom was used to evaluate the kinetic parameters between 25°C and 55°C for both reactions. Then, the proposed kinetic model was used to predict the conversion of the organic pollutant in a flat-plate solar photoreactor placed inside the loop of a batch recycling system. Operating conditions were as follows: i) 25, 40 and 55°C, ii) the time-averaged solar zenith angle was 9.5°, iii) pH = 3.0, iv) the initial formic acid concentration was 2.2 mM, v) the ferric ion concentration was 1 mM, and vi) the initial hydrogen peroxide to formic acid molar ratio was 3. The radiation field and the mass balances previously reported have been used in this work to compute the formic acid and the hydrogen peroxide concentrations as a function of time in the solar reactor. Theoretical and experimental results show that UV solar radiation improves the effectiveness of the Fenton process. At lower temperatures, the pollutant conversion enhancement is significant, but at higher temperatures this effect is less important. For instance, experimental conversion enhancements after 20 minutes of reaction time are 186, 74 and 7% for 25, 40 and 55°C, respectively.