NICHELA daniela Alejandra
congresos y reuniones científicas
Optimization of operational conditions for nitrobenzene (NBE) degradation by Electro-Fenton methods
Foz do Iguaçu, Brazil
Congreso; 6th ISE Spring Meeting , Electrochemistry for a healthy Planet; 2008
Institución organizadora:
International Society of Electrochemistry
Optimization of operational conditions for nitrobenzene (NBE) degradation by Electro-Fenton methods. Daniela Nichela, Felipe Rodriguez Nieto and Fernando García EinschlagInstituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), UNLP64 y Diag 113, CC 16 Suc 4, 1900, La Plata, Argentina Aromatic nitro compounds are commonly used in the manufacture of pesticides, dyes and explosives, and are often detected in industrial effluents, in ambient freshwater. In addition, nitroaromatic hydrocarbons are naturally generated as a result of photochemical reactions produced in the atmosphere. These substances show high toxicity, provoking serious health problems.Electrochemical methods can lead to an efficient destruction of such compounds. Among them, indirect electrooxidation methods based on the cathodic generation of hydrogen peroxide such as electro-Fenton and photoelectro-Fenton are being developed for the destruction of toxic pollutants in acidic wastewaters. These environmentally clean electrochemical methods are usually performed in an electrolytic cell where H2O2 is continuously produced in the contaminated solution from the two-electron reduction of O2 at mercury pool, reticulated vitreous carbon, carbon-felt, activated carbon fiber or carbon-polytetrafluoroethylene (PTFE) O2- diffusion cathodes{1}.                The electro-Fenton method involves the addition of small quantities of Fe2+ as catalyst to the acid solution to enhance the oxidizing ability of H2O2 because of the production of the strong oxidant ●OH through the Fenton’s reaction.In this contribution we report results from the degradation of nitrobenzene (NBE) using electro-fenton methods in aqueous solutions. Two different aproachs were tested: (a) In situ electrochemical production of H2O2 by reduction of O2 using two different carbon-based electrodes. (b) Electro-Fenton degradation of NBE in excess of hydrogen peroxide and catalytic concentrations of Fe(III) or Cu(II) salts using Pt cathodes.The cathodic H2O2 production in acid media was studied in two different carbon materials and the kinetic profiles of H2O2 obtained in several conditions are presented. The rates of O2 reduction depend on the applied potential and the supporting electrolyte concentration.                The results of both thermal and electrochemically-enhanced oxidation of NBE are also compared. The kinetic profiles of the thermal processes induced by Fe(III) or Cu(II) salts show an autocatalytic behavior. A slow initial phase is followed by a Fast phase were both NBE and H2O2 consumption rates are increased. For the electrochemically enhanced oxidation, the rates of the Slow phase are substantially increased for both Fe(III) and Cu(II) catalyzed systems, though the effects of the electrochemical treatment on the fast phases are less evident.References(1)C. Flox, S. Ammar, C. Arias, E. Brillas,A. V. Vargas-Zavala, R. Abdelhedi. Applied Catálisis B: Environmental. 67 (2006) 93(2)S. Yuan, M. Tian, Y. Cui, L. Lin, X. Lu. Journal of  Hazardous Materials B, 137 (2006) 573