Photodegradation of nitroaromatic compounds by the UV/H2O2 process using polychromatic irradiation sources.

FERNANDO S. GARCÍA EINSCHLAG; LUCIANO CARLOS; ALBERTO L. CAPPARELLI; ESTHER OLIVEROS; ANDRÉ M. BRAUN.

Karlsruhe, Alemania

Workshop; Updates in Photochemical Technologies; 2001

            Several studies reported in the literature analyze the photoassisted oxidation of pollutants in aqueous solutions using the UV/H2O2 method. Low, medium or high pressure mercury arch lamps are frequently employed in this kind of studies. The kinetic and mechanistic interpretation of experimental results is relatively much simpler if monochromatic rather than polychromatic radiation sources are used. However, polychromatic lamps are broadly used at laboratory, pilot and industrial scale.             We have recently published some studies on the photodegradation efficiency of nitroaromatic derivatives applying the UV/H2O2 technique. If monochromatic lamps are used, the maximum degradation rate is obtained if             [H2O2]Opt = [S].(kS.eS/ kH.eH)1/2                                                          (1)                 [H2O2]Opt = [S].(kS.eS/ kH.eH)1/2                                                          (1)                 [H2O2]Opt = [S].(kS.eS/ kH.eH)1/2                                                          (1)                 [H2O2]Opt = [S].(kS.eS/ kH.eH)1/2                                                          (1)     where S is the substrate, kS and kH are the rate constants with HO• radicals, eS and eH are the extinction coefficients.             In this communication we study the effect of the spectral distribution of the incident radiation on the UV/H2O2 process. Particularly, we analyze the photodegradation of pollutants in aqueous solutions using a typical half pressure mercury lamp, which presents a continuous background below 254 nm.