TY - JOUR
T1 - Electrochemical mineralization of the azo dye Acid Red 29 (Chromotrope 2R) by photoelectro-Fenton process
AU - Almeida, Lucio Cesar
AU - Garcia-Segura, Sergi
AU - Arias, Conchita
AU - Bocchi, Nerilso
AU - Brillas, Enric
N1 - Funding Information:
The authors thank financial support from MICINN (Ministerio de Ciencia e Innovación, Spain) under the Project CTQ2010-16164/BQU, co-financed with FEDER funds. The Grants awarded to S. Garcia-Segura by MEC (Ministerio de Educación y Ciencia, Spain) and L.C. Almeida by CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brazil) are also acknowledged.
PY - 2012/10
Y1 - 2012/10
N2 - The degradation of 100mL of 244mgL-1 of the azo dye Acid Red 29 (AR29) has been studied by photoelectro-Fenton (PEF) using an undivided cell containing a boron-doped diamond (BDD) anode and an air-diffusion cathode under UVA irradiation. The effect of current density, concentration of catalytic Fe2+ and pH on the process was examined. Quick decolorization and almost total mineralization were achieved due to the synergistic action of UVA light and oxidant hydroxyl radicals formed in the bulk from Fenton's reaction between electrogenerated H2O2 at the cathode and added Fe2+, as well as in the BDD surface from water oxidation. Optimum PEF conditions were found for 0.5-1.0mM Fe2+ and pH 3.0. Comparable electro-Fenton (EF) degradations in the dark yielded much poorer mineralization. The decay kinetics of AR29 followed a pseudo-first-order reaction with similar rate for EF and PEF. The azo dye disappeared much more rapidly than solution color, suggesting the formation of colored conjugated products with λmax similar to that of AR29. Ion-exclusion HPLC allowed the detection and quantification of tetrahydroxy-p-benzoquinone, oxalic, oxalacetic, tartronic, tartaric, oxamic, malonic and fumaric acids as intermediates in the PEF process. Oxalic acid, accumulated in large extent, was quickly destroyed by the efficient photolysis of Fe(III)-oxalate complexes with UVA light, whereas tartronic and oxamic acids were the most persistent byproducts because of the larger stability of their Fe(III) complexes. The mineralization of the initial N of the azo dye yielded NH4+ ion and NO3- ion in smaller proportion.
AB - The degradation of 100mL of 244mgL-1 of the azo dye Acid Red 29 (AR29) has been studied by photoelectro-Fenton (PEF) using an undivided cell containing a boron-doped diamond (BDD) anode and an air-diffusion cathode under UVA irradiation. The effect of current density, concentration of catalytic Fe2+ and pH on the process was examined. Quick decolorization and almost total mineralization were achieved due to the synergistic action of UVA light and oxidant hydroxyl radicals formed in the bulk from Fenton's reaction between electrogenerated H2O2 at the cathode and added Fe2+, as well as in the BDD surface from water oxidation. Optimum PEF conditions were found for 0.5-1.0mM Fe2+ and pH 3.0. Comparable electro-Fenton (EF) degradations in the dark yielded much poorer mineralization. The decay kinetics of AR29 followed a pseudo-first-order reaction with similar rate for EF and PEF. The azo dye disappeared much more rapidly than solution color, suggesting the formation of colored conjugated products with λmax similar to that of AR29. Ion-exclusion HPLC allowed the detection and quantification of tetrahydroxy-p-benzoquinone, oxalic, oxalacetic, tartronic, tartaric, oxamic, malonic and fumaric acids as intermediates in the PEF process. Oxalic acid, accumulated in large extent, was quickly destroyed by the efficient photolysis of Fe(III)-oxalate complexes with UVA light, whereas tartronic and oxamic acids were the most persistent byproducts because of the larger stability of their Fe(III) complexes. The mineralization of the initial N of the azo dye yielded NH4+ ion and NO3- ion in smaller proportion.
KW - Acid Red 29
KW - Boron-doped diamond
KW - Electro-Fenton
KW - Photoelectro-Fenton
KW - Water treatment
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U2 - 10.1016/j.chemosphere.2012.07.007
DO - 10.1016/j.chemosphere.2012.07.007
M3 - Article
C2 - 22854020
AN - SCOPUS:84864926521
SN - 0045-6535
VL - 89
SP - 751
EP - 758
JO - Chemosphere
JF - Chemosphere
IS - 6
ER -