Degradation of 1-hydroxy-2,4-dinitrobenzene from aqueous solutions by electrochemical oxidation: role of anodic material.
Electrochemical oxidation (ECOx) of 1-hydroxy-2,4-dinitrobenzene (or 2,4-dinitrophenol: 2,4-DNP) in aqueous solutions by electrolysis under galvanostatic control was studied at Pb/PbO2, Ti/SnO2, Ti/IrxRuySnO2 and Si/BDD anodes as a function of current density applied. Oxidative degradation of 2,4-DNP has clearly shown that electrode material and the current density applied were important parameters to optimize the oxidation process. It was observed that 2,4-DNP was oxidized at few substrates to CO2 with different results, obtaining good removal efficiencies at Pb/PbO2, Ti/SnO2 and Si/BDD anodes. Trends in degradation way depend on the production of hydroxyl radicals (OH) on these anodic materials, as confirmed in this study. Furthermore, HPLC results suggested that two kinds of intermediates were generated, polyhydroxylated intermediates and carboxylic acids. The formation of these polyhydroxylated intermediates seems to be associated with the denitration step and substitution by OH radicals on aromatic rings, this being the first proposed step in the reaction mechanism. These compounds were successively oxidized, followed by the opening of aromatic rings and the formation of a series of carboxylic acids which were at the end oxidized into CO2 and H2O. On the basis of these information, a reaction scheme was proposed for each type of anode used for 2,4-D oxidation.
Universidad de las Américas Puebla, Grupo de Investigación en Energía y Ambiente, ExHda. Sta. Catarina Martir s/n, Cholula 72820, Puebla, Mexico.
Marco A
MA
Quiroz
Universidad de las Américas Puebla, Grupo de Investigación en Energía y Ambiente, ExHda. Sta. Catarina Martir s/n, Cholula 72820, Puebla, Mexico.
José L
JL
Sánchez-Salas
Universidad de las Américas Puebla, Grupo de Investigación en Energía y Ambiente, ExHda. Sta. Catarina Martir s/n, Cholula 72820, Puebla, Mexico.
Silvia
S
Reyna
Universidad de las Américas Puebla, Grupo de Investigación en Energía y Ambiente, ExHda. Sta. Catarina Martir s/n, Cholula 72820, Puebla, Mexico.
Erick R
ER
Bandala
Centro de Innovación Aplicada en Tecnologías Competitivas, Departamento de Investigación Ambiental Omega-201, Fraccionamiento Industrial Delta, León 37545, Guanajuato, Mexico.
Juan M
JM
Peralta-Hernández
Universidade Federal do Rio Grande do Norte, CCET - Institute of Chemistry, Lagoa Nova, CEP 59.072-970 Natal, RN, Brazil. Electronic address: carlosmh@quimica.ufrn.br.
Carlos A
CA
Martínez-Huitle
D019297:2,4-Dinitrophenol / Q000737:chemistry*; D001895:Boron / Q000737:chemistry*; D018130:Diamond / Q000737:chemistry*; D004563:Electrochemistry; D004566:Electrodes; D019216:Metals, Heavy / Q000737:chemistry*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry; D012996:Solutions; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
D019216:Metals, Heavy; D010087:Oxides; D012996:Solutions; D014874:Water Pollutants, Chemical; D018130:Diamond; D001895:Boron; D019297:2,4-Dinitrophenol
2,4-Dinitrophenol; Electro-oxidation; Electrode activity; Hydroxyl radicals