In the frame of study on the electrochemical incineration of organic pollutants, the reactivity of glucose toward mineralization was studied under different electrolysis conditions. The process was followed at Pt, SnO2-Pt composite, and PbO2 electrodes, at different current densities and temperatures. In all cases, the supporting electrolyte was 2N H2SO4. Chemical oxygen demand and total organic carbon content of the solutions and amount of oxygen evolved were measured as functions of the electrolysis time. From these data, an initial electrochemical oxidation index (EOI) was evaluated following standard methods. Larger values for this parameter were found at the PbO2 electrodes under all conditions of current density and temperature. At Pt and SnO2-Pt, in the room-temperature range, the efficiency of the electrochemical mineralization of glucose was low, particularly at longer electrolysis times. The situation improved by increasing the temperature to 56°C. The extent of mineralization was quite low at SnO2-Pt electrodes under all conditions explored. At Pt and SnO2-Pt electrodes, the main oxidation intermediate was glucaric acid, apparently quite stable toward further attack at these electrodes. In the case of PbO2 electrodes, smaller concentrations of intermediates were detected. Gluconic and 2-ketogluconic acids were also present in amounts comparable with that of glucaric acid. Study of the initial electrochemical oxidation index for gluconic acid and glucaric acid was also carried out, confirming the stability of the latter at Pt and SnO2-Pt electrodes. At PbO2, on the contrary, it was found to be even more reactive than glucose. An explanation for the reactivity of carboxylic acids toward mineralization at the PbO2 electrodes is proposed.
Electrochemical incineration of glucose as a model organic substrate. Part 1: role of the electrode material
FERRO, Sergio;LODI, Gaetano;DE BATTISTI, Achille
1999
Abstract
In the frame of study on the electrochemical incineration of organic pollutants, the reactivity of glucose toward mineralization was studied under different electrolysis conditions. The process was followed at Pt, SnO2-Pt composite, and PbO2 electrodes, at different current densities and temperatures. In all cases, the supporting electrolyte was 2N H2SO4. Chemical oxygen demand and total organic carbon content of the solutions and amount of oxygen evolved were measured as functions of the electrolysis time. From these data, an initial electrochemical oxidation index (EOI) was evaluated following standard methods. Larger values for this parameter were found at the PbO2 electrodes under all conditions of current density and temperature. At Pt and SnO2-Pt, in the room-temperature range, the efficiency of the electrochemical mineralization of glucose was low, particularly at longer electrolysis times. The situation improved by increasing the temperature to 56°C. The extent of mineralization was quite low at SnO2-Pt electrodes under all conditions explored. At Pt and SnO2-Pt electrodes, the main oxidation intermediate was glucaric acid, apparently quite stable toward further attack at these electrodes. In the case of PbO2 electrodes, smaller concentrations of intermediates were detected. Gluconic and 2-ketogluconic acids were also present in amounts comparable with that of glucaric acid. Study of the initial electrochemical oxidation index for gluconic acid and glucaric acid was also carried out, confirming the stability of the latter at Pt and SnO2-Pt electrodes. At PbO2, on the contrary, it was found to be even more reactive than glucose. An explanation for the reactivity of carboxylic acids toward mineralization at the PbO2 electrodes is proposed.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
