The performance of an electrochemical process for the regeneration of granular activated carbon (GAC) was evaluated using boron-doped diamond (BDD) anodes. Three different configurations were tested in the reactor: fluidized bed, packed bed with a divided cell and packed bed with an undivided cell. The GAC used was previously saturated with a synthetic solution of methylene blue (MB). The effects of three operational parameters were evaluated: current density, initial pH and reaction time, and NaCl as the electrolyte. Regeneration efficiencies (REs) of up to 76% ± 2 were achieved with a current density of 6 mA·cm-2 during 24 h of reaction, and a specific electric energy consumption of 1530 kWh ton-1 of GAC was obtained. The best results were obtained using the packed bed reactor with a divided cell and the GAC in the cathodic compartment. The present results were attributed to an improvement in the desorption caused by the local alkaline pH in the cathodic compartment, to the contribution of the electrochemical oxidation by the hydroxyl radical, and, in parallel, to the chemical oxidation of the organic compounds by the oxidizing species formed from the chloride ion. It was also found that the electrochemical regeneration process has a negative effect on the GAC integrity after three cycles of continuous regeneration
Tópico:
Advanced oxidation water treatment
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18
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FuenteJournal of environmental chemical engineering