Electrochemical regeneration of granular activated carbon using an AQS (9,10- anthraquinone-2-sulfonic acid)/PPy modified graphite plate cathode.

In the present study, we investigate the regeneration efficiency of Rhodamine B (RhB)-saturated granular activated carbon (GAC) in an electrochemical regeneration system by using a 9,10-anthraquinone-2-sulfonic acid/polypyrrole modified graphite plate (AQS/PPy-GP) cathode. The response surface methodology based on the Box-Behnken design (RSM-BBD) approach was used to optimize regeneration parameters, whereby the optimum condition of the independent variables was as follows: applied current = 155 mA, concentration of supporting electrolyte = 0.13 M, and regeneration time = 7 h. The electrochemical regeneration system with the AQS/PPy-GP electrode achieved high regeneration efficiency and significantly reduced energy consumption. H2O2 concentration generated in the electrolysis system was notably increased, and the time of complete degradation of organics was shortened by 25% compared to the electrode without modification. The mechanism for RhB degradation was proposed as AQS acting as a catalyst to promote the formation of H2O2. The regeneration study showed that AQS/PPy-GP cathode had appreciable reusability for GAC regeneration with a regeneration efficiency of 76.6% after 8 regeneration cycles. In summary, the electrochemical regeneration based on AQS/PPy-GP cathode would have practical industrial applications in treating spent activated carbons.