Electrochemical regeneration of granular activated carbon.

Laboratory experiments have investigated the feasibility of granular activated carbon (GAC) regeneration via an electrochemical technique. GAC was loaded with phenol by batch adsorption tests, electrochemically regenerated and finally reloaded with phenol. Regeneration was conducted by placing GAC on a platinum elecotrode within a batch reactor filled with electrolyte (generally a 1% NaCl solution), and applying a current to the reactor. Limited experiments show that cathodic regeneration is more efficient than anodic regeneration; the investigation concentrates on the former. Although anodic regeneration is more efficient in destroying residual phenol in the electrolyte, cathodic regeneration can also eliminate these residuals by using longer regeneration times and/or higher currents. Increasing the regeneration current and time could increase the regeneration efficiency (RE) up to 94 percent. Lower currents applied for longer regeneration times yield similar results with slightly lower energy consumption. REs are also significantly affected by the electrolyte type, electrolyte concentration, and GAC particle size, but not by the carbon loading. Multiple regenerations only reduced the REs by an additional 2 percent per cycle. Preliminary analysis indicates that electrochemical regeneration is less expensive than thermal regeneration as it has no obvious carbon losses. Since this electrochemical regeneration process is technologically feasible and probably more economical than thermal regeneration, it merits further investigation