Electrochemical regeneration of granular activated carbon

Abstract

Laboratory experiments investigated the feasibility of a novel granular activated carbon (GAC) regeneration technique: electrochemical regeneration. GAC was loaded with phenol, via batch adsorption tests, then electrochemically regenerated and finally reloaded with phenol. Regeneration was conducted in a batch reactor filled with a 1 % NaCl solution as the electrolyte. As limited experiments showed that cathodic regeneration was 5–10% more efficient than anodic regeneration, the investigation concentrated on the former. Although anodic regeneration was more efficient in destroying phenol residuals from the electrolyte, cathodic regeneration could also eliminate these residuals by using longer regeneration times and/or higher currents. Increasing the regeneration current to 100 mA for 5 hours can increase the regeneration efficiency (RE) to a maximum of 95%. Lower currents applied for longer regeneration times can yield similar results. REs were also significantly affected by the electrolyte type, the electrolyte concentration, and the GAC particle size, but not by the phenol loadings. Multiple regenerations only reduce the REs an additional 2% per cycle. Given the high regeneration efficiencies and no apparent carbon losses, electrochemical regeneration of GAC at a laboratory-scale is a feasible alternative to thermal regeneration and merits further investigation.