Electrochemical regeneration and porosity recovery of phenol-saturated granular activated carbon in an alkaline medium

The electrochemical regeneration of phenol-saturated activated carbon has been carried out in a filter-press electrochemical cell. The feasibility of the electrochemical regeneration has been assessed by monitoring the regeneration efficiency and the textural properties of a phenol-saturated granular activated carbon (GAC) electrolysed in NaOH medium. The influence of the following factors: (i) the electrolysis treatment (either anodic or cathodic); (ii) the separation of compartments; (iii) applied current and (iv) electrolysis time has been studied. Basing on the obtained results, an overall phenomenological mechanism for the electrochemical regeneration has been proposed. The general worse performance of anodic regenerations can be attributed to an important surface blockage of the GAC by reaction products such as quinones, phenolic oligomers and polymers coming from phenol electrooxidation. The cathodic regeneration in NaOH medium, where phenolate desorption is favoured, and in an undivided configuration, where surface blockage is minimized, produces a significant recovery of the porosity of the original GAC, in agreement with the highest RE values (close to 80%).