An investigation of the mechanisms of chemical regeneration of activated carbon

The mechanisms underlying chemical regeneration of activated carbon loaded with physisorbed organics have been explored. Using four aromatic adsorbates and five chemical regenerants in batch equilibrium and regeneration experiments, it has been shown that solubility of the organics and surface characteristics of the adsorbent under regeneration conditions strongly influence the regeneration efficiency. Solubility in the regenerant has been enhanced either by the addition of micelles or by the generation of soluble forms of the adsorbate. In general, the latter technique is more effective. It has been demonstrated that soluble forms of the adsorbate can be obtained by pH control or the use of reactive regenerants. pH can also be used to control surface charge characteristics and, consequently, adsorbate affinity for the adsorbent; For adsorbates that are difficult to solubilize or are very strongly bound to the surface, reduced affinity for the adsorbent through a change in surface charge characteristics can be used to improve regeneration efficiencies.