EFFECT OF DISSOLVED-OXYGEN ON PHENOLS BREAKTHROUGH FROM GAC ADSORBERS

This study demonstrates that molecular oxygen plays an important role in the adsorption of organic compounds from water by activated carbon. It was determined that the adsorptive capacity of granular activated carbon (GAC) for o-cresol can increase by almost 200% as a result of the presence of molecular oxygen in the test environment (oxic conditions). This increase in adsorptive capacity is not due to biological activity but can be totally attributed to the polymerization of o-cresol on the carbon surface under oxic conditions. The rate of adsorbate polymerization is such that the presence of molecular oxygen does not influence adsorption kinetics during the first 12 hours of adsorbent-adsorbate contact. However, the concentration of dissolved oxygen in the feed to a GAC adsorber can significantly influence the breakthrough of adsorbate. As the concentration of dissolved oxygen increased, more of this increased capacity is utilized during the early phase of breakthrough and, consequently, initial breakthrough is delayed. This phenomenon might completely change the existing procedures for the design and operation of GAC adsorbers in that it provides a competitive edge for adsorption as a treatment technology in water purification.