RAPID COMMUNICATION IMPACTS OF DISSOLVED OXYGEN ON THE SORPTION OF HUMIC SUBSTANCES AND THE SUBSEQUENT INHIBITION OF o-CRESOL UPTAKE BY GRANULAR ACTIVATED CARBON

-The impacts of dissolved oxygen (DO) on the sorption of natural and model humic substances by granular activated carbon (GAC) were investigated. Among five substances tested, the sotptions of only two, polymaleic acid (PMA) and peat humic acid, were affected by the presence of DO. The uptake of the target compound o-cresol on virgin GAC and on GAC preloaded with PMA under oxic and anoxic conditions was also examined. The oxic and anoxic preloading conditions had similar effects on subsequent o-cresol reactions under both oxic and anoxic sorption conditions. A reduction of approximately 20 % in o-cresol uptake observed under anoxic conditions by GAC preloaded under each condition is attributed to a decrease in the adsorption capacity of the GAC by preloading. In the presence of oxygen, however, an observed reduction of about 45% in o-cresol uptake by preloaded GAC appears to result from a combination of decreased adsorption and inhibited o-cresol polymerization. Key words--Humic substances, dissolved oxygen, oxidative coupling, o-cresol