DISSOLVED-OXYGEN EFFECTS ON EQUILIBRIUM AND KINETICS OF PHENOLICS ADSORPTION BY ACTIVATED CARBON

Phenol and o-cresol have been shown to undergo oxygen-induced polymerization reactions on activated carbon that enhance their adsorption. Four different levels of dissolved oxygen (DO) were involved in the equilibrium and kinetics studies undertaken. It was found that for both phenol and o-cresol, the adsorptive capacities increase with the increase in DO concentration. The quantities of dimers and trimers formed on the carbon surface were a function of the DO level. Phenol recovery efficiencies around 70 % and 25 % were found for anoxic and oxic isotherms, respectively. The additional capacity attained under oxic conditions was limited by the masses of DO and granular activated carbon (GAC) in the test environment. Two empirical relationships relating the oxic capacity to the ratio of DO to GAC mass and the anoxic capacities were developed. Batch studies have shown that the apparent surface diffusivity coefficient for phenol in GAC decreased with increasing DO levels in the sorbate solution.