Activated carbon adsorption of phenolics in oxic systems: Effect of pH and temperature variations

Studies were undertaken to determine the role of solution pH and temperature in the enhancement of the adsorptive capacity of GAC for phenol and o-cresol stemming from oxygen-induced polymerization. Anoxic and oxic isotherms for the sorbates were conducted at various pHs and temperatures. Adsorption isotherms were conducted at room temperature (21°C) and pHs of 3, 7, and 11. Low pH favors physical adsorption, measured by the anoxic capacity, while pH 11 promoted polymerization. The optimum pH for adsorption of phenolics under oxic conditions was pH 7. Isotherms were also conducted at neutral pH and temperatures of 8°, 21°, and 35°C. Lower temperatures favored physical adsorption and higher temperature achieved significant enhancement in capacity under oxic conditions. However, actual oxic isotherms capacities at 8° and 21°C, were identical. The sorption capacity could increase by more than two fold by changing solution pH and temperature.