EFFECT OF SOLUTION PH ON THE KINETICS OF PHENOLICS UPTAKE ON GRANULARACTIVATED CARBON

The impact of solution pH on the kinetics of adsorption and adsorption -reaction combination of phenol and o-cresol on Granular Activated Car bon (GAC) was evaluated at room temperature (21 degrees C). Batch expe riments were performed under oxic and anoxic conditions at pH values o f 3, 7, and 11. The results showed that the equilibration time for phy sical adsorption increased with the increase in pH and occurred in the time range of (7.5-11) days for the adsorption-reaction combination ( oxic cases). The polymerization reactions lagged by about 10 h under a ll of the pH values. Diffusivity coefficients in the oxic cases increa sed inversely with pH while the highest difference between oxic and an oxic diffusivities was observed at neutral pit. The homogeneous surfac e diffusion model (HSDM) predicted accurately the anoxic batches and d eviated from the oxic data under all pH conditions. Under controlled d issolved oxygen and pH conditions, the isotherm and batch equilibrium capacities matched with maximum deviation of 4%. The effect of solutio n pH on the rate of the DO-induced enhancement was found to follow a s implified form of self retardant reaction model. The aforementioned mo del showed strong predictive capability for the formation of polymers with time.