Separation Science and Technology, Vol.32, No.7, 1255-1272, 1997
Modeling of the Temperature-Variation Effects on the Polymerization Reactions of Phenolics on Granular Activated Carbon
The effect of temperature variation on the kinetics of adsorption and adsorption-reaction combination of phenol and o-cresol on granular activated carbon (GAG) was evaluated throughout this study. Batch experiments were performed under oxic and anoxic conditions at temperatures of 8, 21, and 35 degrees C. The results showed that the equilibration time for physical adsorption increased with the decrease in temperature 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 hours under all of the temperature values. Diffusivity coefficients in the anoxic cases increased proportionally with temperature, with the highest difference between oxic and anoxic diffusivities at a temperature 35 degrees C. The homogeneous surface diffusion model (HSDM) accurately predicted the anoxic batches and deviated from the oxic data. Temperature increases the adsorption and polymerization reaction rates, and thus the predictivity of the HSDM for both oxic and anoxic batches improves. Under controlled dissolved oxygen (DO) and temperature conditions, the isotherm and batch equilibrium capacities matched with a maximum deviation of 4%. The effect of temperature on the rate of the DO-induced enhancement was found to follow a self-retardant reaction model. The developed model showed strong predictive capability for the temporal formation of polymers.