Diffusion of hydrophilic organic micropollutants in granular activated carbon with different pore sizes.

Hydrophilic organic micropollutants are commonly detected in source water used for drinking water production. Effective technologies to remove these micropollutants from water include adsorption onto granular activated carbon in fixed-bed filters. The rate-determining step in adsorption using activated carbon is usually the adsorbate diffusion inside the porous adsorbent. The presence of mesopores can facilitate diffusion, resulting in higher adsorption rates. We used two different types of granular activated carbon, with and without mesopores, to study the adsorption rate of hydrophilic micropollutants. Furthermore, equilibrium studies were performed to determine the affinity of the selected micropollutants for the activated carbons. A pore diffusion model was applied to the kinetic data to obtain pore diffusion coefficients. We observed that the adsorption rate is influenced by the molecular size of the micropollutant as well as the granular activated carbon pore size.