Kinetics of Adsorption on Carbon from Solution

Laboratory investigations show that rates of adsorption of persistent organic compounds on granular carbon are quite low. Intraparticle diffusion of solute appears to control the rate of uptake, thus the rate is partially a function of the pore size distribution of the adsorbent, of the molecular size and configuration of the solute, and of the relative electrokinetic properties of adsorbate and adsorbent. Systemic factors such as temperature and pH will influence the rates of adsorption; rates increase with increasing temperature and decrease with increasing pH. The effect of initial concentration of solute is of considerable significance, the rate of uptake being a linear function of the square-root of concentration within the range of experimentation. Relative reaction rates also vary reciprocally with the square of the diameter of individual carbon particle for a given weight of carbon. Based on the findings of the research, fluidized-bed operation is suggested as an efficient means of using adsorption for treatment of waters and waste waters.