Equilibria and Capacities for Adsorption on Carbon

Abstract

Laboratory investigations show that the ultimate capacity of granular carbon for adsorption of biochemically-resistant organic substances from dilute solution after a sufficient period of contact is on the order of 15% to 25% by weight. Experimental adsorption isotherms for a number of organic substances indicate that adsorption equilibria for solutions of micromolar concentration are well-described by the Langmuir monolayer adsorption theory. Adsorption equilibria for solutions of high concentration appear to be best described by the Brunauer-Emmett-Teller multilayer theory. Interpretation of observed data leads to the conclusion that different types of adsorbed films are formed for high and low concentrations in solution at equilibrium with carbon; the data appear to reveal a range of activities for various parts of the surface area of the adsorbent. Ultimate capacities increase with decreasing temperature, decreasing pH, and decreasing particle size.