A General Isotherm Model for Activated Carbon Adsorption of Typical Natural Organic Matters

摘要

The activated carbon adsorption isotherms of organic matters in natural water were type II and III isotherms, which cannot fitted accurately by the Langmuir and Freundlich models. It is investigated on the different kinds of activated carbon adsorption characteristics for humic, lignin and tannic acid and the fit of the modified SR equation. Results show that the modified SR model has a high degree of fit to all types of isotherms (Coefficient of determination >0.95) compared with the two classical models. In order to make the predicted value of the modified SR model having practical significance, the limiting adsorption capacity, which is related to the pore structure of activated carbon and organic molecular size, is introduced. Limiting equilibrium concentrations are calculated by the modified SR equation and the limiting adsorption capacity.