Mechanisms of humic material adsorption on kaolin clay and activated carbon

Gel permeation chromatography was used for monitoring the changes in humic molecular weight distribution after contact with kaolin clay and activated carbon. The high molecular weight fractions excluded from Sephadex G-50 were less removed by carbon indicating the exclusion effect of pores, but were preferentially adsorbed by clay. The aliphatic portion of humic acids is effectively removed by carbon as suggested by the decrease in E₄: E₆ ratio. The Freundlich and the Langmuir isotherms showed curvilinearity which was resolved into two straight lines. The sorption effect in humic molecular weight distribution suggests the necessity of batch adsorption test with respect to the treated humic material.