Significance of Zeta Potential in the Adsorption of Fulvic Acid on Aluminum Oxide and Activated Carbon

Studies on the adsorption of fulvic acid (FA) on activated carbon Norit GAC 1240 and activated aluminium oxide as adsorbents has been conducted. The adsorbents differed in their chemical composition, chemical properties, surface charge, and related zeta potential. The FA used was obtained from mud sampled at Kolobrzeg. The electrokinetic potential of the adsorbents and adsorbate over a wide range of pH was determined. The electrokinetic potential of FA depends not only on the pH of the solution but also on the charge of cations of the substance used to adjust it. A model of the surface of aluminium oxide is presented. The sorption process was conducted in a static environment. In order to determine the amount of adsorbed FA, the concentration of total organic carbon (TOC) before (TOCi-initial TOC concentration) and after adsorption (TOCe-equilibrium TOC concentration) was measured. After the adsorption process, the zeta potential of activated aluminium oxide was measured. The TOC removed per adsorbent surface unit was higher for aluminium oxide. The specific surface area and the electrokinetic potential may be useful indicators in selecting an adsorbent for particles of known ionic characteristics.