Influence of porosity and surface chemistry of commercially available powdered activated carbons for the removal of dissolved organic carbon

More restricting legislation on Dissolved Organic Carbon (DOC) content in drinking water, especially when applied to waters with high DOC contents and low turbidity, urges the industry to improve, all along the processes, the removal of dissolved organic matter (DOM) in drinking water resources. This work focused on the characterisation of the performances of commercially available powdered activated carbons (PAC). Equilibrium isotherms were carried out on pre-treated water, i.e. after coagulation, flocculation and sedimentation. In order to determine the efficiency of the PAC, the DOM content was estimated through DOC and UV absorbance measures, as well as being characterised by size exclusion chromatography. The various experiments carried out showed some differences in the adsorption capacity, depending on their pore distribution and surface chemistry. The maximum removal ratio reached 82% and 45% for DOC and SUVA respectively. The isotherm equilibrium results can be used to define several kinds of DOC fractions, which were modelled by the Freundlich equation. Finally, the SEC chromatograms showed that the pore size distribution of the activated carbons affected significantly the compound size distribution of the removed DOM.