(623a) Advanced Textural/Surface Characterization and Water Adsorption Properties of Materials Used in Water Treatment Applications

A comprehensive characterization of nanoporous carbon materials has become more important than ever for the optimization of existing and potentially new applications in many areas, including water treatment applications. Furthermore, there are still many open questions concerning the effects of surface properties and pore structure on water adsorption in carbon materials used in water treatment. In order to address these open questions, we focused on a selected series of activated carbons exhibiting various pore networks and diverse surface chemistry characteristics, namely: Filtrasorb 400 (F400), Industrial React High Affinity (IRHA) and Picabiol (PBL), Row 0.8 Supra, Carbon Granular and Picactif TE 80.

Specific surface areas as well as pore structures of these carbons were determined based on argon, nitrogen and carbon dioxide adsorption-desorption isotherms measured at 87.3 K, 77.4 K, and 273.1 K, respectively. Furthermore, state of the art approaches for the analysis of the adsorption data - including a recently developed novel DFT (Density Functional Theory Approach), i.e. QSDFT (Quenched Solid Density Functional Theory [1]) were used, allowing for much more accurate pore size analysis, since QSDFT takes into account the heterogeneous nature of the carbon surface.

A detailed study of the surface chemistry was obtained by applying temperature programmed desorption with attached masspectrometer (TG-TPD-MS) as well as XPS (X-Ray-Photoelectron Scattering). This information coupled with the pore structure information allows to interpret the results of systematic water adsorption measurements (at various temperatures) on these materials, which is crucial for a better understanding of the adsorption phenomena involved in water treatment applications. Our data clearly indicate that water adsorption offers opportunities for the surface and textural characterization of porous carbon materials. In particular the existence of water sorption hysteresis which is associated with the filling of micro- and narrow mesopores [2,3] (in a range where nitrogen and argon isotherms are reversible can (if interpreted correctly) be useful for textural characterization.

[1] A.V Neimark, P.I Ravikovitch, Y. Lin, M. Thommes, Carbon, 47, 1617 (2009) [2] T. Ohba, H. Kanoh, K. Kaneko, J. Phys. Chem B 108, 14964 (2004) [3] D.D.Do and H.D. Do, Carbon 38, 767 (2000