2.5.6. Internal porosity and pore size distribution
Internal porosity and pore size distribution were measured by using a mercury porosimeter (Quantachrome Corporation, Poremaster 60) and a helium pycnometer (Quantachrome Corporation, Ultrapycnometer 1000). Before the experiment, all samples were freeze dried, not to damage the pores, for the operating conditions of the porosimeter. Low pressure, which is in the range of 0–345 kPa, was used in mercury porosimeter experiments. In addition, for total porosity determination a helium pycnometer was used.