3.2 Pore Size Distribution
The entire porous structure is formed by a wide range of pore sizes. The pore size distribution of the RF
gels is shown in figure 1b. There is a shift to the right in the pore size distribution at increasing R/C ratio.
This indicates an increase in mesporosity in the RF gels with increasing R/C ratio. It can be seen that RF
gel with R/C = 100 has the narrowest pore size distribution with the maxima occurring at pores of 2 nm.
The RF gels with R/C = 200 has a wider pore size distribution with the maxima occurring at pores of 4 nm
radius. The width of the pore size distributions increases with increases in R/C ratio. For R/C = 500 and
600 the maxima pore size occur at 20 nm and 40 nm. The maximum pore size for R/C = 700 and 800 was
45 nm. This was due to the fact that the hysteresis was located within the same p/po range (Job et al.
2006). It can be seen from Table 1, the average pore size radius increases with increase in R/C ratio. This
can act as a molecular sieve allowing adsorbate molecules of the adsorbent pore size or less to pass
through to the exclusion larger molecules. This therefore determines the size of the adsorbates that can
enter a pore for adsorption.