As the results in Fig. 4 indicate,EI increases nearly linearly with an increase in DG from 1.30±0.00 at 43.6% to
1.59±0.00 at 72.7%. This result is in accordance with the
findings of Guraya and Toledo (1994). However, the results
were not discussed. A higher gas-retaining capability of the
matrix at increasedDGmight be the reason for an increased
EI. Besides, atDG>64.2%, a larger number of pores created
per cross-sectional area of the pellets may also cause an
increase in EI, even when the pore sizes are shifted to
smaller values.