The obtained results indicated that NaOH modification caused
obviously influence on the pore characteristics of clinoptilolite. The
appropriate concentration of NaOH can substantially create mesoporous
and microporous [14]. Combined with the ICP-OES result,
the alkalis modification would dissolve impurity K in the channel
and Si, Al in the framework. At the low concentration, there appear
more channels and the surface area increase as the removal of
impurity such as Si, Al elements. The high concentration caused the
large quantities removal of Si, Al element, which induced the
decrease of surface area. What's more, pore size changed bigger
that due to the increase of macroporous pore volume.