3.1.3. The change of cation exchange capacity of clinoptilolite
modified by NaOH
The value of cation exchange capacity for clinoptilolite modified
with different concentrations of NaOH is shown in Fig. 2, which
shows that cation exchange capacity of clinoptilolite increased first
and then decreased with the increasing of NaOH concentration for
modification. Clinoptilolite cation exchange capacity reached the
maximum, from 169.67 mmol$(100 g)1 for natural clinoptilolite
increase to 186.25 mmol$(100 g)1, when NaOH concentration for
modification is 1.50 mol L1. Meantime, at this NaOH concentration,
clinoptilolite surface area increases the maximum, increasing from
35.97 m2 g1 for natural clinoptilolite to 51.83 m2 g1. Soluble silica
in clinoptilolite can be selectively removed by alkali modification,
which contributed to reduction of silicon aluminum ratio in