4. Conclusion
The proportion of mesoporous and cation exchange capacity
increased after modified by NaOH. When the NaOH concentration
was 1.5 mol/L, the pore volume ratio of mesoporous and cation
exchange capacity increased from 63.82%,169.67 mmol$(100 g)1 to
74.51%,186.25 mmol$(100 g)1respectively and the ammonia nitrogen
removal rate increased to 79.66% from 53.45%. The high
concentration of alkali may dissolve the impurity in the clinoptilolite,
which will block the channel and led to the decrease of the
specific surface area, cationic activity.