Regulation of the crystal growth of NaP zeolite with organic steric hindrance agents

With sodium silicate and sodium aluminate extracted from fly ash as the raw materials, NaP zeolite was prepared by hydrothermal synthesis method; the synthesis parameters such as crystallization time, temperature and the ratio of silicon/H₂O were optimized via orthogonal tests. The method to regulate the crystal growth process was proposed through controlling the steric hindrance effect. The NaP zeolite was characterized by XRD, FT-IR, SEM and N₂ sorption; the effect of steric hindrance on the crystal phase and grain size was investigated. The results show that the morphology and grain size of NaP zeolite can be effectively regulated by introducing steric hindrance agents into the hydrothermal reaction system. The strength of steric hindrance effect of various agents follows the order of ring structure > linear structure, long chain structure > short chain structure. The adsorption test suggests that removal rate of Zn²⁺ exceeds 99.8% for NaP zeolite under the optimal adsorption conditions.