粉煤灰合成分子筛及处理含氟废水的研究

Preparation and characterization of fly ash based zeolites for fluoride removal

实验利用工业废渣——循环流化床粉煤灰合成出较高结晶度的X型和P型分子筛,合成过程无须高温焙烧预处理。通过XRD分析表征,发现该法合成分子筛结晶度较高,X型和P型分子筛相对结晶度分别达68%～75%和55%。实验应用合成分子筛进行载铁改性,并对NaF模拟的工业含氟废水进行了除氟实验。结果表明,载铁X型分子筛处理工业含氟废水效果良好,除氟率可达74%～98%,除氟容量达25.0～30.0mg/g。在处理含氟废水过程中,载铁合成分子筛与其他除氟剂相比较,具有除氟率高、除氟容量大、反应迅速的特点。

Two types of molecular sieve adsorbents （zeolites） were prepared from power plant residual circulation fluidized bed fly ash by hydrothermal reactions. The X and P zeolites were produced by baking without pretreating the raw materials. The XRD characterizations show that relative crystallinity of the X and P zeolites were 68%- 75 % and 55 %, respectively. FeCl3 was employed for impregnation of Fe^3＋ on the X zeolite, and the effects of FeCl3 loading, impregnation temperature and contact time on the modified zeolite＇s capacity were determined. The Fe impregnated X zeolite removed 74%-98% of F in the test runs with an adsorptive capacity of 25.0-30.0 mg/g it demonstrated a higher capacity, faster and more complete removal of F than the original X zeolites, natural zeolite, clay and fly ash. The formation of FeFn^3-n （n= 1-6） resulted in a higher capacity due to chemical adsorption.