铵饱和天然钙型沸石的化学再生效果

为实现沸石人工湿地的长期高效运行，以铵饱和天然钙型沸石为对象，通过沸石化学再生试验，从6种常用化学再生剂(NaCl+NaOH，NaCl+CaCl₂和NaCl+NaHCO₃组合型，以及NaCl，CaCl₂和NaHCO₃)中筛选出最佳再生剂，并优化了再生剂适用条件. 结果表明，NaCl+CaCl₂组合型再生剂能提升沸石再生率10%～20%，且不影响沸石结构，是一种较优的再生剂. 采用NaCl+CaCl₂组合型再生剂，Na+在沸石再生初期起主导作用，而当c(Na＋)较低时，Ca2+的离子交换作用逐渐起主导作用，因而采用该组合型再生剂能显著提升再生剂效果的持久性. 再生条件优化试验表明，当c(NaCl)∶c(CaCl₂)为7∶3，即当Ca2+和Na+所带正电荷数接近时，组合型再生剂再生率相对较高；当再生温度低于45℃时，升高温度能显著提升沸石再生率；而再生剂投加量为0.6 mol/L(以再生剂中的阳离子浓度计)时，组合型再生剂投加量最经济. 

Chemical Regeneration Performance of Natural Ca-form Zeolite Saturated with Ammonium

The natural Ca-form zeolite saturated with ammonium was studied through chemical regeneration experiments related to ensuring the long-term stable operation of constructed wetlands stuffed with zeolite. The regeneration conditions were optimized for the six common chemical regenerative agents NaCl+NaOH, NaCl+CaCl_2, NaCl+NaHCO_3, NaCl, CaCl_2 and NaHCO_3. The results show that in comparison with other usual chemical agents, the combined regenerative agent NaCl+CaCl_2 exhibits better effects on zeolite regeneration. The agent not only can enhance the zeolite regeneration rate by 10%-20%, but also does not break down the structure of the zeolite. By use of this combined regenerative agent NaCl+CaCl_2, Na~+ plays the major role in the initial stage of zeolite regeneration.Only when Na~+ is depleted gradually Ca~(2+) begins to play an important role. Therefore, by using this combined regenerative agent, the operation durability of the agent can be significantly enhanced. Additionally, when the molar ratio between NaCl and CaCl_2 is 7∶3, namely when the amount of the positive charge of Ca~(2+) and Na~+ are close, the combined regenerative agent displays better regeneration efficiency. And when the temperature is less than 45 ℃, the regeneration efficiency can be significantly enhanced with increasing temperature. Finally, it is most economical when the regenerative agent is added at 0.6 mol/Ｌ concentration.