粉煤灰源分子筛的制备及其氨氮吸附性能探究

Exploration on the Preparation of Molecular Sieve from Fly Ash Source and Its Adsorption Properties of Ammonia Nitrogen

通过碱熔融-水热合成法,以固体废弃物粉煤灰制备NaA型沸石分子筛,再以简单的离子交换法改性制备了CaA型沸石分子筛。结合X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、比表面测试(BET法)等现代分析表征手段,对两种A型分子筛的形貌和结构进行表征,分析了等温线吸附过程并从吸附动力学角度探讨两种分子筛的吸附机理。结果显示,两种分子筛对氨氮的最佳吸附条件是温度为25℃,pH为6~7,分子筛投加量为150 mg,吸附时间为40 min;NaA型和CaA型分子筛对水中氨氮的吸附与准二级动力学和Freundlich模型拟合度更高,吸附以离子交换为主,该过程主要是多层吸附。此外,再生实验数据表明,两种分子筛的再生效率均在95%以上,显示良好的循环稳定性,具有重要的潜在工业应用价值。

NaA zeolite molecular sieve was prepared from solid waste fly ash by alkali melting-hydrothermal synthesis method,and then CaA zeolite molecular sieve was modified by simple ion exchange method.Combined with modern analytical methods such as X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM)and specific surface area testing(BET method),the morphology and structure of the two A-type molecular sieves were characterized,the isotherm adsorption process was analyzed,and the adsorption mechanism of the two molecular sieves was discussed from the perspective of adsorption kinetics.The results show that the optimal adsorption conditions for ammonia nitrogen by the two molecular sieves are as follows:temperature of 25℃,pH of 6~7,molecular sieves dosage of 150 mg,and adsorption time of 40 min.In addition,the regeneration experimental data show that the regeneration efficiency of the two molecular sieves is above 95%,showing good cycling stability and having important potential industrial application value.