磁性4A分子筛的制备及其对氨氮的吸附动力学研究

以高岭土为原料,采用水热法在晶化前加入合成磁铁矿制得Fe₃O₄含量为 4.48%的磁性4A分子筛。通过X 射线粉末衍射分析(XRD)、磁化率分析(MS)及磁回收效果实验对制备的磁性4A分子筛进行物性分析,并将该吸附材料应用于氨氮吸附实验,将吸附实验数据根据相应吸附等温方程进行拟合,随后使用动力学分析手段考查了其吸附过程反应机理。表征结果表明,Fe₃O₄的载入对分子筛的晶体结构影响不大,磁性4A分子筛磁化率稳定,可用来重复使用。该分子筛可以通过磁性分离进行回收,且磁性分离快速高效。吸附实验结果表明磁性4A分子筛容易吸附水中的氨氮,Fe₃O₄的载入对于分子筛本身的吸附容量影响较小。在Langmuir、Freundlich两种等温吸附模型拟合结果中,Freundlich曲线拟合效果更好。Lagergren准二级吸附动力学拟合结果表明,NH⁺₄在磁性4A分子筛上的吸附过程遵循准二级动力学反应机理。

Adsorption kinetic behavior of magnetic zeolite 4A for ammonia nitrogen

In this paper, magnetic zeolite was synthesized by kaolinite by using the hydrothermal method. Before crystallization the synthesized Fe₃O₄ magnetic fluid was added so as to synthesize the magnetic zeolite 4A in which Fe₃O₄ content came to 4.48%. Then the zeolite was applied in the adsorption experiments for the ammonia nitrogen in the solution. A combination of XRD and magnetic susceptibility analysis was performed in this synthesized magnetic zeolite 4A. Besides, the experimental data were utilized to fit the adsorption isotherm equation and then to perform the kinetic analysis. The results showed that the loading of Fe₃O₄ had little effect on the crystal structure, and magnetic susceptibility of magnetic zeolite 4A was stable enough to be reused. Two isotherm adsorption models were used and the Freundlich isotherm was in better agreement with the adsorption results. Furthermore, the fitting results of Lagergren quasi second-order rate equation showed that the adsorption rate was controlled by the chemical adsorption, and the adsorption of ammonia nitrogen conformed to the quasi second-order dynamics mechanism.