School of Resource and Environmental Engineering, Hefei University of Technology, China.
J Colloid Interface Sci. 2013 Jan 15;390(1):204-10. doi: 10.1016/j.jcis.2012.09.010. Epub 2012 Sep 25.
Magnetic zeolite NaA with different Fe(3)O(4) loadings was prepared by hydrothermal synthesis based on metakaolin and Fe(3)O(4). The effect of added Fe(3)O(4) on the removal of ammonium by zeolite NaA was investigated by varying the Fe(3)O(4) loading, pH, adsorption temperature, initial concentration, adsorption time. Langmuir, Freundlich, and pseudo-second-order modeling were used to describe the nature and mechanism of ammonium ion exchange using both zeolite and magnetic zeolite. Thermodynamic parameters such as change in Gibbs free energy, enthalpy and entropy were calculated. The results show that all the selected factors affect the ammonium ion exchange by zeolite and magnetic zeolite, however, the added Fe(3)O(4) apparently does not affect the ion exchange performance of zeolite to the ammonium ion. Freundlich model provides a better description of the adsorption process than Langmuir model. Moreover, kinetic analysis indicates the exchange of ammonium on the two materials follows a pseudo-second-order model. Thermodynamic analysis makes it clear that the adsorption process of ammonium is spontaneous and exothermic. Regardless of kinetic or thermodynamic analysis, all the results suggest that no considerable effect on the adsorption of the ammonium ion by zeolite is found after the addition of Fe(3)O(4). According to the results, magnetic zeolite NaA can be used for the removal of ammonium due to the good adsorption performance and easy separation method from aqueous solution.
基于偏高岭土和 Fe3O4，采用水热合成法制备了不同 Fe3O4 负载量的磁性沸石 NaA。通过改变 Fe3O4 负载量、pH 值、吸附温度、初始浓度和吸附时间，考察了添加的 Fe3O4 对沸石 NaA 去除铵的影响。采用 Langmuir、Freundlich 和拟二级动力学模型描述了沸石和磁性沸石对铵离子交换的性质和机理。计算了热力学参数，如吉布斯自由能、焓和熵的变化。结果表明，所有选定的因素都影响沸石和磁性沸石对铵离子的交换，但添加的 Fe3O4 显然不会影响沸石对铵离子的交换性能。Freundlich 模型比 Langmuir 模型更能描述吸附过程。此外，动力学分析表明，两种材料上的铵交换遵循拟二级动力学模型。热力学分析表明，铵的吸附过程是自发的和放热的。无论从动力学还是热力学分析来看，添加 Fe3O4 后，沸石对铵离子的吸附均未发现明显影响。根据这些结果，由于具有良好的吸附性能和从水溶液中易于分离的方法，磁性沸石 NaA 可用于去除铵。
