乙醇辅助氨基改性NCR-MCM-48分子筛的制备及其对Cr(VI)的吸附性能

以稻壳灰提纯出的硅胶为无机组装硅源,乙醇为辅助试剂,通过水热合成法制备了CR-MCM-48分子筛,并对其氨基改性接枝制备NCR-MCM-48介孔分子筛。实验探讨了硅钠比、晶化温度、晶化时间及乙醇含量对CR-MCM-48介孔结构和形貌的影响。通过X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、N₂吸附-脱附曲线和红外光谱(FT-IR)对合成材料进行了结构和形貌表征,并对NCR-MCM-48介孔材料吸附水溶液中Cr(VI)的性能进行了评价。结果表明,当物料摩尔比n(Si)∶n(CTAB)∶n(H₂O)∶n(NaOH)∶n(C₂H₅OH)=1.0∶0.65∶62∶0.625∶0.25,晶化温度为393 K,晶化时间为72 h,焙烧温度为823 K时,组装合成的CR-MCM-48介孔材料有序度最好。热力学分析结果表明,NCR-MCM-48对Cr(VI)的吸附是自发、吸热反应。在吸附温度为308 K、pH=2.0、吸附时间为150 min的条件下,NCR-MCM-48吸附剂对Cr(VI)的最大吸附容量为88.9 mg·g^-1。

Preparation of Amino Modified NCR-MCM-48 Molecular Sieve by Ethanol Assisting and Its Adsorption Performance of Cr(VI)

CR-MCM-48 molecular sieve was prepared through hydrothermal synthesis method with the silica gel purified from rice husk ash as the source of inorganic assembled silicon and the ethanol as the assisted reagent, and then NCR-MCM-48 mesoporous molecular sieve was synthesized by amino grafting to CR-MCM-48. The effects of the molar ratio of Si and Na, crystallization temperature, crystallization time and the addition of the organic assisted reagent ethanol on the mesoporous structure and the morphology of CR-MCM-48 were investigated. X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), N₂ adsorption-desorption curves and infrared spectroscopy (FT-IR) were used to characterize the structure and the morphology of the synthesized materials. The adsorption performance of Cr(VI) in aqueous solution by NCR-MCM-48 mesoporous material was evaluated. The results show that when n(Si)∶n (CTAB)∶n(H₂O)∶n(NaOH)∶n(C₂H₅OH) is 1.0∶0.65∶62∶0.625∶0.25, the crystallization temperature is 393 K, the crystallization time is 72 h, and the calcination temperature is 823 K, the assembled and synthesized CR-MCM-48 mesoporous material exhibits the best degree of order. The results of thermodynamic analysis show that the adsorption of Cr(VI) by NCR-MCM-48 is a spontaneous and endothermic reaction. The maximum adsorption capacity of NCR-MCM-48 for Cr(VI) is 88.9 mg·g^-1 when the adsorption temperature is 308 K, pH is 2.0, and the adsorption time is 150 min.