碱处理对河北围场天然沸石结构和性能的影响及其机理研究

采用NaOH对围场地区天然沸石进行处理,采用X射线衍射仪、红外光谱仪、N_2吸附-脱附技术、扫描电子显微镜等对材料进行表征分析,采用水蒸气吸附法评价材料的亲水性,采用Cr~(3+)和Mn~(2+)评价材料的离子交换性能,探讨了碱处理对天然沸石的结构、亲水性和离子交换性能的影响及其机理。实验结果表明,围场地区天然沸石中主要含有斜发沸石、石英和伊利石;碱处理可降低天然沸石的硅铝比,且沸石的硅铝比随着碱处理浓度的提高而不断降低;碱处理对斜发沸石结构的影响较石英和伊利石更大;高浓度碱处理导致天然沸石的结构发生破坏,比表面积降低,孔体积提高;伴随着天然沸石硅铝比的降低,其亲水性和离子交换性能不断提高。

The effect of alkali treatment on structure and property of natural zeolite from Weichang area, Hebei Province

In this paper, the natural zeolites from Weichang area were treated with sodium hydroxide. X-ray diffractometer, infrared spectrometer, N₂ adsorption-desorption technique and scanning electron microscope were employed to characterize the materials, water vapor adsorption method was adopted to evaluate the hydrophilicity of materials, and Cr and Mn ions were used to determine the ion exchange property of materials. The effect and the mechanism of alkali treatment on structure, hydrophilicity and ion exchange property of natural zeolites were then investigated. The results show that the natural zeolites from Weichang area contain clinoptilolite, quartz and illite. Alkali treatment could decrease the SiO₂/Al₂O₃ ratio of natural zeolites, and the SiO₂/Al₂O₃ ratio gradually decreases with the increase of alkali concentration. The influence of alkali treatment on structure of clinoptilolite is higher than that of quartz and illite. The structure of natural zeolite is destroyed, the specific surface area of natural zeolite decreases and the pore volume of natural zeolite increases under high alkali concentration. The hydrophilicity and ion exchange property of natural zeolites gradually increase, accompanied by the decrease of SiO₂/Al₂O₃ ratio.