钠化沸石去除稀土矿区废水中氨氮性能及机制研究

doi:10.19741/j.issn.1673-4831.2021.0810

摘要/Abstract

摘要： 氨氮高效吸附材料的研制及酸性氨氮尾水的处理对离子型稀土矿区生态环境建设具有重要的意义。通过浸渍法制备钠化改性沸石(NZ-NaCl),研究不同改性条件对其吸附氨氮的影响,并借助比表面积分析测试仪(BET)、扫描电子显微镜-能谱仪(SEM-EDS)、X射线荧光光谱分析仪(XRF)、傅里叶变换红外光谱仪(FTIR)等对改性前后的沸石进行结构表征。结果表明,NaCl改性可促进天然斜发沸石对氨氮的吸附性能,1 mol·L^-1 NaCl溶液在常温下、固液比(m∶V)为1∶5改性5 min时制备的NZ-NaCl材料对氨氮的平衡吸附容量达到11.12 mg·g^-1,是天然沸石的2.62倍,在实际稀土矿区废水应用中,NZ-NaCl投加量为0.02 g·mL^-1时对氨氮、稀土元素、Pb和Cd的去除率分别为100%、96.2%、99.8%和47.0%,显著高于天然沸石。NaCl改性增加了沸石比表面积,裸露内部的片层结构和孔道,出现类纳米纤维的柱状体;同时Na置换了沸石空穴中其他阳离子的吸附位点,降低了沸石吸附氨氮的空间位阻,加快了内扩散,释放了更多NH₄⁺的吸附位点,进而提高NZ-NaCl对氨氮的吸附和交换性能。此外,在吸附去除氨氮过程中NZ-NaCl比天然沸石有更多的结合形态。研究结果对进一步研发高性能沸石吸附材料,改进稀土矿区酸性氨氮废水治理技术具有重要参考价值。

关键词: 沸石, NaCl, 改性, 氨氮, 吸附机制, 结构表征

Abstract: Development of high-performance adsorption materials and effective treatment of ammonia nitrogen in acid wastewater is crucial to the eco-environment conservation of ion-absorbed rare earth mine area. The NaCl modified natural zeolite (NZ-NaCl) was prepared by impregnation method, and the effects of modified conditions on adsorption of ammonia nitrogen were investigated. The structural characteristics of zeolite before and after modification were determined by BET, SEM-EDS, XRF and FTIR. The results show that NaCl modified zeolite improved the adsorption performance of zeolite for ammonia nitrogen. The zeolite modified by 1 mol·L^-1 NaCl at room temperature and the solid to liquid ratio of 1∶5, the equilibrium adsorption capacity of NZ-NaCl reached to 11.12 mg·g^-1, which was 2.62 times that of natural zeolite. In the actual application of wastewater in ion-absorbed rare earth mine area, the removal rates of ammonia nitrogen, rare earth elements, Pb and Cd were 100%, 96.2%, 99.8% and 47.0%, respectively, when the dosage of NZ-NaCl was 0.02 g·mL^-1. The improvement of adsorption capacity was related to the increase in the specific surface area, exposure of internal lamellar structure and pores, and the occurrence of columnar nanofibers. The modification reduced the steric hindrance of ammonia nitrogen adsorption, accelerated the internal diffusion, released more NH₄⁺ adsorption sites, due to the replacement of other cations in internal zeolite by sodium, and then improved the adsorption performance of NZ-NaCl for ammonia nitrogen. In addition, NZ-NaCl had more binding forms to removal ammonia nitrogen by adsorption than that of natural zeolite. The results could be an important guideline to the further development of high-performance adsorption materials and to the effective removal of ammonia nitrogen in acid wastewater of ion-absorbed rare earth mine area.

Key words: zeolite, NaCl, modified, ammonia nitrogen, adsorption mechanism, structural characterization

中图分类号:

X522

王玉荣, 周志高, 丁昌峰, 张桃林, 王兴祥. 钠化沸石去除稀土矿区废水中氨氮性能及机制研究[J]. 生态与农村环境学报, 2023, 39(6): 795-802.

WANG Yu-rong, ZHOU Zhi-gao, DING Chang-feng, ZHANG Tao-lin, WANG Xing-xiang. Adsorption of Ammonia Nitrogen from Rare Earth Wastewater by NaCl Modified Zeolite and Its Mechanism[J]. Journal of Ecology and Rural Environment, 2023, 39(6): 795-802.

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