地质聚合物及其原位合成沸石去除水溶液中氟离子研究

Study on the Removal of Fluoride Ions with Geopolymer and Zeolites Prepared through Geoplymerization

以NaOH和KOH混合碱液作激发剂,偏高岭土为固体原料,利用相同的工艺,分别制得地质聚合物和沸石样品,采用X射线衍射、扫描电子显微镜、比表面积和孔径分布分析对样品的物相和结构进行了表征,并将其用于水溶液中氟离子的吸附处理,探讨了其吸附去除氟离子的效率和特性。研究结果表明,沸石样品主要以I型钾沸石和F型钾沸石为主,比表面积为74.4 m^(2)/g,远高于地质聚合物的41.1 m^(2)/g。地质聚合物及其原位合成沸石对水溶液中氟离子都具有较好的吸附性能。在pH<4,温度为30℃条件下,地质聚合物样品最大氟离子吸附容量可达236.97 mg/g,沸石样品的吸附容量略大于地质聚合物。地质聚合物样品对氟离子的吸附等温线符合Langmuir模型,而沸石更符合Freundlich模型;两者的吸附动力学可用准二级动力学模型描述,属化学吸附过程。

Zeolite and geopolymer samples were prepared through the same method with NaOH/KOH mixed alkaline solution as activator and metakaolin as raw material,and the phase and microstructure were characterized with X-ray diffraction,scan electron microscope,specific surface area and pores distribution analysis.The samples were applied to treat the fluoride-containing solution and the efficiency and properties of fluoride ions removal were investigated.The results showed that the main phase of zeolite sample were K-I and K-F zeolites;the BET specific area of zeolite sample was 74.4 m^(2)/g,much higher than that of geopolymer sample(41.1 m^(2)/g).Both zeolite and geopolymer samples presented excellent performance of fluoride ions adsorption.The maximum adsorption capacity of geopolymer could reach to 236.97 mg/g and zeolite sample presented slightly higher adsorption capacity under pH<4 and temperature of 30℃.The isotherm data of geopolymer sample fit the Langmuir isotherm model well while that of zeolite sample fit the Freundlich isotherm model well.The kinetics data of two samples exhibited best fit to pseudo-second-order-model,indicating the chemisorption of fluoride ions onto the adsorbents.