咪唑类离子液体在β沸石上的吸附  

Adsorption of imidazolium ionic liquid onto β zeolites

作　　者：赵瑰施 张玲[1] 万玉秋[1] 许昭怡[1] 郑寿荣[1] 

机构地区：[1]污染控制与资源化研究国家重点实验室,南京大学环境学院,南京210046

出　　处：《环境化学》2016年第8期1649-1656,共8页Environmental Chemistry

基　　金：国家自然科学基金(21277066);973项目(2014CB441103)资助

摘　　要：采用硅铝比(SiO_2与Al_2O_3的物质的量之比)为31.66和190.73的两种β沸石分子筛,吸附氯化1,3-二甲基咪唑([DMIM]Cl)、氯化1-丁基-3-甲基咪唑([BMIM]Cl)及氯化1-辛基-3-甲基咪唑([OMIM]Cl)等3种不同分子量大小的咪唑类离子液体,研究不同硅铝比的β沸石对分子大小不同的离子液体的吸附差异.实验结果表明,β沸石对离子液体的吸附等温线符合Freundlich吸附模式,[DMIM]Cl、[BMIM]Cl和[OMIM]Cl在β_1沸石上的吸附容量分别为0.62 mmol·g^(-1)、0.67 mmol·g^(-1)和0.73 mmol·g^(-1),在β_2沸石上的吸附容量分别为0.23 mmol·g^(-1)、0.38 mmol·g^(-1)和0.55 mmol·g^(-1).β_1沸石的吸附效果比β_2沸石要好,且随着离子液体阳离子上烷基侧链碳原子数目增加,针对同一种吸附质,β_1和β_2沸石吸附容量之间的差异逐渐减小.吸附动力学显示[DMIM]Cl、[OMIM]Cl在β沸石上的吸附符合二级动力学,β_1沸石吸附速率高于β_2沸石,且吸附平衡所需时间更短.[DMIM]Cl和[OMIM]Cl在β_1沸石上的吸附速率常数分别为0.0248 g·mg^(-1)·min^(-1)和0.0109 g·mg^(-1)·min^(-1),在β_2沸石上的吸附速率常数分别为0.0171 g·mg^(-1)·min^(-1)和0.0033 g·mg^(-1)·min^(-1).β沸石对离子液体[BMIM]Cl及[OMIM]Cl的吸附容量比目前已报道文献中的活性炭的更高,是去除水体中离子液体的一种潜在优质吸附剂.In this work, we used two β zeolites with Si/A1 ratios （mole ratio of SiO2 to Al2O3 ） of 31.66 and 190.73 to adsorb three imidazolium-based ionic liquids, including 1, 3- Dimethyllmidazolium Chloride （ [ DMIM ] C1）, 1-butyl-3-methyl-imidazolium chloride （ [ BMIM ] C1） and 1-octyl-3-methylimidazolium chloride （[ OMIMJ CI）, to investigate the adsorption mechanism of ionic liquid onto β zeolites. The results showed that the adsorption isotherms of ionic liquid onβ zeolites were well described with the Freundlich model. The adsorption capacity of [ DMIM ] C1, [BMIM] C1 and [ OMIM] C1 on β1 zeolite was 0.62 mmol.g-1, 0.67 mmol.g-1 and 0.73 retool.g-1, respectively, while the adsorption capacity onβ2 zeolite was 0.23 mmol. g-1, 0.38 mmol.g-1 and 0.55 mmol.g-1, respectively. The β1zeolite was proved to have higher adsorption capacity thanβ2 zeolite, and the difference in the adsorption capacity between β1 and β2 zeolites decreased with the number of the carbon atoms of the substituted alkyl chains. The adsorption process of ionic liquid over 13 zeolites could be well described using the pseudo-second-order kinetics, andβ1 zeolite had a shorter adsorption equilibrium time than β2 zeolite. The adsorption rate constants of [ DMIM ] C1 and [ OMIM] C1 ontoβ1 zeolite were 0.0248 g.mg-1. min-1 and 0.0109 g. mg-1. min-1 respectively, and were 0.017 g.mg-l-min-1 and 0.0033 g.mg-l, min-1 ontoβ2 zeolite, respectively. The adsorption capacities of [ BMIM ] C1 and [ OMIM ] C1 onβ zeolite are much higher than those reported on activated carbon, highlighting the potential of zeolite as promising adsorbents for the removal of ionic liquids in water.

关 键 词：Β沸石 离子液体 吸附 

分 类 号：X703[环境科学与工程—环境工程]