【作者】 曲玉萍；

【导师】 李春喜；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2011， 硕士

【摘要】 近年来,离子液体已经逐渐代替传统的有机溶剂被使用于各种化工研究过程。由于离子液体具有蒸汽压低、热稳定性好等特点,被认为是“绿色溶剂”,但这并不意味着离子液体对环境没有任何危害。目前,离子液体对环境的影响方面的研究已有不少,但主要集中在离子液体对不同生物体系毒性的研究,对如何去除水中的离子液体方面的研究还比较少。本文以常见的几种离子液体为对象,研究了四种高级氧化技术对其降解效果；另外,还研究了几种吸附剂对离子液体的吸附行为。主要研究内容包括以下两部分：(1)选取了1-丁基-3-甲基咪唑氯盐([Bmim]Cl)、1-丁基-3-甲基咪唑六氟磷酸盐([Bmim]PF6)、1,3-二甲基咪唑磷酸二甲酯([Mmim]DMP)三种离子液体,研究了几种高级氧化技术,即Fenton试剂法、Fe/C原电池氧化法和湿式催化氧化法,以及Hoffman化学分解法对离子液体的降解能力,并讨论了各种方法的降解特点和效果。结果表明,Fenton试剂法只能够改变咪唑环阳离子的侧链结构(侧链氧化),而不能完全破坏阳离子结构；[Bmim]Cl和[Bmim]PF6两种离子液体与NaOH溶液混合后在180℃共热24h,[Bmim]阳离子也未发生霍夫曼消除反应转化为易挥发性的有机物,因此,要想使用气相催化燃烧法降解离子液体还需要探索更好的使离子液体气化的方法；负载铁活性炭(Fe/C/水泥复合材料)对离子液体的处理过程中,活性炭的吸附作用占了主导地位,而Fe/C原电池的氧化作用几乎没有体现出来；湿式催化氧化法能够完全破坏[Bmim]Cl的结构,降解效果很好,但是,在高温条件下1-丁基-3-甲基咪唑氯盐能够释放出腐蚀性的氯化氢,对设备腐蚀严重。但该方法对离子液体[C1MIm][Me2PO4]的氧化降解效果较差。(2)研究了蒙脱土、活性白土、人造沸石、活性炭、水滑石五种吸附剂对六种离子液体,即[Bmim]Cl、[Bmim]BF4、[Bmim]PF6、[Bmim]DBP、1-己基-3-甲基咪唑氯盐([Hmim]Cl)和1-辛基-3-甲基咪唑氯盐([Omim]Cl)的吸附效果。其中,温度对活性炭的吸附有明显的影响,对蒙脱土、活性白土和人造沸石无明显影响；五种吸附剂对去除水中的[Bmim]Cl效果：蒙脱土>活性白土>活性炭>人造沸石>水滑石,其中,蒙脱土和活性白土的去除效果相差不大,都远远好于活性炭和人造沸石,而水滑石几乎没有吸附作用；蒙脱土对[Bmim]Cl、[Bmim]BF4、[Bmim]PF6及[Bmim]DBP四种离子液体的吸附效果相差不大,说明吸附主要为阳离子交换吸附；蒙脱土对[Bmim]Cl、[Hmim]Cl、[Omim]Cl三种离子液体的平衡吸附量为[Bmim]Cl>[Hmim]Cl>[Omim]Cl,即随着离子液体的阳离子链长的增加,平衡吸附量逐渐减小,因为对于阳离子交换吸附过程,阳离子侧链越长,其离子半径越大,在比表面积和孔容一定的情况下,其达到饱和吸附时所能容纳的阳离子量就越低。更多还原

【Abstract】 In recent years, room temperature ionic liquids (ILs) have received great attention as primary alternatives to the organic solvents traditionally used in chemical processes. ILs having negligible vapor pressures and stable thermal properties are often regarded as "green solvents", but this does not mean that they are not harmful to the environment. Till now some studies have been reported on their environmental impact in terms of ecotoxicity, in contrast the studies on how to degrade and remove them from aqueous solutions are scarce. In this paper we reported the degradation ability of some ILs by four kinds of advanced oxidation methods and adsorptive removal with six kinds of adsorbents at various operation conditions.The main contents of this research include two parts as follows:(1)Using three ILs as prototypes, i.e. 1-butyl-3-methylimidazolium chloride and hexafuorophoshate ([Bmim]Cl and [Bmim]PF6),and 1-methyl-3-methylimidazolium dimethylphosphate ([Mmim]DMP),we studied their degradability by four different approaches, namely advanced oxidation and Hoffman decomposition reaction methods, and compared their performance and characteristics. The results show that (a)Fenton reagent can only change the structure of the alkyl substitute of imidazolium cation of [Bmim]Cl, but not totally destroy the cation or [Bmim]Cl; (b)The cation of ILs [Bmim]Cl and [Bmim]PF6 can not be converted to volatile tertiaryamines by Hoffman reaction at 180℃within 24 h in the presence of NaOH; (c)The removal ability of Fe/active carbon/cements composite for ILs originates predominantly from the adsorption performance of active carbon, while the voltaic oxidation of Fe/C micro cells is negligible; (d)Wet catalytic oxidation at high temperature can completely destroy the structure of [Bmim]Cl leading to the production of HCl and serious sevier corrosion to the steel reacor, however, this method shows a bad degradation ability for [C1MIm][Me2PO4].(2)The adsorption performance of six adsorbents, namely montmorillonite, activated clay, artificial zeolite, active carbon and hydrotalcite on six ILs are studied, viz. [Bmim]Cl, [Bmim]BF4, [Bmim]PF6, [Bmim]DBP, [Hmim]Cl and [Omim]Cl. The results show that (a) temperature has a profound influence on the adsorption performance of active carbon, but little influence on the remaining adsorbents; (b) For IL [Bmim]Cl, the adsorption ability of the adsorbents follows the order of montmorillonite> activeated clay> active carbon> artificial zeolite> hydrotalcite; and hydrotalcite has no adsorption to the IL studied; (c) Montmorillonite has nearly the same adsorption ability for four ILs with the same cation, i.e. [Bmim]Cl, [Bmim]BF4, [Bmim]PF6, and [Bmim]DBP, indicating that the adsorption is of cation exchange type; (d) The equilibrium adsorption of montmorillonite for three ILs with the same anion followeds the order of [Bmim]Cl>[Hmim]Cl>[Omim]Cl, that is, the equilibrium adsorption decreases gradually with the increase of the sidechain length of the ILs due to the limitation of the pore size of the adsorbents and the increasing size of ILs from [Bmim]Cl to [Omim]Cl.更多还原