【摘要】：離子液體,新一代最具有發(fā)展?jié)摿Φ娜軇?其優(yōu)良的特性已經(jīng)吸引了各行各業(yè)專業(yè)人士的研究興趣。以離子液體替代有毒、易燃、易揮發(fā)的有機物用于高放廢液的處理的研究方興未艾。本文選用了1-丁基-3-甲基咪唑六氟磷酸鹽(C4mimPF6)、1-己基-3-甲基咪唑六氟磷酸鹽(C6mimPF6)及1-丁基-3-甲基咪唑雙三氟甲烷磺酰亞胺鹽(C4mimNTf2)三種離子液體。首先將離子液體作為溶劑,將所選的二環(huán)己基-18-冠醚-6(DCH18C6)溶解,得到冠醚-離子液體體系。然后用冠醚-離子液體體系對水相中的鈾酰離子進行萃取研究,最后將冠醚-離子液體體系用物理負載法負載到碳納米管上制成吸附材料,進一步用未負載以及負載化的碳納米管對水相中的鈾的吸附效果及規(guī)律做一系列研究,主要研究結(jié)果如下:以二環(huán)己基-18-冠醚-6為萃取劑,以所選的三種離子液體為溶劑的冠醚-離子液體萃取體系對水相中鈾酰離子(UO22+)的萃取實驗。實驗結(jié)果表明:UO22+在1-丁基-3-甲基咪唑雙三氟磺酰亞胺鹽([C4min]NTf2)體系的去除效率明顯高于六氟磷酸鹽類(PF6-)離子液體。在水相中當硝酸濃度在3mol/L左右時萃取效率最高,體系的萃取效率隨著萃取劑濃度的增加而變大,共存離子的加入會降低體系的萃取效率,但是當加入的是硝酸根離子時,萃取率會相應增大。根據(jù)實驗結(jié)果以及萃取后離子液體相的紅外圖譜分析可以判斷此萃取體系主要為陽離子交換過程。通過物理負載法得到的冠醚-離子液體體系負載型碳納米管對鈾的吸附實驗結(jié)果表明:當pH為5到6之間時,三種吸附材料的吸附容量達到最大,隨著鈾初始濃度的增加,相應的吸附容量也增大。當吸附時間超過60分鐘后,吸附基本達到平衡,隨著溫度的不斷上升,吸附材料的吸附容量都相應的提高,說明本實驗用的吸附材料對鈾的吸附過程屬于吸熱過程,溫度的升高有助于其對鈾更好的吸附。同時我們還對未進行負載的碳納米管進行了對比試驗,可以發(fā)現(xiàn)經(jīng)過負載后的碳納米管吸附容量明顯高于未負載的碳納米管。將吸附實驗的結(jié)果進行動力學和熱力學擬合,結(jié)果表明四種吸附材料對鈾的吸附動力學符合準二級動力學模型,而吸附熱力學符合Langmuir模型假設。說明吸附過程為化學吸附,吸附主要發(fā)生在吸附劑表面。
[Abstract]:Ionic liquids, the most promising solvent of the new generation, have attracted the research interest of all kinds of professionals. The use of ionic liquids to replace toxic, flammable and volatile organic compounds for the treatment of high-level waste liquid is in the ascendant. Three ionic liquids, 1 Ding Ji 3 methyl imidazole hexafluorophosphate (C4mimPF6), 1 hexyl 3 methyl imidazolium hexafluorophosphate (C6mimPF6) and 1 Ding Ji 3 methyl imidazole bisfluoromethane sulfonimide salt (C4mimNTf2), were selected. Firstly, the ionic liquid was used as solvent to dissolve the selected dicyclohexyl-18-crown-6 (DCH18C6) to form the crown ether-ionic liquid system. Then the uranyl ions in water phase were extracted by crown-ether-ionic liquid system. Finally, the crown ether-ionic liquid system was loaded on carbon nanotubes by physical loading method to make adsorption material. A series of studies were carried out on the adsorption efficiency and regularity of unloaded and loaded carbon nanotubes for uranium in water phase. The main results are as follows: using dicyclohexyl-18-crown ether-6 as extractant, The extraction experiment of uranyl ion (UO22) in aqueous phase by Crown Ether Ionic liquid extraction system with three ionic liquids as solvent. The results showed that the removal efficiency of UO22 in [C4min] NTf2 system was significantly higher than that in hexafluorophosphate (PF6-) ionic liquids. When the concentration of nitric acid is about 3mol/L in aqueous phase, the extraction efficiency is the highest, and the extraction efficiency of the system increases with the increase of the concentration of extractant. The extraction efficiency of the system decreases with the addition of coexisting ions, but when the nitrate ion is added, the extraction efficiency of the system increases with the increase of the concentration of the extractant. The extraction rate will increase accordingly. According to the experimental results and the infrared spectrum analysis of the ionic liquid phase after extraction, it can be concluded that the extraction system is mainly a cationic exchange process. The experimental results of adsorption of uranium by crown ether-ionic liquid supported carbon nanotubes obtained by physical loading method show that when pH is between 5 and 6, the adsorption capacity of the three kinds of adsorption materials reaches the maximum, and with the increase of the initial concentration of uranium, the adsorption capacity of the three adsorbed materials reaches the maximum. The corresponding adsorption capacity is also increased. When the adsorption time is more than 60 minutes, the adsorption reaches equilibrium basically, and the adsorption capacity of the adsorbed material increases with the increase of temperature, which indicates that the adsorption of uranium by the adsorption materials in this experiment is an endothermic process. The higher the temperature is, the better the adsorption of uranium is. At the same time, the adsorption capacity of unloaded CNTs is obviously higher than that of unloaded CNTs. The results of adsorption experiments were fitted with kinetics and thermodynamics. The results showed that the adsorption kinetics of uranium by four kinds of adsorption materials was in accordance with the quasi-second-order kinetic model, while the adsorption thermodynamics was in accordance with the hypothesis of Langmuir model. It shows that the adsorption process is chemisorption, and the adsorption occurs mainly on the surface of adsorbent.
【學位授予單位】：南華大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：O647.33;TL941.1

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