以鹼性萃取劑萃取鉬(VI)之研究

A Study on the Extraction of Molybdenum(VI) by Basic Extractant

張文盈(Wen-Ying Chang)

指導教授 ： 蔡德華

國立臺北科技大學/工程學院/化學工程研究所/碩士(2011年)

摘要

本論文探討鉬(VI)在25±0.1℃下，以鹼性萃取劑三辛胺(Alamine336)為載劑，以正辛醇為修飾劑之煤油溶液，與在硫酸系統下的金屬水溶液間萃取平衡之研究。
本研究先使用0.02M鉬酸鈉水溶液與0.05M的萃取劑作為試驗，尋找能協助萃取的酸化劑及其最適化濃度，並尋找最佳的反萃劑及其最適化濃度，以利萃取實驗的進行。實驗結果顯示於金屬水溶液中添加0.05M的硫酸水溶液酸化，可增加Alamine336在萃取時的質子化程度，可以增加萃取的能力；以1N的硝酸水溶液進行反萃可以得到較佳的反萃率。
在25±0.1℃不同的操作條件下，改變金屬水溶液初濃度、不同的載劑濃度，探討鹼性萃取劑三辛胺對鉬(VI)的萃取效果，並以圖解法確認有機相中鉬氧化合物之組成與萃取反應所進行之計量式。實驗結果顯示，以Alamine336為載劑，在0.05M硫酸系統下，對鉬(VI)的萃取有較高的萃取百分比及分配比，其初始pH值隨載劑Alamine336的濃度提高而變大，pH往較高的方向移動。以logDMo(VI)對pH作圖，由圖中直線斜率為1和-2，求出n = -1和2，所Mo(VI)的有機相可能有兩個組成R3NH2MoO4和(R3NH)2MoO4的型態存在 。萃取過程中，水溶液在pH 1.5~3.5約有1個Alamine336分子參與反應，在pH 3.5~6.0約有2個Alamine336分子參與反應。其Kex分別為0.9774和1.265×1012 (mol/dm3)-4。

關鍵字

萃取 ； 反萃 ； 鉬(VI) ； 三辛胺(Alamine336) ； 鹼性萃取劑

並列摘要

In this paper, extraction of molybdenum(VI) ions at 25±0.1℃ from acidic sulfate solutions was studied. The extract used in the extraction was tricaprylylamine
(Alamine336) which was dissolved in kerosene.
We first examined, the effect of molybdenum(VI) concentration(0.02M) on the extraction process has been investigated using Alamine336(0.05M). Hydrochloric acid, nitric acid and sulfuric acid were examined to find the optimal acidification concentration with the highest extraction ability. We also found the best stripping agent and its concentration after test of sodium chloride, hydrochloric acid, nitric acid, sulfuric acid and thiourea. According to the experimental results we found that the optimal acidification agent is sulfuric acid (0.05M) and the best stripping agent is nitric acid (1N).
In the above system, we examined the effects of various parameter at 25±0.1℃, such as the initial concentration of the metal and the different concentration of extractant to effect on the metal extraction and we used graphical method confirmed the organic phase with carried out with the extraction reaction composition measurement type.
We could found in this study that the extraction distribution ratio are correlated with the ratios of metal ions concentrations, the pH value of water phase, and the carrier concentrations in the extraction reaction.
The experimental results of showed that the Alamine336 as carrier agent, in 0.05M sulfuric acid system, the molybdenum (VI) extraction have a higher percentage of extraction and high distribution ratio, the initial pH value increased with the concentration of carrier agent Alamine336 high, move to the higher pH.
The fitting of the molybdenum (VI) extraction of logDMo (VI) to pH, the slope of the diagram said the value of n is-1and 2, so the Mo (VI) of the organic phase may have two components are R3NH2MoO4 and (R3NH)2MoO4 exists.
In the extraction process, There have about 1 Alamine336 molecules involved in the aqueous solution at pH 1.5 ~ 3.5, and there have two Alamine336 molecules involved in the aqueous solution at pH 3.5 ~ 6.0. The Kex were 0.9974 and 1.265×1012 (mol/dm3)-4.

並列關鍵字

extraction ； stripping ； molybdenum ； Alamine336 ； tricaprylylamine

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