Pd(Ⅱ)、Zn(Ⅱ)、Cu(Ⅱ)、原卟啉的非有机溶剂液-固萃取分离

Separation of Pd(Ⅱ),Zn(Ⅱ),Cu(Ⅱ) by Using Liquid-Solid Extraction System without Organic Solvent

难溶于水的原卟啉在1.0%的吐温80水溶液中因氢键作用力变为可溶.研究了Pd（Ⅱ）、Zn（Ⅱ）、Cu（Ⅱ）、原卟啉在吐温80存在下的吸收光谱,并以原卟啉为萃取剂,考察了金属原卟啉在非有机溶剂液-固萃取体系中的分配行为,讨论了分相盐、成相聚合物、萃取剂、萃取酸度等对金属原卟啉在两相分配的影响.结果表明,（NH4）2SO4浓度1.51 mol/L,吐温80质量浓度9.0%,原卟啉浓度6.0×10-5mol/L,萃取酸度分别为5.0与pH 9.0,沸水浴加热15 min的条件下可分别实现Pd（Ⅱ）～Zn（Ⅱ）,Cu（Ⅱ）～Pd（Ⅱ）的定量分离;体系萃取容量为0.020 mg/mL.该法不用有毒溶剂,仅控制萃取酸度分离性质相近的元素.其萃取机理是：金属原卟啉分子上的羰基质子受体与吐温分子上的羟基质子供体形成氢键.

Protoporphyrin becomes soluble in 1.0% aqueous solution of Tween 80 owing to the hydrogen bond formed. The absorbance spectra of Pd（ Ⅱ ）, Zn（Ⅱ） and Cu（Ⅱ ） were studied in this medium. The distribution behavior of Pd （ Ⅱ）, Zn （Ⅱ ） and Cu （ Ⅱ） in the liquid-solid extraction system without organic solvent was investigated by using protoporphyrin as the extractant. Experimental conditions such as the concentration of （NH4）2SO4, Tween 80 and protoporphyrin and the acidity were optimized. Under the conditions of keeping in boiling water bath for 15 min at pH 9.0 and pH 5.0, the quantitative separation of Pd（ Ⅱ ） - Zn（Ⅱ） and Cu（ Ⅱ ） - Pd（ Ⅱ ） was achieved, when the concentration of （NH4）2SO4, Tween 80, and protoporphyrin were fixed at 1.51 mol/L, 9.0%, and 6.0 × 10^-5 mol/L respectively. At room temperature with an extraction capacity of 0.020 mg/mL. Similar metal ions can be separated by controlling the extraction acidity in the absence of nocuons organic solvents. The mechanism of the extractive separation was discussed. It shows that hydrogen bond between the proton acceptor of the carbonyl group in the metal-protoporphyrin chelate and the proton donor of the bydroxy group in the Tween molecule is formed.