离子液体[Bmim]BF_4-NaH_2PO_4-偶氮胂Ⅲ体系中La(Ⅲ)的存在形态及测定

Existing Form and Determination of La(Ⅲ) in Ionic Liquid [Bmim]BF_4-NaH_2PO_4-ArsenazeⅢ System

建立了室温离子液体四氟硼酸1-丁基-3-甲基咪唑（[Bmim]BF4）和NaH2PO4组成的双水相体系,并用于对偶氮胂Ⅲ和La（Ⅲ）配合物萃取测定研究。考察了离子液体用量、溶液酸度、偶氮胂Ⅲ加入量、盐的浓度和加入其他物质对La（Ⅲ）配合物测定的影响。结果表明,离子液在4.0ml,磷酸二氢钠加入量在2.0-3.0g,偶氮胂Ⅲ溶液1.0ml,溶液酸度在pH值为2-6范围,偶氮胂Ⅲ和La（Ⅲ）配合物在离子液相中有较大的吸光度。除阳离子表面活性剂外,其他离子表面活性剂和大多数无机离子不影响La（Ⅲ）的测定。吸收光谱、摩尔比、连续浓度变换、加入表面活性剂等实验表明,在萃取相La（Ⅲ）与偶氮胂Ⅲ是以1∶3络阴离子形式存在的。利用离子液体双水相体系,测定了样品中La（Ⅲ）的含量。

A new method of extraction determination arsenaze Ⅲ and La （Ⅲ） complex in an aqueous twophase system （ATPS） formed from water-soluble ionic liquid [ Bmim ] BF4 （ 1-butyl-3-methylimidazoliumtetrafluoroborate） with salt NaH2PO4 at room temperature was studied. The effects of the amounts of ionic liquid and arsenazo Ⅲ, concentration of, salt added and solution acidity on the partition of complex were investigated systematically. The results showed that under the condition of a pH 2 - 6, a total volume of 10 ml ionic liquid-ATPS system formed from 1.0 ofarsenazem, 4.0 ml [ Bmim] BF4 and 2.0 - 3.0 g of NaH2PO4, arsenazo Ⅲ and La （Ⅲ） in the ion liquid phase had the highest absorbance. Moreover, most of ions of inorganic and other ion surfactants did not interfere with the determination of La （ Ⅲ） complex except for cationic surfactants. Experimental result showed that the complex of La （ Ⅲ ） with arsenaze m was a complex anion consisted of La（Ⅲ） and arsenazo m in the ratio of 1：3 in ionic liquid phase. This method could be applied to the determination of La （ Ⅲ ） in samples.