Study On The Extraction Separation Of Metal Ions In Ionic Liquid Aqueous Two-phase System

Abstract:The Aqueous Two-Phase Systems (ATPS) of ionic liquid based ATPS 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4)-NaH2PO4 was established severally. And the systems were used for extracting of active substrates, such as La³⁺,Cu²⁺,Ni²⁺ . Furthermore, the extraction behaviors of the systems were studied, and affecting factors, such as additions of phase-forming materials, [Bmim]BF₄, NaH₂PO₄ and additions of extracts, the systems'pH, temperature and interferent were explored. And, the optimal situations based on this were confirmed. We also hypothesize the separation mechanism by added Cationic-anionic surfactants and nonionic-surfactants.Experimental result shows that in the ionic liquid aqueous two-phase system of pH 2.0, the La³⁺ combined with Arsenazeâ…¢, and new complex were formed. For Arsenazeâ…¢, the wavelength of maximum absorption of the complex with La³⁺ was 652nm, had the red shift of 111nm compared with Arsenazeâ…¢, and its apparent molar absorption coefficient was 6.21x10⁴ L·mol^-1·cm^-1. The complex of La³⁺ with Arsenazeâ…¢is a complex anion of 1:3 in ionic liquid phase.In the ionic liquid aqueous two-phase system of pH 5.0-6.0, the complex formed by xylenol orange and Ni²⁺ had high absorbance with the maximum absorption of 465 nm. For Ni²⁺ with the apparent molar absorptivity of 7.86×10⁴ L·mol^-1·cm^-1. The complex ratio of xylenol orange and Ni²⁺ was 3:1 .With the solution pH values 5.0-8.0,. the complex was extracted by ionic liquid phase from the aqueous solution . The maximum absorption of the complex is at 590 nm with the molar absorptivity(ε) 5.16x10⁴ L·mol^-1·cm^-1. The copper with CAS formed a stable complex in the molar ratio of 1:3 .The method has been applied to the determination of copper in aluminium alloy. The results are in agreement with the certified values.In ionic liquid [Bmim]BF₄(1-butyl-3-methylimidazoliumtetrafluoroborate) and NaH2PO4 aqueous two-phase system(ATPS), the spectroscopic behavior of the compound of alizarin red S (ARS) and bovine serum albumin (BSA) was investigated. Effects of different acidity, quantities of ionic liquid and salt and coexistent matter on the determination of system were discussed. In the ionic liquid aqueous two-phase system of a pH 6, 1.0mL ARS, 1.5 mL [Bmim]BF4 and 2.0 g NaH₂PO₄, the compound formed by ARS and BSA had high absorbance with the maximum absorption of 531nm. The results showed that compared to ARS spectra,the maximum wavelength of compound shifted to the red by 109 nm, and the apparent molar absorptivity (ε)of 2.32×10⁴ L·mol^-1·cm^-1. With different surfactant, the interaction mechanism of ARS and BSA were discussed initiatively.