Rogers R D, Griffin S T
Department of Chemistry, The University of Alabama, Tuscaloosa 35487, USA.
J Chromatogr B Biomed Sci Appl. 1998 Jun 26;711(1-2):277-83. doi: 10.1016/s0378-4347(98)00087-5.
Poly(ethylene glycol)-based aqueous biphasic systems (PEG-ABS) can be utilized to separate and recover metal ions in environmental and hydrometallurgical applications. A concurrent study was conducted comparing the partitioning of mercury between aqueous layers in an ABS [Me-PEG-5000/(NH4)2SO4] and partitioning of mercury from aqueous solutions to aqueous biphasic extraction chromatographic (ABEC-5000) resins. In ammonium sulfate solutions, mercury partitions to the salt-rich phase in ABS, but by using halide ion extractants, mercury will partition to the PEG-rich phase after formation of a chloro, bromo or iodo complex. The efficacy of the extractant increases in the order Cl- <Br- <I-. This behavior is also observed using the ABEC resins where halo complexes of mercury will adsorb to the resin from (NH4)2SO4 solutions with retention following the same order. The onset of mercury extraction or adsorption is different for the three extractants, occurring at the lowest extractant concentration for I-, followed by Br-, and then Cl-. Fluoride does not extract mercury. Extraction or adsorption of mercury is improved at the lowest halide concentrations in the presence of sulfuric acid. The addition of sulfuric acid to (NH4)2SO4 solution results in ABEC retention of mercury even in the absence of halide extractant.
基于聚乙二醇的双水相体系（PEG-ABS）可用于环境和湿法冶金应用中金属离子的分离与回收。开展了一项对比研究，比较了汞在ABS [Me-PEG-5000/(NH4)2SO4] 水相层之间的分配情况以及汞从水溶液到双水相萃取色谱（ABEC-5000）树脂的分配情况。在硫酸铵溶液中，汞分配到ABS中富含盐的相，但通过使用卤离子萃取剂，汞在形成氯、溴或碘络合物后会分配到富含PEG的相。萃取剂的效果按Cl- <Br- <I- 的顺序增强。使用ABEC树脂时也观察到这种行为，汞的卤络合物会从硫酸铵溶液吸附到树脂上，保留情况遵循相同顺序。三种萃取剂汞的萃取或吸附起始情况不同，碘离子在最低萃取剂浓度时发生，其次是溴离子，然后是氯离子。氟离子不萃取汞。在硫酸存在下，最低卤化物浓度时汞的萃取或吸附得到改善。向硫酸铵溶液中添加硫酸即使在没有卤离子萃取剂的情况下也会导致ABEC对汞的保留。
