PARTITIONING OF MERCURY IN AQUEOUS BIPHASIC SYSTEMS AND ON ABEC(TM) RESINS

Poly(ethylene glycol)-based aqueous biphasic systems (PEG-ABS) can be utilized to separate and recover metal ions in environmental and hydro metallurgical applications. A concurrent study was conducted comparing the partitioning of mercury between aqueous layers in an ABS [Me-PEG- 5000/(NH4)(2)SO4] and partitioning of mercury from aqueous solutions t o aqueous biphasic extraction chromatographic (ABEC-5000) resins.In am monium sulfate solutions, mercury partitions to the salt-rich phase in ABS, but by using halide ion extractants, mercury will partition to t he 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 (NH,),SO, solutions with rete ntion following the same order. The onset of mercury extraction or ads orption is different for the three extractants, occurring at the lowes t extractant concentration for I-, followed by Br-, and then Cl-. Fluo ride does not extract mercury. Extraction or adsorption of mercury is improved at the lowest halide concentrations in the presence of sulfur ic acid. The addition of sulfuric acid to (NH,),SO, solution results i n ABEC retention of mercury even in the absence of halide extractant. (C) 1998 Elsevier Science B.V. All rights reserved.