Recovery of mercury from effluents is fundamental for environmental preservation. A new, green method was developed for separation of mercury from effluent containing different metals. The extraction/separation of Hg(II)was studied using aqueous two-phase system (ATPS) comprising by polyethylene oxide (PEO1500) or triblock copolymers (L64 or L35), electrolyte (sodium citrate or sodium sulfate) and water in the presence or absence of chloride ions. The extraction behavior of the Hg(II) for the macromolecule-rich phase is affected by the following parameters: amount of added extractant, pH, and the nature of the electrolyte and macromolecule of the ATPS. The APTS of PEO1500 + sodium citrate + H2O (pH 1.00 and 0.225 mol kg(-1) KCl) produced the highest Hg(II) %E = (92.3 +/- 5.2)%. Under the same-conditions, excellent separation factors (1.54 x 10(2) - 3.21 x 10(10)) for recovery of mercury in the presence of co-existing metals were obtained. Efficient and selective extraction of Hg(II) from domestic and industrial synthetic effluents was achieved using this ATPS. (C) 2015 Elsevier B.V. All rights reserved.