Abstract

A polymer inclusion membrane (PIM) prepared by casting a solution of cellulose triacetate (CTA), trioctylamine (TOA), and tri-n-butylphosphate (TBP), dissolved in dichloromethane was used for the extraction of bismuth(III) from hydrochloric acid solutions. The optimized PIM, in terms of mechanical properties and its efficiency for the extraction of bismuth(III), was consisted of CTA 40 wt%, TOA 25 wt% and TBP 35 wt%. Contact angle measurements, FESEM, AFM, TGA and stress-strain analysis were used for characterizing the PIM. A 3.5 cm diameter circular membrane segment of the PIM extracts quantitatively the bismuth ions (initial concentration 20 mg L^-1) from 50 mL of 0.3 M HCl, after 120 minutes. The extracted bismuth was fully back-extracted by shaking for 60 minutes of the loaded PIM with 50 mL solution of 2 M Na₂CO₃. It was confirmed that the extraction reaction involves the formation of the ion pair . The developed PIM was stable for using in four extraction/back-extraction cycles of bismuth(III). This stability was enhanced to ten extraction/back-extraction runs by replacing the plasticizer TBP with 2–nitrophenyloctyl ether or dibutyl phthalate. The investigated PIM showed excellent selectivity towards Bi(III) over Cu(II), Pb(II), Zn(II), Ni(II), Co(II), Cd(II), Fe(III), Cr(III), Mo(VI), W(VI), NO₃⁻ and SO₄²⁻.