Removal of lead(II) from aqueous solutions by a polyvinyl-chloride inclusion membrane without added plasticizer

Abstract

In the present work a polymer inclusion membrane (PIM) containing a polyvinyl-chloride (PVC) polymer matrix and bis-(2-ethylhexyl)-phosphoric acid (D2EHPA) as a specific carrier, was prepared without the use of an additional plasticizer. The prepared PIM was used to study the extraction and facilitated transport of Pb(II) ions from model solutions which simulated waste liquid matrices. The influences of the PIM's carrier content, pH and phase composition were investigated in order to estimate their impact both on the transport fluxes and on the permeability of the optimal membrane. Efficient extraction and transport processes occurred with a membrane containing 50%D2EHPA/50%PVC (w/w), from a source solution of Pb(II) at pH 3.0, by using 1.5 mol L −1 HNO 3 as stripping phase. The experiments demonstrated that Pb(II) transport through the membrane is a facilitated counter-transport mechanism. The highest value for the initial flux of 7.19 μmol m −2 s −1 is obtained for a source solution containing 5 × 10 −4 mol L −1 Pb(II). The results obtained under optimal conditions showed that nearly all the Pb(II) ions present in the diluted source solutions (about 99%) are removed in about 180–200 min. In addition, the investigated membrane possesses good reliability and very good selectivity for Pb(II) from mixtures containing Pb(II), Co(II) and Ni(II) in similar concentrations. The obtained data prove that the 50%D2EHPA/50%PVC (w/w) PIM without any additionally added plasticizers, is not only considerably cheaper but it has enhanced Pb(II) transport properties from aqueous solutions compared with other PIMs reported for the same process.