Evidence on the 2-nitrophenyl octyl ether (NPOE) facilitating Copper(II) transport through polymer inclusion membranes

• The Cu (II) transport in PIMs was improved significantly by NPOE.
• Molecular interactions among membrane components have been studied.
• NPOE molecules can bond with PVC chains.
• NPOE molecules can provide a solvent-like environment.

Polymer inclusion membranes (PIMs) containing 2-nitrophenyl octyl ether (NPOE) as plasticizer, LIX 84 I as carrier and poly (vinyl chloride) (PVC) as polymer were prepared to transport Cu (II) from ammoniacal solutions. The influence of membrane components, especially NPOE, on Cu (II) transport efficiency of PIMs was investigated and the interactions of membrane components were evaluated by attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The results show that the extraction and back-extraction efficiencies of Cu (II) in the PIMs could be significantly improved by addition of 30 wt% NPOE. The ATR-FTIR and XPS analyses indicate that NPOE molecules could bond with PVC chains, as a new peak located at 800 cm−1 appears in the spectra of PIMs with high content NPOE. Moreover, XPS spectra of the PIMs before and after transport experiments suggest that NPOE molecules could provide a solvent-like environment to transport the carriers and LIX 84 I–Cu (II) complexes in the membrane phase.