Selective Transmembrane Transport of Iodide based on Electrochemically Induced Iodide-trap BiOI/MWCNTs/PVA Composite Membrane

An electrochemically induced bismuth iodine oxide/multiwalled carbon nanotubes/polyvinyl alcohol (BiOI/MWCNTs/PVA) composite membrane electrode with iodide ion trap (I--trap) was fabricated by prerelease of I- under reduction potential. The I--trap BiOI/MWCNTs/PVA composite membrane with unique lattice confinement structures was used for the selective extraction of I- in an electrochemically switched ion permselective (ESIP) process. In the ESIP system, the direct uptake and release of I- were realized by applying a cell voltage-pulse potential (CV-PP) coupling circuit on the membranes to switch the oxidation/reduction state. The I--trap BiOI/MWCNTs/PVA composite membrane exhibited a maximum flux of 8.32 mg·m-2·min-1 and superior electrochemical stability. The separation factors of I-/Br-, I-/Cl-, I-/NO3-, and I-/SO42-in the mixed solutions were 2.67, 3.71, 3.82, and 6.70 respectively. Therefore, such a novel I--trap BiOI/MWCNTs/PVA composite membrane could be used in the ESIP system for the selective extraction of I- ions from low concentration solutions.