Comparable investigation for incorporation of zirconium MOF@PVDF membrane as cation selective membranes for lithium-ion separation

Abstract

To improve the efficiency of lithium-ion separation and removal from contaminated water, the performance of zirconium MOFs as filler for PVDF composite membranes in lithium-ion separation was investigated in this work utilizing the electrodialysis technique. Two different cations selective PVDF-based membranes, UiO-66/PVDF and UiO-66/ZIF-8/PVDF were casted using the phase inversion technique. Various spectroscopic techniques were utilized to validate the physicochemical properties of fabricated PVDF composite membranes, which include FTIR, XRD, SEM, and XPS. It was evident that the fabricated UiO-66/ZIF-8/PVDF membrane exhibits superior lithium-ion removal (94%) from contaminated water, compared to the UiO-66/PVDF membrane which exhibits 75% removal at a high Li ion concentration (400 ppm). It was evident that the UiO-66/ZIF-8/PVDF membrane exhibits adsorptive qualities towards Li-ion removal, making it more appropriate for water treatment. In contrast, UiO-66/PVDF showed higher cation migration capabilities, which is encouraging for lithium recovery. These different separation mechanisms of the fabricated PVDF-based composite membranes toward Li ions are owed to the properties and the functionality of MOFs utilized as membrane fillers beside the intercalated pore structure of the fabricated composite membrane that produces ion channels with ion adsorptive characteristics. The promising features of the fabricated composite membranes render them suitable for lithium separation from contaminated water.