Preparation of cationic exchange membranes based on organo‐montmorillonite/poly(vinylidene fluoride) by two‐step chemically induced grafting method

Abstract

In this research, OMMT/PVDF-based cationic exchange membranes were prepared by two-step chemically induced grafting method. The various preparation conditions, such as alkaline treatment, initiation, and grafting conditions, and the relationship between the preparation conditions and the cationic exchange membrane performance, such as area resistance and cationic permselectivity, were investigated. The chemical and crystal changes on the membrane surface were characterized by Fourier transform infrared spectroscopy (FTIR), energy dispersive spectrum (EDS), and X-ray diffraction (XRD), respectively. Surface morphological changes were also characterized by scanning electron microscopy (SEM). The results reveal that the OMMT/PVDF-based cationic exchange membrane was successfully prepared by this method. The OMMT/PVDF-based cationic exchange membrane doped 8.5% OMMT prepared using optimum preparation parameters showed excellent basic properties. The area resistance was measured as low as 1.8 X cm 2 , while the cationic permselectivity was as high as 93.4%.

Preparation of PVDF anionic exchange membrane by chemical grafting of GMA onto PVDF macromolecule

“…The anionic permselectivity was determined from the measured membrane potentials [10][11][12]. The studied membrane was placed between two compartments of a diffusion cell.…”

“…This cell was composed of two compartments with two dimensional stability electrodes (DSA). The two compartments of the cell were separated by the PVDF anionic exchange membrane [10]. The active area of electrodes as well as that of membrane S was 1 cm 2 .…”

“…One effective method to introduce ionic conducting groups to PVDF membranes and prepare PVDF ion-exchange membranes is chemically induced radical grafting polymerization [4][5][6][7][8][9][10]. The PVDF membranes are treated in oxidant or alkaline solutions with introduction of active sites to proceed radical grafting polymerization.…”

“…Guibao Guo et al [4][5][6][7] had also investigated PVDF-g-PSSA membrane and poly (vinylidene fluoride)-graft-poly (2-acrylamido-2-methylpropane sulfonic acid) (PVDF-g-PAMPS) membrane prepared by the method of chemically induced radical grafting polymerization. In our previous work [10], OMMT/PVDF-based cationic exchange membranes were prepared by two-step chemically induced grafting method. However, for the chemically induced grafting methods reported in references [4][5][6][7][8][9][10], the grafting reaction is usually used to introduce cation-exchange groups and almost conducted on the surface of the treated PVDF membrane.…”

“…In our previous work [10], OMMT/PVDF-based cationic exchange membranes were prepared by two-step chemically induced grafting method. However, for the chemically induced grafting methods reported in references [4][5][6][7][8][9][10], the grafting reaction is usually used to introduce cation-exchange groups and almost conducted on the surface of the treated PVDF membrane. The internal grafting reaction is limited and the cation-exchange groups are mainly grafted on the surface of the membranes, which limits the physical and chemical properties of the obtained PVDF cationexchange membranes.…”