Effect of SiO2 nanoparticle addition on the characteristics of a new organic–inorganic hybrid membrane

Poly(vinylidene fluoride) composite membranes filled with different weight fractions of SiO2 nanoparticles have been prepared by a blending method. Cation-exchange groups were introduced by the copolymerization of glycidyl methacrylate with divinylbenzene and subsequent sulfonation. These hybrid membranes have been characterized by Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and water uptake and ion-exchange capacity measurements. Membrane potential and membrane conductivity measurements have been carried out with different counter ions to investigate the relationship between ionic migration and the SiO2 nanoparticle content. The counter-ion transport number and permselectivity of these membranes are found to be highly dependent on the SiO2 content in the membrane phase and the nature of the counter ion. Membrane conductance was analyzed in terms of phenomenological coefficients using non-equilibrium thermodynamic principles. It can be concluded that these hybrid membranes exhibit high thermal stability, improved selectivity, and moderate membrane conductivity, and may be suitable for use in the electro-driven separation processes.