Effects of Functionalized Silica Nanoparticles on Characteristics of Nanocomposites PES Cation Exchange Membranes

Nanocomposite cation exchange membranes (CEMs) were prepared by adding various loadings of functionalized silica nanoparticles to the sulfonated polyethersulfone (sPES) polymeric matrix. The silica nanoparticles were functionalized by mercaptopropyl (F-1, IEC=0), propylsulfonic acid (F-2, IEC=2.71), and sulfonic acid (F-3, IEC=2.84). The properties of prepared membranes were investigated by varying the loadings of functionalized silica nanoparticles. Applying functionalized nanoparticles provides additional ion exchange groups and enhances water contents as well as conductivities and permselectivities of the membranes. The maximum IEC of 1.9 meq.g(-1) was obtained for the membrane having 3wt% F-3 nanoparticles and the maximum conductivity of 0.237 S.cm(-1) was achieved for the membrane having 2wt% F-3 nanoparticles, which were 19.6% and 64% higher than the corresponding values for sPES membrane, respectively. The excellent properties of the nanocomposite cation-exchange membranes make them appropriate candidates for electrodialysis and desalination processes.