Synthesis, characterization and efficiency of new organically modified montmorillonite polyethersulfone membranes for removal of zinc ions from wastewasters

Abstract

The goal of the present paper was to study the separation efficiency of zinc ions of new synthesized polymer membranes based on polyethersulfone (PES) and organically (unmodified and modified) montmorillonite (Mt). The membranes were prepared by a combination of solution dispersion and wet-phase inversion methods. Further, the membranes were used in the removal of zinc ions at concentrations of 2g/L and 4g/L from aqueous model solution, at an applied voltage of 10V, via a laboratory-scale electrodialysis system. The presence of modified montmorillonite influenced the thermal behavior of the samples as evaluated by thermogravimetrical analysis. The XRD data indicated that partially exfoliated and/or intercalated montmorillonite PSf (nano) composite membranes were obtained. The presence of advanced modified montmorillonite influenced the water evaporation enthalpy calculated by DSC, the water contact angle, as well as the silicon peak according to XRF plots. The pore size decreased with montmorillonite addition according to SEM pictures while TEM photomicrographs showed that mostly intercalated nanocomposites were obtained. The performance of electrodialysis cell was evaluated in terms of mass flow (J) and rejection (R) of zinc ions, which increased with the increase of concentration of zinc ions. J and R values were higher, at 4g/L (45.40±0.12g−2h−1, 94.59±0.25%), for the membranes that incorporated the Mt functionalized with octadecyl chain which favored the dispersibility of the filler in the PSf membrane. Finally, advanced modified montmorillonite improved the separation efficiency of the final membranes.