Clay-hyperbranched epoxy/polyphenylsulfone nanocomposite membranes

Abstract

Nanocomposite membranes containing polyphenylsulfone (PPSU) and a clay modified with a hyperbranched epoxy (HBE) were prepared by blending of modified montmorillonite (m-MMT) with a polymer solution using phase inversion method. The hyperbranched epoxy synthesized by polycondensation reaction of bisphenol A and triethanolamine with epichlorohydrin was grafted to amine-functionalized MMT by reaction between the epoxy groups of hyperbranched epoxy and the amine groups on the MMT surface. In this way, the m-MMT was exfoliated into single layers of nanoparticles in a solvent medium and the polymer chains were intercalated into m-MMT layers. The aim was to study the effect of this additive on the membrane separation efficiency. For this purpose, pure water flux, fouling, and pigment and heavy metal rejection were measured by a home-made dead end filtration cell and the performance of the prepared membranes was investigated. Hydrophilicity of the nanocomposite membranes was specified by water contact angle measurements. Degree of dispersion of additive into the polymer matrix and membrane morphology were studied by FESEM. Membrane surface area, pore size, and volume were evaluated by BET. The results indicated that the surface hydrophilicity increased after incorporation of m-MMT. Furthermore, the water permeability, salt rejection, and antifouling resistance of PPSU membranes were improved significantly. Membrane with 3 wt% m-MMT showed the best performance compared to other membranes.