PAA grafting onto new acrylate-alumoxane/PES mixed matrix nano-enhanced membrane: Preparation, characterization and performance in dye removal

Nanoboehmite particles were modified by acrylic acid to produce new alumoxane nanoparticles. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to realize shape, size and functional groups of synthesized acrylate-alumoxane nanoparticles. The analyses declared that spherical acrylate-alumoxane nanoparticles were formed with hydroxyl and acrylate groups on their surface. Boehmite and acrylate-alumoxane were successfully introduced into polyethersulfone (PES) membrane matrix by the phase inversion method. Fabricated membranes were examined for water permeability, dye (acid blue 193) retention capability and fouling resistance against whey proteins. The field emission scanning electron microscopy (FE-SEM) images were used to estimate the changes in skin-layer morphology and bulk porosity of the prepared membranes. As a result, the directly arrayed finger-like macro-voids as well as bulk porosity were gained by adding acrylate-alumoxane nanoparticles compared to pristine PES membrane. However, different quantities of acrylate-alumoxane in the casting solution induced no noticeable alteration in the membranes bulk porosity. The membranes containing 1 wt.% of acrylate-alumoxane and 1 wt.% of nanoboehmite were selected to be grafted by polyacrylic acid (PAA). Comparison of grafting efficiency for pristine PES membrane and nanofiller blended membranes proved that acrylate-alumoxane offered more effective grafted membrane by providing polymerization initiation sites on mixed matrix membrane surface. In addition to high water permeability (around 19 kg/m2 h bar), the acrylate-alumoxane mixed/PAA grafted membrane showed superior dye removal and fouling resistance. Atomic force microscopy (AFM) as well as water contact angle test was applied for investigation of membranes surface properties.

► Nano-sized acrylate-alumoxane was synthesized using acrylic acid and nanoboehmite.
► Boehmite and acrylate-alumoxane were added to PES casting dope.
► Grafting of PAA on acrylate-alumoxane/PES membrane results in high flux NF membrane.
► Grafted nanocomposite membrane shows superior dye removal and antifouling property.
► Grafting on nanocomposite membrane is a new way to obtain preferable modification.