Document Type: Research Paper
Department of Applied Chemistry, Faculty of Science, University of Johannesburg, P. O. Box 17011, Doornfontein 2028, Johannesburg, South Africa
DST/Mintek Nanotechnology Innovation Centre, Advanced Materials Division, Mintek, 200 Malibongwe Drive, Randburg, 2125, Johannesburg, South Africa
Department of Applied Chemistry, University of Johannesburg, Johannesburg, South Africa
In this work, 2,2’-azo-bis-butyronitrile (AIBN) was exploited as an initiator for the successful bulk heterogeneous functionalization of polyethersulfone (PES) using polymethacrylic acid (PMAA), for the first time. To this end, pH-responsive and exceptionally low fouling membranes of extremely low grafting degrees with low adhesion and high rejection of protein were fabricated. An added advantage of this method is the accomplishment of graft polymerization of methacrylic acid (MAA) in water in the absence of toxic solvents, scavengers or catalysts. Changes to surface functional groups of the PES powder were determined using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and thereafter validated with X-ray photoelectron spectroscopy (XPS). The phase inversion technique was used to fabricate microfiltration membranes (MFs), which were found to possess up to 40% improved hydrophilicity relative to pristine PES membranes. Protein adsorption was reduced by more than 80% while its rejection and the pure water permeate flux recovery ratio (FR) were 97%, and 86%, respectively. Furthermore, the membrane maintained 90% FR over 10 cycles. The newly fabricated membranes possess enhanced response to pH stimulus.