Document Type: Research Paper
Department of Applied Chemistry, DST/Mintek Nanotechnology Innovation Centre Water Research Node,
Department of Applied Chemistry
Department of Applied Chemistry, University of Johannesburg, P.O. Box 17011, Doornfontein, 2028, South Africa.
Department of Applied Chemistry, DST/Mintek Nanotechnology Innovation Center Water Research Node, University of Johannesburg, Johannesburg, South Africa
This paper reports on the synthesis and characterisation of polysulfone (PSf) ultrafltration (UF) membranes modifed with carbon coated alumina Ni-doped titanium dioxide (CCA/Ni-TiO2) nanoparticles. The syntheses of the membranes was carried out using the phase inversion process. The permeate ﬂux of the membrane modifed with 0.25% CCA/Ni-TiO2 nanoparticles (213.5±6.40 L.m-2.h-1) was found to be higher than that of the unmodifed membrane (130.95±4.50 L.m-2.h-1) at 13.8 bar. The membrane modifed with 0.50% CCA/NiTiO2 nanoparticles had the lowest permeate ﬂux at 105.18±4.52 L.m-2.h-1. The improved water permeability was brought about by the hydrophilicity resulting from introduction of the hydroxyl groups of the nanoparticles. At 13.8 bar, the NaCl salt rejection properties of the mixed matrix membranes were relatively higher (31.38±1.23%) for the 0.25% PSf/CCA/Ni-TiO2 membranes compared to that of the unmodifed PSf membrane (12.76±1.10%). Similar observations were made for the Cr3+ heavy metal rejection, which ranged between 56.27±2.54% and 60.48±2.52% for the modifed membranes. These results have demonstrated the role the electrostatic eﬀects of the nanoparticles play in the rejection mechanism of the modifed membranes when compared to the unmodifed membranes. Unmodifed membranes were found to reject 28.32±1.65% of Cr3+ heavy metals at the same pressure. Over a period of 180 minutes, the membranes were found to be more photocatalytically active towards bromophenol blue, and a maximum photodegradation efciency of 81% was achieved compared to only 50.5% for methyl orange. The photo-degradation process for both dyes followed a pseudo-frst-order reaction rate.