Removing Organic Dye by Cellulose Acetate Nanocomposite Membrane Ultrafiltration: Effect of Bio-Nanoparticle Size

This work reported a new perspective on improving the green synthesis of titanium dioxide (TiO2) nanoparticles (NPs) from Aloe vera plant leaf extract and their incorporation into membranes for several applications. The X-ray diffraction of the powder depicted that the size of the samples TiO2 NPs (1 h) and TiO2 NPs (5 h) were 83 ± 15 (Ø2) nm and 23 ± 1.6 nm (Ø1), respectively. With two sizes of TiO2 NPs as an additive, cellulose acetate (CA) membranes and a series of TiO2/CA hybrid membranes were prepared using a phase-inversion method. The membrane characterization was carried out by Fourier transform-infrared spectroscopy, scanning electron microscope (SEM), water content, contact angle, porosity, and pure water flux measurements. The cross-section SEM images indicated that the size of macro-voids was reduced and the width of the membrane pores was slightly increased by the addition of TiO2 (Ø1). Membrane performance has been investigated in terms of dye Remazol Brilliant Red F3B (Reactive Red 180, RR 180) removal, which could be, however, affected by the competitive effect of another chemical species present in the solution such as NaCl salt. Indeed, NaCl decreased the retention rate of dye due to electrostatic interactions, as the chloride ions compete with the anionic dye molecules during the complexation process. The retention rate decreased at alkaline pH due to interaction forces between the membrane surface and anions of the RR 180.