Removal of dyes by a new nano–TiO2 ultrafiltration membrane deposited on low-cost support prepared from natural Moroccan bentonite

Abstract This paper reports the preparation and characterization of a low-cost nano-TiO 2 ultrafiltration membrane deposited on a bentonite support. The ultrafiltration layer was obtained by dip-coating process using nano-TiO 2 , followed by sintering at 750 °C. Environmental Scanning Electron Microscope (ESEM) analysis of prepared ultrafiltration membrane showed that the deposited layer is homogeneous and shows a good adhesion on the support presenting a mean thickness of 4 ± 0.2 μm. The average pore diameter and water permeability of the obtained membrane are respectively 10 ± 0.5 nm and 16.08 L/h m 2  bar. The membrane performance was evaluated by filtration of three different dyes: two anionic (Direct red 80 and Acid orange 74) and a cationic one (Methylene blue). Effect of feed pH and dyes concentration on membrane rejection was investigated at a pressure of 4 bar. The experimental filtration results showed that rejection of Direct Red 80, Acid Orange 74 and Methylene Blue achieved maximum values of 98%, 85% and 94% respectively, depending on filtration conditions and each dye characteristics.