LAUSR

Abstract Al3+-doped TiO2 (AT) tight ultrafiltration membrane with stable anatase phase was prepared by a modified sol-gel process using butyl titanate and aluminum chloride as the precursor and aluminum source respectively. The removal of Alizarin red-S was investigated by filtration experiment. A dip-coating process on homemade flat Al2O3 intermediate layer by TiO2 sol followed by heat treatment was adopted to obtain the desired AT membrane. The addition of Al3+ inhibits the phase transformation of nanosized TiO2 from anatase to rutile and restrains the growth of crystallite, resulting in the pore size of the separation layer reducing to 3.5 nm. The prepared AT1-500 membrane exhibits enhanced hydrophilicity with no cracks or pinholes, and shows a water permeability of 9.6 L m-2 h−1 bar−1 and cut-off molecular weight (MWCO) of 4650 Da. The membrane demonstrated a retention rate of 96.9% for Alizarin Red-S (250 ppm) and maintained almost constant under repeated using.