ISSN print edition: 0366-6352
ISSN electronic edition: 1336-9075
Registr. No.: MK SR 9/7
Preparation of ceramic γ-Al2O3–TiO2 nanofiltration membranes for desalination
Mohsen Khalili, Samad Sabbaghi, and Mohammad Mahdi Zerafat
Nanochemical Engineering Department, Faculty of Advanced Technologies, Shiraz University, Mollasadra St., 7134851154 Shiraz, Iran
Abstract: As one of the most recently developed membrane separation processes, nanofiltration (NF) has found a number of industrial applications. Ceramic NF membranes are also regarded as the appropriate choice in many applications, due to their higher chemical and physical stability. In this study, the rejection of the chloride ion is investigated using bi-layered γ-Al2O3-TiO2 NF membranes based on α-alumina supports. Compression is used in preparation of the supports and sol-gel dip-coating for the top-layer formation. SEM micrographs, XRD, and nitrogen adsorption/desorption isotherms are used for membrane characterisation. The results show that the calcination temperature (600◦C) results in different crystal structures including the brookite phase of TiO2, the γ phase of Al2O3, and a combined phase of aluminium-titanium oxides. The average pore size of the membrane was identified as 1.6 nm using an adsorption/desorption isotherm. The rejection was also studied for the chloride ion, using a cross-flow filtration module. Filtration tests were carried out under different pressures, pH values, and salt concentrations; these showed a smoother behaviour particularly around the isoelectric points (IEPs) due to the dual-layer structure, with the best rejection at pH of approximately 5.
Keywords: ceramic membranes – nanofiltration – γ-alumina – titania
Full paper is available at www.springerlink.com.
Chemical Papers 69 (2) 309–315 (2015)