ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

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

E-mail: Sabbaghi@Shirazu.ac.ir

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.

DOI: 10.1515/chempap-2015-0023

Chemical Papers 69 (2) 309–315 (2015)