Structural Characterization of Sol-gel TiO2 and CeO2 Coated Ceramics Membranes

Wastewater reuse is considered as the most suitable and reliable alternative for sustainable water management and agricultural development [1] and membrane separation technology emerged as one of the tools to tackle the water stress problem. Ceramic membranes (CMs) offer durability and high integrity during filtration [2]. The most commonly used CMs for water treatment are alumina (Al2O3), titania (TiO2), zirconia (ZrO2), silicon carbide (SiC) and silica (SiO2) based. The structure and morphology of ceramic membranes have substantial effects on their performance. Based on their pore size, CMs could be classified into microfiltration (MF), ultrafiltration (UF) and nanofiltration (NF) with pore size ranging from > 50 nm, 2–50 nm and < 2 nm, respectively. In this study, four commercial CMs with different composition and pore size were used: three UF ceramic membranes of TiO2/ZrO2 composition with 50 kDa, 150 kDa and 300 kDa molecular weight cut-off (MWCO) respectively, and a MF ceramic membrane of TiO2/ZrO2+TiO2 composition with a pore size of 200 nm. The membranes were modified by sol-gel deposition of TiO2 [3] or CeO2 [4] film. One, two or three layers of each film were deposited on the each of the four membranes using the vacuum impregnation method to derive catalysts for application in hybrid ozonisationfiltration system. The composites were dried and subsequently thermally treated. Both the unmodified and surface-modified ceramics membranes were characterized in order to evaluate their chemical composition, phase composition, morphologic parameters, using scanning electron microscopy with energy dispersive X-ray spectroscopy, atomic force microscopy, nitrogen adsorption/desorption isotherms, X-ray diffraction analysis and Fourier transformed infrared spectroscopy.