Enhanced performance of a macroporous ceramic support for nanofiltration by using α-Al₂O₃ with narrow size distribution

Enhanced performance of a macroporous disk alumina support was fabricated through colloidal filtration route, by using α-Al₂O₃ powder with an average particle size of 1.1 μm. The support, sintered at 1250 °C, showed relative high permeances towards water (101 L h^-1 m^-2 bar^-1) and nitrogen (∼2×10^-6 mol m^-2 s^-1 Pa^-1), with an average surface roughness of ∼175 nm and a high mechanical strength of 61.1 MPa. Titania supported γ-Al₂O₃ mesoporous layers were deposited onto this promising disk α-Al₂O₃ support through dip-coating. The disk membrane A1100/TiO₂/γ-Al ₂O₃, with pore size of ca. 4.4 nm, showed a pure water flux as high as 4.5 L m^-2 h^-1 bar^-1, which is four times higher than that of γ-Al₂O₃ membrane reported in literature. This mesoporous membrane showed relative high retention rate (∼80%) towards di-valent cations like Ca²⁺, Mg²⁺, but not for the mono-valent cation (Na⁺).