Low temperature preparation of high-flux α-alumina tight ultrafiltration membrane by modified co-sintering process

A high-efficiency α-alumina ultrafiltration membrane was proposed and fabricated by co-sintering a gel layer with a pre-sintered interlayer. A pre-sintered interlayer with rigidity and low roughness was used, which was conducive to the preparation of a defect-free and ultra-thin separation layer. In the process of co-sintering, the crystal phase of the separation layer was completely transformed to α-alumina at 950 °C, and permeation of pre-sintered interlayer increase with calcination temperature. The prepared α-alumina ultrafiltration membrane had an ultrathin thickness of only ∼140 nm, pure water permeability as high as 230 L m⁻²h⁻¹ bar⁻¹, and average pore size approximately ∼7 nm. In the separation of polyvinyl alcohol (PVA) wastewater, the membrane had a rejection rate of 99 % and permeability of 60 L m⁻²h⁻¹ bar⁻¹. In the removal of Congo red dye, it showed a high rejection rate of >99 % and permeability of 212 L m⁻²h⁻¹ bar⁻¹.