Preparation of α-alumina/γ-alumina/γ-alumina-titania ceramic composite membrane for chloride ion removal

Abstract

It is a universally acknowledged truth that ceramic membranes with high heat and chemical resistance play a crucial role in the nanofiltration (NF) process under harsh conditions. Although the ceramic membranes are challenging to use for salt filtration due to pore size and surface charge constraints. In this study, sol-gel and dip-coating techniques are used to make alumina–titania composite ceramic membranes with an γ-alumina interlayer for salt rejection. Then, particle size distribution was determined using dynamic light scattering (DLS), and membrane surface quality and morphology were examined using scanning electron microscopy (SEM). The microstructural properties of the membrane have been investigated using X-Ray Diffraction (XRD). A dead-end module is used to measure water permeability and salt rejection. After calcination at 450 °C, SEM shows the crack-free membrane surfaces. The interlayer and top layer membrane thicknesses were estimated to be 1.5 and 0.5 μm, respectively. In addition, XRD measurements show an alumina crystal structure for the interlayer and anatase, rutile, and alumina phases for the composite membranes. Finally, it was shown that the amount of chlorine rejection was pH-dependent, with the rejection rate increasing from 12.7% to 67% as the pH climbed from 4 to 12. Overall, this research provides a composite ceramic nanofiltration for high-pressure desalination, and it is shown that the membrane's surface does not alter after five cycles, which allows for a long-term chemical process and it could be a promising candidate in the wastewater treatment field.