Characterization and performance of porous photocatalytic ceramic membranes coated with TiO₂ via different dip-coating routes

Porous photocatalytic ceramic membranes have been extensively used for separation and purification processes. This study investigates the characterization and performance of porous ceramic membranes coated with TiO₂. The flat sheet membranes were prepared via phase inversion. The membranes were dip-coated in different concentrations of TiO₂ nanoparticle suspensions (0.01, 0.03 and 0.05 wt%) before sintering or after the sintering process. The ceramic membranes coated with 0.03 wt% TiO₂ before sintering at showed excellent morphology with a porous top, dense bottom, and the cross section showed strong adhesion of the penetrated TiO₂-coated layer on the surface and within the pores. This membrane exhibited the lowest surface roughness (0.05 μm) and optimum physical properties, permeation of pure water flux (128.28 L m⁻²h⁻¹), rejection rate (86.06%), better antifouling (highest normalized flux ratio) and self-cleaning performance through increased humic acid rejection flux (94.32 L m⁻²h⁻¹) and rejection rate (98.56%) subsequent to exposure to UV light. All of the membranes coated with different concentrations of TiO₂ prior to the sintering process showed uniform, homogenous coating with enhanced properties and performance. This can be related to the good penetration of TiO₂ nanoparticles and better absorption by the membrane structure. The accumulation of closely tied TiO₂ nanoparticle suspension on the surface of membranes coated after sintering has essentially blocked the membrane surface and pores which might concurrently explained their reduced performance.