Enhancing mechanical and photocatalytic performances on TiO₂/Ti composite ultrafiltration membranes via Ag doping method

The hybrid ceramic-metallic composite membranes combine the advantages of ceramic layers and metallic supports, but the composite membranes tend to crack during sintering process. The metal has superior ductility that could release the shrinkage stress, so that doping the metal into the ceramic membranes can resolve the problem of membrane cracking during sintering process. A new TiO₂/Ti ceramic-metallic composite membrane was prepared by Ag doping method, from which the properties and performances were systematically investigated. It was found that the appropriate amount of 6 dwb% (on a dry weight of TiO₂ basis, dwb) Ag doping can obtain the uniform Ag nanoparticles with about 5 nm, that can efficiently enhance the mechanical properties of strength and toughness of the supported TiO₂ membranes due to the ductility of Ag nanoparticles, overcoming the thermal expansion mismatch between ceramic membranes and metallic supports. The novel as-prepared TiO₂/Ti composite membranes presented a molecular weight cut-off (MWCO) of 180 kDa and a pure water flux of 178 L/(m² h bar). Moreover, the Ag doping method showed a superior photocatalytic performances on dye decomposition, so that a kind of photocatalytic membrane can be prepared for ultrafiltration (UF) process.