Synthesis of nanostructured titania/zirconia membrane and investigation of its physical separation and photocatalytic properties in treatment of textile industries wastewater

nanostructured tio2/zro2 composite membranes with varying compositions were obtained by sol–gel technique. the influence of 0–30 mol% zirconia doping on microstructure, water permeability, photocatalytic and physical separation properties, removal of methyl violet of textile industries wastewater and thermal and mechanical stability of titania/zirconia composite membranes was described. firstly, alumina supports were coated with tio2 intermediate layers using the colloidal sol–gel route. the tio2/zro2 composite sols were prepared via a polymeric sol–gel method and dip-coated on tio2 intermediate layer. the samples were characterized by dls, tg-dta, xrd, ftir, bet-bjh, uv–visible, sem, tem and afm. it was shown that zirconia retards the phase transformation of anatase to rutile until at least 700 °c. the minimum pore size and maximum surface area obtained were 1.2 nm and 153 m2/g, respectively, attributed to the sample with 20 mol% zirconia. the mechanical strength of titania membranes was significantly improved by addition of zirconia. the most methyl violet removal efficiency obtained, with and without uv-irradiation, is 80.8 and 72.6%, respectively, attributed to the sample with 20 mol% zirconia.