Preparation and characterization of organic chelate ligand (OCL)-templated TiO2-ZrO2 nanofiltration membranes

Organic chelate ligand (OCL)-templated TiO2-ZrO2 nanofiltration membranes were fabricated. Three types of OLCs, isoeugenol (ISOH), 2,3-dihydroxynaphthalene (DHN), and ethyl acetoacetate (EAA) were examined for use in the preparation of a TiO2-ZrO2 thin separation layer. All employed OCLs were completely decomposed and removed with firing at 500 degrees C under air, but OCL-templated TiO2-ZrO2 composite materials maintained their amorphous structure after firing. ISOH- and DHN-templated TiO2-ZrO2 composite powder samples were more microporous with a higher BET specific surface area than ordinary pure TiO2-ZrO2 composite material without OCL. On the other hand, EAA-templated TiO2-ZrO2 had a less-microporous structure similar to that of non-templated TiO2-ZrO2 powder. The average pore sizes of ISOH-, DHN-, and EAA-templated membranes were 2.0, 2.0, and 1.4 nm, respectively, while that of a non-templated TiO2-ZrO2 membrane was 1.4 nm. ISOH and DHN were more effective as an OCL for changing the characteristics of ordinary TiO2-ZrO2 composite materials. The molecular weight cut-off (MWCO) of OCL-templated TiO2-ZrO2 membranes was 600-1000 g/mol, and water permeability was 3.7-11.41/(m(2) h bar) (LMH/bar). OCLs could be useful for improvements in the water permeability of porous ceramic membranes that retain their solute rejection or separation characteristics.