CeO₂-TiO₂ coated ceramic membrane with catalytic ozonation capability for treatment of tetracycline in drinking water

A catalytic membrane with CeO₂-TiO₂ active layer has been prepared via an aqueous colloidal sol-gel process for the removal of tetracycline in drinking water using a hybrid ozonation-ultrafiltration method. The catalytic activity of CeO₂-TiO₂ catalysts was firstly optimized by controlling Ce/Ti molar ratios and sintering temperature. The additive concentration and the sintering control have been emphasized in the fabrication process. As confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen sorption isotherms, a typical graded multilayer mesoporous membrane with a continuous and ultra-smooth functional layer was successfully fabricated by optimizing the manufacturing process. The as-prepared membrane was about 1.5 μm thick with the mean pore size of about 9 nm. The permeability and the molecular weight cut-off were characterized to be 83 L/m2 h bar and 80 000 Dalton in a continuous filtration system, respectively. The results of treatment of tetracycline in drinking water showed that the removal rate of tetracycline and humic acid was substantially increased by using the as-prepared CeO₂-TiO₂ coated catalytic membrane as a key device in a combined ozone-membrane process. The synergetic effect of membrane filtration and catalytic ozonation was examined to be the most important reason for the efficient removal of tetracycline and humic acid.