Sol–gel synthesis of macro–mesoporous titania monoliths and their applications to chromatographic separation media for organophosphate compounds

Abstract

We have developed a method of independently tailoring the macro- and mesoporous structures in titania (TiO 2) monoliths in order to achieve liquid chromatographic separations of phosphorous-containing compounds. Anatase TiO 2 monolithic gels with well-defined bicontinuous macropores and microstructured skeletons are obtained via the sol–gel process in strongly acidic conditions using poly(ethylene oxide) as a phase separator and N-methylformamide as a proton scavenger. Aging treatment of the wet gels in the mother liquor at temperatures of 100–200 °C and subsequent heat treatment at 400 °C allow the formation and control of mesoporous structures with uniform pore size distributions in the gel skeletons, without disturbing the preformed macroporous morphology. The monolithic TiO 2 rod columns with bimodal macro–mesoporous structures possess the phospho-sensitivity and exhibit excellent chromatographic separations of phosphorus-containing compounds.