A new method for the synthesis of monodisperse-porous titania microbeads by using polymethacrylate microbeads as template


MICROPOROUS AND MESOPOROUS MATERIALS, vol.207, pp.17-26, 2015 (SCI-Expanded) identifier identifier


Monodisperse-porous titania microbeads were synthesized by sol-gel templating method by using a new type of polymethacrylate microbeads as template. Monodisperse-porous poly(3-chloro-2-hydroxypropyl methacrylate-co-ethylene dimethacrylate), poly(HPMA-Cl-co-EDMA) microbeads 5.4 mu m in size were used as starting material for the preparation of new template. Strong cation exchanger -SO3Na groups were generated on the selected polymethacrylate template via the reaction between chloropropyl groups of template and sodium bisulfite. -SO3Na functionalized-polymethacrylate microbeads were treated with the precursor, TiCl4 in an aqueous medium and subsequently treated with ammonia to obtain titania-polymer composite microbeads. The composite microbeads were then calcined at 450 degrees C to have monodisperse-porous titania microbeads. Monodisperse-porous titania microbeads in the size range of 3.0-5.0 mu m with crater-like or fine porous structures with specific surface areas ranging between 50 and 91 m(2)/g were obtained by changing the concentration, crosslinking density of the template beads and the calcination temperature. The selection of a polymethacrylate template decomposed at lower temperatures with respect to poly(styrene-co-divinylbenzene) type templates, commonly used for synthesis of porous titania microbeads, allowed to perform the calcination of titania-polymer composite microbeads at lower temperatures. Monodisperse-porous titania microbeads with higher specific surface area and a crystalline structure with higher percent of anatase phase could be obtained by performing calcination at lower temperatures. The photocatalytic activity of monodisperse-porous titania microbeads was investigated using an anionic azo-dye, Remazol Black 5 (RB5) in batch-fashion. Higher photodegradation rates were observed with the monodisperse-porous titania microbeads in the acidic pH region compared to TiO2 nanoparticles. (C) 2015 Elsevier Inc. All rights reserved.