Synthesis and characterization of TiO_2 pillared montmorillonites: Application for methylene blue degradation

摘要

TiO_2 pillared clay composites were prepared by modifying of montmorillonite (Mt) with cetyl-trimethyammoniumbromide (CTAB) and then using an acidic solution of hydrolyzed Ti alkoxide to intercalate into the interlayer space of the organic modified Mt. The as-prepared materials were characterized by XRD, FTIR, TEM, SEM TG-DTA, specific surface area and porosity measurements. The composites had a porous delaminated structure with pillared fragments and well dispersed TiO_2 nanoparticles. Introduction of CTAB into the synthetic system accelerated the hydrolysis and condensation of the Ti source, which promoted TiO_2 formation. In addition, the CTAB also significantly increased the porosity and surface area of the composites. A number of anatase particles, with crystal sizes of 5-10nm, were homogenously distributed on the surface of the Mt as the result of the templating role of CTAB. The resultant TiO_2 pillared Mt exhibited good thermal stability as indicated by its surface area after calcination at 800°C. No phase transformations from anatase to rutile were observed even under calcination at 900°C. The grain size of the anatase in prepared sample increased from 2.67nm to 13.42nm as the calcination temperature increased from 300°C to 900°C. The photocatalytic performance of these new porous materials was evaluated by using methylene blue degradation. The composite exhibited better photocatalytic property than P 25. The maximum removal efficiency of this composite was up to 99% within 60min.