Preparation Of Visible-Light-Responsive TiO₂ Pillared Montmorillonite Photocatalyst

In order to solve the increasingly serious environmental pollution problems, semiconductor photocatalyst TiO₂ attracts much attention because of particular advandages. Owing to the wide band gap (3.2eV for anatase) and a small portion (3-5%) of the solar spectrum is absorbed, the extensive application of TiO₂ was limited in the last several decades. At present, the studies about TiO₂ are foucs on the carrier of the catalysts; enhance the photocatalytic activities and the utilization ratio of visible light. Photocatalytic oxidation technology possesses high treatment efficiency, simple processing equipment, operation conditions controlled easily, non-selectively, non-secondary pollution and etc advantages on treatment organic waste-water. So it can provide new thoughts and pathways for industrialization treatment of organic wastewater.In present work, we synthesized titania pillared montmorillonite (TiO₂-PILM) used sodium montmorillonite (Na-MMT) as the carrier and TiCl₄ as the precursor of TiO₂ through sol method. On this condition, we synthesized N and S co-doped TiO₂-PILM photocatalyst.The X-ray diffraction analyses indicate that the anatase phase of TiO₂ was formed at low-temperature, which may be caused by the introduction of MMT. The as-prepared samples do not exhibit (001) reflections of MMT, which have been referred to the delaminated phenomena during the process of fabricating the composites but the layed structure of MMT was not destroyed completely. The FT-IR absorption spectra indicate that the basic structure of the clay remains on pillaring. The specific surface area of the as-prepared samples increased from 9.5433m²/g of MMT to 225.8280m²/g measured by the BET method. The "house of cards" disorder structure causes the nonuniform pillaring of the clay layers. Two different aggregates between the particles leading bimodal pore size distributions in the mesoporous and macro-porous regions. The XPS survey spectrum shows that the N and S successfully doped into the TiO₂ and the UV-vis diffuse reflectance spectra illuminate that the catalyst's adsorption edge has a red-shift in comparison with that of pure TiO₂.The results of photodegradation acid red G solution show that the catalysts of TiO₂-PILM have good photocatalytic properties. The N and S co-doped TiO₂-PILM obtained at 350℃for 2h and with a molar ratio of 1:4 of Ti:S has better degradation efficiency than that of P25 under Dy lamp irradiation through photodegradation 4BS aqueous solution. The UV-vis absorption spectra of 4BS solution illuminate that the catalyst not destroyed the chromophore of 4BS, but also decomposed the naphthalene ring and benzene ring partly.