Study On Preparation And Synergistic Effect Photocatalytic Activity Of Ordered Mesoporous TiO₂/Porous Carbon Materials By Using Template

The ordered mesoporous TiO2(OMPT) was successfully prepared by a.evaporation induced self-assembly technique using cetyl trimethyl ammonium bromideCTAB as liquid crystal template, tetrabutyl titanate as titanium source, the obtainedOMPT has high thermal stability and shows a2D hexagonal mesostructure with thesmall particle size and high surface areas. In the photocatalytic of degradation themethylene blue (MB), the results show that which lead to higher degradation efficiencythan commercial P25and nanoparticle TiO2(NPT) fabricated by sol-gel process. Theoptimal conditions are a MB concentration of5mg/L at pH6with OMPT concentrationof1.5mg/L for the fastest rate of MB degradation. Total organic carbon (TOC) analysisindicates complete mineralisation of MB in240min by OMPT, of which rate constant isalso higher than NPT and P25.By surfactant template technique with the aid of ultrasound systerm, the orderedmesoporous titania (OMPT) and OMPT/activated carbon (OMPTA) were prepared byusing cetyl trimethyl ammonium bromide (CTAB) surfactant and tetrabutyl titanate ascreating-pore template and titanium source, respectively. Compared to pure OMPT,OMPTA has grain growth with high activation energy, the smalle the particle size andmesoporous structure for high thermal stability, because the activated carbon adsorptionand amorphous phases hinder the crystalline grain growth. Due to hore-hole synergisticamplification effect of photocatalytsis, OMPTA has the highest catalytic activity amongNPTA (ultrasound-sol-gel technique was applied to synthesize nonporous titaniadioxide/activated carbon), OMPT, P25, and OMPT–AC mixture. The heat treatmenttemperature and the times of loaded are strongly affected OMPTA photocatalyticactivity, and OMPT-500and OMPT-3has the highest photocatalytic activity. It isattributed to the fact that it has crystallinity, a relatively high concentration of hydroxyland Ti3+ions, it also has high surface area and concentration of hydroxyl radicals.Meanwhile, OMPTA also shows high photocatalytic properties in the repeated usage.When ARB is degraded by OMPTA-500-3, the optimum catalytic conditions arecatalyst concentration of1g/L with ARB concentration of15mg/L and pH of5.Carbon nanotube (CNT)-embedded mesoporous titania (MT)(CNMT) werecontrolled fabricated in supercritical conditions by deposition of titanium sol containinga liquid crystal template. MT in hybrid materials maintained mesoporous structure up to600℃. This result can be attributed to the structure of CNTs embedded in the anatasematrix. Embedding of CNTs in the nanophase titania matrix helped protect themesoporous framework against collapsing, inhibited undesirable grain growth,suppressed transformation of anatase into rutile, and increased the thermal stability ofMT during calcination. A possible mechanism for the formation of highly thermostable MT in the hybrid materials is also proposed. The maximum phenol degradation (99%after140min) is observed for CNMT-500samples. It is attributed to the wellmesostructure, which facilitates mass transport, the large surface area that offers moreactive sites and hydroxyl radicals, and perfect crystallinity that favors the separation ofphotogenerated electron-hole pairs, confirmed by photoluminescence emissionspectrum.