Deep Eutectic Solvent Assisted Preparation Of Microcrystalline TiO₂

TiO₂ is non-toxic and harmless, corrosion resistance, oxidation ability, excellent features such as low cost, good stability, is by far the most widely used light catalyst, and is ideal green environmental protection light catalytic material, has the very high photocatalytic activity, and no secondary pollution, and, in such aspects as environmental purification, air treatment has a wide application prospect.Sol gel method for synthesis of anatase TiO₂ generally need high temperature calcination to promote the formation of crystal type, but high temperature calcination collapse pore size and specific surface area will be reduced, for the semiconductor photocatalyst, in addition to the crystal structure and band gap width, aperture, pore volume and specific surface area is also light catalytic properties of catalysts have a big impact.In this paper, using ionic liquid as the template agent first successfully prepared the anatase mesoporous and high specific surface area of Ti O₂, and the line of a series of characterization, in order to solve the problem of ionic liquid price higher we use eutectic solvent instead of ionic liquids to the preparation of TiO₂, BiOCl/TiO₂ composite photocatalyst, specific experiment is as follows:（1） we（[C6mim] Br） in ionic liquids, by sol gel method, under the condition of low atmospheric pressure without high temperature calcination successful preparation of anatase mesoporous titanium dioxide, The powder X-ray diffraction（XRD）, N₂ adsorptione-desorption isotherms, transmission electron micrographs（TEM） were used to characterize the as-prepared samples, 40 mg/L by degradation of reactive brilliant blue aqueous solution preparation by testing the photocatalytic performance of the sample.Found in the ionic liquid with the help of the preparation of TiO₂ has formed the anatase crystal while maintaining the titanium dioxide ratio of surface area（up to 216 m2/g）;But no preparation of TiO₂ by using ionic liquids show the amorphous structure, specific surface area is 63 m2/g only.In addition in preparation of ionic liquid assisted photocatalytic activity of TiO₂ was obviously higher than that of did not join the preparation of TiO₂ by ionic liquids.Through the above results that ionic liquid of TiO₂ prepared by sol gel at low temperature play a key role.（2） because of the price is high, ionic liquids to be highly purified in the process of synthesis, poor biodegradability, in order to overcome the ionic liquid of these problems, we adopt the price cheap, biodegradable, easy synthesis of eutectic solvent（choline chloride mixed with urea to mole ratio of 1:2） replace agent of ionic liquid as a template synthesis of anatase mesoporous titanium dioxide. +The powder X-ray diffraction（XRD）, N₂ adsorptione-desorption isotherms, transmission electron micrographs（TEM） were used to characterize the as-prepared samples, and the results showed that with the help of eutectic solvent also prepared anatase TiO₂ crystal type, and specific surface area（up to 249 m2/g） is larger than that of ionic liquid assisted preparation of TiO₂ specific surface area（216 m2/g）.And further investigates the template agent concentration, aging liquid concentration, aging time on the preparation of samples of TiO₂ photocatalytic degradation of reactive brilliant blue performance research.（3） eutectic solvent in the process of preparation of Ti O₂ crystal, late recovery difficult and will cause a lot of waste and pollution caused by the problem. At the same time because of anatase Ti O₂ forbidden band width is 3.2 eV can only absorb sunlight is less than 10%, so in order to improve the TiO₂ to absorb the sun’s rays and reduce the waste of eutectic solvent, we join in the process of sol prepared different amount of Bi（NO3）3, make the eutectic solvent in assisting the TiO₂ crystal formation at the same time as the BiOCl/Ti O₂ composite photocatalyst BiOCl chlorine source. The powder X-ray diffraction（XRD）, N₂ adsorptione-desorption isotherms, scanning electron microscopy（SEM）, transmission electron micrographs（TEM）, UV–vis diffuse reflectance spectra（DRS）, Roman were used to characterize the as-prepared samples., and found that with the increase of Bi/Ti ratio, BiOCl crystal structure strength is higher and higher;When doping amount was 4%, TiO₂ grain size distribution on the BiOCl chip, thus effectively together, both to visible light absorption increased significantly, forbidden band width is significantly reduced, the efficiency of photocatalytic degradation of reactive brilliant blue supreme;But when doping amount to 5%, TiO₂ grain size since the reunion and only some TiO₂ grain size distribution on the flake BiOCl, the combination of both cannot effectively forbidden band width rather than 4% BiOCl/TiO₂ composite photocatalyst forbidden band width is big, the efficiency of photocatalytic degradation of reactive brilliant blue also fell, illustrate the Bi/Ti ratio on BiOCl/TiO₂ composite photocatalyst has great effect on the catalytic efficiency.