A new simple method is described, allowing introduction of nitrogen into the TiO2 lattice at low temperatures. The technique is based on the introduction of oxophilic molecules, such as CCl4, into the reaction mixture. The treatment of titanium dioxide powders by NH3–CCl4 mixtures leads to highly dispersed N-doped TiO2. As compared to bare TiO2 or to the same oxide treated with sole NH3, the solids treated with NH3–CCl4 mixtures showed a stronger red shift in optical absorption and enhanced photocatalytic activity under visible light, as demonstrated for two reactions of formic acid oxidation and photocatalytic production of hydrogen from methanol. The nitridation temperature can be significantly decreased by introducing CCl4, because of a favorable change of the reaction thermodynamics. Not only can higher specific surface area of materials be obtained as a result of avoiding sintering but a higher amount of nitrogen is introduced in a position beneficial for the enhanced catalytic activity. The X-ray photoelectron spectroscopy study demonstrated increased surface concentration of nitrogen having N 1s binding energy near 399 eV. As established by ESR, the nature of paramagnetic species generated by treatments is strongly dependent on the titania polymorph variety and crystallinity as well as on the treatment conditions, but in all cases the major part of introduced nitrogen remains ESR-silent.

Experimental research of photocatalytical oxidation (PCO) of aqueous solutions of de-icing agents (ethylene glycol and ethylene glycol monoethyl ether) and methyltert-butyl ether (MTBE) was undertaken. These chemicals are water-soluble components of jet and motor fuels accidentally disposed to the environment. Titanium dioxide (Degussa P25) under near-UV irradiation was selected as a photocatalyst. A slightly acidic medium was preferable for the process efficiency for MTBE, whereas a neutral medium was beneficial for de-icing agents and jet fuel aqueous extracts.TiO2suspension fractional composition was found to be dependent on pH and the presence of organic admixtures: the minimum size ofTiO2particles at their maximum uniformity was established in an acidic medium, where the efficiency of PCO of de-icing agents was the poorest. On the other hand, neutral and slightly acidic media, beneficial for PCO efficiency, were favourable for particle agglomeration, which indicates a minimal role for photocatalyst particle size in PCO efficiency. PCO efficiency increased with increasing MTBE and icing inhibitor concentration. The biodegradability of aqueous solutions of oxygenated additives increased as PCO proceeded. The influence of mineral additives—sulphate, calcium, ferric and manganese ions—on the process efficiency was found to be complex. Special attention was paid to energy-saving PCO with a photocatalyst attached to buoyant glass micro-spheres and reduced intensity of stirring of the slurry.

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