TiO2-based nanomaterials are attracting much attention in many areas, such as photocatalysis, photoelectricity, probing, electrochromism, photochromism, etc. They are widely used in paints, polymers, sunscreens, and toothpaste. There are various ways of synthesis that affect the size, shape, and crystallinity of TiO2 nanoparticles. The main methods of obtaining titanium dioxide (with the structure of anatase, rutile or brookite) in the form of spheres, rods, fibers, and tubes include: sol-gel technology, hydrothermal and solvothermal methods, microwave method involving high-frequency electromagnetic waves, template method, electrodeposition, a sonochemical method using ultrasound, chemical and physical vapor deposition, "green" methods, etc. This literature review presents modern scientific results on the production of TiO2 nanoparticles by various methods.

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The effect of Sn doping on the structure and morphology of Sn-doped TiO2 samples has been investigated. The doped titania has been obtained by sol-gel synthesis using titanium aquacomplex precursor [Ti(OH2)6] 3+ •3Cl -and SnCl4 as a modifier. The structure and morphology of the samples have been studied through XRD analysis, TEM, low-temperature porometry, IR-spectroscopy, and EDS analysis. The conductivity of Sn-doped TiO2 samples has been investigated by impedance spectroscopy. It was shown that the Sn-doped titania samples contain both anatase and rutile phases. The anatase/rutile ratio depends on the Sn content: the increasing Sn (IV) content from 3 to 12 % (wt.) leads to an increase in rutile content from 33.8 to 97.1 % (wt.). An increase in Sn content causes a decrease in the lattice parameter a and an increase in the parameter c. The presence of rod-shaped and needle-like rutile particles in the Sn-doped TiO2 samples has been observed by TEM. The specific surface area for 6Sn/TiO2 reached 290 m 2 /g. All the Sn-doped titania samples belong to the mesoporous materials. The mechanism of structure-forming processes is explained by existing Sn(OH)4•2H2O molecules in the reaction medium, which act as the centers of nucleation, growth and crystallization for rutile nanoparticles. The increase in Sn content leads to a decrease in the specific resistance of the studied materials compared to the undoped titania sample.

This work studies the adsorption of zirconium ions by mesoporous titanium dioxide and by sodium-modified mesoporous titanium dioxide. Experimental maximal adsorption values of zirconium ions by H-TiO2 and Na-TiO2 were found to be 64 mg/g and 109,5 mg/g respectively. This process depends on the interaction time, equilibrium concentration of zirconium ions and acidity of the solution. Adsorption kinetics fit well into the diffusion kinetic model and indicate a several stages of zirconium ions adsorption. Equilibrium adsorption of zirconium ions is well described by the Langmuir's adsorption theory for both adsorbents. The results obtained by inductively coupled plasma mass spectrometry showed that the investigated adsorbent selectively adsorb zirconium ions from the mixture with strontium and yttrium ions in the range of solution pH = 0-1. The percentage of maximum extraction of zirconium ions is 86,61% for H-TiO2 and 94,11% for Na-TiO2. This fact is extremely valuable for nuclear forensics or for the determination of 90Sr in low activity background samples.