The analysis of the literature data shows that oxides with different characteristics and improved photocatalytic and adsorption properties can be obtained by varying the treatment conditions. Moreover, the efficiency of MWT and MChT application for regulation of physical–chemical properties of other semiconductor oxides was demonstrated in the studies. This was exemplarily confirmed using oxides and phosphates. Additional possibilities for adjusting the parameters of the porous structure are provided by modification in the wet gel stage before drying. As well hydrothermal conditions are satisfied during the mechanochemical treatment (MChT) in water. Ī similar effect but in a shorter time can be achieved using the hydrothermal treatment with microwave heating (microwave treatment, MWT). These results are summarized in the reviews. The effect of classical hydrothermal treatment (in autoclaves) on zirconium dioxide structure was earlier studied by Chertov and co-workers as well as Sharygin and co-workers. The hydrothermal method is the most effective for preparation of crystalline ZrO 2 with a developed mesoporous structure. Modification of precipitated oxides allows to control porous structure parameters. The disadvantages of zirconium dioxide obtained by conventional methods (such as precipitation, sol–gel) are a significant content of micropores and an underdeveloped mesoporous structure. All these applications require certain crystal structure and electronic characteristics as well as developed specific surface area and porous structure of ZrO 2. Therefore, ZrO 2 exhibits photocatalytic activity only under UV-irradiation. Its use as a photocatalyst is confined by a large band gap: 3.5–5.0 eV depending on preparation methods and calcination conditions. As this oxide can be obtained in a highly dispersed state (as non-porous and porous powders or porous xerogels), it is widely applied as the catalysts, the adsorbent or the support for catalysts. Zirconium dioxide is a versatile material. As follows from the investigations, each way of modification results in the shift of the absorption edge toward higher wavelength values and causes photocatalytic degradation of RhB under UV irradiation and makes the obtained materials effective photocatalysts in the visible region. The DTA and XRD results showed the formation of crystalline structure during MWT. In most samples, the specific surface area increase was observed. The results show that the microwave and MChT, differing in mill rotation speed, temperature or treatment media, causes significant changes in the porous structure of the obtained samples. Photocatalytic properties of the samples were also studied as regards the rhodamine B (RhB) degradation in the aqueous solution. The obtained materials were characterized using the N 2 adsorption/desorption, thermogravimetry (TG, DTG, DTA), XRD and UV–Vis/DRS methods. The effects of the microwave treatment (MWT) and mechanochemical treatment (MChT) on the structure and physicochemical properties of precipitated zirconium oxide were investigated.
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