## 3 Results
### Testing of Synthesized CoFe\({}_{2}\)O\({}_{4}\)/PVP Nanocomtite during Phenol Oxidation
The maximum yield of benzoquinone, 48-52%, is observed at temperatures of 70-80 \({}^{\circ}\)C, which is confirmed by the HPLC data. In the studied temperature range, a linear dependence of \(\mathrm{lg}\) k on 1/T is observed (Figure 10b). The apparent activation energy determined from this dependence and calculated by the Arrhenius equation in this temperature range is 37.8 kJ/mol. Intermediate products were detected, such as catechin, hydroquinone, and formic acid, as oxidation products. Figure 5:0 Conversion curves of phenol oxidation on different amounts of catalyst on CoFe\({}_{2}\)O\({}_{4}\)/PVP at T-353K, P\({}_{02}\)-1.0 MPa. Dependence of the oxygen absorption rate, W\({}_{02}\), on the amount of absorbed oxygen, Q\({}_{02}\) (**a**). Designation of curves: 1—0.01 g, 2—0.02 g, 3—0.06 g, 4—0.1 g. The directly proportional dependence of the initial oxidation rate on the amount of catalyst (**b**). Figure 5:1 Phenol oxidation over CoFe\({}_{2}\)O\({}_{4}\)/PVP catalyst at different temperatures: (**a**) conversion curves of phenol oxidation as a function of temperature. Curve designations: 1—T = 40 \({}^{\circ}\)C; 2—T = 60 \({}^{\circ}\)C; 3—T = 70 \({}^{\circ}\)C; 4—T = 80 \({}^{\circ}\)C. (**b**) Dependence of Ig k on 1/T\(\cdot\)10\({}^{3}\). Hydroquinone, 1,4-benzoquinone, and condensation products were found in the reaction mass after phenol oxidation. Figure 11 shows a chromatogram of phenol oxidation products after 120 min; the main product is benzoquinone (50%). Figure 5:2 Oxidation of phenol with oxygen in the presence of H\({}_{2}\)O\({}_{2}\) on CoFe\({}_{2}\)O\({}_{4}\)/PVP. Dependence of the oxygen absorption rate, W\({}_{\text{O2}}\), on the amount of absorbed oxygen, Q\({}_{\text{O2}}\) (**a**). Dependence of the oxygen absorption rate, W\({}_{\text{O2}}\), on the concentration of phenol, C\({}_{\text{C}\text{HISOH}}\) (**b**). Process conditions: T = 0.02 g CoFe\({}_{2}\)O\({}_{4}\)/PVP catalyst, 120 \(\mu\)L H\({}_{2}\)O\({}_{2}\), P\({}_{\text{O2}}\) = 1 MPa, C\({}_{\text{C2 HISOH}}\)-10, mol/L: 1—0.5; 2—1.0; 3—2.0; 4—3.0. In the presence of CoFe\({}_{2}\)O\({}_{4}\)/PVP, the content of the oxidized intermediate product detected by HPLC increases sharply in the first 30 min of the reaction; then, for 2 h of the reaction, the content of the main products (hydroquinone, benzoquinone) does not change significantly at a phenol conversion of 95%. The HPLC analysis of the reaction mixtures obtained in the presence of the CoFe\({}_{2}\)O\({}_{4}\)/PVP catalyst revealed a decrease in the phenol concentration already at the beginning of 15 min (55-60%), and for 30 min, the phenol concentration decreased to 21.83%. After 2 h, the phenol conversion is already more than 95%. Totals of 28% hydroquinone and 50% benzoquinone were detected in the product. For the control experiments, we conducted preliminary studies of the process of oxidation of phenol with oxygen on CoFe\({}_{2}\)O\({}_{4}\) in order to assess the concentration of phenol in the sample and to perform a primary qualitative assessment of the oxidation of phenol. The content of phenol and benzoquinone was analyzed by UV and IR spectroscopy. In the IR spectra of phenols, the characteristic absorption bands of valence vibrations of the OH group lie in the frequency range of 3390-3600 cm\({}^{-1}\), and valence vibrations of the C-O group are observed at 1230 cm\({}^{-1}\). In the UV spectra, the absorption bands of phenol are as follows: 210 (\(E\) = 6200 L/mol-cm) and 270 nm (\(E\) = 1450 L/mol-cm). Figure 12 shows the absorption spectra of the initial aqueous solution of phenol (a) and from the oxidation time ((b, 1 h) and (c, 2.0 h)). Figure 5:3 Chromatogram of the products of the phenol oxidation reaction on CoFe\({}_{2}\)O\({}_{4}\)/PVP after 120 min of the process.