The Study of Co–Ni-Mn Ferrites for the Catalytic Decomposition of 4-Nitrophenol

In this work, Co–Ni-Mn ferrites were prepared using a modified chemical co-precipitation method with contact nonequilibrium low-temperature plasma treatment. The structural properties of the ferrites samples were systematically studied using XRD, EPR spectroscopy, vibration magnetometry, and UV-VS spectra analysis. The photocatalytic properties of the prepared samples were comparatively studied during the photodegradation of 4-nitrophenol under UV illumination. The photodegradation rate of 4-nitrophenol (4-NP) in the photocatalytic process was 68–92%, depending on the composition of ferrites. The values of the reaction constant of 4-nitrophenol degradation were calculated. The simplex analysis method made it possible to establish the dependence of the photocatalytic properties of ferrites on the type of EPR spectrum and energy band gap. It was found that for the decomposition reaction of 4-NPs, the intensity of the EPR spectrum peak correlates with photocatalytic activity ferrites. It was established that the optimal compositions for the decomposition of 4-nitrophenol correspond to complex ferrites of nickel and cobalt. In the decomposition reaction of 4-NP, the appearance of galvanic pairs between cations in tetrahedral and octahedral positions is important. The photocatalytic activity in the 4-NP decomposition reaction increases in the series MnFe 2 O 4