## 1 Introduction
It is reported that the replacement of Fe by other elements, such as Ce,La, Al, etc., occupies the B sites and modifies the magnetic and electrical properties of MnFe\({}_{2}\)O\({}_{4}\)[22]. The great effort made by previous studies demonstrates that the substitution of Ce for Fe in MgFe\({}_{2}\)O\({}_{4}\) effectively tunes the size of the crystallites, enhances the magnetization, and alters the electrical properties [23]. Since the preparation method plays a dominant role in deciding the size of the crystallites and its properties, in the present work we intend to synthesize nanocrystalline MnCe\({}_{x}\)Fe\({}_{2-x}\)O\({}_{4}\) ferrites using a microwave combustion method, which is not reported in earlier literature surveys. The present method is practically efficient, due to the short reaction time and a relatively low temperature of processing. In recent years, many physical and chemical methods have been used to synthesize nanosized ferrites. Because their composition and microstructure influence their structural, magnetic, and electrical properties, they are vastly reliant on the preparation method and conditions. [PERSON] et al. reported the adsorption properties of montmorillonite (MMT) using graphene oxide (GO) and CoFe\({}_{2}\)O\({}_{4}\) magnetic nanoparticles for methyl violet (MV) removal. They observed that the MMT/GO/CoFe\({}_{2}\)O\({}_{4}\) magnetic composite demonstrates the high adsorption capacity and suitable reusability toward MV removal from aqueous media [24]. [PERSON] et al. reported a new nanocomposite of kaolin/copper iron oxide (CuFe\({}_{2}\)O\({}_{4}\)), which were used to remove cationic dyes of methylene blue (MB) and methyl violet (MV) from an aqueous media in a batch system. They observed that, under the optimal conditions, the removal efficiency of MB and MV dyes using a kaolin/CuFe\({}_{2}\)O\({}_{4}\) nanocomposite was obtained with values of 98.64% and 99.25%, respectively, which show the highest removal ever achieved for MB and MV [25]. Additionally, the elimination of methyl violet dye (MVD) and Nile blue dye (NBD) from a water solution using a CNT/MgO/CuFe\({}_{2}\)O\({}_{4}\) magnetic composite powder produced by co-precipitation was investigated. The magnetic composite powder could be used several times in the adsorption process of MVD and NBD without a significant reduction in removal efficiency. The results showed that the CNT/MgO/CuFe\({}_{2}\)O\({}_{4}\) magnetic composite powder can be successfully used in textile wastewater treatment [26]. [PERSON] et al. reported activated carbon oak wood (ACOW600) and modified activated carbon using ZnO (ACOW600/ZnO) and Fe\({}_{3}\)O\({}_{4}\) (ACOW600/ZnO/Fe\({}_{3}\)O\({}_{4}\)) nanoparticles were used to remove methyl violet 2B dye (MV2B) from aqueous solutions. Textile wastewater was significantly treated by ACOW600, ACOW600/ZnO, and ACOW600/ZnO/Fe\({}_{3}\)O\({}_{4}\) adsorbents. The recycling of the adsorbents was demonstrated that the investigated adsorbents could be re-utilized many times in the MV2B removal process [27]. Additionally, a new nanocomposite, clinoptilolite (CLT)/Starch/CoFe\({}_{2}\)O\({}_{4}\), was synthesized using the co-precipitation method. The prepared magnetic composite powder was utilized for the decontamination of methylene blue dye (MBD), methyl violet dye (MVD), and crystal violet dye (CVD) from water media. The maximum adsorption capacity of CVD, MBD, and MVD to the desired composite was determined as 32.84 mg\(\cdot\)g\({}^{-1}\), 31.81 mg\(\cdot\)g\({}^{-1}\), and 31.15 mg\(\cdot\)g\({}^{-1}\), respectively. Finally, the ad(de)sorption experiments' results showed that the synthesized nanocomposite adsorbent has an excellent ability to adsorb cationic dyes after several consecutive cycles [28]. Among all the spinel ferrite systems, rare earth element (REE) doped MnFe\({}_{2}\)O\({}_{4}\) are soft materials called ferromagnetic materials.