## 3 Results and Discussions  
### Nanocomposite Characterization  
The synthesized materials morphology was characterized using a TEM image, as shown in Figure 1. According to Figure 1, the TEM image of MnFe\({}_{2}\)O\({}_{4}\) nanoparticles in Figure 1a showed an agglomeration of the nanoparticles, while Figure 1b showed stacking of GO sheets that are appeared to be folded and wrinkles. Figure 1c showed the TEM image of MnFe\({}_{2}\)O\({}_{4}\)/GO nanocomposite that clearly appears the well-distribution of MnFe\({}_{2}\)O\({}_{4}\) NPs over the GO sheets with nanocomposite size ranging from 11 to 26 nm. Figure 1d showed the SEM image of MnFe\({}_{2}\)O\({}_{4}\)/GO nanocomposite at high magnification. Figure 1d shows the homogenous distribution of spherical MnFe\({}_{2}\)O\({}_{4}\) NPs over GO sheets that confirms the TEM image results. MnFe\({}_{2}\)O\({}_{4}\)/GO nanocomposite XRD was shown in Figure 2a to investigate the crystalline structure and phase purity. Figure 1: TEM image of MnFe\({}_{2}\)O\({}_{4}\) nanoparticles (**a**), graphene oxide (**b**), and MnFe\({}_{2}\)O\({}_{4}\)/graphene oxide nanocomposite (**c**); SEM image of MnFe\({}_{2}\)O\({}_{4}\)/graphene oxide nanocomposite (**d**). According to Figure 2a, XRD shows the peaks corresponding to (731), (533), (440), (511), (422), (400), (222), (311), and (220) crystal plans that appeared in both XRD of MnFe\({}_{2}\)O\({}_{4}\) and MnFe\({}_{2}\)O\({}_{4}\)/graphene oxide nanocomposite. Graphene oxide peak was observed at 12.99\({}^{\circ}\) that represents (001) plane. The graphene oxide plane decreased in the XRD of MnFe\({}_{2}\)O\({}_{4}\)/graphene oxide nanocomposite, indicating the reduction of graphene oxide during nanocomposite synthesis. The purity of the synthesized sample was indicated from the absence of XRD peaks related to the formation of metal oxides, either manganese or iron, and indicated the formation of the nanocomposite. As nanoparticles grown on graphene oxide surface preclude it from restacking, the peak of graphene oxide is significantly reduced. The average particle size of MnFe\({}_{2}\)O\({}_{4}\) nanoparticles alone and MnFe\({}_{2}\)O\({}_{4}\) in nanocomposite was calculated using the Debye-Scherrer equation, which was found equal to 12 nm and 9 nm, respectively. The decreased size of MnFe\({}_{2}\)O\({}_{4}\) in the nanocomposite was attributed to the blocked growth of nanoparticles from one side during the growth over graphene oxide sheets. For more details about the nanocomposite composition, FT-IR spectra were shown in Figure 2b to determine the functional groups. According to the FT-IR results, the vibrations of functional groups O-C, C=C, C=O, and OH graphene oxide were represented by 750.20, 1383.48, 1628.34, 1628.34, 1722.43, and 3450 cm\({}^{-1}\), respectively [44]. Additionally, MnFe\({}_{2}\)O\({}_{4}\) (Mn-O and Fe-O) bonds are represented by 481.25 and 663.29 cm\({}^{-1}\), respectively. The absorption peak at 540 cm\({}^{-1}\) is a characteristic peak corresponding to the stretching vibrations of the Mn-Fe-O linkage. FT-IR results showed an excellent linkage between graphene oxide and MnFe\({}_{2}\)O\({}_{4}\) NPs [45]. Furthermore, the composition more details were obtained via wide scan XPS, as shown in Figure 3a for MnFe\({}_{2}\)O\({}_{4}\)/GO nanocomposite. According to Figure 3a, Fe 2p, Mn 2p, O 1s of adsorbed oxygen, and C 1s in sp2 carbon were represented by peaks at 710.33, 640.14, 528.59, and 284.34, respectively. The high purity of the synthesized nanocomposite was also indicated by the absence of any other pollutants' peaks in the wide scan XPS. As one of the advantages of this nanocomposite is the magnetic property that allowing the simple separation using a magnet, we study the magnetization curve of the currently synthesized nanocomposite as shown in Figure 3b.