Magnetic nanocomposites composed of superparamagnetic magnetite nanoparticles in a pectin matrix were synthesized by an in situ coprecipitation method. The pectin matrix acted as a stabilizer and size control host for the magnetite nanoparticles (MNPs) ensuring particle size homogeneity. The effects of the different reactant ratios and nanocomposite drying conditions on the magnetic properties were investigated. The nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), Fourier-transform infrared (FT-IR) spectroscopy, and superconducting quantum interference device magnetometer (SQUID). Superparamagnetic magnetite nanoparticles with mean diameters of 9 and 13 nm were obtained, and the freeze-dried nanocomposites had a saturation magnetization of 54 and 53 emu/g, respectively.

Co 3 O 4 and ZnO nanoparticles with different morphologies were synthesised by the thermal decomposition of single source precursors obtained from readily available and eco-friendly starting materials (hexamethylenetetramine and metal nitrates). The precursors, which were characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction and thermal gravimetric analysis, were calcined at 500ºC for 2 h, and the oxide samples obtained were characterized by FTIR, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and nitrogen physisorption. XRD showed that the oxides obtained were crystalline and free of extraneous impurity phases. The morphology of the nanoparticles obtained changed from cube-like (Co 3 O 4) to hexagonal-prism like morphology (ZnO), while the particle size increased from 19.6 to 64.5 nm, respectively. The method used simple and cheap precursors, which should make it suitable for large-scale synthesis.

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