This paper presents different methodologies for the preparation of Fe₂O₃@SiO₂ nanoparticles (composites) and their characterization. The composite nanoparticles were prepared directly from rice husks. Two methodologies were used, (i) impregnation with an ionic iron solution of rice husks followed with a thermal treatment and (ii) impregnation of the pre-calcinated and lixiviated rice husks. In both methods, a low density, homogenous and highly porous SiO₂ nanoparticles with a mean diameter of 20 nm and loaded with different types of iron oxide are generated. The synthetized products were systematically characterized by SEM, AFM, DLS, FT-IR, Mössbauer and VSM. The results show that two different composites were obtained, one mostly composed by α-Fe₂O₃@SiO₂ and a second one mostly composed by γ-Fe₂O₃@SiO₂. Mössbauer and VMS spectra show that iron oxide nanoparticles are formed in the pores of the SiO₂ nanoparticles and the first method promote production of composites with magnetic properties. These results highlight a new one-step methodology to obtain silica nanoparticles loaded with iron oxides and with high magnetic properties.

本文介绍了Fe ₂ O ₃ @SiO ₂纳米粒子（复合材料）的制备及其表征的不同方法。复合纳米颗粒直接由稻壳制成。使用了两种方法：（i）用稻壳的离子铁溶液进行浸渍，然后进行热处理；（ii）将预煅烧和沥干的稻壳进行浸渍。在这两种方法中，低密度，均质和高度多孔的SiO ₂生成平均直径为20 nm的纳米颗粒，并负载了不同类型的氧化铁。通过SEM，AFM，DLS，FT-IR，Mössbauer和VSM对合成产物进行了系统表征。结果表明，得到的是两种不同的复合材料，一个主要由的α-Fe组成的₂ ö ₃ @SiO ₂和主要由γ-的Fe组成的第二个₂ ö ₃ @SiO ₂。Mössbauer和VMS光谱表明，氧化铁纳米颗粒形成在SiO ₂的孔中纳米颗粒和第一种方法促进具有磁性的复合材料的生产。这些结果突显了一种新的一步法来获得负载有氧化铁且具有高磁性的二氧化硅纳米粒子。