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Herein, tetracycline adsorption employing magnetic chitosan (CS‧Fe3O4) as the adsorbent is reported. The magnetic adsorbent was synthesized by the co-precipitation method and characterized through FTIR, XRD, SEM, and VSM analyses. The experimental data showed that the highest maximum adsorption capacity was reached at pH 7.0 (211.21 mg g−1). The efficiency of the magnetic adsorbent in tetracycline removal was dependent on the pH, initial concentration of adsorbate, and the adsorbent dosage. Additionally, the ionic strength showed a significant effect on the process. The equilibrium and kinetics studies demonstrate that Sips and Elovich models showed the best adjustment for experimental data, suggesting that the adsorption occurs in a heterogeneous surface and predominantly by chemical mechanisms. The experimental results suggest that tetracycline adsorption is mainly governed by the hydrogen bonds and cation–π interactions due to its pH dependence as well as the enhancement in the removal efficiency with the magnetite incorporation on the chitosan surface, respectively. Thermodynamic parameters indicate a spontaneous and exothermic process. Finally, magnetic chitosan proves to be efficient in TC removal even after several adsorption/desorption cycles.

Silica nanoparticles have been widely explored in biomedical applications, mainly related to drug delivery and cancer treatment. These nanoparticles have excellent properties, high biocompatibility, chemical and thermal stability, and ease of functionalization. Moreover, silica is used to coat magnetic nanoparticles protecting against acid leaching and aggregation as well as increasing cytocompatibility. This review reports the recent advances of silica-based magnetic nanoparticles focusing on drug delivery, drug target systems, and their use in magnetohyperthermia and magnetic resonance imaging. Notwithstanding, the application in other biomedical fields is also reported and discussed. Finally, this work provides an overview of the challenges and perspectives related to the use of silica-based magnetic nanoparticles in the biomedical field.

The exceptional properties of graphite, such as excellent thermal and electrical conductivity, corrosion resistance, allow this material to be widely explored in the industrial sector as an anatomic component in different material applications for instance lithium batteries. Magnetic nanoparticles, such as magnetite, presented biocompatibility, biodegradability, thermal conductivity, chemical stability, and the possibility of formation of nanocomposites. Thus, this work proposed the magnetization of graphite through a co-precipitation method that employs FeCl 2 as an iron source. This methodology proved a magnetics nanocomposite with different amounts of magnetite incorporated and control of that. The results obtained through the instrumental analysis of XRD demonstrate a high crystallinity of the material and the presence of magnetite on the surface of the graphite. The average crystallite size, updated by the Scherrer equation, shows a decrease of the size as more nanoparticles are incorporated into the nanomaterial. Finally, it is possible to confirm the obtainment of a magnetic nanocomposite using a fast, economical and efficient method.

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