Magnetic materials prepared from natural sources: synthesis, characterization and environmental applications

Iron-based nanomaterials have found many applications in several technologic fields, including drug delivery systems or waste-water treatments [1], due to their unique magnetic properties. The main advantage related to the use of iron salts and oxides is their relatively low toxicity and cheapness. In addition, the production of materials containing magnetic nanoparticles (m-NPs) offers advantages over the non-magnetic ones because they can be easily separated from liquid and solid media applying an external magnetic field. However, problems related to this system is that m-NPs tend to easily aggregate and oxidize into the non-magnetic hematite, thus m-NPs need to be stabilized in order to preserve their behaviors. This can be obtained covering m-NPs with protective coatings, such as organic and/or polymeric matrices. Magnetic materials consisting of iron oxide particles (typically magnetite and/or maghemite) dispersed in organic matrices received great attention as a new generation of magnetic-responsive hybrid materials, which combine the features of both components [2]. Chitosans (biopolymers derived from fish industry wastes) and soluble bio-based products (SBOs, macromolecules obtained from green wastes composted) are considered potential candidates for the production of magnetic composites for their very limited cost and for the wastes valorization. Thanks to their complex and versatile structures, these classes of compounds were used and tested in the waste water purification from heavy metals and/or dyes, in marine water bioremediation from oil spills, in membrane technologies, etc. [3,4]. Aim of this study is the synthesis of hybrid systems obtained by alkaline coprecipitation method from Fe (II) and Fe (III) salts in aqueous media in the presence of different amount of chitosans and SBOs [5]. The resulting hybrid magnetic systems are physico-chemical characterized by means of microscopic, diffractometric, spectroscopic, gas-volumetric and thermo-gravimetric analyses and tested as adsorbent materials for the abatement of cationic dyes, representing model pollutants, in aqueous environment. [1] Boris I. Kharisov, et al., RSC Advances 2 (2012) 9325–9358. [2] S. Babel, et al.,J. Hazard. Mater. 97 (2003) 219-243. [3] W.S. Wan Ngah, et al., Carbohyd. Polym. 83 (2011) 1446-1456. [4] M.D. Baxter; et al., Industrial & engineering chemistry research 53 (2014) 3612-3621. [5] G. Magnacca, et al., ACS Sustainable Chem. Eng. 2 (2014) 1518-1524