Magnetic adsorbents based on micro- and nano-structured materials

Micro- and nano-sized magnetic adsorbents based on elemental metals, iron oxides, and ferrites and supported by inorganic (carbon, graphene, silica, and zeolites) or organic (macromolecules, polysaccharides, polymers, and biomolecules) compounds are reviewed. The main focus is on magnetic hydrogels, xerogels, and aerogels due to their high number of environmental and biomedical applications. The roles of carbohydrates and polysaccharides (starch, alginic acid, chitosan, etc.) in the stabilisation of magnetic nanoparticles and the use of the formed composites for adsorption purposes are described. Magnetic adsorbents are mainly used for heavy metal removal, for the separation, destruction and adsorption of oil, dyes, toxic organic compounds, several biomolecules and drugs, as well as in a wide variety of catalytic processes. These last applications of magnetic adsorbents, particularly ferrites, are emphasised. The main advantage of magnetic absorbents for these or other possible applications is that the adsorbent or catalyst can be easily removed from the reaction medium after adsorption or reaction completion via a simple magnet. Magnetic behaviour studies of magnetic adsorbents are also discussed.