Water quality has become one of the most critical issue of concern worldwide. The main challenge of the scientific community is to develop innovative and sustainable water treatment technologies with high efficiencies and low production costs. In recent years, the use of nanomaterials with magnetic properties used as adsorbents in the water decontamination process has received considerable attention since they can be easily separated and reused. This review focuses on the state-of-art of magnetic core–shell nanoparticles and nanocomposites developed for the adsorption of organic pollutants from water. Special attention is paid to magnetic nanoadsorbents based on silica, clay composites, carbonaceous materials, polymers and wastes. Furthermore, we compare different synthesis approaches and adsorption performance of every nanomaterials. The data gathered in this review will provide information for the further development of new efficient water treatment technologies.

We propose here a novel green synthesis route of core-shell magnetic nanomaterials based on the polyol method, which uses bio-based substances (BBS) derived from biowaste, as stabilizer and directing agent. First, we studied the effect of BBS concentration on the size, morphology, and composition of magnetic iron oxides nanoparticles obtained in the presence of BBS via the polyol synthesis method (MBBS). Then, as a proof of concept, we further coated MBBS with mesoporous silica (MBBS@mSiO₂) or titanium dioxide (MBBS@TiO₂) to obtain magnetic nanostructured core-shell materials. All the materials were deeply characterized with diverse physicochemical techniques. Results showed that both the size of the nanocrystals and their aggregation strongly depend on the BBS concentration used in the synthesis: the higher the concentration of BBS, the smaller the sizes of the iron oxide nanoparticles. On the other hand, the as-prepared magnetic core-shell nanomaterials were applied with good performance in different systems. In particular, MBBS@SiO₂ showed to be an excellent nanocarrier of ibuprofen and successful adsorbent of methylene blue (MB) from aqueous solution. MBBS@TiO₂ was capable of degrading MB with the same efficiency of pristine TiO₂. These excellent results encourage the use of bio-based substances in different types of synthesis methods since they could reduce the fabrication costs and the environmental impact.