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.

A natural clay (Mn) modified with γ-aminopropyltrimethoxysilane (Mn–S) and silver (Mn–S–Ag) were evaluated as a potential adsorption media for nitrate removal from water. These materials were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, zeta-potential, thermogravimetric analysis, scanning electron microscopy and elemental analyses. First, the adsorption capacity of the Mn–S clay for Ag⁺ was studied. The cation adsorption capacity was almost three times greater for Mn–S than for Mn because a metal-amino group complex is favored. Second, the nitrate adsorption on Mn–S and Mn–S–Ag was studied as a function of contact time, pH, temperature and adsorbent dosage using batch techniques. In the absence of Ag⁺, adsorption was high at low pH and the amount of adsorbed nitrate decreased as the pH increased. For the Mn–S, the following monolayer adsorption capacities were obtained: Q_max = 0.80, 0.72 and 0.68 mmol /g at pH 3, 5 and 7, respectively, whereas for the Mn–S–Ag the values obtained were: Q_max = 0.77, 0.74 and 0.42 mmol /g at pH 3, 5 and 7, respectively. From the results obtained, adsorption occurs over surface groups without involving the Ag⁺ cation in the adsorption process.