A novel 1,8-naphthalimide-functionalized Fe3O4@SiO2 core/shell magnetic fluorescent nanoparticles (MFNPs) for simultaneous detection and adsorption of Hg2+ was designed and synthesized. A series of adsorption studies were carried out with various Hg2+ concentrations, temperature, time and pH. The maximum adsorption capacity is higher than 30 mg/g over a broad temperature (0 degrees C, 25 degrees C, and 50 degrees C) and pH (4-10). The results showed that MFNPs possesses an excellent reusability and the high adsorption specificity toward Hg2+. The detection limit for Hg2+ is 3.4 nM. In addition, owing to the aggregation of MFNPs occurring in the Hg2+ aqueous solution, the adsorbent was separated easily by the settlement or the external magnetic field, which facilitated the removal of Hg2+. (C) 2013 Elsevier B.V. All rights reserved.