A reusable naphthalimide-functionalized magnetic fluorescent nanosensor for the simultaneous determination and removal of trace Hg2+ in aqueous solution

On the basis of high selective and sensitive interaction of 1,8-naphthalimide with Hg 2+ and the formation of stable neutral imide-Hg-imide complexes, we designed and synthesized a novel magnetic fluorescent sensor ( S1 ) employed Fe 3 O 4 magnetic nanoparticles and 1,8-naphthalimide fluorescent sensor. Under optimum conditions, S1 exhibits the high selectivity toward Hg 2+ over other metal ions, with the detection limit of 1.03   ×   10 −8   M. We demonstrated that a reliable fluorescence response of S1 toward Hg 2+ over a broad pH range (pH   =   5.0–9.0) could be reused at least four cycles. The maximum sorption capacity of S1 was about 5.6   mg   g −1 . In addition, the removal of Hg 2+ in water was achieved by the aggregation-induced sedimentation (AIS) strategy. Moreover, the suspended magnetic nanoparticles could be removed by external magnetic field , and the secondary pollution was avoided. The above-mentioned results indicate that this approach may serve as a foundation of the preparation of the multifunctional magnetic fluorescent sensor for simple, rapid, and simultaneous determination and removal of trace Hg 2+ and other pollutants in environmental samples.