Carnivorous fishes can possess higher mercury levels than omnivorous fishes: A selective detection and efficient removal strategy for mercury using magnetic melamine-platinum composites fabricated by supermolecular self-assembly

Mercury (II) ion (Hg 2 + ) as highly toxic heavy metal may be accumulated in aquatic ecosystems and animals species so as to enter human body to conduct health harm. To ensure the safety of fishes food, hence, it is of great interest to evaluate the Hg 2+ levels in different kinds of fishes as well as Hg 2+ removal in aquaculture tailwater. In this article, a selective colormetric detection and efficient removal strategy has been developed for Hg 2+ ions by the controlled supermolecular self-assembly of melamine (MA)-platinum (Pt) composites onto mesoporous Fe 3 O 4 carriers. The resulting Fe 3 O 4 @MA-Pt exhibited the largely enhanced catalysis properties, which might rationally decrease in the presence of Hg 2+ ions through the strong Pt-Hg and MA-Hg interactions. A colorimetric analysis technique based on Fe 3 O 4 @MA-Pt catalysis was thereby designed for detecting Hg 2+ ions with the linear concentrations ranging from 0.010 to 1.0 μM. Moreover, Hg 2+ levels in muscles samples of four kinds of carnivorous and omnivorous fishes were evaluated, displaying an obvious difference in order of snakehead > largemouth bass > crucian carp > silver carp. The data indicate that the carnivorous fishes should possess higher Hg 2+ levels than the omnivorous ones, thus providing a recognizable guidance to the safety evaluation of Hg 2+ in different kinds of fishes. Furthermore, the Fe 3 O 4 @MA-Pt composites with high surface-to-volume ratios were utilized to adsorb Hg 2+ ions in aquaculture tailwater, achieving the adsorption efficiencies up to 99.73 %. Such a colorimetric analysis and removal strategy for Hg 2+ ions may promise for aquatic food safety, clinical diagnostics, environmental monitoring, and tailwater treatments.