Facile synthesis of bagasse waste derived carbon dots for trace mercury detection

In this paper, water-soluble nitrogen doped fluorescent carbon dots (N-CDs) have been prepared by a facile hydrothermal treatment of bagasse waste and urea. The prepared N-CDs were characterized by high resolution TEM, fluorescence spectroscopy, FTIR and x-ray photoelectron spectroscopy. The results revealed that the prepared N-CDs were mainly composed of hydroxyl, carboxyl and amino groups with an average size of ca. 5.0 nm. The prepared N-CDs exhibited excellent photoluminescence and emitted light blue fluorescence under a 365 nm UV light. Owing to the selective fluorescent quenching response of Hg²⁺, the prepared N-CDs have been used as a fluorescent probe for sensitive detection of Hg²⁺ in water. The fluorescent quenching mechanism could be due to the special coordination interaction between Hg²⁺ and the surface functional groups of the fluorescent N-CDs. Meanwhile, the fluorescence quenching efficiency decreased linearly with Hg²⁺ in the concentration range of 0.005–0.8 μM. The detection limit is low to 0.002 μM. The synthesized N-CDs were further applied to the detection of Hg²⁺ in real water samples. (paper)