Remarkable fluorimetric response and colorimetric sense on the mercury deionization in aqueous solution by a new adsorbent based on chitosan

Rhodamine chromophore was introduced into a chitosan based adsorbent developing for Hg (II) detection and removal in aqueous solution. The adsorbent displayed highly sensitive and selective fluorimetric and colorimetric response to Hg (II) with barely interference with more than ten kinds of competitive metal ions. The adsorbent exhibited strong orange fluorescence emission while encountering Hg (II) with the colour turning to red immediately and could be easily detected by naked eyes. In addition, the detection limit of the adsorbent was calculated to be 8.24 × 10 −7 M, and the adsorption capacity was as high as 139.08 mg/g according to the batch adsorption experiments. Furthermore, the interaction between adsorbent and Hg (II) was verified to fit well with Langmuir isotherm model and the pseudo-second-order kinetic model. Thermodynamic studies demonstrated that lower temperature was benefit for the adsorption.