Green chemical method for the synthesis of chromogenic fiber and its application for the detection and extraction of Hg and Cu in environmental medium.

To advocate environment friendly detection idea, we adopted the green chemical method to synthesis the 1-(2 amino ethyl) piperidine functionalized polyacrylonitrile fiber (APF) and the chromogenic fiber 4-(2-pyridylazo) resorcinol (APF-PAR). The APF has high adsorption selectivity of Hg and Cu, and the change of structure, surface morphology and thermo-stability before and after adsorption have been characterized by the infrared spectra, scanning electron microscope and thermogravimetric analysis. The APF achieved the adsorption equilibrium of Hg just in 25 min and the adsorption capacity is 435.1 mg/g, while the adsorption equilibrium of Cu costs 30 min and the adsorption capacity is 141.7 mg/g. The chromogenic fiber APF-PAR can recognize the Hg and Cu in 2 s, which benefits from the rapid mass transfer and small fluid resistance of the chelating PAN fiber. The color changed from orange to purplish red due to the variation of HOMO-LOMO energy gaps during the reaction which confirmed by the UV-vis absorption spectrum. It also has high selectivity and excellent adsorption performance, which provides more convenient, accurate, reliable and faster testing methods of Hg and Cu in environmental medium.