Green chemical method for the synthesis of chromogenic fiber and its application for the detection and extraction of Hg2+ and Cu2+ in environmental medium.

Graphical abstract Highlights • We report a green chemical method to synthesis the chelating fiber APF and the APF-PAR. • The APF has excellent selective adsorption with Hg2+ and Cu2+, with 435.1 mg/g and 141.7 mg/g just in 25–30 min. • The APF-PAR can recognize the Hg2+ just in 2 s, and it can be clearly recognized by naked eyes. • It is the first time to define the solid-base chromogenic sensor to detect heavy metal ions. Abstract 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 Hg2+ and Cu2+, 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 Hg2+ just in 25 min and the adsorption capacity is 435.1 mg/g, while the adsorption equilibrium of Cu2+ costs 30 min and the adsorption capacity is 141.7 mg/g. The chromogenic fiber APF-PAR can recognize the Hg2+ and Cu2+ 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 Hg2+ and Cu2+ in environmental medium. [ABSTRACT FROM AUTHOR]