Fabrication of Organic Probe Decorated Water-Soluble Polymer Chains on Natural Fibers for Selective Detection and Efficient Removal of Hg2+ Ions in Pure Aqueous Media

Developing dual-functional materials that can simultaneously detect and remove toxic heavy metal ions is of practical importance but still remains a challenging task. Herein, an ion-recognizable material, MA-SAPQA@NFs, was facilely fabricated through covalent grafting of salicylaldehyde-containing polymeric quaternary ammonium (SAPQA) chains onto the lotus seedpod-derived natural fibers (NFs), followed by decoration with 2-mercaptoaniline (MA). Several remarkable features for MA- SAPQA@NFs, which could rarely be achieved in previous studies, were integration of good hydrophilicity, high content of organic probe units, and specific visual recognition ability toward Hg2+, making it an excellent candidate as a dual-functional platform for simultaneous detection and removal of Hg2+ under completely aqueous conditions. The distinctive color change as result of Hg2+ binding to MA-SAPQA@NFs could be detected easily by the naked eye and allowed quantitative termination of Hg2+ in simulated and real water samples with the assistance of a smartphone. Meanwhile, the MA-SAPQA@NFs was demonstrated to be highly efficient in removal of Hg2+, exhibiting a very high adsorption capacity (218.21 mg g(-1)), strong anti-interference ability, rapid kinetics, and satisfying reusability. Furthermore, characterization analysis in combination with theoretical calculations revealed the possible binding mechanism behind the detection and adsorption processes. All these findings indicate that the MA-SAPQA@NFs is highly promising for applications in assessment and remediation of heavy metal pollution.