Pyrene-functionalized halloysite nanotubes for simultaneously detecting and separating Hg(ii) in aqueous media: A comprehensive comparison on interparticle and intraparticle excimers

The development of a facile approach to simultaneously detect and separate Hg(ii) ions in an aqueous solution is a challenging topic in the chemosensing field. Herein, we focus on constructing the Hg(ii)-sensitive fluorescence “turn-on”-type composite materials by using halloysite nanotube (HNT) as substrate. Two types of HNTs-based chemosensors, HNTs-PHT and HNTs-BP, were developed in this study, which exhibit Hg(ii)-sensitive fluorescence “turn on” behavior by forming interparticle and intraparticle excimers, respectively. Fortunately, HNTs-PHT is able to effectively restrict the solvent relaxation of π–π* transition and make it a better detection tool in aqueous solution than HNTs-BP. The addition of Hg(ii) can trigger a dramatical increase at 469 nm in emission curves of HNTs-PHT, which cannot exhibit emission behaviors without the addition of Hg(ii). Furthermore, the formation of interparticle excimers makes Hg(ii) serve as a crosslinker to aggregate HNTs-PHT into precipitations. Following this way, Hg(ii) ions can be facilely removed from the water via a simple filtration or centrifugation approach. The as-prepared HNTs-PHT shows high specificity and precision in simultaneously detecting and separating Hg(ii) without the recourse to energy consumption, which will give a novel insight to deal with heavy metal pollution.