Abstract
We fabricated silica nanotubes with hexagonally ordered mesopores (6 nm) inside a membrane disc with a uniform channel neck size of 200 nm and a longitudinal thickness of 60 μm to design an optical sensor membrane (OSM) for the screening and sensing of extremely toxic Hg(II) ions. The optical detection and quantitative recognition of Hg(II) ions in water were conducted even at trace concentrations without the need for sophisticated instruments. The OSM design was based on the physical interaction of a responsive organic probe with silica pore surfaces followed by strong and selective binding Hg(II)–probe interactions under specific sensing conditions, particularly at pH 5. Ultra-trace concentrations of Hg(II) ions were easily detected with the naked eye using the OSM. The remarkable ion spectral response of Hg(II) ion–OSM ensured the excellent quantification of the OSM for Hg(II) ion sensing over a wide range of concentrations with a detection limit of 1.75 × 10−9 M. This result indicated that low concentrations of Hg(II) ions can be detected with a high sensitivity. One of the key issues of OSM is the Hg(II) ion-selective workability even in the presence of high doses of competitive matrices and species. The OSM design showed significant Hg(II) ion-sensing capability despite the number of reuse/recycles using simple decomplexation. Given its high selectivity, fast response, and sensitivity, the OSM could be developed into a specific Hg(II) ion-sensing kit in aqueous solutions.
Highlights
The selective and sensitive detection of toxic heavy metal ions is important because of their negative effects on human health and the environment [1,2,3,4,5,6]
Mesoporous silica NTs with a mesocylinder pore of approximately 6 nm inside alumina membranes (AAMs) channels of 200 nm neck pores may serve as a new class of membranes with toxic ion-sensing functionality
Platforms occurred during the detection of Hg(II) ions in aqueous solutions (Scheme 1E–F). These results indicated that the stability of the fabricated optical sensor membrane (OSM) incorporated with DPTZ may enhance the fast response optical color signal, Hg(II) ion-stripping under severe condition of reuse/recycles, and selectivity of Hg(II) ions among competitive matrices and species (Scheme 1)
Summary
The selective and sensitive detection of toxic heavy metal ions is important because of their negative effects on human health and the environment [1,2,3,4,5,6]. Among these ions, Hg(II) is the most ubiquitous because of its high toxicity and bioaccumulation [7,8,9,10]. The applications of these methods are limited by their time-consuming process, high cost, low sensitivity and selectivity, and complicated sample preparation. We designed a new method with simple operation, rapid completion, low consumption, high sensitivity and selectivity, and possible applications in field tests and on-site Hg(II) monitoring [19,20,21,22]
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