Cu(II) Ion Adsorption by Aniline Grafted Chitosan and Its Responsive Fluorescence Properties
Date
2020-02-26
Authors
Vafakish, Bahareh
Wilson, Lee
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MDPI
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Article
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Abstract
The detection and removal of heavy metal species in aquatic environments is of continued interest to address ongoing efforts in water security. This study was focused on the preparation and characterization of aniline grafted chitosan (CS-Ac-An), and evaluation of its adsorption properties with Cu(II) under variable conditions. Materials characterization provides support for the grafting of aniline onto chitosan, where the kinetic and thermodynamic adsorption properties reveal a notably greater uptake (>20-fold) of Cu(II) relative to chitosan, where the adsorption capacity (Qm) of CS-Ac-An was 106.6 mg/g. Adsorbent regeneration was demonstrated over multiple adsorption-desorption cycles with good uptake efficiency. CS-Ac-An has a strong fluorescence emission that undergoes prominent quenching at part per billion levels in aqueous solution. The quenching process displays a linear response over variable Cu(II) concentration (0.05–5 mM) that affords reliable detection of low level Cu(II) levels by an in situ “turn-off” process. The tweezer-like chelation properties of CS-Ac-An with Cu(II) was characterized by complementary spectroscopic methods: IR, NMR, X-ray photoelectron (XPS), and scanning electron microscopy (SEM). The role of synergistic effects are inferred among two types of active adsorption sites: electron rich arene rings and amine groups of chitosan with Cu(II) species to afford a tweezer-like binding modality.
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The version of record of this article, first published in MDPI, is available online at Publisher’s website: https://doi.org/10.3390/molecules25051052
Keywords
chitosan, grafting, Cu(II) adsorption, adsorption mechanism, fluorescence, in situ sensor
Citation
Vafakish, B.; Wilson, L.D. Cu(II) Ion Adsorption by Aniline Grafted Chitosan and Its Responsive Fluorescence Properties. Molecules 2020, 25, 1052. https://doi.org/10.3390/molecules25051052
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DOI
10.3390/molecules25051052