The structural design of polyacrylonitrile fibre-based colorimetric sensors and their synergistic interaction mechanism
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The structural design of polyacrylonitrile fibre-based colorimetric sensors and their synergistic interaction mechanism for Cu2+ detection Shile Zhou1,2, Hui He1,2
1 2
, Lei Wang1,2, Hongxiang Zhu1,2,*, and Shuangfei Wang1,2
School of Light Industry and Food Engineering, Guangxi University, Nanning 530004, People’s Republic of China Guangxi Key Laboratory of Clean Pulp and Papermaking and Pollution Control, Nanning 530004, People’s Republic of China
Received: 8 March 2020
ABSTRACT
Accepted: 30 August 2020
Excessive content of Cu2? in water is not allowed since it is pathogenic to human beings and most aquatic animals. In this report, to reveal the general colorimetric recognition mechanism of solid-based sensors, containing soft acid coordination ligand types (–COOH, –C=O, –S–) for Cu2?, a series of polyacrylonitrile fibre-based colorimetric sensors (PAN-TEPA-X) with regular precise coordination structures was designed and prepared, where axially symmetric carboxylic acid molecules (X, (CH2)mSn(COOH)2, 3 \ m \ 7, n \ 3) were grafted onto aminated polyacrylonitrile (PAN-TEPA), respectively. For the PANTEPA-X, the limit detection of Cu2? decreased from 1 9 10–5 to 1 9 10–6 mol/L and to 1 9 10-7 mol/L with the increase in the number (n) of S coordination atoms in (CH2)mSn(COOH)2; thus, –S– was a significant ligand type for improving the colorimetric limit of detection of PAN-TEPA-X for Cu2?. The selective recognition mechanism of PAN-TEPA-X for Cu2? was unified and revealed that a portion of the Cu2? was reduced to Cu1 species, and then, the Cu2/Cu1 species were chelated and enriched on the PAN-TEPA-X fibres through a tetradentate ligand reaction (arranged ‘‘tail to tail’’ and ‘‘shoulder to shoulder’’) between the coordination ligand types (–COOH, –C=O, and –S–) of PAN-TEPA-X and Cu2/Cu1 according to the theory of hard and soft acids and bases.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
Handling Editor: Chris Cornelius.
Address correspondence to E-mail: [email protected]
https://doi.org/10.1007/s10853-020-05217-x
J Mater Sci
Introduction The detection of copper ions (Cu2?) in water is necessary and cannot be ignored because it is closely related to the ecological balance and human health [1–4]. The frequently used precise methods for monitoring Cu2?, including atomic absorption spectrometry (AAS), inductively coupled plasma mass spectrometry (ICP-MS), etc., cannot meet the demand for field-based or on-site monitoring because of high cost, complex sample preparation procedures or time-consuming analysis [5–7]. Recently, a number of new methods for the on-site monitoring Cu2? have been developed, such as fluorescence methods, electrochemical assays and colorimetric approaches [8–13]. Among these, colorimetric approaches for monitoring Cu2? are completely independent, i.e. not requiring facilities, due to the direct assessment of Cu2? by a colour change. Small molecule colorimetric sensors require an extraordinary water solubility and are separated difficultly from water, which resu
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