The synthesis and investigation of alizan-based functional chromogenic probes for heavy mental sensing in aqueous medium
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Date
2022
Journal Title
Journal ISSN
Volume Title
Publisher
University of Namibia
Abstract
Heavy metal contamination of drinking water is a global concern. Conventional analytical techniques that are commonly used for metal ion detection in water, such as atomic absorption spectrometry and mass spectrometry, are not suitable for mass monitoring purposes. Suitable chromogenic probes could provide an alternative to conventional methods. Moreover, chromogenic probes such as off the shelf, commercially available organic reagents enable rapid and cost efficient in situ monitoring of water sources without the requirement of laborious sampling. Sensor AB and EF, an alizarin derivative was synthesised and characterised using UV-vis, 1H-NMR and FT-IR spectroscopy. The aim of this study was to investigate a colorimetric method based on Schiff base synthesised sensors and other probes such as ready-to-use alizarin organic dye, as well as two organic reagents, dithizone and phenylfluorone for heavy metal detection in borehole water and commercially available water.
Sensor AB and EF showed strong colorimetric response upon the molar addition of various cations (including Fe2+, Fe3+, Hg 2+, Co2+, Ag+, Zn2+, Cu2+) and anions (including AcO-, OH-, CN-) in DMSO, acetonitrile and DMF:water (1:9). Similarly, alizarin and phenylfluorone also showed strong colorimetric response in DMF:water (1:9) and ethanol solvent systems. Whereas vivid colour changes were observed when dithizone complexed with ions. Subsequently, in addition to sensing of cations and anions, all chromogenic probes were employed for signaling of commercial water and borehole water in different solvent systems. Sensor AB reported lack of sensitivity towards water samples, yielding in no colour change for water sensing. Furthermore, spectroscopy results of UV-vis and FT-IR as well as colorimetric results of sensor EF indicate close similarities to alizarin, demonstrating little to no effect of modification of alizarin. Solvatochromism effect associated with dithizone, alizarin and phenylfluorone was observed. Varied and sensitive chromic behaviour was observed in dithizone, displaying colour variances in DMF, methanol, acetonitrile, chloroform, acetone and ethanol.
Description
A thesis submitted in fulfilment of the requirements for the degree of
Master of Science (Chemistry)
Keywords
Chemosensor, Heavy metals, Dithizone, Sensing