Date of Award

20-8-2024

Document Type

Thesis

School

School of Electrical & Electroncis Engineering

Programme

Ph.D.-Doctoral of Philosophy

First Advisor

Prof.R.John Bosco Balaguru

Keywords

Metal Organic Frameworks, Chemical Warfare Agent, Textiles, Detoxification, Simulant

Abstract

Chemical Warfare Agents (CWAs) have been listed as lethal weapons of mass destruction due to their extreme toxicity and devastating effects. Malfeasant usage of CWAs involved in the current world praxis poses threat to humankind. Owing to their acute lethal toxicity, the pursuit of favorable approaches for the detoxification/degradation are in continuous progress. In current trends, an imminent development of self-detoxification filters is highly desirable against the CWAs exposure. Exploiting protective materials that can be applicable in day – today life for an instantaneous detoxification will be of prodigious importance.

With this background, a series of Zirconium based UiO-66 and UiO-66-NH2 metal-organic frameworks (MOFs) featured with structural defects were synthesized using solvothermal technique by varying the modulator pKa, HCl modulator concentration, water molecules, synthesis temperature and ligands ratio. The structural, morphological, elemental, functional, and thermal properties of synthesized MOFs were analyzed using X-ray Diffractometer, Scanning Electron Microscope, X-ray Photoelectron Spectrometer, Fourier Transform Infrared Spectrometer, and Thermogravimetric Analyzer.

The present study contributes additional evidence that the considered synthesis parameters outset the creation of open framework in its own metrics. By fine tuning the synthesis practices, the formation of structural defects has been greatly induced. Further, the impact of structural defects possessed by the synthesized samples was systematically investigated against Methyl-paraoxon (DMNP), a CWA simulant. The role of catalytic features of UiO-66 and UiO-66-NH2 obtained by tailoring their defects in enhancing the degradation efficiency has been systematically investigated using UV-vis spectrophotometer.

The detoxification efficiency of 98.5% with a half-life time of 0.23 min has confirmed the effectiveness of engineered defects in enhancing the catalytic activity of UiO-66 in detoxifying the identified simulant. The coexistence of amine group (-NH2) representing Bronsted basic sites, and Lewis’s acid sites of metal clusters in UiO-66-NH2 unveils the maximum conversion efficiency up to 93.6% with an ultrafast transient degradation rate (k) and shorter half-life time of 1.567 min-1 and 0.44 min, respectively.

The self-standing UiO-66 and UiO-66-NH2 functionalized fabrics (MOFabrics) exhibited an expeditious detoxification performance against DMNP with a maximum removal percent conversion of 88.9% and 90.68% respectively. Also, UiO- 66 and UiO-66-NH2 impregnated fabrics have showed a reduced half-life of about 10.16 and 11.23 min for DMNP degradation, in comparison with an unmodified/carboxymethylated fabric of 462 min. This substantial catalytic performance conferred the ability of self-detoxifying MOFabrics, to be well suited for a protective garments’ application in a real time scenario.

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