Abstract
Volatile organic compounds (VOCs) widely exist in the environment, and the majority of VOCs are highly toxic. Exposure to VOCs is harmful to humans, animals, and the environment. Therefore, it is necessary to both detect and identify harmful VOCs. Gas chromatography (GC) is one of the most reliable and commonly used techniques for the detection of VOCs. However, traditional GC systems are usually bulky, energy-intensive, and expensive. In comparison, micro gas chromatography (μGC) systems are portable, energy-efficient, low-cost, and suitable for on-site and real-time analysis. A typical configuration of μGC includes a carrier gas source, preconcentrator, separation column, gas detector, pump, valves, and software system. The design of the micro gas detector is critical for the success of μGC systems.This thesis presents a new micro helium dielectric barrier plasma discharge-based photoionization detector (μHDBD-PID) using a combination of 3D printing technology and GlassomerTM material. The μHDBD-PID successfully achieved the detection and identification of different classes of VOCs (straight-chain alkanes, aromatics, and polar organic compounds) based on the change in light intensity converted from plasma colour change after sample injection. A minimum limit of detection (LoD) of 10 ng for benzene was achieved. Furthermore, the μHDBD-PID was coupled with a Hamamatsu C12880MA mini spectrometer and created a μHDBD optical emission spectra (μHDBD-OES) detection system for the identification of VOCs. The best LoD of the μHDBD-OES system is about 19 ng for benzene. Finally, a preconcentrator coated with a metal-organic framework (HKUST-1) was manufactured to further improve the detection limit. The detector was able to detect 10 ppm of methane in a calibrated air sample after enrichment performed by the preconcentrator, demonstrating the potential of our detector for practical applications.
| Date of Award | Dec 2024 |
|---|---|
| Original language | English |
| Awarding Institution |
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| Sponsors | Northern Ireland Department for the Economy |
| Supervisor | David McNeill (Supervisor) & Hamza Shakeel (Supervisor) |
Keywords
- dielectric barrier discharge plasma
- photoionization detector
- volatile organic compounds
- micro gas chromatography
- optical emission spectra
- preconcentrator
- methane detection