Read, Tania L. (2016) Development of boron doped diamond electrodes for heavy metal detection. PhD thesis, University of Warwick.

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Abstract

Due to their high toxicity and prevalence in natural waters, trace heavy metals are of great concern to environmental analysts. The development of techniques with the ability to detect and quantify ppb levels of heavy metal species in the environment, without the need for sample removal and pretreatment, is therefore a key interest. Popular methods for heavy metal detection such as X-ray Fluorescence (XRF) provide easy elemental identification but lack the low detection limits desirable, whereas electrochemical methods can provide low detection limits but signal assignment in complex samples is often difficult. In addition to this, one of the biggest issues with current methods is the non-ideal nature of the environmental matrices for analysis, for example where the pH of natural waters is usually in the range 6-9; Heavy metal analysis is generally improved under acidic conditions. In this thesis a number of methods are developed with the aim of addressing these issues and moving towards in situ heavy metal detection. Electrochemistry offers an ideal platform for in situ use due to its ease of portability and low power requirements, furthermore the use of conductive boron doped diamond (BDD) electrodes provide a robust sensor resistant to both corrosion and fouling and therefore ideal for long term environmental deployment. Herein BDD dual electrode systems are developed and employed for electrochemical heavy metal detection with simultaneous control of local pH. Fabrication and electrochemical characterisation of these devices is described and compared to finite element simulation. It is shown that using such devices it is possible to control the local pH of a solution even in solutions containing up to 10 mM buffer, allowing manipulation of heavy metal (Hg and Cu) speciation and therefore improved electrochemical detection. The development of all-diamond ring disc electrodes is described; by growing BDD electrodes in insulating diamond, robust well-sealed devices where the sensor and its housing both exhibit the desirable mechanical properties of diamond can be produced. Finally, the newly developed Electrochemical XRF (EC-XRF) technique is optimised and applied to the detection of Cd and Hg.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Electrodes, Heavy metals, Semiconductor doping
Official Date:	June 2016
Dates:	Date Event June 2016 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Macpherson, Julie V.
Extent:	xviii, 199 leaves : illustrations
Language:	eng

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