Nanoparticle Based Sensors for the Detection of Mercury

Many natural gas reservoirs worldwide are contaminated with traces of naturally occurring mercury. Mercury is often present in its elemental form, although it can also be found as mercury sulphide (cinnabar), organo-mercury compounds or ionic halides (S.M WILHELM & n. Bloom 'Mercury in petroleum', Fuel processing technology 63 (2000) 1-27). The safety regulation of mercury wastes disposal imposed by the governments became increasingly strict after the Minamata disease, it was first recognised in Japan in 1956, where more than 2,200 victims were diagnosed as having Minamata disease from the lack of mercury treatment in wastewater before dumping it into the local river. In the US, hydrocarbon combustion was identified as the major anthropogenic sources of mercury emissions to the atmosphere. Mercury is corrosive to metals used commonly in heat exchangers, gas pipelines and storage tanks, and as environmentally hazardous element, it must be removed during petroleum production line before it enters the consumers market. It is important to quantify the mercury concentration since this determines how it is removed. The concentration of mercury within a gas stream is often determined by gas sampling and subsequent laboratory analysis such as purification and pre-concentration procedures. Since mercury often adsorbs on most surfaces once its cools down, the gas sampling method often leads to a significant error. Moreover, it requires professionally trained staff and a long analytical time. This project collaborates with Schlumberger and aims to develop a new mercury sensor. The Compton group has significant experience in the characterisation and electrochemistry of nanoparticles in general. The electrochemical approach of this project will utilise silver nanoparticles (AgNPs) and build on proof-of-concept experiments recently conducted within the group which show that Hg(0) and Hg(II) both react with the nanoparticle either in the case of Hg(0) via amalgam formation or for Hg(II) via galvanic reaction (Analytical Chemistry 2017 89 (13), 7166-7173). The size and capping agents of the AgNPs will be optimised and it is envisaged that by using a range of particle sizes a wider range of concentrations of Hg can be measured. The project firmly embraces two of the research areas identified within the EPSRC vision and strategy, in particular Analytical Science where the 'development of novel techniques... to analyse... chemical systems...' is sought explicitly and Sensors and Instrumentation with impact on the EPSRC research of Physical Sciences, Engineering, Healthcare and Energy. This project falls within the EPSRC Physical sciences research area.