Temperature stability of mercury compounds in solid substrates

The major aim of the newly adopted Mercury Convention is to reduce global mercury (Hg) emissions to the environment. In high temperature industrial processes, including coal combustion, Hg compounds present as impurities in solid materials are decomposed and evaporated leading to the emission of Hg to the atmosphere. The behaviour of different Hg compounds and their mixtures during heating have been the subject of numerous studies, and is the topic of the present work. Controlled heating can be used to fractionate Hg compounds in solid substrates, offering the possibility of identification and quantification of Hg compounds. In the attempt to develop a method for temperature fractionation of Hg, experiments were conducted with pure Hg compounds, and the compounds mixed with different substrates (SiO2 and CaSO4 • 2H2O), for calibration purposes. Detection was performed by two methods, namely Cold Vapour Atomic Absorption Spectrometry (CV AAS) with Zeeman background correction, and Nier-type Mass Spectrometry with a Knudsen cell (MS). Further investigation is in process.