Mercury compounds characterization by thermal desorption

Abstract

The ability to accurately determine metal mercury content and identify different mercury species in solid samples is essential for developing remediation and control strategies. The aim of the present study is to characterize mercury compounds based on thermal desorption. For this purpose a series of samples was prepared and the operational parameters-heating velocity, carrier gas-were optimized. Fifteen commercial mercury compounds were analyzed for use as fingerprints. The results of the study show that the identification of mercury species by the method of thermal desorption is possible. The temperature of desorption increased according to the following order HgI2<HgBr2<Hg2Cl2=HgCl2<Hg(CN)2<HgCl2O8·H2O<Hg(SCN)2<HgS (red)<HgF2<Hg2(NO3)2·2H2O<Hg(NO3)2·H2O<HgO (yellow, red)<Hg2SO4<HgSO4. A comparison of the estimated total mercury content with the mercury content calculated by integrating the area of the desorption curve shows that recoveries of 79-104% for HgS can be estimated. The proposed method represents a significant step forward in direct mercury analysis in solid samples.

Temperature programmed desorption as a tool for the identification of mercury fate in wet-desulphurization systems

“…One of the most promising of these methods is based on the selective thermal desorption of mercury species from the solid sample, referred to in this work as HgTPD. This method has already been employed to identify the mercury composition of soils, sediments, airborne particulate matter and FGD gypsum among others [17][18][19][20][21]. Nevertheless, it still needs to be validated and the scientific community has yet to demonstrate that the method is reproducible for any solid matrix.…”

“…Briefly, in this work, a thermal desorption procedure that was performed using a previously optimised and validated device [20], was employed to identify mercury species WFGD gypsum samples obtained from both industrial processes and laboratory tests under different operational conditions. The aim was to assess the scope of the method for identifying mercury species in WFGD gypsums and its capacity to predict the fate of mercury in these systems.…”

A comparison of devices using thermal desorption for mercury speciation in solids

“…When the reference compounds were prepared using the same matrix of the samples studied (fly ash, gypsum and soil), the high-peak temperatures obtained were similar. Possible interferences or interactions during the thermal release of the different mercury species were discarded when several Hg compound mixtures were analysed [14]. The tests for speciation of mercury in the different matrices were carried out in HgTPD-1 in the case of fly ash, gypsum and soil samples and in HgTPD-3 for fly ash and gypsum.…”

“…A promising technique with low detection limits is that based on thermal programmed desorption (HgTPD) [12][13][14]. Moreover, HgTPD is an easily accessible technique which can be implemented without the need for complicated instrumentation or for the time-consuming sample pre-treatment required by EXAFS and SCE.…”

Thermal Stability and Adsorption of Mercury Compounds in Fly Ash

“…Hg p is easily removed by dust control equipment, such as electrostatic precipitator (ESP) or bag house filters. Lopez-Anton et al [13,14] demonstrated that HgCl 2 , HgS, HgO, and HgSO 4 were the main Hg species in coal-fired ash. Due to the diverse thermal stabilities of different mercury species, the mercury speciation can be identified via analyzing their thermal stabilities.…”