Projects / Programmes
Speciation and interactions of chemical contaminants at trace level in aqueous media to support the developement of cost-effective removal technologies
| Code |
Science |
Field |
Subfield |
| 1.04.05 |
Natural sciences and mathematics |
Chemistry |
Analytical chemistry |
| Code |
Science |
Field |
| T350 |
Technological sciences |
Chemical technology and engineering |
| Code |
Science |
Field |
| 2.07 |
Engineering and Technology |
Environmental engineering
|
mercury, selenium, speciation, thermodynamics, chemical equilibria, chemical kinetics, modelling, aqueous solutions, wet desulphurisation equipment
Researchers (24)
Organisations (2)
Abstract
Emission of trace elements from fossil fuel burning enhanced natural occurrence of a number of elements at local, regional and global scale. Among those elements mercury has received most attention as it is confirmed that anthropogenic activity doubled its concentrations on a global scale. Mercury and its chemical compounds are extremely hazardous and can exist in a large number of different physical and chemical forms with a wide range of properties. Conversion between these different forms provides the basis for mercury's complex distribution pattern in local and global cycles and for its biological enrichment and effects. It also affects the efficiency of clean technologies, particularly in case of wet purification systems, such as the flue gas desulphurisation equipment in coal burning power plants. Mercury exists in oxidation states of zero (Hg0 or Hg(0)) and 1+ (Hg22+or Hg(I) in addition to the expected state of 2+ (Hg2+ or Hg(II)). Biologically mediated transformations in natural system can cause the formation of highly toxic monomethylmercury (CH3Hg+ or MeHg, and dimethylmercury ((CH3)2Hg or DMeHg)). There is a general biogeochemical cycle by which MeHg and Hg(II) compounds, DMeHg and Hg(0) may interchange in the atmospheric, aquatic, and terrestrial environments. In recent years, new analytical techniques have become available and have been used in environmental studies and industrial settings and consequently the understanding of mercury chemistry in natural systems as well as in industry has improved. Modelling tools have also been developed by which mercury transformation and transport in the environment can be simulated and used in scenarios for the reduction of emission as well as the management of contaminated environments. The modelling tools, however, still suffer from large uncertainties and their use in cost effective management is still limited. Although the transport (e.g. hydrodynamics and sediment transports) modules are well developed, poor understanding of mercury chemistry in complex aquatic system still inhibits the proper use of modelling tools. Therefore, the main objective of this project is to improve understanding of mercury chemistry in complex aqueous media. This will include investigation of prevailing directions of chemical reactions of mercury, their mechanisms and kinetics for the following reactions: dissolution of Hg(0), catalytic oxidation of Hg(0) to Hg(I) and Hg(II) by air, complexation, association of complexes with solids and the reduction of ionic mercury species. Complex aqueous media will inter alia include the groups of compounds such as oxygen-sulphur compounds, halogenides, and carbonates and selected other trace elements, known to interact with mercury (selenium, sulphur). Analytical chemistry will include classical methods and novel instrumental methods (mass spectrometry, Raman spectrometry, EXAFS, PIXE, etc..). Transformation mechanisms and partitioning between solid and aqueous media will be studied by the use of stable and radioactive tracers of mercury, selenium and chlorine. Improvement of currently available chemical models and their validation will be performed. The models will be tested on a continuous small pilot plant scale flue gas desulphurisation system. As a result of this fundamental research, improved and validated chemical modules will be developed to be used in integrated modelling approaches for industrial use.
Significance for science
The chemistry of mercury (the targeted pollutant in this study) in industrial settings and the environment is very complex. Understanding of the chemistry in industrial environment is fundamental for the development of clean technologies in which mercury is not emitted into the environment (air, water, solid wastes). In the environment mercury behaviour depends on numerous factors (redox, pH, bacteria, light, T, presence of other chemicals…). In order to improve the environmental models, chemical modules need to be improved. Therefore, the main contribution of the present proposal is to improve the performance of chemical modules used in modelling chemical contaminants in industry and the environment. The project has deepening the understanding of the chemistry of some toxic elements like Hg, Cd, Se, As, in their different chemical forms through development of more accurate mass balances of the pollutants and through development of dynamic models of pollutants distribution in some industrial processes. Using these tolls and knowledge developed the contribution to technical sciences are expected with further development of engineering solutions in high temperature industrial processes in TPPs, cement works and FBC incinerators of relevant wastes. The combination of the theoretical and practical applications is an approach that guarantee optimal design of clean technology. The combination of the approaches can also be considered as an innovation. This can further be argued by the fact that in Slovenia a group that has been largely involved in environmental sciences and health related subjects will use the knowledge and expertise and develop the basis for the development of advanced technology for the removal of contaminants from water waste streams. the liaison with international groups will further strengthen the implementation and high quality work. The improved integrated modelling tools for mercury in the contaminated environment will improve the uncertainty, particularly in the chemical module.
Significance for the country
The project presents the fundamental research with great applied possibilities. The understanding of chemistry of mercury (and some other elements) and its integration into the modelling framework provides excellent tools for applied research. Without science based knowledge the uncertainty of modelling results inhibits practical applications. The work was implemented with industrial partners, however, without their direct financial contributions at this basic research stage. This primarely includes the Thermopower station in Šoštanj, that is in the process startof opening the of the block 6 soon. The knowledge gained in the proposed project will be directly applicable in the optimization of the clean devices during the construction/operation of the WFGD device. Additional co financing will further be explored among the companies that intend to proceed with their business in China, Eastern Europe and Russia, and the Slovenian market as well. The results of these studies are relevant n the following sectors: · The knowledge developed can be marketed in the energy sector, cement production, and other environmental technologies. Marketing is possible in Asia and Europe. · The potential users in Slovenia are fossil fuel based energy sectors and cement production facilities. In addition, thermal treatment of waste requires similar technologies for removal of contaminants and will have to be optimized. · Modelling tools will also improve the existing integrated modelling tools available for the management of contaminated environment in several Slovenian contaminated sites.
Most important scientific results
Annual report
2011,
2012,
2013,
final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Annual report
2011,
2012,
2013,
final report,
complete report on dLib.si
