Research On New Materials For Gaseous Elemental Mercury Removal

In this thesis, fenton-like reagent was used as liquid absorbent for elemental mercury removal. The variables such as type of ferric salt, initial pH, initial mercury concentration, reaction temperature, halogen ions, and formic acid were investigated. The initial pH affected the removal efficiency significantly. The removal reaction performed better at lower pH. The maximum removal efficiency was76.4%at pH3.48. Temperature played an important role in removal reaction. The concentrations of inlet mercury in the range of31μg m-3to54μg m-3had little effect on removal efficiency. If the concentration increased higher, the efficiency decreased slightly. The addition of halogen ions and formic acid benefited elemental mercury removal obviously. The removal efficiency reached90%as the maximum.The composite carbon nanotubes (CNTs) and magnetic CNTs were synthesized in our work. The materials were characterized by VSM, SEM, TEM and XRD, and used as adsorbents for elemental removal. The possible effects caused by the variables including amount of elements loaded on CNTs, initial concentration of mercury, temperature, oxygen, carbon dioxide, and water vapor were evaluated and investigated. The highest removal efficiency by Ag/CNTs, Pd/CNTs, Se/CNTs, Fe/CNTs, Ag-Fe/CNTs, Pd-Fe/CNTs, Se-Fe/CNTs was98.5%,100%,100%,80%,92%,92%,95%, respectively. Compared with CNTs modified by nitric acid, the removal ability of composite CNTs was enhanced greatly. Ag/CNTs, Se/CNTs, Ag-Fe/CNTs, and Se-Fe/CNTs were sensitive to temperature. They would be more suitable to be used at low temperature. Pd/CNTs and Pd-Fe/CNTs had high removal efficiency even at150℃. The results showed that the removal ability of carbon nanotubes was significantly improved after modification by Ag, Pd, Se. Magnetic modification of CNTs enabled the adsorbent to be separated by magnetic field, and also made the re-collection of adsorbent easier. The methods for the regeneration of adsorbents were also investigated. Some of the adsorbents synthesized in our work were regenerated and reused.