Structural effect of the in situ generated titania on its ability to oxidize and capture the gas-phase elemental mercury.

Structural effect of the in situ generated TiO(2) sorbent particle was examined for its ability to capture elemental mercury under UV irradiation in a simulated combustion flue gas. Titania particles were prepared by thermal gas-phase oxidation of Titanium (IV) isopropoxide (TTIP) using a high temperature electric furnace reactor. The structural characteristics of the in situ generated TiO(2) at various synthesis temperatures were investigated; size distribution and the geometric mean diameter were measured using a scanning mobility particle sizer, while fractal dimension and radius of gyration were evaluated from the transmission electron microscopy images. Results from the Hg(0) capture experiment show that with increasing titania synthesis temperature, the overall aggregate size increases and the morphology becomes more open-structured to gas-phase Hg(0) and UV light, resulting in the improved mercury removal capability.

Mercury emissions from selected stationary combustion sources in Korea.

Mercury emissions from various stationary combustion sources such as coal-fired power plants, oil-fired power plants, industrial utility oil boilers, iron manufacturing plants, and industrial waste incinerators, were measured. The US EPA (Environmental protection agency) method 101A and the Ontario hydro method were used to sample the mercury containing combustion flue gases, at the inlet of the air pollution control devices (APCDs) and at the stack. Collected samples of both gaseous and particulate forms were then analyzed using CVAA (cold vapor atomic absorption) type analyzer. Measurement results from the coal-fired power plant showed percentages of elemental mercury (Hg0) as high as 31.4% and as low as 9.5%. However, the content of Hg0 was in the range of 1.3-3.7% from the industrial waste incinerator. Differences in mercury speciation from various stationary combustion sources are believed to be coming from: (1) difference in the fuel types; (2) difference in the major flue gas compositions (ex. HCl and SOx); and (3) difference in the types of air pollution control devices (APCDs). When the measurement results obtained using different sampling methods were compared, the Ontario Hydro Method gave a slightly higher mercury concentration measurement than that of the US EPA Method 101A.