Dry Deposition of Atmospheric Particle-Bound Mercury in the Middle Taiwan

The influences of sulfur, HNO 3 , and thermal treatments on the properties and Hg adsorption of activated carbon (AC) derived from bituminous coals were evaluated. These ACs were impregnated with either polysulfide or elemental sulfur at 120, 200, and 600°C. Additional ACs were treated with HNO 3 at 95°C to incorporate oxygen functionalities, and then subjected to temperature-programmed desorption to 950°C to remove surface oxygen groups and create nascent active sites on the AC surface. Polysulfide and elemental sulfur impregnation at < 200°C did not improve Hg 0 adsorption. However, improvement in HgCl 2 adsorption by up to 97% was observed. Elemental sulfur impregnation at 600°C enhanced Hg 0 and HgCl 2 adsorption by up to 42% and 404%, respectively, for ACs derived from a low-organic-sulfur coal. Improvements in Hg 0 adsorption for ACs from high-organic-sulfur coals were not observed after sulfur impregnation. HNO 3 and thermal treatments reduced Hg-active groups such as sulfur. Oxygen surface groups and the nascent carbon sites appeared to be more reactive towards other flue gas components than Hg, because HNO 3 and thermal treatments led to a reduction in Hg 0 and HgCl 2 adsorption. These results suggest that AC's physical and chemical properties after sulfur treatment influence Hg 0 adsorption, while HgCl 2 adsorption is mainly affected by AC's chemical characteristics.

Section: Introductionmentioning

confidence: 99%

Effects of Sulfur, Nitric Acid, and Thermal Treatments on the Properties and Mercury Adsorption of Activated Carbons from Bituminous Coals

Hsi

Rood

Rostam-Abadi

et al. 2013

“…Coal-fired power plants are known to be the largest source of Hg in most countries with high Hg emissions (Fang et al, 2012;Wu et al, 2012). Nevertheless, low-concentration Hg, within 1-10 ppb v in the coal-combustion flue gases, is difficult to control due to mass transfer limitations.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Cu-Doped TiO2 Photocatalyst with Thermal Plasma Torch for Low-Concentration Mercury Removal

Tsai

Hsi

Kuo

et al. 2013

A high-quality, Cu-doped TiO 2 photocatalyst was prepared via a single-step process using an atmospheric-pressure plasma torch system. Degussa P-25 was thermally doped with Cu at Cu/(Cu + TiO 2 ) ratios of 0-5 wt.%. The raw and resulting nanoparticles were characterized using TEM, XRD, UV-Vis, and XPS. TEM showed that the particle size of plasma-treated TiO 2 was generally < 50 nm. 67-75% of the resulting particles, by number were between 10 and 20 nm. The remaining particles were < 10 nm (~10%) and between 20 and 30 nm (~10%). The XRD results showed that Cu doping decreased the anatase/rutile crystalline ratio compared to untreated P-25. Nevertheless, the greater the amount of Cu added, the greater the anatase/rutile ratio was for the Cu-doped TiO 2 . The UV-Vis results showed that the absorption wavelength for plasma-treated TiO 2 extended to the visible light range, especially for TiO 2 doped with 5 wt.% Cu.

“…To date, not many field studies have been conducted for atmospheric mercury measurements in Taiwan (Kuo et al, 2006;Sheu et al, 2010;Fang et al, 2010;Jen et al, 2010;Fang et al, 2012, Jen et al, 2012), yet none have been done for measuring atmospheric mercury speciation and concentration at Taiwan's offshore islands. In this study, continuous field monitoring of TGM was conducted to investigate its seasonal and daily variations at the Penghu Islands, as the correlations of TGM concentrations with the meteorological parameters and several criteria air pollutants being further examined and discussed.…”

Section: Introductionmentioning

confidence: 99%

Field Measurement of Total Gaseous Mercury and Its Correlation with Meteorological Parameters and Criteria Air Pollutants at a Coastal Site of the Penghu Islands

Jen

Chen

Hung

et al. 2014

This study investigated the seasonal and daily variations of the total gaseous mercury (TGM) concentration in the ambient atmosphere, the correlation of TGM concentration with meteorological parameters (e.g., temperature, humidity, and wind speed) and criteria air pollutant concentrations (e.g., SO 2 , NO x , CO, O 3 , PM 10 , and PM 2.5 ), as well as the transportation routes, at the Penghu Islands. The field measurement results showed that the average TGM concentration during the monitoring period was 3.17 ± 1.17 ng/m 3 , within the range of 1.17-8.63 ng/m 3 , with the highest concentration being observed in spring, while the TGM concentration typically increased in the morning, reached its peak concentration, and then started to decrease at nightfall. Moreover, the lowest average TGM concentration of 1.81 ± 0.15 ng/m 3 was observed in summer, and this figure is close to the background TGM concentration of the Northern Hemisphere (1.6-1.8 ng/m 3 ). The correlation analysis indicated that TGM concentration correlated positively with SO 2 , NO x , CO, O 3 , PM 10 , PM 2.5 and negatively with ambient temperature, relative humidity, and wind speed. In addition, the transportation route analysis showed that elevated TGM concentrations could be transported from either North China, East China, or South China to the Penghu Islands, while those originating from the South China Sea had the lowest contribution to the TGM levels at the Penghu Islands. Therefore, local sources and open burning might be mainly influenced by the long-range transportation of air masses, as the prevailing wind direction and air mass transportation routes potentially play critical roles in the variation of TGM concentration at the Penghu Islands.