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Zan Qu - One of the best experts on this subject based on the ideXlab platform.
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study on the regenerable sulfur resistant sorbent for mercury removal from nonferrous Metal Smelting flue gas
Fuel, 2019Co-Authors: Zongwen Quan, Yong Liao, Haomiao Xu, Wenjun Huang, Zan QuAbstract:Abstract In order to remove and recycle elemental mercury from nonferrous Smelting flue gas, cobalt sulfide sorbents were synthesized and tested. The mercury adsorption capacity of sorbent at 100 °C was 43.03 mg/g with 50% breakthrough threshold. The influences of the flue gas components and reaction temperature on the mercury adsorption capacity were investigated, respectively. The results shown that SO2, H2O, NO and O2 had negligible impact on mercury adsorption of sorbents. Transmission electron microscopy (TEM), X-ray diffractometer (XRD), mercury programmed desorption (Hg-TPD) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the sorbents. The mercury desorption activation energy from the sorbent was calculated based on a model built by the mercury temperature-programmed desorption data. Additionally, the used cobalt sulfide sorbent was regenerated. The results showed that the cobalt sulfide sorbent could maintain good adsorption performance after regeneration during several cycling tests. Therefore, cobalt sulfide is a suitable sorbent for the mercury removal and recycling from nonferrous Metal Smelting flue gas.
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recyclable cus sorbent with large mercury adsorption capacity in the presence of so2 from non ferrous Metal Smelting flue gas
Fuel, 2019Co-Authors: Haomiao Xu, Zongwen Quan, Yong Liao, Sichao Li, Songjian Zhao, Zan QuAbstract:Abstract Gaseous elemental mercury (Hg0) is difficult to dispose using traditional sorbents when co-existed with high concentration of SO2 from non-ferrous Smelting gas. CuS was selected for Hg0 removal from non-ferrous Metal Smelting flue gas due to large Hg0 uptake capacity under SO2 condition. Hg0 removal experiments indicated that CuS has the largest Hg0 adsorption capacity compared to that of ZnS, CdS, MnS and SnS. The Hg0 adsorption rate and capacity of CuS at 50 °C was 0.0716 mg/(g·min) and 50.17 mg/g with 50% breakthrough threshold, respectively. In addition, the effects of reaction factors such as reaction temperatures and gas components (O2, SO2, H2O, SO3) on Hg0 removal performances were investigated. O2, H2O and SO2 showed negligible influences on Hg0 capture. However, SO3 competed with mercury for adsorption sites, resulting in a decrease of mercury adsorption capacity. The XPS analysis and Hg-TPD results indicated that the adsorbed mercury mainly existed as HgS on the material surface. CuS exhibited high mercury adsorption capacity under SO2 atmosphere at low temperature, appeared to be a promising material for Hg0 capture from non-ferrous Metal Smelting flue gas. They can be used co-benefit with electrostatic demister (ESD), upstream entering the acid plant for SO2 recovery.
Yong Liao - One of the best experts on this subject based on the ideXlab platform.
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immobilization of elemental mercury in non ferrous Metal Smelting gas using znse1 xsx nanoparticles
Fuel, 2019Co-Authors: Wei Liu, Yong Liao, Yongfu Guo, Yong Yuan, Naiqiang YanAbstract:Abstract Gaseous elemental mercury (Hg0) in non-ferrous Smelting gas is generally accompanied by a high concentration of SO2. Traditional sorbents for Hg0 removal often suffer from SO2 poisoning. To develop a sorbent that has high mercury removal efficiency and excellent sulfur resistance, Zn-Se-S composites were selected. The experimental results indicated that the ZnSe0.7S0.3 composite had the best Hg0 removal performance, achieving an Hg0 removal efficiency higher than 99% after 120 min of reaction at 150 °C. A “hump” was observed in the adsorption breakthrough curve. This phenomenon is due to the activation of surface Se0, with reduction in surface oxidation state (from Se2+ to Se0) by Hg0 or SO2. This composite has multiple adsorption sites (Se0 and active S) for mercury uptake from Smelting gas. Moreover, this specific Zn-Se-S composite had excellent SO2 resistance. Even high concentrations (1000 or 2000 ppm) of SO2 barely influenced Hg0 removal performances. The Zn-Se-S composite exhibited potential for Hg0 removal from non-ferrous Smelting gas.
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study on the regenerable sulfur resistant sorbent for mercury removal from nonferrous Metal Smelting flue gas
Fuel, 2019Co-Authors: Zongwen Quan, Yong Liao, Haomiao Xu, Wenjun Huang, Zan QuAbstract:Abstract In order to remove and recycle elemental mercury from nonferrous Smelting flue gas, cobalt sulfide sorbents were synthesized and tested. The mercury adsorption capacity of sorbent at 100 °C was 43.03 mg/g with 50% breakthrough threshold. The influences of the flue gas components and reaction temperature on the mercury adsorption capacity were investigated, respectively. The results shown that SO2, H2O, NO and O2 had negligible impact on mercury adsorption of sorbents. Transmission electron microscopy (TEM), X-ray diffractometer (XRD), mercury programmed desorption (Hg-TPD) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the sorbents. The mercury desorption activation energy from the sorbent was calculated based on a model built by the mercury temperature-programmed desorption data. Additionally, the used cobalt sulfide sorbent was regenerated. The results showed that the cobalt sulfide sorbent could maintain good adsorption performance after regeneration during several cycling tests. Therefore, cobalt sulfide is a suitable sorbent for the mercury removal and recycling from nonferrous Metal Smelting flue gas.
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recyclable cus sorbent with large mercury adsorption capacity in the presence of so2 from non ferrous Metal Smelting flue gas
Fuel, 2019Co-Authors: Haomiao Xu, Zongwen Quan, Yong Liao, Sichao Li, Songjian Zhao, Zan QuAbstract:Abstract Gaseous elemental mercury (Hg0) is difficult to dispose using traditional sorbents when co-existed with high concentration of SO2 from non-ferrous Smelting gas. CuS was selected for Hg0 removal from non-ferrous Metal Smelting flue gas due to large Hg0 uptake capacity under SO2 condition. Hg0 removal experiments indicated that CuS has the largest Hg0 adsorption capacity compared to that of ZnS, CdS, MnS and SnS. The Hg0 adsorption rate and capacity of CuS at 50 °C was 0.0716 mg/(g·min) and 50.17 mg/g with 50% breakthrough threshold, respectively. In addition, the effects of reaction factors such as reaction temperatures and gas components (O2, SO2, H2O, SO3) on Hg0 removal performances were investigated. O2, H2O and SO2 showed negligible influences on Hg0 capture. However, SO3 competed with mercury for adsorption sites, resulting in a decrease of mercury adsorption capacity. The XPS analysis and Hg-TPD results indicated that the adsorbed mercury mainly existed as HgS on the material surface. CuS exhibited high mercury adsorption capacity under SO2 atmosphere at low temperature, appeared to be a promising material for Hg0 capture from non-ferrous Metal Smelting flue gas. They can be used co-benefit with electrostatic demister (ESD), upstream entering the acid plant for SO2 recovery.
Haomiao Xu - One of the best experts on this subject based on the ideXlab platform.
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study on the regenerable sulfur resistant sorbent for mercury removal from nonferrous Metal Smelting flue gas
Fuel, 2019Co-Authors: Zongwen Quan, Yong Liao, Haomiao Xu, Wenjun Huang, Zan QuAbstract:Abstract In order to remove and recycle elemental mercury from nonferrous Smelting flue gas, cobalt sulfide sorbents were synthesized and tested. The mercury adsorption capacity of sorbent at 100 °C was 43.03 mg/g with 50% breakthrough threshold. The influences of the flue gas components and reaction temperature on the mercury adsorption capacity were investigated, respectively. The results shown that SO2, H2O, NO and O2 had negligible impact on mercury adsorption of sorbents. Transmission electron microscopy (TEM), X-ray diffractometer (XRD), mercury programmed desorption (Hg-TPD) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the sorbents. The mercury desorption activation energy from the sorbent was calculated based on a model built by the mercury temperature-programmed desorption data. Additionally, the used cobalt sulfide sorbent was regenerated. The results showed that the cobalt sulfide sorbent could maintain good adsorption performance after regeneration during several cycling tests. Therefore, cobalt sulfide is a suitable sorbent for the mercury removal and recycling from nonferrous Metal Smelting flue gas.
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recyclable cus sorbent with large mercury adsorption capacity in the presence of so2 from non ferrous Metal Smelting flue gas
Fuel, 2019Co-Authors: Haomiao Xu, Zongwen Quan, Yong Liao, Sichao Li, Songjian Zhao, Zan QuAbstract:Abstract Gaseous elemental mercury (Hg0) is difficult to dispose using traditional sorbents when co-existed with high concentration of SO2 from non-ferrous Smelting gas. CuS was selected for Hg0 removal from non-ferrous Metal Smelting flue gas due to large Hg0 uptake capacity under SO2 condition. Hg0 removal experiments indicated that CuS has the largest Hg0 adsorption capacity compared to that of ZnS, CdS, MnS and SnS. The Hg0 adsorption rate and capacity of CuS at 50 °C was 0.0716 mg/(g·min) and 50.17 mg/g with 50% breakthrough threshold, respectively. In addition, the effects of reaction factors such as reaction temperatures and gas components (O2, SO2, H2O, SO3) on Hg0 removal performances were investigated. O2, H2O and SO2 showed negligible influences on Hg0 capture. However, SO3 competed with mercury for adsorption sites, resulting in a decrease of mercury adsorption capacity. The XPS analysis and Hg-TPD results indicated that the adsorbed mercury mainly existed as HgS on the material surface. CuS exhibited high mercury adsorption capacity under SO2 atmosphere at low temperature, appeared to be a promising material for Hg0 capture from non-ferrous Metal Smelting flue gas. They can be used co-benefit with electrostatic demister (ESD), upstream entering the acid plant for SO2 recovery.
Shuxiao Wang - One of the best experts on this subject based on the ideXlab platform.
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development of a unit based industrial emission inventory in the beijing tianjin hebei region and resulting improvement in air quality modeling
Atmospheric Chemistry and Physics, 2019Co-Authors: Haotian Zheng, Shuxiao Wang, Siyi Cai, Bin Zhao, Xing Chang, Ji-ming HaoAbstract:Abstract. The Beijing–Tianjin–Hebei (BTH) region is a metropolitan area with the most severe fine particle (PM 2.5 ) pollution in China. An accurate emission inventory plays an important role in air pollution control policy making. In this study, we develop a unit-based emission inventory for industrial sectors in the BTH region, including power plants, industrial boilers, steel, non-ferrous Metal Smelting, coking plants, cement, glass, brick, lime, ceramics, refineries, and chemical industries, based on detailed information for each enterprise, such as location, annual production, production technology/processes, and air pollution control facilities. In the BTH region, the emissions of sulfur dioxide ( SO2 ), nitrogen oxide ( NOx ), particulate matter with diameter less than 10 µ m (PM 10 ), PM 2.5 , black carbon (BC), organic carbon (OC), and non-methane volatile organic compounds (NMVOCs) from industrial sectors were 869, 1164, 910, 622, 71, 63, and 1390 kt in 2014, respectively, accounting for a respective 61 %, 55 %, 62 %, 56 %, 58 %, 22 %, and 36 % of the total emissions. Compared with the traditional proxy-based emission inventory, much less emissions in the high-resolution unit-based inventory are allocated to the urban centers due to the accurate positioning of industrial enterprises. We apply the Community Multi-scale Air Quality (CMAQ; version 5.0.2) model simulation to evaluate the unit-based inventory. The simulation results show that the unit-based emission inventory shows better performance with respect to both PM 2.5 and gaseous pollutants than the proxy-based emission inventory. The normalized mean biases (NMBs) are 81 %, 21 %, 1 %, and −7 % for the concentrations of SO2 , NO2 , ozone ( O3 ), and PM 2.5 , respectively, with the unit-based inventory, in contrast to 124 %, 39 %, −8 %, and 9 % with the proxy-based inventory; furthermore, the concentration gradients of PM 2.5 , which are defined as the ratio of the urban concentration to the suburban concentration, are 1.6, 2.1, and 1.5 in January and 1.3, 1.5, and 1.3 in July, for simulations with the unit-based inventory, simulations with the proxy-based inventory, and observations, respectively, in Beijing. For O3 , the corresponding gradients are 0.7, 0.5, and 0.9 in January and 0.9, 0.8, and 1.1 in July, implying that the unit-based emission inventory better reproduces the distributions of pollutant emissions between the urban and suburban areas.
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Mitigation Options of Atmospheric Hg Emissions in China
2018Co-Authors: Shuxiao Wang, Kaiyun Liu, Ji-ming HaoAbstract:As the Minamata Convention on Mercury comes into effect, controlling atmospheric mercury (Hg) emissions has become a compulsory goal. This study determined the mitigation options for the five Convention specified sources by considering their reduction potential of Hg emissions and the impact of future technology changes on emitted Hg forms and cross-media releases. Hg emissions will be reduced from 371 t in 2015 to 242 t in 2020 mainly by applying multipollutant control measures. Hg emissions will be reduced to 71 t in 2030 mainly with alternative measures and specific Hg removal measures (SMR). Alternative measures are effective for the studied sources except waste incineration (WI). SMR is preferentially recommended in cement clinker production due to the benefit of sectoral emissions and local deposition. Stringent requirements of Hg emission control will promote the use of SMR in WI. In case of nonferrous Metal Smelting (NFMS), only 8.7 t of Hg emissions will be reduced by SMR. However, the cobenefit of Hg reduction in sulfuric acid and local deposition will increase the relevance. On the contrary, applying SMR in coal-fired power plants (CFPPs) and coal-fired industrial boilers (CFIBs) requires comprehensive evaluation in terms of cost benefit and cross-media effect
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mercury transformation and speciation in flue gases from anthropogenic emission sources a critical review
Atmospheric Chemistry and Physics, 2015Co-Authors: Lei Zhang, Qingru Wu, Fengyang Wang, Leiming Zhang, Shuxiao Wang, Mei Yang, Haitao SuAbstract:Abstract. Mercury transformation mechanisms and speciation profiles are reviewed for mercury formed in and released from flue gases of coal-fired boilers, non-ferrous Metal smelters, cement plants, iron and steel plants, waste incinerators, biomass burning and so on. Mercury in coal, ores, and other raw materials is released to flue gases in the form of Hg0 during combustion or Smelting in boilers, kilns or furnaces. Decreasing temperature from over 800 °C to below 300 °C in flue gases leaving boilers, kilns or furnaces promotes homogeneous and heterogeneous oxidation of Hg0 to gaseous divalent mercury (Hg2+), with a portion of Hg2+ adsorbed onto fly ash to form particulate-bound mercury (Hgp). Halogen is the primary oxidizer for Hg0 in flue gases, and active components (e.g., TiO2, Fe2O3, etc.) on fly ash promote heterogeneous oxidation and adsorption processes. In addition to mercury removal, mercury transformation also occurs when passing through air pollution control devices (APCDs), affecting the mercury speciation in flue gases. In coal-fired power plants, selective catalytic reduction (SCR) system promotes mercury oxidation by 34–85 %, electrostatic precipitator (ESP) and fabric filter (FF) remove over 99 % of Hgp, and wet flue gas desulfurization system (WFGD) captures 60–95 % of Hg2+. In non-ferrous Metal smelters, most Hg0 is converted to Hg2+ and removed in acid plants (APs). For cement clinker production, mercury cycling and operational conditions promote heterogeneous mercury oxidation and adsorption. The mercury speciation profiles in flue gases emitted to the atmosphere are determined by transformation mechanisms and mercury removal efficiencies by various APCDs. For all the sectors reviewed in this study, Hgp accounts for less than 5 % in flue gases. In China, mercury emission has a higher Hg0 fraction (66–82 % of total mercury) in flue gases from coal combustion, in contrast to a greater Hg2+ fraction (29–90 %) from non-ferrous Metal Smelting, cement and iron and/or steel production. The higher Hg2+ fractions shown here than previous estimates may imply stronger local environmental impacts than previously thought, caused by mercury emissions in East Asia. Future research should focus on determining mercury speciation in flue gases from iron and steel plants, waste incineration and biomass burning, and on elucidating the mechanisms of mercury oxidation and adsorption in flue gases.
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mercury transformation and speciation in flue gases from anthropogenic emission sources a critical review
Atmospheric Chemistry and Physics, 2015Co-Authors: Lei Zhang, Qingru Wu, Fengyang Wang, Leiming Zhang, Shuxiao Wang, Mei Yang, Haitao SuAbstract:Abstract. Mercury transformation mechanisms and speciation profiles are reviewed for mercury formed in and released from flue gases of coal-fired boilers, non-ferrous Metal smelters, cement plants, iron and steel plants, waste incinerators, biomass burning and so on. Mercury in coal, ores, and other raw materials is released to flue gases in the form of Hg0 during combustion or Smelting in boilers, kilns or furnaces. Decreasing temperature from over 800 °C to below 300 °C in flue gases leaving boilers, kilns or furnaces promotes homogeneous and heterogeneous oxidation of Hg0 to gaseous divalent mercury (Hg2+), with a portion of Hg2+ adsorbed onto fly ash to form particulate-bound mercury (Hgp). Halogen is the primary oxidizer for Hg0 in flue gases, and active components (e.g., TiO2, Fe2O3, etc.) on fly ash promote heterogeneous oxidation and adsorption processes. In addition to mercury removal, mercury transformation also occurs when passing through air pollution control devices (APCDs), affecting the mercury speciation in flue gases. In coal-fired power plants, selective catalytic reduction (SCR) system promotes mercury oxidation by 34–85 %, electrostatic precipitator (ESP) and fabric filter (FF) remove over 99 % of Hgp, and wet flue gas desulfurization system (WFGD) captures 60–95 % of Hg2+. In non-ferrous Metal smelters, most Hg0 is converted to Hg2+ and removed in acid plants (APs). For cement clinker production, mercury cycling and operational conditions promote heterogeneous mercury oxidation and adsorption. The mercury speciation profiles in flue gases emitted to the atmosphere are determined by transformation mechanisms and mercury removal efficiencies by various APCDs. For all the sectors reviewed in this study, Hgp accounts for less than 5 % in flue gases. In China, mercury emission has a higher Hg0 fraction (66–82 % of total mercury) in flue gases from coal combustion, in contrast to a greater Hg2+ fraction (29–90 %) from non-ferrous Metal Smelting, cement and iron and/or steel production. The higher Hg2+ fractions shown here than previous estimates may imply stronger local environmental impacts than previously thought, caused by mercury emissions in East Asia. Future research should focus on determining mercury speciation in flue gases from iron and steel plants, waste incineration and biomass burning, and on elucidating the mechanisms of mercury oxidation and adsorption in flue gases.
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updated emission inventories for speciated atmospheric mercury from anthropogenic sources in china
Environmental Science & Technology, 2015Co-Authors: Lei Zhang, Ji-ming Hao, Fengyang Wang, Shuxiao Wang, Mei Yang, Long Wang, Hai Yang, Lei Duan, Xiang LiuAbstract:China is the largest contributor to global atmospheric mercury (Hg), and accurate emission inventories in China are needed to reduce large gaps existing in global Hg mass balance estimates and assess Hg effects on various ecosystems. The China Atmospheric Mercury Emission (CAME) model was developed in this study using probabilistic emission factors generated from abundant on-site measurements and literature data. Using this model, total anthropogenic Hg emissions were estimated to be continuously increasing from 356 t in 2000 to 538 t in 2010 with an average annual increase rate of 4.2%. Industrial coal combustion, coal-fired power plants, nonferrous Metal Smelting, and cement production were identified to be the dominant Hg emission sources in China. The ten largest contributing provinces accounted for nearly 60% of the total Hg emissions in 2010. Speciated Hg emission inventory was developed over China with a grid-resolution of 36 × 36 km, providing needed emission fields for Hg transport models. In thi...
Haitao Su - One of the best experts on this subject based on the ideXlab platform.
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mercury transformation and speciation in flue gases from anthropogenic emission sources a critical review
Atmospheric Chemistry and Physics, 2015Co-Authors: Lei Zhang, Qingru Wu, Fengyang Wang, Leiming Zhang, Shuxiao Wang, Mei Yang, Haitao SuAbstract:Abstract. Mercury transformation mechanisms and speciation profiles are reviewed for mercury formed in and released from flue gases of coal-fired boilers, non-ferrous Metal smelters, cement plants, iron and steel plants, waste incinerators, biomass burning and so on. Mercury in coal, ores, and other raw materials is released to flue gases in the form of Hg0 during combustion or Smelting in boilers, kilns or furnaces. Decreasing temperature from over 800 °C to below 300 °C in flue gases leaving boilers, kilns or furnaces promotes homogeneous and heterogeneous oxidation of Hg0 to gaseous divalent mercury (Hg2+), with a portion of Hg2+ adsorbed onto fly ash to form particulate-bound mercury (Hgp). Halogen is the primary oxidizer for Hg0 in flue gases, and active components (e.g., TiO2, Fe2O3, etc.) on fly ash promote heterogeneous oxidation and adsorption processes. In addition to mercury removal, mercury transformation also occurs when passing through air pollution control devices (APCDs), affecting the mercury speciation in flue gases. In coal-fired power plants, selective catalytic reduction (SCR) system promotes mercury oxidation by 34–85 %, electrostatic precipitator (ESP) and fabric filter (FF) remove over 99 % of Hgp, and wet flue gas desulfurization system (WFGD) captures 60–95 % of Hg2+. In non-ferrous Metal smelters, most Hg0 is converted to Hg2+ and removed in acid plants (APs). For cement clinker production, mercury cycling and operational conditions promote heterogeneous mercury oxidation and adsorption. The mercury speciation profiles in flue gases emitted to the atmosphere are determined by transformation mechanisms and mercury removal efficiencies by various APCDs. For all the sectors reviewed in this study, Hgp accounts for less than 5 % in flue gases. In China, mercury emission has a higher Hg0 fraction (66–82 % of total mercury) in flue gases from coal combustion, in contrast to a greater Hg2+ fraction (29–90 %) from non-ferrous Metal Smelting, cement and iron and/or steel production. The higher Hg2+ fractions shown here than previous estimates may imply stronger local environmental impacts than previously thought, caused by mercury emissions in East Asia. Future research should focus on determining mercury speciation in flue gases from iron and steel plants, waste incineration and biomass burning, and on elucidating the mechanisms of mercury oxidation and adsorption in flue gases.
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mercury transformation and speciation in flue gases from anthropogenic emission sources a critical review
Atmospheric Chemistry and Physics, 2015Co-Authors: Lei Zhang, Qingru Wu, Fengyang Wang, Leiming Zhang, Shuxiao Wang, Mei Yang, Haitao SuAbstract:Abstract. Mercury transformation mechanisms and speciation profiles are reviewed for mercury formed in and released from flue gases of coal-fired boilers, non-ferrous Metal smelters, cement plants, iron and steel plants, waste incinerators, biomass burning and so on. Mercury in coal, ores, and other raw materials is released to flue gases in the form of Hg0 during combustion or Smelting in boilers, kilns or furnaces. Decreasing temperature from over 800 °C to below 300 °C in flue gases leaving boilers, kilns or furnaces promotes homogeneous and heterogeneous oxidation of Hg0 to gaseous divalent mercury (Hg2+), with a portion of Hg2+ adsorbed onto fly ash to form particulate-bound mercury (Hgp). Halogen is the primary oxidizer for Hg0 in flue gases, and active components (e.g., TiO2, Fe2O3, etc.) on fly ash promote heterogeneous oxidation and adsorption processes. In addition to mercury removal, mercury transformation also occurs when passing through air pollution control devices (APCDs), affecting the mercury speciation in flue gases. In coal-fired power plants, selective catalytic reduction (SCR) system promotes mercury oxidation by 34–85 %, electrostatic precipitator (ESP) and fabric filter (FF) remove over 99 % of Hgp, and wet flue gas desulfurization system (WFGD) captures 60–95 % of Hg2+. In non-ferrous Metal smelters, most Hg0 is converted to Hg2+ and removed in acid plants (APs). For cement clinker production, mercury cycling and operational conditions promote heterogeneous mercury oxidation and adsorption. The mercury speciation profiles in flue gases emitted to the atmosphere are determined by transformation mechanisms and mercury removal efficiencies by various APCDs. For all the sectors reviewed in this study, Hgp accounts for less than 5 % in flue gases. In China, mercury emission has a higher Hg0 fraction (66–82 % of total mercury) in flue gases from coal combustion, in contrast to a greater Hg2+ fraction (29–90 %) from non-ferrous Metal Smelting, cement and iron and/or steel production. The higher Hg2+ fractions shown here than previous estimates may imply stronger local environmental impacts than previously thought, caused by mercury emissions in East Asia. Future research should focus on determining mercury speciation in flue gases from iron and steel plants, waste incineration and biomass burning, and on elucidating the mechanisms of mercury oxidation and adsorption in flue gases.