Mercury Control Research Articles

Electrochemical Hg2+ sensor based on electrospun cellulose acetate nanofibers doped with Ag nanoparticles

Mercury (Hg) sensors are critical for environmental monitoring, industrial processes, and public health. They are designed to measure the presence and concentration of mercury ions (Hg2+) in various matrices, including air, water, soil, and biological samples. Mercury in the environment raises concerns due to its toxicity and potential for bioaccumulation. Therefore, this work aims to develop an improved, eco-friendly mercury sensor to address the evolving need for monitoring and control of mercury. The electrochemical sensor for reported here is based on the ability of silver (Ag) to catalyze the reduction of the mercury species Hg2+ to elemental mercury (Hg0), forming an Ag/Hg amalgam. To optimize this sensor, the concentration of silver nanoparticles (AgNPs) on modified nanofibers is determined using differential pulse voltammetry (DPV). Morphological studies and chemical characterization reveal a fiber thickness ranging from 250 to 450 nm and characteristic functional groups, respectively. The sensoŕs analytical performance for detecting Hg2+ concentrations is evaluated through cyclic voltammetry (CV) and DPV in 0.1 M potassium chloride as a supporting electrolyte. The sensor’s detection limit (LOD) for Hg2+ was 0.43 μg/L, with a sensitivity of 0.33 mA/μg/L. In conclusion, the electrochemical sensor exhibits sensitivity and selectivity for Hg2+ detection in the presence of other interfering metal ions, along with eco-friendly and cost-effective features, making it a reliable and practical tool for detecting Hg2+ concentration in water samples.

Review on Mercury Control during Co-Firing Coal and Biomass under O2/CO2 Atmosphere

Combining biomass co-firing with oxy-fuel combustion is a promising Bioenergy with Carbon Capture and Storage (BECCS) technology. It has the potential to achieve a large-scale reduction in carbon emissions from traditional power plants, making it a powerful tool for addressing global climate change. However, mercury in the fuel can be released into the flue gas during combustion, posing a significant threat to the environment and human health. More importantly, mercury can also cause the fracture of metal equipment via amalgamation, which is a major risk for the system. Therefore, compared to conventional coal-fired power plants, the requirements for the mercury concentration in BECCS systems are much stricter. This article reviews the latest progress in mercury control under oxy-fuel biomass co-firing conditions, clarifies the impact of biomass co-firing on mercury species transformation, reveals the influence mechanisms of various flue gas components on elemental mercury oxidation under oxy-fuel combustion conditions, evaluates the advantages and disadvantages of various mercury removal methods, and finally provides an outlook for mercury control in BECCS systems. Research shows that after biomass co-firing, the concentrations of chlorine and alkali metals in the flue gas increase, which is beneficial for homogeneous and heterogeneous mercury oxidation. The changes in the particulate matter content could affect the transformation of gaseous mercury to particulate mercury. The high concentrations of CO2 and H2O in oxy-fuel flue gas inhibit mercury oxidation, while the effects of NOx and SO2 are dual-sided. Higher concentrations of fly ash in oxy-fuel flue gas are conducive to the removal of Hg0. Additionally, under oxy-fuel conditions, CO2 and metal ions such as Fe2+ can inhibit the re-emission of mercury in WFGD systems. The development of efficient adsorbents and catalysts is the key to achieving deep mercury removal. Fully utilizing the advantages of chlorine, alkali metals, and CO2 in oxy-fuel biomass co-firing flue gas will be the future focus of deep mercury removal from BECCS systems.

Impact of Glasgow Climate Pact and Updated Nationally Determined Contribution on Mercury Mitigation Abiding by the Minamata Convention in India.

India is one of the largest emitters of atmospheric anthropogenic mercury (Hg) and the third-largest emitter of greenhouse gases in the world. In the past decade, India has been committed to the Minamata Convention (2017) in addition to the Paris Climate Change Agreement (2015) and the Glasgow Pact (2021). More than 70% to 80% of India's mercury and carbon dioxide emissions occur because of anthropogenic activities from coal usage. This study explores nine policy scenarios, the nationally determined contribution (NDC) scenario, and two deep decarbonization pathways (DDP) with and without mercury control technologies in the energy and carbon-intensive sectors using a bottom-up, techno-economic model, AIM/Enduse India. It is estimated that NDC scenarios reduce mercury emissions by 4%-10% by 2070; while coal intensive (DDP-CCS) pathways and focus on renewables (DDP-R) reduce emissions by 10%-54% and 15%-59%, respectively. Increase in the renewables share (power sector) can result in a significant reduction in the costs of additional pollution-abating technologies in the DDP-R scenario when compared with the coal intensive DDP-CCS scenario. However, the industry sector, especially iron and steel and metal production, will require stringent policies to encourage installation of pollution-abating technologies to mitigate mercury emissions under all the scenarios.

Optimized core design and shield analysis of a medium temperature heat pipe cooled reactor

Medium Temperature heat pipe cooled Reactor (MTR) is a new reactor concept proposed by Li et al. in (2022). Low enriched uranium zirconium hydride fuel and mercury heat pipe are introduced in MTR. The unique advantages of MTR have been verified (Li et al., 2022) and it is considered as a potential candidate for energy supply in decentralized markets. In this work, an optimized MTR core design is proposed with detailed neutronic analysis and evaluation on mercury heat pipe, reflector and control rod arrangement, further increasing the economic efficiency and mobility of MTR. Heat transfer limit of the improved heat pipe model is further increased, contributing to a great reduction on core volume. Reflector material and thickness are analyzed in detail for mass minimization. Core physics characteristics are analyzed for four control rod arrangement schemes. The control mechanism is further simplified with only 9 control rods involved in the normal regulation of the core. Core lifetime is far more than 10 years. High inherent safety of the core is ensured. Besides, preliminary design of the shielding system is also carried out. A shieling layer of 60 cm LiH and 20 cm Pb can reduce the total dose to less than 40 % of the design limits. The total mass of the optimized core is greatly reduced and its specific power is increased by 60 % compared with that of the previous design.

Aqueous Bromide Discharges from U.S. Coal-Fired Power Plants: Points of Origin, Concentration Ranges, and Effluent Treatment Costs

Bromide discharges from coal-fired power plants have received increased attention from regulatory bodies due to their contribution to the formation of disinfection byproducts (DBPs) in downstream drinking water treatment plants. This paper characterizes the relative contributions of bromide from coal feedstocks and bromine-based mercury control processes, estimates the distribution of bromide concentrations at 85 active coal-fired power plants across the United States (U.S.) with wet flue gas desulfurization units, and estimates the cost of bromide removal from wastewater discharge using year 2020 data. Bromide discharges are estimated at the plant level using a combination of the reported coal rank and composition combusted, estimates of bromide addition in mercury control techniques under multiple halogen addition scenarios, and the estimated flue gas desulfurization (FGD) wastewater flow rate. The median, simulated plant-level estimation of total FGD wastewater flow is 18.3 gallons/min at a bromide concentration of 319 mg/L, equivalent to ∼11.6 tonnes/year of bromide discharges to the environment. Next, we evaluated the expected cost of employing the best available technology (BAT) to control bromide discharges in FGD wastewater to prevent contributions to DBP formation. Treatment would need to remove more than 99.8% of bromide to reach the 0.2 mg/L voluntary incentive program (VIP) limit. The total cost of treatment depends on whether disposal is on- or off-site; the average costs for all plants combined come to an average of $110 million ($95.2/kgal) in 2021 U.S. dollars for on-site disposal, or $134 million ($115/kgal) for off-site disposal.

Ex Ante Costs Versus Ex Post Costs of the Large Municipal Waste Combustor Rule

AbstractThis article compares the U.S. Environmental Protection Agency’s (EPA) ex ante cost analysis of its 1995 Large Municipal Waste Combustor (MWC): New Source Performance Standards and Emissions Guidelines rule to an ex post assessment of its cost. Unlike many retrospective cost analyses, where ex post assessments are limited due to lack of data on compliance costs, this case study is unique because we located and used plant-level survey data from the U.S. Department of Energy and Governmental Advisory Associates in a comparison of ex ante and ex post costs of individual MWCs. We find the ex post capital expenditures for nitrogen oxide control systems are typically lower than the EPA ex ante estimates, while the ex post capital expenditures for mercury control systems tend to be higher than the EPA ex ante estimates. Finally, while we find a few outliers, the average ratio of ex post to ex ante capital expenditures for particulate matter and sulfur dioxide emissions control is near unity.

Migration and control of mercury in hazardous chemical waste incineration

This study evaluated the emission and control characteristics of mercury during hazardous chemical waste incineration. Meanwhile, for the complex flue gas conditions generated by hazardous chemical waste incineration, the commercial activated carbon used in the incineration system was modified with CuBr2, and its Hg0 removal performance was tested. The results showed that the major proportion of Hg was in the fly ash, and the content accounted for 74.53 % of the total Hg. The Hg content in the fly ash increased with decreasing fly ash particle size. In the exhaust flue gas, the Hg content was 11.05 % of the total Hg, in which the mass percentages of Hg2+ and Hg0 were 59.08 % and 40.92 %, respectively. The flue gas purification equipment of the incineration system had a removal efficiency of 92.40 % for HgT. The saturated Hg0 removal capacity of the modified activated carbon was improved by 33.51 times. Under simulated incineration flue gas conditions, the modified activated carbon was able to achieve an Hg0 removal efficiency of 92.85 %. The results can contribute to the understanding of Hg emissions from hazardous chemical incineration systems and provide guidance for efficient Hg removal from activated carbon.

Synergistic effect of copper and vanadium species on Hg0 removal of Cu-SCR catalyst: A DFT and experimental study

The synergistic effect of Cu and V species on the improved Hg0 removal performance of Cu-SCR catalyst was analyzed in depth by experiments and theoretical calculations based on density functional theory (DFT). Possible CuVOx/TiO2(001) surface models were constructed for Hg adsorption and oxidation calculations in the presence of O2. According to the results of partial density of states (PDOS) and charge populations, Cu transfers electrons to V through bridge O, and the strong hybridization of Cu 3d and O 2p orbitals facilitate the generation of O−. Although copper doping slightly promotes the Hg adsorption and oxidation ability of VOx species, the O− bonded with Cu provides the optimal adsorption sites and active centers. Strongly hybridized with CuO, Hg easily transfers charge to O− and generate HgO to desorb from the surface, and the oxygen vacancy thus formed can be supplemented by gaseous O2. Characterizations including Raman, fourier transform infrared spectroscopy (FTIR), H2 temperature program reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS) verifies the formation of Cu-O-V structure and the higher involvement of CuOx in Hg0 oxidation, and Hg0 temperature program desorption (Hg0-TPD) were conducted to verify the reaction mechanism. This study reveals the good potential of copper species in Hg0 removal, and provides a reference for designing new materials for mercury control.

Examining the inconsistency of mercury flow in post-Minamata Convention global trade concerning artisanal and small-scale gold mining activity

In 2017, the Minamata Convention (MC) on mercury (Hg) control entered into force. However, whether the MC is effective and how it reshapes the global Hg flow remain unclear. In this study, we established a method to detect inconsistencies in data on global Hg trade, and calculated the gap between the demand and supply of Hg to the artisanal and small-scale gold mining (ASGM) sector (i.e., the largest source of Hg emissions globally) in 39 countries across four regions. According to our results, inconsistencies in statistical data concerning Hg for ASGM activities exist in both Africa and Central and South America. Asia showed a considerably lower amount of Hg applied to ASGM than apparent Hg consumption; nevertheless, the largest consumer of Hg was Asia, predominantly China and India. Many countries in which ASGM is conducted are already MC parties; however, only few submitted their national action plans (NAPs) or have established/enforced specific laws to curb Hg use in ASGM. Analysis of Hg-related trade information suggests that in 2017, the trade of metallic Hg disappeared in some African and Central and South American countries, but new trade flows of goods with higher Hg content emerged. The method established in this study can support the search for countries implementing ASGM with hidden Hg use and flows, thereby contributing to the planning of further Hg control regulations. To enforce sound Hg management, the submission of NAPs should also be promoted in addition to the expansion of MC parties.

Mercury emission characteristics and mechanism in the raw mill system of cement clinker production

Mercury pollution has attracted worldwide attention due to its toxicity, bioaccumulation and persistence. Cement clinker production is the top emitter of atmospheric mercury in China and the emissions from raw mill systems account for about 85% of all emissions. However, the mercury emission characteristics and mechanisms as a function of time during an operation cycle are still unclear. This study aims to reveal the mercury emission characteristics and mechanisms in cement plants by comprehensively using offline and online field measurements, control experiments and heat transfer analysis. Research results indicated that an intermediate temperature (300–500 °C) desorption and the heterogeneous oxidation of mercury in the precalciner, the selective adsorption of oxidized gaseous mercury (Hg2+) to raw meal, and Hg2+ re-vaporization in the conditioning tower jointly caused an increase in the Hg2+ ratio (15.3%−83.6%) during the mill-off mode. In addition, mercury concentrations remained at approximately 6.5 μg/Nm3 during the mill-on mode while the values reached a peak of 1835.4 μg/Nm3 during the mill-off mode. Thus, atmospheric mercury emissions during the mill-off mode accounted for 35.0%− 71.7% of the emissions during the entire cycle, although the mill-off period only lasted for 5%− 17% of the whole cycle. Our results therefore suggest that supervisory monitoring of mercury in cement clinker production should specify the operating status of raw mills. Mercury control technologies targeting a relatively short period for the mill-off mode can substantially reduce mercury emissions from cement clinker production, and thus, the related impacts on ecosystems and human health.

Migration and Control of Mercury in Hazardous Chemical Waste Incineration

Migration and Control of Mercury in Hazardous Chemical Waste Incineration

Effect of the Coal Preparation Process on Mercury Flows and Emissions in Coal Combustion Systems.

Coal preparation is effective in controlling primary mercury emissions in coal combustion systems; however, the combustion of coal preparation byproducts may cause secondary emissions. The inconsistent coal preparation statistics, unclear mercury distribution characteristics during coal preparation, and limited information regarding the byproduct utilization pathways lead to great uncertainty in the evaluation of the effect of coal preparation in China. This study elucidated the mercury distribution in coal preparation based on the activity levels of 2886 coal preparation plants, coal mercury content database, tested mercury distribution factors of typical plants, and then traced the mercury flows and emissions in the downstream sectors using a cross-industry mercury flow model. We found that coal preparation altered the mercury flows by reducing 68 tonnes of mercury to sectors such as coking and increasing the flows to byproduct utilization sectors. Combusting cleaned coal rather than raw coal reduced the mercury emissions by 47 tonnes; however, this was offset by secondary mercury emissions. Coal gangue spontaneous combustion and the cement kiln coprocessing process were dominant secondary emitters. Our results highlight the necessity of whole-process emission control of atmospheric mercury based on flow maps. Future comprehensive utilization of wastes in China should fully evaluate the potential secondary mercury emissions.

Sustained-release of interlayer chloride in iron oxychloride for mercury oxidation from industrial flue gas

Conversion of gaseous elemental mercury (Hg0) to its higher valence state is essential for mercury control using the current air pollution devices from industrial flue gas. Traditional technologies often use selective catalytic reduction (SCR) units to enhance the Hg0 oxidation performance but highly depend on the high-temperature catalysts, the presence of HCl, and the downstream liquid absorption system. This study proposes a novel method coupled with a low-temperature catalyst and a dust removal device to realize mercury immobilization. The iron oxychloride (FeOCl) 2D-nanosheets are put into practice as the low-temperature catalyst. The results indicate superior Hg0 oxidation performance at low oxidizing conditions and a wide temperature window (100–300 °C). The FeOCl catalyst can further combine with MnO2 to achieve mercury fixation. The outstanding property is attributed to the chloride with high activity between the Van Der Waals layer of FeOCl. The oxidative products HgCl2(g) in high yield are attributed to the low Fe-Cl bonding energy in FeOCl relative to metal chloride. This study highlights the conversion process of gaseous Hg0 to HgCl2 in oxidized form and provides a new idea that can be used in conjunction with dust removal equipment to expand the removal method of flue gas mercury.

Two-dimensional WS2 as a new mercury removal material: Mercury conversion pathway and effect of defect

Two-dimensional tungstenite (WS2) has great potential to efficiently control gaseous Hg0 release, because of its wide surface area and the high affinity between mercury and sulfur in WS2. The mercury species adsorption and conversion mechanism over raw and defective WS2(001) surface was investigated on the basis of density functional theory (DFT). The results show that Sdefect site on the WS2 surface exhibits more outstanding ability than Stop site to strongly adsorb Hg0. The oxidizing mercury species (HgO, HgS, HgCl and HgBr) are much easier to be adsorbed by WS2 than elemental mercury, with higher adsorption energy (from −76.09 to −182.59 kJ/mol). The reaction path in the formation of HgS includes a two-step process on S-WS2: Hg0 → HgS(ads) → HgS. In the first reaction step, the energy barrier of surface reaction between elemental mercury and defective S-WS2 is just 4.02 kJ/mol. The second desorption step is an endothermic process and the rate-determining step. The verifying experiment show that WS2 has excellent mercury removal ability at low reaction temperatures under different kinds of flue gas environment. In the whole, WS2 is one of most promising sorbent materials, which can be used for the efficient control of gaseous mercury.

Holistic health risk assessment in an artisanal mercury mining region in Mexico.

Mexico is one of the world's leading mercury producers and exporters. However, mercury mining is carried out using artisanal procedures, which highly impact ecosystems. In the municipality of Pinal de Amoles, Queretaro, Mexico, artisanal mercury mining (AMM) is practiced in a region that has been categorized as a Biosphere Reserve. Therefore, a holistic health risk assessment for mercury was performed in the region, including environmental monitoring (air, water, and soil) and mercury exposure in both humans (children, women, and miners) and biota (plants, rodents, and worms). The atmospheric mercury determination was carried out using the JEROME® J405 analyzer, whereas total mercury in environmental and biological samples was determined by atomic absorption spectrophotometry/cold vapor. Results showed that mercury concentrations in the environmental and biological matrices exceeded their respective reference values. These results demonstrate the direct influence of AMM in the increasing levels of mercury in all the components of the studied ecosystem. Therefore, comprehensive intervention strategies must be implemented to reduce and prevent human health and ecological risks due to the presence of mercury. In this regard, the Minamata Convention for mercury control should include biomonitoring programs not only for humans but also for critical ecological receptors in polluted ecosystems.

Critical transmission sectors in embodied atmospheric mercury emission network in China

AbstractAtmospheric mercury is a crucial pollutant that must be well‐controlled to avoid damaging public health. It is thus necessary to understand from multiple perspectives the roles played by different industrial sectors, as well as their geographical distribution. Existing studies have overlooked the transmission sectors in the economic supply chains of the embodied atmospheric mercury emission network. In this paper, we offer a betweenness‐based account (BBA) for Chinese regions and industrial sectors in transmitting embodied atmospheric mercury emissions and in doing so have identified the transmitting hubs. Our results show that the Henan province acts as the transmission hub of the embodied atmospheric mercury emission network in China. The metallurgy, chemical, and construction industries generally play important roles in the transmission of embodied atmospheric mercury emissions across China. Henan's metallurgy sector, the third highest of all, is more closely linked with inter‐provincial sectors than the top two transmission sectors (the metallurgy industry of Jiangsu and the chemical industry of Shandong). This study can help policy makers improve mercury control measures by focusing on transmission processes for effective and comprehensive atmospheric mercury emission control.

我国汞污染防控体系建设现状浅析

我国汞污染防控体系建设现状浅析

An Experimental Study on Oxidized Mercury Adsorption by Bromide Blended Coal Combustion Fly Ash

The application of forced mercury oxidation technology would lead to an increase of Hg2+ concentration in the flue gas. Although Hg2+ can be easily removed in the WFGD, the mercury re-emission in the WFGD can decrease the total removal of mercury from coal-fired power plants. Hence, it is necessary to control Hg2+ concentration in the devices before the WFGD. Fly ash adsorbent is considered as a potential alternative for commercial activated carbon adsorbent. However, the adsorption efficiency of the original fly ash is low. Modification procedure is needed to enhance the adsorption performance. In this study, the adsorption of Hg2+ by brominated fly ash was studied. The fly ash was collected from the full-scale power plant utilizing bromide-blended coal combustion technology. The brominated fly ash exhibited excellent performance for Hg2+ removal. The flue gas component HBr and SO2 could improve adsorbent’s performance, while HCl would hinder its adsorption process. Also, it was demonstrated by Hg-TPD experiments that the adsorbed Hg2+ mainly existed on the fly ash surface in the form of HgBr2. In summary, the brominated fly ash has a broad application prospect for mercury control.

Atmospheric mercury in Australia

Mercury is a toxic bioaccumulative pollutant, with the atmosphere being the primary pathway for global distribution. Although atmospheric mercury cycling has been extensively monitored and modeled across the Northern Hemisphere, there has long been a dearth of mercury data for the Southern Hemisphere. Recent efforts in Australia are helping to fill this gap, with new observational records that span environments ranging from cool temperate to warm tropical climates and near-source to background conditions. Here, we review recent research on atmospheric mercury in Australia, highlighting new observational constraints on atmospheric concentrations, emissions, and deposition and, where possible, comparing these to model estimates. We also provide our best estimate of the current Australian atmospheric mercury budget. Ambient mercury observations collected to date show unique features not captured at other observing sites across the Southern Hemisphere, including very low concentrations at inland sites and a monsoon season drawdown in the tropical north. Previously compiled estimates of Australian anthropogenic mercury emissions differ substantially due to both methodological differences (e.g., assumptions about mercury control technology in coal-fired power plants) and recent closures of major Australian mercury sources, and none are appropriate for modern-day Australia. For mercury emissions from biomass burning, new measurements from Australian smoke plumes show emission factors for both savanna and temperate forest fires are significantly lower than measured elsewhere in the world, and prior estimates based on non-Australian data are likely too high. Although significant uncertainties remain, our analysis suggests that emissions from terrestrial sources (both newly released and legacy) significantly exceed those from anthropogenic sources. However, recent bidirectional air-surface flux observations suggest this source is likely balanced by deposition and surface uptake at local scales. Throughout, we highlight lingering uncertainties and identify critical future research needs for understanding Australian atmospheric mercury and its role in Southern Hemisphere mercury cycling.

Characterization of input materials to provide an estimate of mercury emissions related to China's cement industry

In the cement production process, in addition to conventional pollutants (such as particulate matter, NOX and SO2), heavy metal pollutants including mercury are also emitted. Globally, the cement industry is one of the most important sources of atmospheric mercury. China's cement production accounts for 50% of global cement production. To obtain a more detailed inventory of atmospheric mercury emissions from China's cement industry, a total of 344 solid samples (limestone: 79; coal: 78; corrective materials: 131; and clinker: 56) from 60 production lines in 23 provinces and cities nationwide were collected and tested. Using statistical analysis, the best estimates of the mercury concentrations of limestone, coal, corrective materials and clinker were 0.047 mg/kg, 0.141 mg/kg, 0.061 mg/kg and 0.011 mg/kg. Thus, we estimated that the annual input of mercury is 132 t/a. Based on the principle of conservation of mass, the atmospheric mercury emissions from the cement industry in 2015 were estimated to be 118 t/a, yielding an emission factor of 0.091 g/t clinker. These data improve the accuracy of the atmospheric mercury emission inventory related to the cement industry and support development of mercury control technologies in China.