Mercury Removal Technology Research Articles

Purification of process solutions from mercury by sorption

At JSC «Uralelectromed», selenium-containing raw materials and industrial products are processed, resulting in solutions containing a mixture of mercury with concentrations as follows (g/dm3): 157–210 Se; 0.004–0.02 Hg; 0.15–0.20 Te; 2–3 As; 0.15–0.20 Sb; and 45–50 S. To produce branded selenium, the mercury concentration in the solution must be kept below 0.001 g/dm3. Various methods, such ashydrometallurgical and electrochemical processes, are known for mercury purification from solutions. JSC «Uralelectromed» has selected sorption technology for mercury removal using the weak-base macroporous anionite Lewatit MP-68 (Germany), which allows for control over the degree of solution purification. In pursuit of import substitution for the Western European sorbent Lewatit MP-68, we investigated several pre-selected industrial sorbents for extracting mercury anionic complexes produced in Russia (AM-2B, AN-31, AV 17-8, VP-3Ap), China (Seplite MA 940 and LSC 710), and India (Tulsion CH-95 and CH-97). Initially, in static mode, we determined the distribution coefficient (Cd), the degree of element extraction (ε), the static exchange capacity of the resins (SEC, g/dm3), and the mercury/selenium separation coefficient (DHg/Se) which led to the selection of the best samples: AV 17-8, Seplite MA 940, AM-2B, and CH-97, with SEC values of 0.95–0.97 g/dm3 (SEC = 0.98 g/dm3 of resin Lewatit MP-68). Subsequently, in dynamic mode, we ranked the ionites by decreasing dynamic exchange capacity (DEC / TDEC): AV 17-8 ≥ Lewatit MP-68 > AM-2B > Seplite MA 940 > Tulsion CH-97. Resins AV 17-8, Seplite MA 940, and AM-2B demonstrated similar dynamic sorption characteristics; under comparable conditions, mercury breakthrough occurred after processing at least 950 specific volumes of the initial solution. In contrast, with Lewatit MP-68 ionite, mercury breakthrough occurred after no more than 750 specific volumes, indicating the need to increase the number of sorption steps in the solution purification cascade. Considering the totality of ion-exchange properties, for further industrial testing, it is recommended to use the domestically produced resin AV 17-8 instead of the foreign sorbent Lewatit MP-68 in the sorption purification process of selenic acid to remove mercury, thereby ensuring the production of branded selenium.

Hg0 chemisorption of magnetic manganese cobalt nano ferrite from simulated flue gas

Mercury (Hg) emissions from the flue gas of coal-fired power plants constituted the primary source of atmospheric mercury pollution, manifesting in three distinct forms: granular mercury, oxidized mercury, and elemental mercury. This pollution posed significant threats to the ecological environment. There was an urgent demand for a more effective and economically viable mercury removal technology. The magnetic Mn0.5Co0.5Fe2O4 nanoparticles were prepared via a rapid combustion process. Their capacities for mercury adsorption and regeneration were scrutinized through a fixed-bed experimental system. The outcomes revealed that Mn0.5Co0.5Fe2O4 nanoparticles, prepared at a calcination temperature of 400 °C with 20 ml of anhydrous ethanol, exhibited the most proficient adsorption of Hg°. Under these specific conditions, the average particle size of the Mn0.5Co0.5Fe2O4 nanoparticles was approximately 26.8 nm. These nanoparticles demonstrated a superior adsorption capacity of 9.48 μg·g−1 for Hg° at an adsorption temperature of 30 °C under a space velocity of 2.4 × 104 h−1. Elevating the permeation temperature to 70 °C resulted in an impressive adsorption capacity for Hg°, reaching 560.59 μg·g−1. The Hg-TPD (Hg-Temperature Programmed Desorption) and XPS (X-ray photoelectron spectroscopy) analyses revealed the involvement of chemisorbed oxygen (Oads), Mn3+, and Fe3+ in the adsorbent, facilitating the oxidation of Hg° and generating HgO on the adsorbent surface. Following six cycles of adsorption and desorption, the adsorption capacity of Mn0.5Co0.5Fe2O4 nanoparticles for Hg° retained 71% of the first adsorption capacity, which indicated that magnetic Mn0.5Co0.5Fe2O4 nanoparticles held great promise as an adsorbent for mercury removal.

Swirl diffusion strategy boosts mercury removal effectiveness of magnetospheres injector

The emissions of mercury from coal-fired flue gas poses a major threat to public health and ecosystems. Modified magnetospheres (CC-MF) mercury removal technology provides an economical, reusable, and eco-friendly solution, overcoming the drawbacks of conventional activated carbon injection (ACI) techniques. To address the issues of inadequate particle diffusion and uneven injection in traditional mercury removal injectors, this study developed a single-hole swirl injector. Furthermore, a mathematical model for mercury removal was developed and imported in the form of a UDF into Fluent for the evaluation of section coverage rate and mercury removal efficiency. The simulation results demonstrated that the section coverage rate of the swirl injector improved by 51.0%, reaching 81.0% compared to the direct injector. Additionally, the mercury removal efficiency increased by 41.3%, reaching 88.7%. This work identified the optimal operational parameters for the CC-MF mercury removal system, providing valuable insights for its practical application.

Wet removal of elemental mercury by acid-assisted electrochemical oxidation method

As a global pollutant, mercury emission is increasingly restricted in recent years. It is urgent to explore a new and efficient mercury removal technology for coal-fired power plants. A new acid-assisted electrochemical oxidation (AEO) technique for mercury removal was proposed using platinum plate as cathode and fluorine-doped tin dioxide (FTO) glass as anode. The effects of acid type, acid concentration, applied direct current (DC) voltage, electrolyte type, SO2, NO and O2 on the Hg0 removal efficiency were carried out. The results indicated that the mercury removal efficiency increased with the increase of DC voltage and nitric acid concentration. When the concentration of nitric acid increased to 0.15 mol/L, the mercury removal efficiency remained unchanged. SO2 and NO inhibited the removal of Hg0 in AEO system, but the inhibition was reversible. Compared with the mercury removal efficiency under single experimental conditions, the mercury removal efficiency of electrochemical oxidation can reach 96% under the experimental conditions of 0.1 mol/L nitric acid and 4V DC voltage, suggesting that the synergistic effect of nitric acid and DC voltage plays a key role. According to the experimental results, the mechanism of Hg0 removal in AEO system was analyzed. At the anode, Hg0 was oxidized by hydroxyl radical (.OH) generated by the oxidation reaction on the anode surface. At the cathode, dissolved oxygen or O2 adsorbed on the surface of Pt is reduced to form anionic superoxide radicals (.O−2). Moreover, parts of .O−2 would produce .OH with the aid of electron at acidic condition. Free radicals capture experiments showed that .O−2 and .OH were the main active substances for the removal of Hg0 by acid-assisted electrochemical method. The research is helpful for the development of effective electrochemical techniques for industrial mercury removal and recycling of industrial acid waste.

Numerical simulation on adsorbent injection system for mercury removal from coal-fired flue gas

Optimizing the injection system significantly reduces the cost of adsorbent injection technology for mercury removal from coal-fired flue gas. In this work, the effects of three common injection system layouts, namely single-sided four-way pipe (SFP), quadtree (QT), and long to short (L-S), on adsorbent particle concentration, mercury concentration, and mercury removal efficiency were systematically investigated by simulation calculation. It shows adsorbent coverage, and particle concentration standard deviation coefficient at the initial injection satisfies SFP > QT > L-S. The number of nozzle and injection directions affect the distribution of adsorbent particle concentration. The apparent mercury removal occurs within 2 s after adsorbent injection. The SFP arrangement has the best average coverage rate of adsorbent (86.86%), average standard deviation coefficient (2.40), and mercury removal efficiency (60.12%). The coupling degree between particle concentration and flue gas mercury concentration field is essential in determining mercury removal performance.

Scenarios for reducing copper smelting-related atmospheric mercury emissions through copper recycling and mercury removal technologies in major countries

Scenarios for reducing copper smelting-related atmospheric mercury emissions through copper recycling and mercury removal technologies in major countries

Economic evaluation of mercury removal from flue gas by recyclable CuCl2 modified magnetospheres catalyst for 1000 MW coal-fired power plant

Economic sustainability is one of the main factors restricting development of mercury pollution control technology in the flue gas. Renewable magnetospheres separated from fly ash can be used as adsorbent for mercury removal from coal-fired flue gas. Based on the actual working condition of the 1000 WM coal-fired unit, this paper analyzes the impact of magnetosphere and mercury recovery technology on the economic benefits of this technology. The results show that the recovery of magnetospheres and mercury can obtain higher economic returns. This not only can realize the deduction of operating costs, but also has certain economic investment potential. When the magnetic separation rate is greater than 6% and the selling price of the magnetosphere is greater than 720 CNY/t, the revenue of the magnetosphere recovery system can offset the operating cost of whole system. The internal rate of return of the system can reach 50% at most. When the selling price of mercury selenide is lower than 450 CNY/g, the single mercury recovery income is insufficient to offset the mercury removal cost. Within the selling price range of 450–500 CNY/g mercury selenide, the system can generate revenue, and the product qualification rate directly affects the profit and loss of the system. The coupling of magnetospheres and mercury recovery systems can make economic and technical parameters more moderate. When the selling price of magnetospheres is higher than 600 CNY/t, the magnetic separation rate is higher than 6%, and the selling price of mercury selenide is higher than 350 CNY/g, the internal return of the system will fluctuate within 13%∼120%, and the static investment recovery period will remain within 6 years. Overall, this study can provide economic guidance for mercury removal technology with renewable magnetospheres and provide data support for further commercialization of technology.

Surface sulfidation modification of magnetospheres from fly ash for elemental mercury removal from coal combustion flue gas

Reduction of elemental mercury (Hg0) emission from coal-fired power plants is an enormous challenge. In this work, magnetospheres separated from fly ash was modified through H2S as an efficient sorbent (i.e., S-MS) for Hg0. Elemental sulfur with high affinity towards Hg0 was formed on the S-MS surface through selective catalytic oxidation of H2S. The sulfidation temperature played an important role in Hg0 adsorption over S-MS, ascribing to the variation of sulfur species on S-MS. The S-MS exhibited above 80% Hg0 adsorption efficiency with a sulfidation temperature of 150 °C for 30 min. The optimal Hg0 adsorption performance was obtained at 50 and 75 °C, implying that the S-MS could be adopted by injecting into the duct upstream of wet electrostatic precipitator (WESP) system. The gaseous Hg0 was immobilized by S-MS as stable mercury sulfide (HgS) owing to the presence of abundant sulfur species that is active for binding Hg0. The leaching ratio of mercury from spent S-MS in WESP effluent was as low as 1%, hence minimizing the secondary mercury pollution from the industrial waste. The cost analysis demonstrates that the mercury removal technology on the basis of magnetospheres adsorbents exhibited much superiority in operation cost compared with commercial activated carbon injection technology. Thus, the S-MS, with specific features, such as high Hg0 adsorption performance, minimized environmental hazardous and recyclability, displayed great potential in Hg0 sequestration.

Removal of elemental mercury from flue gas by recyclable CuCl2 modified magnetospheres catalyst from fly ash: Part 6. Commercial scale demonstration at a 1000MWth coal-fired power plant

CuCl2–MF was a cost–efficient and highly efficient sorbent for Hg removal from flue gas in coal-fired units. In this study, the Hg0 adsorption and oxidation performance of CuCl2–MF with different conditions were studied at a 1000 MW commercial scaled coal-fired power plant. Under the optimal conditions, the total removal efficiency of Hg and the Hg recovery rate reached 98.72% and 52.76% using CuCl2–MF injection combined with the existing pollutant control device. The magnetosphere particle size of 45 μm–75 μm exhibited the highest mercury removal capacity. Additionally, the final mercury emission concentration was 0.334 μg/m3 and the corresponding relative mercury removal efficiency was 89.81%. The results of this study proved that elemental mercury removal by CuCl2–MF was also suitable for large-scale coal-fired units with a high Hg removal efficiency even in the low concentrations of mercury, which provided a reference for the practical application of this technology in other units in the future and supplied valuable experience for other mercury removal technologies.

Carbon Footprint for Mercury Capture from Coal-Fired Boiler Flue Gas

Power production from coal combustion is one of two major anthropogenic sources of mercury emission to the atmosphere. The aim of this study is the analysis of the carbon footprint of mercury removal technologies through sorbents injection related to the removal of 1 kg of mercury from flue gases. Two sorbents, i.e., powdered activated carbon and the coke dust, were analysed. The assessment included both direct and indirect emissions related to various energy and material needs life cycle including coal mining and transport, sorbents production, transport of sorbents to the power plants, and injection into flue gases. The results show that at the average mercury concentration in processed flue gasses accounting to 28.0 µg Hg/Nm3, removal of 1 kg of mercury from flue gases required 14.925 Mg of powdered activated carbon and 33.594 Mg of coke dust, respectively. However, the whole life cycle carbon footprint for powdered activated carbon amounted to 89.548 Mg CO2-e·kg−1 Hg, whereas for coke dust this value was around three times lower and amounted to 24.452 Mg CO2-e·kg−1 Hg. Considering the relatively low price of coke dust and its lower impact on GHG emissions, it can be found as a promising alternative to commercial powdered activated carbon.

Elemental mercury removal from flue gas using modified tonstein: Performance of adsorbent injection at an entrained flow reactor system and 50-MW coal-fired power plant in China

The application of mercury removal technology in coal-fired power plants has attracted much attention. In this paper, performances of CuBr2-modified tonstein from coal seams (MTCS) injection at an entrained flow reactor system and a 50-MW coal-fired power plant and their corresponding mechanisms were studied. The results showed that the increase of the injection rate, the reduction of the particle size, the extension of the residence time, and the increase of the initial Hg0 concentration were all conducive to mercury removal. At an entrained flow reactor, SO2 and H2O obviously inhibited mercury removal, but this inhibition could be reduced with the increase of the residence time or the participation of NO and HCl. Specifically, with the participation of 1200 ppm SO2, the Hg0 removal efficiency was 56.9% and 82.8% at 0.6 s and 1.2 s, respectively. In the temperature range of 30–150 °C, the Hg0 removal efficiency in the flue gas at the simulated flue exit was approximately 83–93%. In addition, at a 50-MW coal-fired power plant, the injection of MTCS was beneficial to Hg0 removal. In this process, most Hg0 was converted to Hg2+ by active substances, and then captured using fabric filter (FF) and wet flue gas desulfurization (WFGD) device. Injecting MTCS with a particle size of 300 mesh and concentration of 0.31 g/m3 can result in a relative mercury removal efficiency of up to 82.9% in the flue gas at the WFGD outlet, indicating that the low-cost mineral adsorbent MTCS is a suitable choice for mercury control in coal-fired power plants.

A comprehensive exploration of mercury adsorption sites on the carbonaceous surface: A DFT study

Mercury pollution released from coal-fired power plants has caused worldwide concern for its toxicity, global range transportation, and bioaccumulation. Unburned carbon in fly ash is considered to be a promising adsorbent to effectively remove elemental mercury. However, the active sites of the unburned carbon for Hg0 adsorption have not been clearly identified, which greatly hinders the development of effective adsorbents. To reveal the adsorption sites of the carbonaceous surface, the adsorption process of Hg0 on different carbonaceous surfaces was systematically investigated through density functional theory. The Mayer bond order, Electron localization function, and Electron density difference were used to analyze the adsorption mechanism of Hg0. Meanwhile, the oxygen-containing functional groups were also considered to research the influence on mercury adsorption with the defective surface. The adsorption of Hg0 on defective carbonaceous surfaces is associated with stable chemisorption, and surface defects can significantly improve the adsorption energy of Hg0. This theoretical study provides theoretical guidance for the development of mercury removal technology with carbon materials in the coal-fired power plant.

Removal of elemental mercury from flue gas by recyclable CuCl2 modified magnetospheres from fly ash: Part 5. Industrial scale studies at a 50 MWth coal-fired power plant

The mercury removal performance of a low-cost recyclable CuCl2 modified magnetospheres (Cu-MF) was investigated at a 50 MWth coal-fired power plant. An increase in the Cu-MF injection rate facilitated the mercury removal and recovery process. With the combination of the existing pollutant control devices and the Cu-MF injection, an overall mercury removal efficiency of 99.3% could be achieved. Under optimal conditions, the mercury emitted from the stack was reduced to 0.10 μg/m3. Most of the mercury in the flue gas migrated to the fly ash with the spent Cu-MF. Subsequently, through magnetic separation, 67.4% of the input mercury could be recovered. The comparison of experimental results showed that Cu-MF was more effective than fly ash in removing and recovering mercury from the flue gas. With the injection of Cu-MF, HgCl2 was formed on the magnetospheres and was identified by the mercury-temperature-programmed decomposition (Hg-TPD) experiments. The magnetospheres with the lowest particle size showed the highest mercury removal capacity. This work is expected to provide valuable guidance for optimising the mercury removal technology in large scale commercial applications in future.

Industrial Application of Non-thermal Plasma (NTP) for Mercury and Dioxin Removal in Flue Gas

At present, there is an urgent demand for mercury and dioxin pollution control technology, internationally. It is necessary to find a solution other than the activated carbon adsorption process. In recent years, our self-developed low temperature plasma coupling system has been applied for mercury and dioxin removal in the flue gas, the system is composed of corona discharge plasma reactor and ceramic nano-material adsorption tank. The parameters of the plasma are 35-40kV, 400-450A, 1000Hz. The saturated adsorption capacity of ceramic nano-materials for Hg2+ is more than 5156μ g(Hg2+)/g. Pilot plant testes have been conducted in several industries, including collaborative disposal of cement kiln, medical waste incineration, recovery of waste mercury catalyst, recycling of waste fluorescent tubes, and achieved ideal result (Hg removal efficiency > 95%). It is expected to be an economical and efficient technology for mercury and dioxin removal, with great promotion value and social significance.

An Overview of Mercury Emission Sources and Application of Activated Carbon for Mercury Removal from Flue Gas

Mercury emission into the atmosphere is a global concern due to its detrimental effects on human health in general. The two main sources of mercury emission are natural sources and anthropogenic sources. Mercury emission from natural sources include volcanic activity, weathering of rocks, water movement and biological processes which are obviously inevitable. The anthropogenic sources of mercury emission are from coal combustion, cement production and waste incineration. Thus, in order to reduce mercury emission it is appropriate to investigate how mercury is released from the anthropogenic sources and consequently the mercury removal technology that can be implemented in order to reduce mercury emission into the atmosphere. Many alternatives have been developed to reduce mercury emission and the recent application of activated carbon showed high potential in the adsorption of elemental mercury. This paper discusses the ability of activated carbon and variable parameters that influence mercury removal efficiency in flue gas.

Technology for mercury removal from flue gas of coal based thermal power plants: A comprehensive review

Vapor phase mercury is a toxic gas emitted largely from coal-based thermal power plants (CTPPs). By the year 2020, approximately 477 tonnes/year of mercury is estimated to be released globally from CTPPs. To address this concern, various regulations, international agreements and action plans have been formulated. Thus, there is an emerging need to address the mercury emission issue from CTPPs in an efficient and cost-effective manner. Over the last five years (2012–2017), a number of research papers have demonstrated different technologies for control of mercury emissions from flue gas. There is a need to create a synthesis of a large number of research efforts to provide insight into technologies their applications, limitations and future advancements. Specifically, this review article integrates the technology developments (from the past five years) into a scientific repository which can provide a ready reference for technology application and at the same time outlines the challenges. This review article is expected to spur further research to address the current gaps and develop technologies for the removal of mercury and other pollutants from CTPPs.

Integrated assessment of the environmental and economic effects of an ultra-clean flue gas treatment process in coal-fired power plant

China’s coal production and consumption levels rank first in the world. Coal-fired power plants currently account for 65.5% of the total electricity output of China’s power grid. Coal-fired thermal power is the main industry consuming coal in China and the main source of atmospheric pollutants. To alleviate environmental pollution, the Chinese government recently released stringent flue gas emission standards for coal-fired power units. These standards require that the emission of dust, sulfur dioxide, and nitrogen oxides does not exceed 10 mg/m³, 35 mg/m³, and 50 mg/m³, respectively, to achieve ultra-clean emissions. Life-cycle assessment and life cycle costing methods are combined to analyze and compare the environmental and economic effects before and after ultra-clean emission retrofit in a 315 MW unit. The environmental impact of flue gas processing for 1000 kWh power plants decreased from 0.1529 to 0.1295 after ultra-clean emission retrofit. Desulfurization and discharged flue gas after treatment are the key processes examined in this case study, while power consumption during desulfurization and residual mercury in flue gas are key substances. Therefore, looking ahead, decreasing power consumption in desulfurization and using mercury removal technology are important aspects for decreasing the environmental impact of flue gas treatment systems in coal power units.

Study of Enzyme Purification Method and Growth Pattern for Pseudomonas putida in Mercury Removal

Mercury is one of the toxic element and very harmful. The exposure of the mercury will mainly cause health effect and the exposure can be in term of dose, age of person exposed, duration exposed route exposed and duration of exposed. In Malaysia, Mercury is one of the heavy metals of concern, found in wastewaters coming from oil refinery and petrochemical industries. Mercury and mercurial compounds are highly toxic contaminants in the aquatic systems and soils. The proper disposal of wastewater should be implement with the Department of Environment of Malaysia (DOE) which is the concentration of mercury should be 0.05 ppm for standard B in wastewater for the sake of people and environment health. There are many types of mercury removal technology to reduce the concentration of mercury such as chemical treatment, ion exchange, membrane filtration, adsorption as well as bioremediation which used for mercury removal in this study. This paper present the activity of enzyme from Pseudomonas putida (P. putida) is produced in the mercury treatment from petrochemical wastewater at optimum condition. P. putida growth at optimum condition in mercury different concentration was observed. Conclusion optimum condition concentration of mercury and shaker speed at 7 ppm is 41 ˚C and 180 rpm respectively, with able to reduce 92.59 % mercury concentration. During the processes of mercury removal, mercuric reductase was produced at value of 56 kDa.

Study on the effects of carrier and modifier on mercury adsorption behavior over halides modified sorbents using temperature programmed desorption method

Halides modified sorbents injection equipped with dust removal units is considered as the most promising technology for elemental mercury (Hg0) removal from coal-fired flue gas. However, Hg0 adsorption behavior over different halides modified sorbents remains controversial. In this study, the effects of carriers (activated carbon and neutral Al2O3) and modifiers (NaCl, NaBr, CuCl2, and CuBr2) on the behavior of Hg0 adsorption over modified sorbents were investigated using temperature programmed desorption (TPD) method. Both mercury adsorption experiments and TPD experiments were conducted in the bench-scale fixed bed. The results indicated that CuBr2-modified activated carbon (AC) showed the best mercury removal performance due to the lower bond energy of CuBr2. The decomposition temperature of mercury compounds generated on AC was different from that on neutral Al2O3. Further analysis indicated that the modifiers with lower bond energy could release halogens during modification. The released halogens could react with AC to form active CCl or CBr group. Moreover, the lower bond energy of modifiers made it easier for halogens to release. But Al2O3 carrier could not react with modifiers to form active group during modification. The Hg0 adsorption process over modified Al2O3 could be explained by Langmuir-Hinshelwood mechanism.

Unveiling Adsorption Mechanisms of Elemental Mercury on Defective Boron Nitride Monolayer: A Computational Study

The control of mercury in flue gas is challenging, especially that of elemental mercury (Hg0). Recently, many researchers have focused on various mercury removal technologies. Here, by performing density functional theory (DFT) calculations, we systematically studied the adsorption of Hg0 on several experimentally available hexagonal boron nitride (h-BN) nanosheets with no defects, nitrogen vacancies (VN), boron vacancies (VB), and both nitrogen and boron vacancies (VN+B) as well as their structures and electronic properties. Our calculation results show that the presence of VN, VB, and VN+B enhances the adsorption energies of Hg0 by 9, 45, and 214 kJ/mol, respectively. Moreover, a more negative potential at the VB and VN+B sites makes the h-BN-VB and h-BN-VN+B surfaces more reactive than those of h-BN and h-BN-VN. The partial density of states analysis reveals that the Hg atom interacts firmly with surface B or/and N atoms through orbital hybridization. The trend of the equilibrium constant implies that ...