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[Display omitted] • A Mn/Cu co-doping mesoporous carbon was synthesized via template method for mercury removal. • The MnCu 0.1 -C sorbent displayed high mercury removal performance with main product of HgO. • Mn doping on the mesoporous carbon greatly improved the mercury removal ability of sorbent. • Cu doping improved the SO 2 tolerance of sorbent due to a larger affinity of Cu to sulfur. • DFT analysis displayed that Hg0 was mainly chemisorbed on the surface of MnCu 0.1 -C sorbent. Mn/Cu co-doping mesoporous carbon sorbent (MnCu x -C) was synthesized via using hard template method. Thymol blue (C 27 H 30 O 5 S) was used as carbon source and MCM-41 was applied as template agent. Copper nitrate trihydrate (Cu(NO 3) 2 ·3H 2 O) and manganese acetate tetrahydrate (MnC 4 H 6 O 4 ·4H 2 O) was in-situ co-doped with carbon source as Cu/Mn metals precursor. Mercury removal on the MnCu x -C sorbent was investigated on a fixed bed experimental apparatus. The physical and chemical characteristics of the MnCu x -C sorbent were investigated by using BET, SEM, FTIR, XRD and XPS, respectively. Combing with mercury programmed temperature desorption (Hg-TPD) and density functional theory (DFT), the mechanism of mercury adsorption on the MnCu x -C sorbent was revealed. The results showed that the synthesized MnCu 0.1 -C sorbent displayed high mercury removal performance at 150℃, which was considered to be a potential sorbent for mercury removal from industrial flue gas. Mn doping on the mesoporous carbon greatly improved the mercury removal ability of sorbent with mercury capture rate increasing from 6 % to 89 %. Doping of Cu can effectively improve the SO 2 tolerance of the MnCu 0.1 -C sorbent for mercury removal. With different concentration of SO 2 existing in flue gas, the MnCu 0.1 -C sorbent still kept high mercury removal ability. O 2 in flue gas promoted mercury removal on the MnCu 0.1 -C sorbent with main product of HgO. In the presence of SO 2 , a small amount of HgSO 4 formed on the MnCu 0.1 -C sorbent. The DFT analysis further displayed that Hg0 was mainly chemisorbed on the surface of MnCu 0.1 -C sorbent with formation of HgO. [ABSTRACT FROM AUTHOR]

• Cigarette butts combustion is a proper sulfation method for MnCe-based catalyst. • After sulfation, Hg removal efficiency increased from 66.46 % to 88.76 % at 150 °C. • After sulfation, the O ad concentration on the catalyst surface almost doubled. MnO x -CeO 2 is a promising catalyst for Hg0 removal from coal flue gas at ∼150 °C but exhibits insufficient catalytic activity. Even though sulfation enhances the catalytic activity of MnO x -CeO 2 , gas-phase sulfation leads to SO 2 poisoning and catalyst deactivation. In this study, we developed a liquid-phase sulfation strategy involving the direct combustion of cigarette butts soaked in a solution of sulfate and metal precursors to directly synthesize sulfated MnCe catalyst (SMC). SMC was characterized via N 2 adsorption–desorption isotherms, SEM-EDS, XRD, XPS, and Hg-TPD. Both the MnCe catalyst and SMC exhibited good Hg0 oxidation efficiencies (66.46 % and 88.76 %, respectively) at 150 °C. The enhanced performance of SMC was attributed to the generation of abundant chemically adsorbed oxygen species on the SMC surface during sulfation. Moreover, the synergistic effect between the Ce4+ and Mn4+ species contributed to the improved catalytic performance of SMC. This strategy not only provides a one-step synthesis of sulfated catalysts but also has potential applications in Hg0 removal from coal flue gas in coal-fired power plants. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co 3 O 4 nanosheets with different amount of oxygen vacancies were synthesized. • Higher reduction level can over reduce Co 3 O 4 leading to lower oxygen vacancies. • The over reduced Co 3 O 4 will adsorb O 2 forming lattice oxygen not chemisorbed one. • Suitable reduction condition give more oxygen vacancies and improve Hg0 removal. Oxygen vacancy is very important for the Hg0 oxidation process due to it can capture and activate gaseous oxygen forming surface chemisorbed oxygen to oxidize Hg0 to HgO. Precise control of oxygen vacancies amount is a big challenge in this field. For Co 3 O 4 , oxygen vacancy can be generated by Co3+ reduction to Co2+ and Co3+ mainly exist in (2 2 0) facet. Thus, in the present work, Co 3 O 4 nanosheets preferentially growing (2 2 0) facet with more Co3+ were synthesized and CO was used as reduction agent to reduce Co 3 O 4 at different reduction condition. After that, Co 3 O 4 nanosheets with different amount of oxygen vacancies were obtained. XPS, Raman and PL results show that, the amount of oxygen vacancies increase firstly and then decrease with the increase of reduction temperature and time. CO can reduce Co3+ to Co2+ forming oxygen vacancies. However, when the reduction temperature and time are at a high level, Co 3 O 4 will be over reduced to CoO leading to a decrease of oxygen vacancies. DFT confirm that, when Co 3 O 4 is over reduced, O 2 will hard to adsorb on Co 3 O 4 surface and lattice oxygen will be formed even after O 2 adsorption. Co 3 O 4 -Te 300 Ti 2 has an optimal reduction degree leading to higher oxygen vacancy concentration and better O 2 adsorption and activation ability. Therefore, Co 3 O 4 -Te 300 Ti 2 has a high Hg0 oxidation efficiency which is over 96 % in a wide temperature range of 150–300 °C at a high GHSV of 180,000 h−1. [ABSTRACT FROM AUTHOR]

• The removal of Hg0 by HEMS was systematically investigated for the first time. • The HEMS display obviously better Hg0 capture ability than the quaternary sulfide counterpart. • Ce-HEMS has excellent mercury removal performance at the elevated temperature. • Ce increases the HEMS of unsaturated sulfur species and high valence state metal cations. Regulating the surface coordination environment and improving the formation of active species represent the key factor in designing high-performance metal sulfide-based sorbents for gaseous Hg0 capture. This paper reported the Hg0 adsorption by high entropy metal sulfides for the first time, and clarified the mechanisms involved in the evolutions of active species as well as the Hg0 adsorption. The multiple metal components of the high entropy metal sulfides have great significance in improving the surface chemistry. The addition of Ce helps not only the formation of chemically homogeneous structure, but also the generation of high valence state metal cations and unsaturated sulfur species, thereby improving obviously the Hg0 removal ability. The synthesized CeNiCoMnCuS x has a high Hg0 adsorption capacity of 10.52 mg·g−1 at 80 %-breakthrough, and a Hg0 adsorption rate of 4.31 μg·g−1·min−1. The high valence state metal cations (Ni3+, Co3+, Mn4+, Cu2+ and Ce4+) and unsaturated S x 2− and S 2 2− species can directly oxidize Hg0 and convert it into HgS. In comparison, the quaternary sulfide counterpart (NiCoMnCuS x) cannot form a main phase structure, and has obviously lower percentages of high valence state metal cations and unsaturated sulfur species. This work provides a new space for developing metal sulfides for Hg0 adsorption. [ABSTRACT FROM AUTHOR]

• O 3 accelerates the electron transfer between Mn4+/Mn3+ in the Mn-TiO 2 catalyst. • O 3 synergizes with the Mn-TiO 2 catalyst to increase the mercury removal efficiency to 98%. • O 3 enables the oxidation adsorption of Hg0 in ESP temperature window (120–150 °C). • After the addition of O 3 , O latt becomes the primary active oxygen species. Ozone, known for its strong oxidizing properties, is commonly utilized in water pollution control. However, the catalytic ozonation of gaseous pollutants also shows potential as an emission reduction technology. The challenge lies in the high concentrations of ozone required in the catalytic process, which increases costs and complexity, hindering widespread adoption. Industrial electrostatic precipitators (ESPs) powered by high-voltage sources can produce ozone during operation, potentially causing environmental pollution if not managed. This study suggests utilizing a catalyst in the low-concentration ozone environment generated by an ESP for the catalytic oxidation of Hg0 in flue gas. The removal efficiency of Hg0 by either the catalyst alone or ozone alone (O 3 : 10 ppm) is modest at 43 % and 8 % respectively. However, when combined, the catalyst and ozone demonstrate a remarkable removal efficiency of over 98 %, significantly outperforming their individual capabilities. Furthermore, this process exhibits consistent high efficiency in a wide temperature range of 50–150 ℃. The study reveals that in the absence of O 3 , adsorbed oxygen acts as the primary oxidant, limiting the oxidation of Hg0. The introduction of O 3 enhances electron transfer within the Mn-Ti catalyst, optimizing the electronic structure of oxygen and enhancing the oxidizing capacity of lattice oxygen, resulting in superior Hg0 removal efficiency. These findings offer valuable insights for the catalytic ozonation of Hg0. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mn modified Ce-Sn catalyst was studied for simultaneous Hg0 oxidation and NO reduction. • CeO 2 contributed to NH 3 -SCR activity and SnO 2 was more sensitive to mercury adsorption and oxidation. • Electronic interactions between Mn-Ce-Sn resulted in the desired low-temperature performance. The synergistic catalytic removal of NO and Hg0 under low temperatures is still a great challenge. Here, we report a Mn-modified Ce-Sn catalyst for simultaneous removal of NO and Hg0 at low temperature. The optimum Mn 0.2 /Ce 0.33 Sn 0.67 exhibited more than 95 % NO conversion and N 2 selectivity above 86 % at 150–250 ℃ as well as Hg0 removal of nearly 100 % within 150–300 ℃. SnO 2 -promoted Ce-Sn solid solution enhanced the surface proportion of Ce3+, the number of surface chemisorbed oxygen and the electronic interaction within Ce-Sn linkage. Mn modification further reasonably promoted redox cycling at low temperatures and improved acidic distribution of catalyst. Under the cooperation of Ce-Sn and Mn sites, the presence of Hg0 could substantially facilitate the reduction of NO at 250–300 ℃ and the SCR atmosphere had a weak inhibitory effect on Hg0 removal. During the SCR process, the NH 4 + and NH 2 species that directly reacted with gaseous NO following the Eley − Rideal mechanism and the improved reactivity of NH 2 with nitrates following the Langmuir − Hinshelwood mechanism enhanced the NO conversion efficiency at low temperature. Meanwhile, Mn modification could alleviate competitive adsorption of NH 3 on Hg0 and promote the formation of more chemically adsorbed mercury species. This work will provide guidance for the design of low-temperature catalysts for the simultaneous removal of NO and Hg0 in flue gas. [ABSTRACT FROM AUTHOR]

[Display omitted] • The re-oxidation of Hg0 by Cl, HCl, ClO, Cl 2 hinders the HTR reaction. • A novel alkaline dechlorination agent is developed for adsorbing Cl-related species. • Two-stage filling dechlorination agent can meet the requirements of Hg-CEMS. • DFT indicates dechlorination agent eliminate Cl, HCl, ClO at elevated temperatures but not Cl 2. The high temperature reduction (HTR) of flue gas divalent mercury to elemental mercury is the core technology for the mercury continuous emission monitoring system (Hg-CEMS). In this work, the high temperature reduction of HgCl 2 to Hg0 was systematically investigated. The results show that HgCl 2 can entirely decompose to Hg0 at 800 °C, but Cl, ClO, Cl 2 , and HCl can easily oxidize Hg0 at low temperature. A new efficient alkaline dechlorination agent for eliminating these Cl species was proposed firstly. The dechlorination agent can efficiently capture the HCl, Cl, and ClO but fail to completely adsorb Cl 2. Consequently, a scheme was created that a pair of dechlorination agents were filled in inlet and outlet of the HTR furnace respectively. It features that the upper layer removes HCl and prevents the generation of Cl 2 because HCl is the precursor of Cl 2 , and the lower layer adsorbs the Cl and ClO generated by the HTR process. The feasibility of the method was successfully verified in both a fixed-bed reactor and a Hg-CEMS pretreatment device. DFT calculation indicates that the adsorption of Cl, ClO, and HCl on CaO falls into the category of strong chemisorption while Cl 2 is weakly chemisorbed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The sulfur species in co-pyrolysis chars were regulated through SO 2 activation. • The BET surface area and pore volume were greatly increased after SO 2 activation. • More sulfur- and oxygen-containing groups were generated after SO 2 activation. • The sulfurized co-pyrolysis chars exhibited excellent resistance to H 2 O and SO 2. In this study, novel S-doped sorbents synthesized via one-step co-pyrolysis of biomass and scrap tires under SO 2 atmosphere were developed for elemental mercury (Hg0) removal from coal-fired flue gas. The presence of SO 2 could regulate the sulfur species in S-doped sorbents and improve their Hg0 removal performance. Sample characterization exhibited that SO 2 activation increased the sulfur content and decreased the carbon content in sorbents due to the occurrence of carbothermal reduction reaction. The specific surface area, pore volume, and micropore content in S-doped sorbents were obviously improved compared with raw sorbents. After SO 2 activation, partial inorganic sulfide was converted into sulfur-containing functional groups and more oxygen-containing functional groups were generated on the sorbents. The S-doped sorbents presented more excellent performance for Hg0 removal compared with raw sorbents. The optimal pyrolysis temperature and SO 2 concentration in activation atmosphere were 700 °C and 10%, respectively. It was surprising that SO 2 facilitated Hg0 removal and the S-doped sorbents showed good water-resistance due to the presence of ZnS. O 2 and NO had positive effects on Hg0 removal. A close fitting to the pseudo-second-order model was obtained for the behavior of Hg0 removal over S-doped sorbents. Aliphatic sulfur, sulfoxide, carbonyl and carboxyl/ester groups functioned as active components for Hg0 removal. [ABSTRACT FROM AUTHOR]

• Two-dimensional layered Bi 2 WO 6 nanosheets were prepared using a hydrothermal method. • C 2 /2D-BWO exhibits a photocatalytic mercury removal efficiency of up to 86.3 %. • The effects of SO 2 and NO in flue gas on Hg oxidation were also studied. • The experiments and DFT calculations showed that CQDs improved the photoactivity of 2D-BWO. Photocatalytic technology has the advantages of environmental friendliness, low energy consumption, and fast reaction speed, which can be applied in the field of visible light mercury removal. High stability and narrow bandgap are fundamental factors for ideal semiconductor photocatalysts. A novel method of hydrothermal synthesis of CQDs/2D-BWO composite catalyst to improve the oxidation efficiency of elemental mercury was proposed. The morphology, physicochemical properties, and optical performance of the materials were fully characterized. The experiment of Hg oxidation efficiency under visible light showed that C 2 /2D-BWO exhibited a Hg removal efficiency of was as high as 86.3 % under visible light and adequate cyclic stability. The effects of SO 2 and NO on Hg oxidation were also studied, and the reasons for the improved of photocatalytic activity of CQDs on 2D-BWO were analyzed based on DFT calculations. The reaction mechanism of the catalytic oxidation of Hg by C 2 /2D-BWO was proposed, and C 2 /2D-BWO was found to be an efficient and stable visible light catalyst. [ABSTRACT FROM AUTHOR]

• Various synthetic methods for metal sulfides are introduced and compared. • Performances, merits, and flaws of metal sulfides are summarized and commented. • Layered metal sulfides, MoS 2 , WS 2 and SnS 2 , are the most promising mercury sorbents. • Effects of gas ingredients on the performances of metal sulfides are summed up. • Mercury capture mechanisms for metal sulfides are outlined and discussed. Mercury is largely emitted into the atmosphere during fossil fuel combustion or gasification, which causes a long-term contamination problem and poses great threats to human health. Currently, novel metal sulfides have been extensively investigated in capturing gaseous mercury because of their intense Hg0 affinities, large mercury uptakes, and distinguished tolerance to sulfur dioxide. This article overviews the recent progress on elemental mercury capture by diverse metal sulfides, i.e., CuS, ZnS, pyrite-phase metal sulfides, layered metal sulfides, Bi 2 S 3 and In 2 S 3. CuS and ZnS show good performances in a narrow temperature range due to the poor thermal stability and the compact crystal structure, respectively. Bi 2 S 3 and In 2 S 3 are also active in Hg0 adsorption, however, their performances are still unsatisfactory. Most pyrite-phase metal sulfides show moderate Hg0 capture abilities likely due to their compact crystal structures. Loading pyrites onto carriers or creating S vacancies in pyrite lattices seem to be feasible pathways to improve their performances. MoS 2 and WS 2 attained via molten salt method significantly outperform the ones obtained via hydrothermal method at elevated temperatures due to the production of ample sulfur variances and chemisorbed oxygen. Incorporating heteroatoms and expanding the interlayer distance by ions intercalation are effective routes to further strengthen their performances probably due to promoted electron transfer and increased accessibility of active sites, respectively. [ABSTRACT FROM AUTHOR]

• Ti 3 C 2 MXene/Cu 2 Se sorbent was prepared via a Lewis acid etching route. • The Hg0 removal ability of Ti 3 C 2 MXene/Cu 2 Se excelled other metal selenides. • Ti 3 C 2 MXene/Cu 2 Se showed favorable Hg0 removal performance over 100 °C. • Industrial flue gas exerted no effects on Hg0 capture of Ti 3 C 2 MXene/Cu 2 Se. A fundamental obstacle that restricts the use of metal selenides for gaseous elemental mercury (Hg0) immobilization is the failure to take both the optimization of intrinsic structure favorable for Hg0 diffusion and adequate exposure of metal selenide towards Hg0 into consideration. In this work, a Ti 3 C 2 MXene/Cu 2 Se sorbent for Hg0 sequestration was synthesized via a Lewis acid etching route combined with room-temperature selenization pathway. During this strategy, copper chloride plays a dual role, i.e., an etching agent for the Ti 3 C 2 MXene synthesis and a precursor for Cu0 decoration. Cu 2 Se precursors (Cu0) were dispersedly and firmly pre-anchored on the substrate, effectively avoiding the agglomeration and warranting excellent dispersion of Cu 2 Se. Compared with pristine Cu 2 Se, Ti 3 C 2 MXene/Cu 2 Se exhibits advantageous structural characteristics fully boosting Hg0 diffusion kinetics. Meanwhile, the enhanced dispersion of Cu 2 Se from the prefixation of Cu0 largely enhances the exposure and utilization of selenide. Consequently, Ti 3 C 2 MXene/Cu 2 Se shows a Hg0 adsorption capacity of 147.64 mg g−1, which is much higher than those of Cu 2 Se and most other metal selenides. Impressively, its uptake rate of 688.99 μg g−1 min−1 is the highest record rate in metal selenides. Moreover, Ti 3 C 2 MXene/Cu 2 Se still maintained outstanding Hg0 adsorption performance under relatively high reaction temperature with the shelter of Ti 3 C 2 MXene. Typical fuel gas situations including coal combustion flue gas, smelting flue gas, natural gas have negligible influences on its Hg0 adsorption performance, indicating its extensive applicability and flexibility for actual industrial situations. This work also provides valuable hints for the trade-off of structural properties and ligands exposure to design Hg0 sorbents with satisfactory Hg0 sequestration performances. [ABSTRACT FROM AUTHOR]

• Review the pretreatment of natural gas and condensates before Hg detection. • The detection techniques of total mercury and speciated mercury were summarized. • Focus on the adsorbent's acid gas resistance and mercury adsorption selectivity. • Appropriate sampling process and regenerable adsorbents were put forward. The requirement to characterize and remove mercury from natural gas and its condensate span a wide range of subject fields, from environmental science and analytical chemistry to material design and chemical engineering. The first part of this review discusses the mercury species and exposure limits in natural gas and gas condensate. In the second and third parts, the analytical techniques and pretreatment steps for analyzing mercury in natural gas and gas condensate are described separately. In the fourth part, the conventional gas processing operations are introduced together with the limit values of mercury distribution in natural gas processing operations. By analyzing the distribution and transformation of mercury in natural gas processing, the location of the mercury removal unit (MRU) for natural gas plants is optimized. In the fifth part, the different types of adsorbents for mercury removal from natural gas and liquid media are enumerated based on different mechanisms. The wet and acidic resistance of the different adsorbents in removing Hg0 from natural gas and flue gas is introduced. In the sixth part, as the species of mercury in a condensate are more complex than those in natural gas, the adsorption selectivity of each adsorbent for mercury removal from natural gas condensate is listed for comparison. Finally, the remaining challenges for mercury species determination and removal together with the expected future developments for mercury adsorbents are concluded. [ABSTRACT FROM AUTHOR]

• 21 %-ES-SC is the best mercury removal adsorbent with removal efficiency of 97.1 %. • Thiophene/elemental sulfur are main sulfur species for promoting mercury removal. • SO 2 and NO inhibit the mercury removal, while HCl has a promoting effect. • Mercury forms of the used ES- SC are mainly oxidized and residual forms. This work uses widely sourced rice straw as raw material, sulfur containing substances as modifiers, and mechanochemistry as modification methods to prepare the mechanochemical sulfur modified rice straw char mercury removal adsorbent (S-SC). The influence of modifiers, flue gas components, and the environmental stability of mercury removal products were systematically studied. The mechanochemical sulfur modification (elemental sulfur (ES), Na 2 S, NaHS) can improve the mercury removal performance of raw rice straw char (R-SC). It enhances mercury adsorption and capture. The ES is the best sulfur specie whose mercury removal rate firstly increases and then decreases as the amount of sulfur added increases. Sulfur modification promotes mercury forms convert to HgS (red) or even HgSO 4 with higher thermal stability. The thiophene/elemental sulfur are the main sulfur species for promoting mercury removal. SO 2 and NO inhibit mercury removal by ES-SC, while HCl has a promoting effect. As their concentration in the flue gas increases, the proportion of mercury removed by adsorption increases, and the adsorbed mercury transforms into a more thermally stable mercury form. The mercury forms of the spent ES-SC are mainly oxidized and residual form with TCLP leaching rate of zero, which has good environmental leaching stability. [ABSTRACT FROM AUTHOR]

• The synthesis and characterization methods of oxygen vacancy are described systematically. • The mechanism of photocatalyst oxidation of Hg0 with oxygen vacancy was summarized in detail from the electronic level. • The comprehensive prospect provides scientific guidance for the development of photocatalysts containing oxygen vacancy. As a common crystal defect, oxygen vacancy has a significant effect on the optical properties of semiconductor photocatalysts. Improving the photocatalytic activity of photocatalysts by introducing and regulating oxygen vacancy is one of the current research focuses. Meanwhile, oxygen vacancies can capture and activate molecular oxygen, which plays an important role in the photocatalytic oxidation of elemental mercury. In this review, the preparation and characterization methods of oxygen vacancy are reviewed systematically and the mechanism of photocatalytic oxidation of elemental mercury is revealed in detail. In addition, the mechanism of the effect of oxygen vacancy in optimizing the energy band structure, promoting carrier separation, surface reactions and changing the electron transfer path is discussed in depth. Finally, the future development prospects of oxygen vacancies in the field of photocatalytic oxidation of elemental mercury are prospected. This work can provide valuable theoretical reference and scientific basis for the design and research of photocatalysts containing oxygen vacancies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous SmCe 0.1 Mn 1.9 O 5 catalysts display high catalytic performance for Hg0 and chlorobenzene due to more Ce3+-O-Mn4+ active sites. • The influence of flue gas components on the byproducts distribution and formation mechanism are studied. • The Hg0 removal and the chlorobenzene oxidation process follow the Mars-Maessen and Mars-van Krevelen mechanism, respectively. The efficient control of co-existing Hg0 and chlorobenzene in flue gas through catalytic oxidation is a major challenge in the field of energy-intensive industry. In this study, a porous SmCe 0.1 Mn 1.9 O 5 catalyst is prepared via a sol–gel method followed with acid etching for the synergistic elimination of Hg0 and chlorobenzene. The optimized Ce-SM-E exhibits near 100% removal efficiency of Hg0 within 100–400 °C and 90% chlorobenzene conversion above 275 °C as well as excellent performance under complex flue gas conditions. The Ce substituting Mn3+ in the mullite structure enables favorable electron transfers from SmMn 2 O 5 to CeO 2 while causing more active defects. Subsequent acid etching removes the surface Sm species and modulates the electronic state of Mn atoms, inducing formation of more Ce3+-O-Mn4+ active sites, consequently enhancing the redox cycle. Especially, the generation of aldehydes, aromatic rings, maleate species and monodentate carbonate species are considered as the main rate-limiting steps in the chlorobenzene degradation path. The influence of complex flue gas components (SO 2 , NO, H 2 O, etc) on the distribution of reaction by-products is analyzed. The sulfation poisoning from SO 2 consumes reactive oxygen species and promotes more dichlorobenzenes through electrophilic reactions. The presence of NH 3 /NO and H 2 O are found to promote the generation of NH 4 Cl and HCl, respectively, but the addition of which also generates much oxygen-containing byproducts such as acetophenone, benzoyl chloride and benzenecarboxylic acid via the Friedel-Crafts reaction. These results provide a promising approach for engineering efficient catalysts and benefit the evaluation of environmental risk under industrial conditions. [ABSTRACT FROM AUTHOR]

• Adsorbent with dual organic/inorganic Hg-targeted sites (Thiol/MnO x) is constructed. • MnO x facilitated chemical adsorption between Hg0 and SH sites. • Thiol and MnO x promote Hg0 oxidation on SH-MnO x /TiO 2 adsorbent. Emissions of elemental mercury (Hg0) from coal-fired power plant have become a great threaten to the ecosystems. Adsorption is a practical strategy for abating Hg0, but limited Hg0-targeted sites is a stumbling block to developing high-efficiency adsorbents. This work aims to design an efficient adsorbent for Hg0 purification at high gas hourly space velocities (GHSV) is achieved by co-implanting porous TiO 2 with inorganic–organic dual functional sites (SH and MnO x). The 2SH-MnO x /TiO 2 prepared at SH: MnO x ratios of 2:6 is demonstrated a Hg0 removal efficiency of 90 % at 175 °C under a GHSV of 120,000 h−1. Based on Hg-Temperature Program Desorption (Hg-TPD) analysis, the adsorbed Hg0 converted to HgS and HgO at the SH and MnO x sites of the adsorbents, respectively. The existence of MnO x was revealed to facilitate the generation of HgS. Theoretical calculations suggested that the co-existence of SH and MnO x promotes Hg0 adsorption and boost electrons transfer from Hg0 to adsorbent surface. This study provides a new prospect in developing an advanced alternative adsorbent to increase the efficiency of Hg0 removal from coal-combustion flue gas. [ABSTRACT FROM AUTHOR]

• The material is synthesized by controlling the growth time and direction. • CuS-2h exhibited excellent anti-SO 2 toxic property. • The appropriate crystallinity make CuS expose more active sites and defects. • The active ingredient S 2 2− of CuS-2h facilitates electron transfer. Mercury, a heavy metal, seriously threatens the natural environment and human health. This work synthesized a series of CuS materials by controlling the crystals growth time, growth rate and direction, using for Hg0 removal. XRD, BET, SEM, TGA, XPS, etc characterized these materials. It can be found that CuS-2h had lower crystallinity and rougher surface compared to other materials. The appropriate crystallinity make CuS exposed more active sites and defects. The performance and reaction mechanism of removing Hg0 of CuS materials with different morphologies were systematically studied. The results showed that CuS-2h materials reacted had excellent mercury removal efficiency in the temperature of 50 °C–125 °C, and had excellent anti-toxicity to SO 2. The advantages of this material can be attributed to the fact that copper can expose more active sites to sulfur-based materials. The active components of CuS-2h with higher oxidation potential, S 2 2−, was conducive to electron transfer and can promote the oxidative adsorption of mercury. [ABSTRACT FROM AUTHOR]

[Display omitted] • Removal of mercury species from gaseous nitrogen. • The Knudsen model overpredicts diffusion coefficients due to neglect of fluid–solid interaction. • Kinetic selectivity of N 2 over Hg or HgO is too low for kinetic separation to be feasible. • Equilibrium separation in silica provides high selectivity for Hg or HgO over N 2. • The optimum pore radius for Hg separation is 0.3 nm, while that for HgO is 0.75 nm. The separation of Hg and HgO from industrial flue gas is an issue of much interest in the control of heavy metal emissions, and its feasibility for kinetic and equilibrium separation of Hg and HgO from N 2 using disordered silica is theoretically investigated here using a combination of pore level transport modelling and effective medium theory. It is found that the classical Knudsen model generally leads to considerable over-prediction of the effective diffusion coefficient in the nanoporous silica compared to the more accurate Oscillator model that considers fluid–solid interaction. It is seen that nanoporous silica membranes are kinetically selective to nitrogen, the major component of flue gas, relative to Hg and HgO. Nevertheless, the kinetic selectivity for N 2 is low, and only about 2–3, indicating that the kinetic separation of mercury species from flue gas is not practically feasible. On the other hand, the equilibrium selectivity of HgO over N 2 is over 50 at 0.75 nm modal radius, while that for Hg exceeds 30 at 0.3 nm radius, suggesting this method of separation to be appropriate. Narrow pore silica materials of uniform nanopore size of about 0.3–0.75 nm are found to be optimal for the removal of mercury species. [ABSTRACT FROM AUTHOR]

Removal mechanism and relationship of NO, Hg0 and toluene on the CuO-TiO 2 @CeO 2 catalyst. [Display omitted] • CuO-TiO 2 @CeO 2 with multiple active sites was successfully prepared. • Constructing core–shell structure to form multiple active sites. • CeO 2 shell produce abundant oxygen vacancy defect sites and active sites for reaction. • The interplay between Hg0/toluene oxidation and NH 3 -SCR reactions were explored. • Reaction pathways for simultaneous removal of NO, Hg0 and toluene were proposed. The core–shell structure CuO-TiO 2 @CeO 2 catalysts with multiple active sites synthesized via a self-assembly method was applied to study the simultaneous removal of NO, Hg0 and toluene. The results indicated that using CeO 2 as sheath could remarkably enhance the catalytic performance. The CeO 2 shell layer could not only be conducive to the exposure of active sites on the catalyst surface and enhance the adsorption of the toluene, NH 3 and NO species, but also produce abundant oxygen vacancy defect sites through the strong interaction between CeO 2 shell and CuO-TiO 2 core. Coordinately NH 3 on Lewis acid sites were the key intermediates for NH 3 -SCR reaction that takes place both through the Eley-Rideal and Langmuir-Hinshelwood pathways. Gaseous Hg0 was firstly adsorbed over multiple oxidation sites that generated via the redox cycle of Cu2+ + Ce3+ ↔ Cu+ + Ce4+, and then was oxidized to HgO by lattice oxygen species (O β). Meanwhile, NO could react with surface chemisorbed oxygen (O α) to produce NO 2 , which could oxidize Hg0 into Hg(NO 3) 2. Toluene could be removed via the reaction path: toluene → benzyl alcohol → benzoate species → maleic acid species → CO 2 + H 2 O. The interaction mechanisms between different gas components on CuO-TiO 2 @CeO 2 were proposed. [ABSTRACT FROM AUTHOR]

Gaseous elemental mercury (Hg0) removal tests, using copper-based sorbents (CBS) developed in-house, were performed in a laboratory scale fixed-bed reactor. The aim was to find potential candidate sorbents to use in a dry syngas purification process plant. The dry purification process is under development for oxy-fuel integrated gasification combined cycle (IGCC) power generation with an efficient carbon dioxide separation function. The performance of CBS was evaluated as a function of two major characteristics. First, Hg0 removal performance of the CBS is improved by pre-sulfidation. Second, Hg0 removal performance of the spent CBS is recovered through moderate heating under diluted O 2 conditions. A honeycomb type sorbent was prepared by impregnating raw material of the CBS onto the honeycomb-shaped support. Since copper sulfide will effectively capture Hg0 in a reducing gas atmosphere, the CBS honeycomb was initially pre-sulfurized by H 2 S diluted with N 2 at 120 °C in a fixed-bed reactor until complete breakthrough of H 2 S. The simulated syngas from the oxy-fuel IGCC was fed into the reactor with conditions set at 140 °C and 0.98 MPa, where the Hg0 in the syngas was reduced to below 1.0 µg/m3 N by the CBS honeycomb. The spent CBS honeycomb was regenerated by introducing 1 vol-% of O 2 diluted with N 2 at 280 °C. The sequential operation of pre-sulfidation, mercury removal, and regeneration steps was performed cyclically three times, during which the CBS honeycomb maintained a satisfying Hg0 removal performance. These results revealed that the A-CBS honeycomb is a potential candidate for the dry mercury removal process in the Oxy-fuel IGCC power generation plant. [ABSTRACT FROM AUTHOR]

• The C–S groups generated in the plasma promote the removal of mercury. • The mercury removal efficiency of biochar increased from 26.4% to 95.5% after modification. • Hg0 is adsorbed on the modified sample to form HgS and HgO. • Active S released from broken C–S bonds at high temperature reacts with Hg0 in the gas phase. Six biomasses (rice, tobacco, corn, wheat, millet and black bean straws) were used to prepare biochar. The mercury removal performance of the obtained biochars after H 2 S plasma modification was tested, and characterisation was by FTIR (including in-situ FTIR), XPS and TPD. The mercury removal efficiency of biochar was enhanced after H 2 S plasma modification. The initial efficiency of wheat straw biochar was raised from 26.4% to 95.5% after modification. The number of sulfur-containing and carboxyl functional groups on the surface of the biochar increased through plasma modification. C–S and carboxyl are considered as the main functional groups forming HgS and HgO in mercury removal. The biochar after modification exhibited better mercury removal capacity at low temperatures. Active S is released from the C–S bonds at high temperature and further oxidises Hg0 in the gas phase. The adsorption process of modified samples is controlled by physical and chemical adsorption at 30 °C, while the main part of the reaction at 150 °C takes place in the gas phase. [ABSTRACT FROM AUTHOR]

• Mercury occurrence and thermal stability in high ash bituminous coal were determined. • The relations of Hg content with organic sulfur, sulfate and sulfide were obtained. • Mercury species in various density fractions were quite distinct. • The matrix-bound Hg, HCl soluble Hg, HgS and Hg(NO 3) 2 ·xH 2 O were thermally unstable and released before 400 °C. • The pyrite-bound Hg mainly enriched in density >2.0 g/cm3 fraction and released at 400–600 °C. The high-ash coals have gradually become essential energy resources due to their availability, and the occurrence of Hg in coals and its thermal stability could be significantly influenced by ash-forming minerals. In this work, a high-ash bituminous coal was divided into 4 density fractions using sink-float procedure. The sequential chemical extraction procedures, temperature-programmed pyrolysis and TG/DTG experiments were carried to investigate the Hg occurrence and thermal stability in different samples. The results showed that the Hg contents in samples has a positive relation with the ash, sulfate and sulfide contents, and the correlation coefficients were 0.868, 0.535 and 0.924, respectively. However, the negative value with correlation coefficient of 0.751 between the Hg and organic sulfur content was obtained. The Hg species in different samples were quite distinct, the organic matrix-bound Hg was the dominate form in SG1 with the content of 76.14%, the SG2 and SG3 were mainly composed of HCl soluble Hg and Hg(NO 3) 2 ·xH 2 O, and the Hg species occurred in SG4 were mainly HCl soluble Hg and pyrite-bound Hg. In the process of pyrolysis, the matrix-bound Hg, HCl soluble Hg, HgS and Hg(NO 3) 2 ·xH 2 O were thermally unstable and could be released into gas in the drying and desorption stage of 30–400 °C, while the pyrite-bound Hg mainly released with the decomposition of pyrite in the temperature range of 400–600 °C. There was only little Hg released in the temperature range of 600–850 °C, indicating the negligible relationship of Hg with carbonate and silicate minerals. [ABSTRACT FROM AUTHOR]

The aim of this work was to determine the Hg and As behaviour during coal combustion and flue gas purification process in terms of reducing their emissions into the atmosphere. The distribution of Hg and As between the solid phase (ash) and the gaseous phase was determined. Due to the high volatility, almost all of the mercury introduced into the installation passed to the flue gas. In the case of the As, more than 70% of the As passed to the flue gas, while the rest was recorded in the ashes. Three dusty sorbents were examined in terms of the effectiveness of flue gas purification from Hg and As: powdered activated carbon PAC, coke dust, and filter cake. The average efficiency of mercury removal for subbituminous coal and lignite ranged from 85 to 93% and 61 to 80%, respectively. On the other hand, the efficiency of As removal for subbituminous coal ranged from 21.8% to 90.8% depending on the sorbent used. The research was carried out in a laboratory scale tube furnace. The coal sample was burned in the flow of air and flue gas was directed through the sorbent container or scrubbers. The analysis was performed in defined and controlled conditions which included: combustion temperature, time, temperature of flue gas passing through the sorbent and flow rate. [ABSTRACT FROM AUTHOR]

• Hg in flue gas out of boiler consisted of 95.11–99.26% Hgp regardless of fuel types. • Air pollution control devices can remove >98.53% of Hg in flue gas, mostly by dust collector (>97%) • Total Hg in stack gas was low (0.19–0.24 µg·m−3) for the two CFB utility boilers. • Mercury emission factors of the two power plants were 1.19–1.54 mg Hg·t−1 coal. Mercury (Hg) emitted from two circulating fluidized bed (CFB) utility boilers (150 MW, P#1 and 300 MW, P#2) in Guizhou province, Southwest China, was characterized. P#1 used anthracite coal and was equipped with in-furnace desulfurization (IFD) and electrostatic precipitator (ESP). P#2 co-burned gangue and coal slime and was equipped with selective non-catalytic reduction (SNCR), ESP, fabric filter (FF) and limestone gypsum wet flue gas desulfurization (WFGD). Flue gas samples from the inlets and outlets of air pollution control devices (APCDs) in the two plants were analyzed using the Ontario Hydro Method (OHM). Solid samples including feed coal, limestone, bottom ash, fly ash and gypsum were also collected and analyzed. Hg removal efficiency by the APCDs and Hg emission factors (MEFs) were estimated. Total Hg (THg) in the flue gas at the inlet of ESP are 32.3 µg·m−3 and 15.3 µg·m−3 for P#1 and P#2, respectively, both dominated (95.11–99.26%) by the particulate form (Hgp). THg decreased significantly to 0.19–0.24 µg·m−3 at the final APCDs outlets of these two power plants, yielding an overall Hg removal efficiency of 98.53–99.41% for THg. Mass balance analysis indicated that >97% of Hg in coals ended up in captured fly ash. MEFs of the two tested power plants are relatively lower than the values typically found in CFB and pulverized coal (PC) utility boiler power plants. The emission data of Hg from CFB coal-fired power plants should be updated and attention should be directed to the secondary emission/release of Hg from the captured fly ash. [ABSTRACT FROM AUTHOR]

The abatement of mercury from oxyfuel combustion flue gas should be paid special attention due to the metal embrittlement and aluminum corrosion for CO 2 compression device. The effects of enriched CO 2 and H 2 O in oxyfuel combustion atmosphere on mercury removal over biochar (BC) and magnetic biochar (MBC) was studied. Hg0 was firstly captured by physical adsorption and then oxidized to various mercury compounds. A large amount of organic groups, especially C O group, were formed with the assistance of enriched CO 2. As a result, more Hg0 was oxidized over BC and more organic Hg (Hg-OM) was formed on BC and MBC. However, the content of chemisorbed oxygen on MBC was reduced under oxyfuel combustion atmosphere, hence reducing the formation of HgO on MBC compared with air combustion atmosphere. The enriched H 2 O significantly inhibited the removal of mercury over MBC. Chlorine was demonstrated as the most significant active components for mercury removal, since HgCl 2 was the dominant species on MBC. This work clarified the effects of enriched CO 2 and H 2 O on Hg0 adsorption over BC and MBC, which is essential for further improving the adsorption activity. [ABSTRACT FROM AUTHOR]

• Mercury emission from both air and fuel reactors for CLC of coal is summarized. • Mercury in coal, temperature, and water vapor promote the release of mercury in fuel reactor. • Oxygen carriers promote the conversion of Hg0 to Hg2+ and HgP. • The impacts of different gas components on mercury removal are discussed. Chemical looping combustion (CLC) of coal for carbon capture utilization and storage is an effective technology to reduce carbon emission due to smaller energy penalty and inherent low emission of pollutants. However, a large uncertainty exists in mercury emission from both air and fuel reactor for coal-fired chemical looping combustion. This paper attempts to reveal the underlining mechanisms for the transformation of mercury-related species both in combustion and post-combustion process. Mercury in coal, temperature, and water vapor promote the release of mercury in fuel reactor. Oxygen carriers (OCs) promote the conversion of Hg0 to Hg2+ and HgP. Both oxygen release and adsorption ability of reduced OCs contributes to the mercury removal efficiency. HCl is the dominant species for Hg0 oxidation. NO, SO 2 , CO, and H 2 have negative impacts on Hg0 oxidation; while O 2 promotes Hg0 oxidation; the influence of H 2 O on Hg0 oxidation depends on concentration. H 2 S may promotes Hg0 removal by formation metal sulfides. In the post combustion mercury removal by adsorption and catalytic oxidation process, O 2 , HCl, NO, and CO 2 promote the oxidation of Hg0, whereas SO 2 , CO, and H 2 inhibit the oxidation of Hg0. The impacts of H 2 S and H 2 O on Hg0 oxidation depends on their concentrations. Simultaneous removal of SO 2 , NO, and Hg0 by green oxidation-based absorption using free radicals or in the compression process have a good prospect due to potential low cost. This work will encourage wider discussion on flue gas treatment possibilities to reduce the cost of future CLC power plant. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ce-doped LaCoO 3 supported on CeO 2 was employed for mercury removal from coal-fired power plant. • Ce can be successfully doped into the LaCoO 3 crystal lattice via a sol–gel method. • Approaching 100% Hg0 removal efficiency was observed in the presence of O 2. • H 2 O and SO 2 reduced the Hg0 removal efficiency due to competitive adsorption. Mercury has a significant impact on environment and is mainly derived from coal-fired power plant. Herein, we report a potential route for efficient removal of Hg0 via oxidation reactions using Ce-doped LaCoO 3 supported on CeO 2 catalyst. Catalyst characterization results proved that Ce can successfully substitute a desired part of Co into the LaCoO 3 crystal lattice via a sol–gel method. The Hg0 removal experiments suggest that Hg0 removal efficiency decreased in the order of La 0.875 Ce 0.125 CoO 3 /CeO 2 > La 0.875 Ce 0.125 CoO 3 > LaCoO 3. The presence of O 2 provided more active oxygen and resulted in approaching 100% Hg0 removal efficiency. Introducing H 2 O and sole SO 2 would significantly reduce the Hg0 removal efficiency as a result of competitive adsorption on the actives sites of the catalyst. On the other hand, SO 2 could reacted with Hg0 in the presence of O 2 and thereby recover the high Hg0 removal efficiency and the La 0.875 Ce 0.125 CoO 3 /CeO 2 catalyst presented a good performance towards sulfur resistance. Furthermore, the catalyst still exhibited a high Hg0 removal efficiency performance after five times consecutive recycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • Iron-based sucrose foam is an effective and regenerable mercury sorbent. • αFe 2 O 3 nanoneedles on the sucrose foam are the active sites for mercury removal. • The SO 2 and H 2 O do not affect the efficiency of mercury retention. • The O 2 present in the flue gas key to regenerating the sorbent. Although various methods for removal of elemental mercury from gas streams have been proposed, the control of mercury emissions to the environment from anthropogenic sources, mainly coal-fired power plants, remains unresolved in many countries worldwide. Meanwhile, the Minamata Convention and the IED of the European Commission continue to impose restrictions for its control and mitigation. In this work, a new material based on a sucrose foam impregnated with iron oxide nanoparticles has been developed for the adsorption of elemental mercury from flue gases allowing the regeneration of the material and the recovery of elemental mercury. Of the different iron oxides supported on the sucrose foam, αFe 2 O 3 nanoneedles were found to be the most efficient in capturing mercury through a Mars-Maessen mechanism and the forming of HgO. The adsorbents developed proved to be effective in the presence of SO 2 and H 2 O, with the O 2 present in the gas playing a key role in the regeneration of the material. From the results found sucrose foam-based αFe 2 O 3 composite could be an attractive alternative to traditional non-regenerable activated carbons, reducing costs and being environmentally sustainable. [ABSTRACT FROM AUTHOR]

• Mercury distribution in an offshore natural gas processing platform is simulated. • The UMR-PRU and SRK thermodynamic models are employed. • The effect of a possible reaction between Hg0 and H 2 S is also studied. • Simulation results are compared to measured Hg concentrations in process fluids. In this work, the distribution of mercury in an offshore natural gas processing platform in Norway is simulated, and the results are compared to field measurements regarding elemental and total mercury concentration in process fluids. The effect of a possible reaction between mercury and H 2 S that leads to solid β-HgS formation is also examined. For the simulation, the UMR-PRU group-contribution equation of state (EoS) and the SRK cubic EoS are employed, which have been extended to mercury mixtures in our previous works. The results show that both models satisfactorily predict mercury concentration in process gases, while they overpredict mercury concentration in condensates as compared to the field measurements. When the reaction is also considered, the predicted mercury concentrations in condensates are closer to the measured values. Overall, it is concluded that both models can satisfactorily predict the distribution of mercury in a gas processing plant. [ABSTRACT FROM AUTHOR]

• The recycling method of bimetallic chalcogenide adsorbent is analyzed. • The experimental and theoretical calculation methods for improving the removal efficiency of Hg0 with bimetallic chalcogenide adsorbent are proposed. • It provides an idea for further understanding of the reaction mechanism of mercury removal with high performance bimetallic chalcogenide adsorbents. • It offers the direction for the removal of Hg0 by bimetallic chalcogenide adsorbents from the laboratory to the full range of industrial applications in coal-fired power plants. Mercury is considered as a global harmful air pollutant because of its strong toxicity and volatility. Controlling flue gas mercury emissions has been a serious task for the global environment and human health. Mercury removal technology has been widely concerned by researchers as a research hotspot in the field of mercury pollution control in flue gas of coal-fired power plants. In recent years, bimetallic chalcogenides have attracted more and more attention due to their abundant active sulfur sites. In this review, the mercury removal properties of various bimetallic chalcogenide adsorbents are firstly summarized. Secondly, the effects of flue gas temperature and different gas components (O 2 , SO 2 , NO, H 2 O，HCl) on the removal of mercury by bimetallic chalcogenide adsorbents are systematically discussed. Moreover, the recovery and regeneration properties of adsorbents are introduced. Then, the mechanism of mercury removal of bimetallic chalcogenide adsorbents is revealed via density functional theory (DFT) in terms of binding energy and electron transfer. Finally, the modified strategy to improve the mercury removal performance of bimetallic chalcogenide adsorbents is proposed, and the future development is prospected. This work provides a reference for the design and exploration of bimetallic chalcogenide adsorbents to remove pollutant. [ABSTRACT FROM AUTHOR]

[Display omitted] • A two-step craft was proposed to prepare Hg0 sorbent from high organic sulfur coal. • Fe 2 O 3 doping changed organic sulfur to FeS x during carbonization process. • KOH changed FeS x to various active sulfur during activation process. • This two-step craft can be expanded to other organic sulfur materials. It is a win–win strategy to prepare mercury sorbents from low-cost high-sulfur raw materials. In part 1, mercury sorbents with excellent performance were prepared from high inorganic sulfur coal through KOH activation. However, this method does not work for high organic sulfur coal. In this work, a two-step preparation method is developed to prepare mercury sorbents from high organic sulfur coal. The first step is the co-pyrolysis/carbonization of Fe 2 O 3 and coal, during which organic sulfur in coal is converted into FeS x. XPS shows that the percentage of S x 2–/S on the surface of the carbonized samples gradually increases from 5.4% to 22.2% with the m(Fe):m(S o) ratio from 0:4 to 5:4. The second step is KOH activation, and it converts FeS x into various S species, including C-S, S0, S 2 2− and S2−. Among the prepared mercury sorbents, LF+3Fe/4S-A (m(Fe):m(S o) = 3:4) shows the best mercury removal performance, and its mercury removal efficiency remains above 84% for 120 min under N 2 +O 2 at 120 °C. The Hg-TPDD and XPS results indicate that S*, including C-S, S0 and S 2 2−, are the major active sites for mercury removal rather than Fe element, and HgS is the main existing form of mercury on the used sorbents. Besides LF coal, this two-step process is also applicable to other high organic sulfur coals (such as LL coal, WJZ coal, and SY coal) and high-sulfur petroleum coke. [ABSTRACT FROM AUTHOR]

Highlights • Small angle neutron scattering (SANS) was employed in characterizing the pore structures of Bakken shale. • The pore surface area and pore size distribution from different methods were calculated and compared. • The multifractal analysis was used to quantify the pore heterogeneity from these three methods. • The impact of the rock compositions on the pore structure was analyzed. Abstract Small angle neutron scattering (SANS) analysis was performed on six Bakken Shale samples with different maturities to reveal the complexities in the pore structure. Pore size distribution (PSD), porosity and specific surface area (SSA) were calculated from SANS data via the Polydisperse Spherical Pore (PDSP) model and compared with the data from N 2 adsorption and mercury intrusion. The results showed that the Bakken samples have a very small porosity value (less than 1%) and a very larger specific surface area (larger than 180995 cm−1) in the measuring pore size range (pore diameter: 1–200 nm). SANS and N 2 adsorption can detect pores in the similar size range (2–200 nm). The SSA measured by SANS and mercury intrusion was found larger than the one detected by N 2 adsorption. Pore structure information that is obtained from SANS, N 2 adsorption, and mercury intrusion methods exhibited a fractal and multifractal behavior. Moreover, the pore size distribution that is calculated from SANS data was the most heterogeneous. Finally, the effects of rock composition on pore structures demonstrated that organic matter hosts some isolated pores while clay minerals do not host a large quantity of pores that are either connected or isolated. [ABSTRACT FROM AUTHOR]

Highlights • Hg0 removal using VUV and heat coactivation of Oxone/H 2 O/O 2 is studied. • Mechanism and kinetics of Hg0 removal are studied. • SO 4 − , OH, O and O 3 are the key active species for Hg0 removal. • Hg0 removal follows a fast reaction in VUV/heat/Oxone/H 2 O/O 2 system. Abstract A novel process on gaseous elemental mercury removal using vacuum ultraviolet light (VUV) and heat coactivation of Oxone/H 2 O/O 2 (i.e., VUV/heat/Oxone/H 2 O/O 2 system) in a VUV-spraying reactor was investigated for the first time. Experiments were carried out to evaluate the effects of several operating parameters (e.g, VUV wavelength, Oxone concentration, VUV radiation intensity, activation temperature, solution pH and O 2 concentration) on Hg0 removal. Mechanism and kinetic law of Hg0 removal were also revealed. The results demonstrated that 185 nm wavelength showed the best performance. Hg0 removal was promoted by increasing VUV radiation intensity, Oxone concentration and O 2 concentration, and was weakened by increasing solution pH and SO 2 concentration. Activation temperature exhibited dual influence on Hg0 removal. Hg0 was removed by six pathways: (1) oxidized by SO 4 − and OH that are produced from VUV activation of Oxone; (2) oxidized by O 3 and O that are produced from VUV photolysis of O 2 ; (3) oxidized by OH that is produced from VUV photolysis of H 2 O; (4) removed by light-water excitation reaction; (5) oxidized by SO 4 − and OH that are produced from heat activation of Oxone; (6) oxidized directly by Oxone. Hg0 removal process followed a fast reaction in VUV/heat/Oxone/H 2 O/O 2 system (i.e., presence of VUV) and a medium speed reaction in heat/Oxone/H 2 O/O 2 system (i.e., absence of VUV). [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Magnetic Fe-Cl/biochars are synthesized via a simple one-step pyrolysis procedure. • The pore structure and surface functional groups are improved under Fe catalysis. • Fe-Cl/biochars exhibit far better Hg0 removal performance compared to Cl/biochars. • T7Fe5 is superior in adsorption capacity/rate to a commercial activated carbon. • Fe 3 O 4 , C Cl and C O groups serve as active sites for Hg0 removal. Abstract Chlorinated biochars (Cl/biochars) prepared by co-pyrolysis of biomass and polyvinyl chloride (PVC) waste were demonstrated as cost-effective sorbents for elemental mercury (Hg0) removal in our previous study. But the decrease in specific surface area of Cl/biochars caused by PVC melting inhibits the further increase of Hg0 removal performance. Moreover, the difficulty in separating the used Cl/biochars from fly ash restricts the utilization of fly ash as a cement additive. To solve these problems, magnetic chlorinated biochars (Fe-Cl/biochars) are synthesized through one-step pyrolysis of Fe(NO 3) 3 -laden wood/PVC mixtures in this study. The sample characterization showed that magnetic Fe 3 O 4 was introduced into the Fe-Cl/biochars. Besides the magnetism, both increased specific surface area and more C O groups were obtained under Fe catalysis. The Fe-Cl/biochars showed far better Hg0 removal performance compared to the Cl/biochars over a broad reaction temperature range (25–220 °C). O 2 , HCl and NO promoted Hg0 removal whereas SO 2 had little effect on Hg0 removal H 2 O slightly suppressed Hg0 removal. Compared to the commercial activated carbon manufactured specifically for Hg0 removal, Fe-Cl/biochars was superior in both Hg0 adsorption capacity and adsorption rate at 140 °C. The mechanism of Hg0 removal over Fe-Cl/biochars was chemisorption reaction, where Fe 3 O 4 , C Cl and C O provided active sites for Hg0 removal. [ABSTRACT FROM AUTHOR]

Abstract Ag nano-particles (NPs) with high dispersion possess the capacity for elemental mercury (Hg0) removal in low temperature. To further enhance its thermo-stability and electron transfer ability, Ag-Fe 3 O 4 @rGO ternary magnetic composite was synthesized for gaseous Hg0 capture. Results indicated that such composite has a Hg0 removal performance with higher than 92% removal efficiency at 100 °C. The ternary composite has a higher Hg0 removal performance than that of pure rGO and Fe 3 O 4 @rGO. The physical-chemical characterization results indicated that Ag nano-particles in-situ grow on the surface of Fe 3 O 4 @rGO support. The large surface area of rGO supply efficient reaction room for Hg and Ag atoms. Ag-Hg amalgam is ascribed to the mercury uptake mechanism. The spent materials can be regenerated by a simple thermal-desorption method. In addition, this magnetic material provide an opportunity that can be separated from fly ashes when used in real flue gas. [ABSTRACT FROM AUTHOR]

Highlights • The corn cob activated carbons was prepared by chemical activation using ZnCl 2. • The prepared sorbent was applied to remove Hg0 in flue gas with high efficiency. • ZnCl 2 played a key role in mercury removal process. Abstract It is a big challenge to effectively remove elemental mercury (Hg0) from coal fired flue gas with affordable adsorbents. To explore new adsorbents with low cost and high capacity for mercury removal is urgently demanded. On the other hand, it will be a good way to reduce the environmental burden by beneficially utilizing agricultural waste. In this study, one kind of agricultural waste, corn cob, was beneficially used for Hg0 control. The corn cob activated carbon (CCAC) with large surface area was prepared by chemical activation using ZnCl 2 and was employed to remove elemental mercury (Hg0) from simulated flue gas (SFG) for the first time. The results demonstrated that the corn cob activated carbon performed high mercury removal efficiency up to 91.4% at 150 °C. The effects of activator, reaction temperature and main flue gas components were studied. Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX) were used to characterize the physicochemical properties of the adsorbents. The possible mechanism of mercury removal was discussed based on XPS analysis and characterization. The results indicated that ZnCl 2 could not only activate microporous structures of carbon but also played an important role for removal of elemental mercury. The produced AC can be used as an effective adsorbent with low cost for mercury pollution control in flue gas. [ABSTRACT FROM AUTHOR]

Highlights • Oxidant injection increased Hg2+ concentration in flue gas. • pH, ORP, C 6 H 10 O 4 concentration and molar ratio X impact mercury re-emission. • Re-emission of Hg0 can be reduced by adjusting the FGD absorber operating parameters. Abstract The paper presents the results of an industrial scale study of mercury re-emission phenomenon from the flue gas desulphurization (FGD) absorber that purifies the lignite combustion gases. The available research results on re-emission phenomena at a laboratory and pilot scale were reviewed and verified in full scale conditions. It was confirmed that the phenomenon of re-emission is dependent on the FGD absorber operating conditions (pH, ORP) and the concentration of adipic acid in the sorption solution. Based on the conducted tests it was found that proper regulation of the FGD absorber's operating parameters can significantly reduce Hg0 re-emission to the atmosphere. The interesting phenomenon was observed during the test, when the oxidant was fed to flue gas (X > 0.75) and average values of ORP < 140 mV and pH < 6.0 a large amount of HgT was released from tested FGD absorber to atmosphere (up to 200 µg/m3). [ABSTRACT FROM AUTHOR]

Abstract The fate of mercury (Hg) content of four poor quality coals was investigated under various pyrolysis conditions (temperature, time, pressure), using helium flow. The resulting chars were analyzed for Hg and compared with the parent coal's content. Hg removal efficiency was found to be affected by both pyrolysis temperature and residence time. Mercury removal continuously increased for pyrolysis temperatures up to 600 °C, and was sharply decelerated for higher ones, resulting in a rather sigmoid shape of the Hg removal curve. Pyrolysis time up to 20 min showed significant impact on Hg removal, negligibly affected Hg release. Thus, pyrolysis at temperatures between 500 and 600 °C for ∼20 min could be considered sufficient enough for "Hg-free" coal production. The role of pyrolysis pressure on Hg removal was found to be limited, and its impact (if any) was observed at short pyrolysis times (≤10 min), being diminished when the residence time is prolonged (up to 20 min). The results revealed three characteristic temperature regimes; a low temperature (200 °C–300 °C) physical desorption mechanism with low apparent activation energy, a mild temperature regime (300 °C–600 °C) with mixed physico-chemical desorption and sublimation mechanism with higher activation energy, and a high temperature regime (700 °C–900 °C) where Hg evolution dramatically decreased. Mercury coal removal during pyrolysis was simulated using a simple first order volume reaction model for the three temperature regimes identified. Τhe apparent activation energy was initially found ∼3.1 kJ/mol at the low temperature regime, increased to ∼6.1 kcal/mol at the mild temperature range, and almost fourfold to ∼22.4 kJ/mol at the high temperature regime. As the apparent activation energy increased, the pre-exponential factor (k 0) also increased linearly, tending to compensate the increase of the activation energy. However, the conventional compensation theory does not offer a robust explanation of this behavior and further investigation is required. [ABSTRACT FROM AUTHOR]

Abstract Bamboo carbon (BC) is a renewable and low-cost material used as sorbent in the industry. Hydrogen peroxide (H 2 O 2) has been used to modify BCs to enhance its mercury adsorption ability. However, the mechanism of enhancement needs to be further investigated because the H 2 O 2 modification technique is environment-friendly. The Brunauer–Emmett–Teller (BET) method, ultimate analysis (UA), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) were used to reveal the physicochemical characteristics of the modified BCs. Our results indicated that the action of H 2 O 2 on BC increased the number of C–O and OH oxygen functional groups on the surface of BC, thus significantly enhancing the efficiency of mercury adsorption. At the same time, H 2 O 2 modification increased the BET surface area of BCs. Increasing both the number of oxygen functional groups and BET surface area of BCs helped improve the adsorption of elemental mercury (Hg0). The presence of oxidized mercury (Hg2+) both in the flue gas and on the surface of BCs after the adsorption process indicated that chemisorption occurred on the surfaces of the H 2 O 2 modified BCs. Simulating a pseudo-second-order reaction model also demonstrated that the chemisorption of Hg0 occurred on the surfaces of H 2 O 2 -modified BCs. When compared with commercial activated carbon (AC), H 2 O 2 -modified BC was demonstrated to be a promising sorbent for mercury removal from flue gas. [ABSTRACT FROM AUTHOR]

Abstract Gaseous elemental mercury (Hg0) is difficult to dispose using traditional sorbents when co-existed with high concentration of SO 2 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 SO 2 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 (O 2 , SO 2 , H 2 O, SO 3) on Hg0 removal performances were investigated. O 2 , H 2 O and SO 2 showed negligible influences on Hg0 capture. However, SO 3 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 SO 2 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 SO 2 recovery. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • ZnO is simultaneously laden on activated carbon during the ZnCl 2 -activation. • Physisorption is not significant and only accounts for about 7% in 130 °C. • Mercury adsorption by ZnO and carbonyl accounts for more than 70%. • ZnO catalyses the Hg0 into HgS with the presence of H 2 S. • The C O group of carbonyl acts as an oxidation site. Abstract In this work, activated carbon with ZnO laden on the surface was prepared by ZnCl 2 -one-step activation of different types of biomass (corn straw, bamboo powder and sawdust) and employed for mercury removal in the coal gas. During the activation, a part of ZnCl 2 is converted into ZnO and laden on activated carbon, which greatly promotes the mercury removal performance with the presence of H 2 S. The ZnO content varies greatly with the content of SiO 2 in the biomass due to its inactivation of ZnO and formation of Zn 2 SiO 4. Carbonyl, which is important to mercury removal is largely retained after the activation at 500 °C and the amount of carbonyl seems to be positively correlated with the specific surface area (related to the lignin content). The temperature programmed desorption method was applied to further analyse the mercury adsorption in the coal gas. The results showed that ZnO and carbonyl play an important role in mercury removal, while the physisorption is not significant and only accounts for approximately 7% at 130 °C. The mechanism study showed that ZnO serves as a catalytic active site and catalyses the Hg0 into HgS with the presence of H 2 S. While the C O group of carbonyl acts as adsorption sites and turns into C O after the adsorption. This study provided a promising preparation method of mercury sorbents in the coal gas, and the influence of surface functional groups was also investigated in detail. [ABSTRACT FROM AUTHOR]

Highlights • Steady and dynamic ORP models are developed using LSSVM and WFGD operating data. • Input parameters are analyzed to develop the steady ORP model. • Time delays of input parameters are optimized to develop the dynamic ORP model. • Sensitivity analysis was made to analyze influence of parameters and time delays. • Models can be extended to conduct optimization of WFGDs to mitigate Hg re-emission. Abstract The oxidation-reduction potential (ORP) is highly related to Hg re-emission in wet flue gas desulfurization (WFGD) systems in coal-fired power plants. Developing an accurate model that describes the ORP characteristics is beneficial to achieve the operation optimization of the WFGD system and Hg re-emission reduction. In this paper, steady and dynamic ORP models were reported based on the least squares support vector machine (LSSVM) technique and using operating data acquired from a coal-fired power plant. For the steady model, input parameters consisted of flue gas flow, flue gas temperature, inlet SO 2 concentration, oxidation air flow, recycle pump currents, and slurry feed flow. For the dynamic model, in addition to the parameters listed above, time delays of these parameters were also considered in the modeling scheme. Both models achieved high accurate predictions. Model sensitivity analysis was conducted to investigate the influence of the input parameters and time delays on ORP. Results show that the parameters are adequate to describe the characteristics of the ORP. In addition, parametric time delays play an important role to represent the dynamic characteristics of the ORP. These models can be extended to design process control strategy and conduct the ORP operation optimization of the WFGD system in power plants to mitigate Hg re-emission from the scrubber. [ABSTRACT FROM AUTHOR]

Highlights • The effect of O 2 -ionized products on HgO oxidation is greater than that of H 2 O-ionized products in WESP. • H 2 O played an inhibitive effect on Hg0 removal in WESP. • Wash-down by the water film had slight effect on Hg0 removal rate. Abstract The elemental mercury (Hg0) removal performance of wet electrostatic precipitator (WESP) was studied on a lab-scale experimental device. Increasing voltage in WESP promoted the Hg0 oxidation because higher-energy electrons in the electric field accelerated the discharge of O 2 and H 2 O to form free radicals like O, O 3 and OH. The oxidation of Hg0 by O 2 -ionized products was the dominant pathway for Hg0 removal in WESP. H 2 O played an inhibitive role in Hg0 removal. The presence of H 2 O competed with O 2 for electron energy to form OH, thus inhibiting the generation of O and/or O 3. The OH could oxidize Hg0 into HgOH; however, HgOH tended to decompose and release as Hg0. The wash-down effect of water film could collect part of Hg0, which could partly offset the inhibitive effect of H 2 O on Hg0 removal. As Hg0 is insoluble, the Hg0 removal by wash-down of the water film was insignificant in WESP. Mercury re-emission existed in WESP because of the water-insolubility of Hg0 and the instability of HgOH. The findings indicate that oxidizing Hg0 by radicals in the electric field of WESP might be a feasible method for removing Hg0 from power plants. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel sorbent synthesized from calcium acetate and silica was reported. • KCl and K 2 CO 3 were chosen as the dopants to enhance the performance of sorbent. • A variety of alkaline sites on the surface of sorbent were confirmed. • HgCl 2 adsorption behaviors were materialized into three adsorption configurations. Abstract calcium-based sorbents are the potential materials for mercury chloride (HgCl 2) adsorption while inert to elemental mercury (Hg0) due to their basic property. A series of calcium-based sorbents were chosen to evaluate the selective adsorption performance of mercury, these sorbents included a calcium oxide adsorbent, a KCl-doped calcium oxide adsorbent and a K 2 CO 3 -doped calcium oxide adsorbent which all supported by the mesoporous silica (C-SiO 2 , CKL-SiO 2 and CKO-SiO 2) and were synthesized by an impregnation method. All sorbents were firstly characterized by Powder X-ray Diffraction (XRD), Brunauer-Emmett-Teller (BET) and Scanning Electron Microscope (SEM). Characterization results show that C-SiO 2 has the best surface structure while the doped KCl would evidently reduce the specific surface area and micropores volume of the sorbent, the doped K 2 CO 3 also has an adverse effect on the surface structure of CaO sorbent but it can significantly improve the basicity of sorbent. Mercury adsorption performance of the sorbents was then evaluated in fixed bed apparatus, the results indicated that all sorbents exhibited a complete breakthrough for gaseous Hg0. Due to the modification of K 2 CO 3 to the CaO sorbent, HgCl 2 was fully adsorbed by CKO-SiO 2 no matter the SO 2 presented or not. CO 2 -TPD combined with HgCl 2 -TPD confirmed that diverse basic sites exist on the calcium-based sorbent surfaces and three HgCl 2 adsorption behaviors occurred during the adsorption process. Three HgCl 2 adsorption configurations were introduced to represent the different adsorption behaviors and the binding intensity of these configurations are in the successive order: monodentate < tridentate < bidentate. The monodentate adsorption configuration is the main HgCl 2 adsorption manner on the CaO surface while the bidentate adsorption configuration occurs on the defect surface of sorbent. [ABSTRACT FROM AUTHOR]

Elemental mercury is a natural occurring trace component of fossil fuels, which poses significant health and safety risks during oil and gas processing due to its highly toxic and corrosive nature. In order to anticipate and control the distribution of mercury during industrial processes, there is a necessity for thermodynamic models, which can accurately predict its partitioning in the various phases. In this work, the UMR-PRU model is extended to systems that contain elemental mercury and is employed for predicting its solubility in hydrocarbons, compressed gases, water and methanol. A comparison is also made between UMR-PRU and the two most widely used equations of state, Soave-Redlich-Kwong and Peng-Robinson, with modified attractive terms. The results reveal that all three models can accurately describe the solubility of mercury in the aforementioned compounds, with UMR-PRU being the most accurate. [ABSTRACT FROM AUTHOR]

Hematite (α-Fe 2 O 3 ) has been proved to be a promising sorbent for mercury removal in various situations. The mercury removal performance of α-Fe 2 O 3 was investigated using a simulated coal gasification syngas containing Hg 0 , N 2 , HCl, and/or H 2 S, a series of experiments were designed with HCl and H 2 S separately and both employed. For a better understanding in the interaction between HCl and H 2 S in mercury removal, the differences in mercury oxidation were demonstrated on the basis of density functional theory calculations. The rate-limiting step in HgCl 2 formation is Hg 0  → HgCl with the energy barrier of 139.47 kJ/mol, but for H 2 S in mercury oxidation, the generation of active sulfur species is the key step and the rate-limiting step is detachment of second H with an energy barrier of 57.53 kJ/mol. Experimental results point that HCl has inhibition on H 2 S for mercury removal, it may be ascribed to the competition of active Fe sites on Fe 2 O 3 . Conversely, HCl contributes to the mercury oxidation at high temperature while H 2 S has a limit effect at elevated temperature. [ABSTRACT FROM AUTHOR]

Sulfur abundant S/FeS 2 prepared by a hydrothermal method was employed for removing elemental mercury (Hg 0 ) from coal-fired flue gas at low temperature. The S/FeS 2 exhibited optimal Hg 0 adsorption performance at 80 °C, which matched the temperature window between the flue gas desulfurization (FGD) and wet electrostatic precipitator (WESP) systems. The adverse effects of H 2 O and SO 2 on Hg 0 adsorption were slight. The Hg 0 adsorption capacity of S/FeS 2 was up to 2732 μg/g when achieved 50% breakthrough threshold. Both elemental sulfur (S) and FeS 2 in the S/FeS 2 contributed to the excellent Hg 0 adsorption capacity. The mercury leaching tests show that only 0.00076% mercury adsorbed on the S/FeS 2 was leached out. The mercury concentration in leachate was 0.694 μg·L −1 , which was much lower than that for a commercial AC (1.214 μg·L −1 ). Furthermore, the S/FeS 2 presented about 95% oxidized mercury (Hg 2+ ) adsorption efficiency from WESP effluent. The Hg 2+ concentration could decreased rapidly from 50 μg·L −1 to below 2.5 μg·L −1 in 30 min, which was much lower than the World Health Organization (WHO) guideline (6 μg·L −1 ). With these advantages, S/FeS 2 appears to be a promising material for co-beneficial gaseous Hg 0 and aqueous Hg 2+ removal from power plants by injecting upstream of a WESP system. [ABSTRACT FROM AUTHOR]

The photocatalytic Hg 0 (gaseous elemental mercury) removal performance of the multi-walled carbon nanotubes (MWCNTs) impregnated with titanium dioxide (MWCNTs/TiO 2 ) was experimentally investigated in a fixed-bed reactor with the simulated flue gas. Transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV–Vis diffuse reflectance spectra (DRS) were used to characterize the prepared photocatalysts. The addition of MWCNTs inhibited the grain growth of TiO 2 and improved the pore property of the photocatalyst. Besides, the presence of MWCNTs also significantly influenced the morphology of TiO 2 , and enhanced its photochemical and optical properties. The effects of the MWCNTs and the individual flue gas components, including SO 2 , NO, O 2 and H 2 O, on Hg 0 removal were also investigated. The results indicated that compared to the pure TiO 2 , the MWCNTs/TiO 2 exhibited a higher photocatalytic removal ability for Hg 0 that mainly due to the higher surface area, the better properties of electrons transportation, and the abundant active species such as the surface chemisorbed oxygen (O ∗ ) and C O bond. The removal efficiency of Hg 0 was found to be significantly affected by the flue gas components. Oxygen promoted Hg 0 removal by replenishing surface chemisorbed oxygen (O ∗ ) and assisting in electron-hole pair separation. Water vapor inhibited photocatalytic performance due to the competitive adsorption. SO 2 and NO were found to play an inhibitory role in the photocatalytic Hg 0 removal reaction since SO 2 and NO scavenged hydroxyl radicals ( OH), which were produced by ultraviolet (UV) irradiation. In addition, mercury species remained on the MWCNTs/TiO 2 surface were also determined by XPS analysis to understand the further reaction mechanism. [ABSTRACT FROM AUTHOR]

A series of biochars were prepared from rice(RI), tobacco(TO), corn(CO), wheat(WH), millet(MI), and black bean straw(BB). These biochars were used to study the mechanism of elemental mercury(Hg 0 ) adsorption by hydrochloric acid modified biochars. The biochars were modified by 1 M hydrochloric acid (HCl) and then used in a fixed-bed Hg 0 adsorption experiment. As would be expected, the results indicated that HCl modification increased the Hg 0 adsorption performance of the six biochars. After modification, the Hg 0 adsorption efficiency of tobacco biochar increased from 8.2% to 100.0%, and the average Hg 0 adsorption capacity of the biochars increased by 61 times. The acid modification dissolved the metal compounds in the biochar, reducing the metal content and increasing the average surface area of the biochar. The average surface area of the raw biochars increased from 29.9 to 110.1 m 2 /g after HCl modification. The extra surface area was mostly created in the micropores, leading to a significant increase in the amount of micropores. These micropores effectively adsorbed the Cl atoms, which acted as active sites for Hg 0 . In the adsorption process, Hg 0 diffused into the interior of modified biochars via mesopores, and finally the adsorbed Cl in the micropores reacted with Hg 0 to form HgCl 2 . [ABSTRACT FROM AUTHOR]

CuO loaded MnO x /TiO 2 mixed oxide (CuMnTi) synthesized by an ultrasonic-assisted impregnation method was for the first time employed for simultaneous nitrogen monoxide (NO) reduction and elemental mercury (Hg 0 ) oxidation under selective catalytic reduction (SCR) atmosphere with the presence of NH 3 . The CuMnTi catalyst exhibited a wide temperature window from 150 to 250 °C for both NO reduction and Hg 0 oxidation. At the optimal temperature of 175 °C, CuMnTi reduced 96.4% of the inlet NO and oxidized 100% of the inlet Hg 0 at a very high gas hourly space velocity (GHSV) of 40,000 h −1 . O 2 , HCl and NO significantly promoted Hg 0 oxidation and offset the adverse effect of detrimental flue gas components such as water vapor, SO 2 and NH 3 . The protection effect of CuO over MnO x reserved enough active sites of CuMnTi for Hg 0 oxidation in the presence of NH 3 or SO 2 . Compared with MnO x /TiO 2 (MnTi), the superior redox property, enlarged Hg 0 adsorption capacity and decent SO 2 resistance of CuMnTi ternary system were evidenced to account for its improved catalytic activity. This study indicated future potential for applying CuMnTi catalyst in simultaneous NO reduction and Hg 0 oxidation in low-temperature (150–250 °C) and low-rank (sub-bituminous and lignite) coal combustion flue gases. [ABSTRACT FROM AUTHOR]