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[Display omitted] • Different proportions of MoS 2 /MnO 2 adsorbents were synthesized. • Mm-30 adsorbents show great removal efficiency for mercury. • Mm-30 have a higher specific surface area than pure MoS 2. • The adsorption of Hg on Mm-30 follows the M−K mechanism. • Mm-30 adsorbent has good resistance to SO 2 under the condition of 400 ppm S+ N 2. In this work, MoS 2 /MnO 2 synthesized by hydrothermal methods was employed to remove Hg0 in flue gas. Benefited from the growth of MnO 2 on the surface of MoS 2 , the specific surface area of the Mm adsorbent has increased. Compared with pure MoS 2 , specific surface area of Mm-30 has increased by 26.0287 m2/g. The MoS 2 modified with 30 w.t. % MnO 2 revealed higher mercury removal performance at 120 °C, which reached 93%. The oxidation of mercury over Mm-30 is proposed to follow Mars-van Krevelen mechanism, whereby the lattice oxygen in the adsorbent is consumed. In presence of NO, HCl, O 2 and SO 2 , the effect of different concentrations on mercury oxidation is observed. Mm-30 adsorbent reveals stable mercury removal performance in the presence of NO and HCl, while it also exhibited good sulfur resistance under the condition of 400 ppm SO 2 + N 2. This phenomenon indicates that the adsorbent can be applied in power plants with medium concentrations of SO 2 , which facilitated the application of Mm-30 as a potential mercury removal adsorbent for power plants. [ABSTRACT FROM AUTHOR]

• Different proportions of MoS 2 /Fe 3 O 4 adsorbents were synthesized. • MoS 2 /Fe 3 O 4 adsorbents show great removal efficiency for mercury. • MF-10 have a higher specific surface area than pure MoS 2. • High specific surface area and lattice oxygen play an important role in mercury removal. • MF-10 has good magnetic and recycling ability. At the front end of the Electrostatic precipitator (ESP), activated carbon injection is a common method to remove mercury from flue gas, but the high cost, low efficiency and non-recyclability limit the practical application of activated carbon. MoS 2 , a transition metal sulfide with a two-dimensional layered structure, was found to have favourable performances in removing contaminant. In this work, Fe 3 O 4 was successfully grown on the surface of flower-like MoS 2 by two-steps hydrothermal methods. The experimental results showed that the specific surface area of MoS 2 /Fe 3 O 4 (MF) was the largest when the ratio is 10 wt% (MF-10). Compared with pure MoS 2 , the specific surface area of MF-10 increased by 6.7467 m2/g, which was attributed to the growth of Fe 3 O 4. At the same time, the introduction of Fe 3 O 4 made the MF possess superparamagnetism to facilitate its retrievability under an external magnetic field. In addition, MF-10 also showed a mercury removal efficiency of almost 100%. Although the efficiency of the MF-10 has decreased after 5 cycles and 24 h, it could still maintain about 90%, revealing a stable cycle life. Due to its mercury removal performance and recyclability, MF can be considered as a favorable adsorbent for removing elemental mercury. [ABSTRACT FROM AUTHOR]

• Different proportions of M n / γ - F e 3 O 4 adsorbents were synthesized. • M n / γ - F e 3 O 4 adsorbents have good adsorption and oxidation capacity for mercury. • High valence Mn and Fe play an important role in the oxidation of mercury. • External magnetic field can effectively improve the mercury removal effect of M n / γ - F e 3 O 4 adsorbents. • The kinetic analysis is consistent with the experimental results. In this paper, we used coprecipitation method to prepare different ratios of Mn / γ - Fe 3 O 4 to remove Hg0. Different ratios of Mn and Fe could affect the mercury removal efficiency of M n / γ - F e 3 O 4. The mechanism of Hg0 adsorption on the surface of M n / γ - F e 3 O 4 matches the Mars-van Krevelen reaction mechanism. The catalytic oxidation of mercury on the surface of the sample is related to Fe and Mn. We also performed a pseudo-first-order kinetic model and an improved pseudo-n-order kinetic model. In addition, the external magnetic field has a certain promoting effect on the mercury removal. [ABSTRACT FROM AUTHOR]

The atomic interaction between elemental mercury in the flue gas and defective carbonaceous surface is studied by the first-principles calculation. The defective carbonaceous surface is modeled by a nine-fused benzene cluster with two adjacent atomic vacancies. The results indicate that vacancies can increase the activity of their neighboring carbon atoms. However, the vacant sites present the decrease in mercury removal capacity, which is different from the behavior of the defective carbonaceous surface with only one atomic vacancy. In addition, flue gas molecules (FGMs) including CO, CO 2 , NO, NO 2 , SO 2 and H 2 O, are examined to evaluate the influence on the mercury removal of the defective carbonaceous surface. The calculated results demonstrate that different adsorption behaviors for Hg0 occur on the defective carbonaceous surface due to the presence of FGMs. It can be found that CO may enhance the mercury removal capacity of the defective carbonaceous surface when its concentration is higher than that of Hg0. Meanwhile, SO 2 presents the remarkable positive effect on the mercury removal efficiency at the vacancy. On the contrary, the presence of CO 2 , NO, NO 2 and H 2 O leads to the increase in the adsorption energies of mercury on the defective carbonaceous surface. ga1 • Hg0 adsorption on defective carbonaceous surface with FGMs is studied by DFT method. • Two adjacent vacancies will reduce the mercury removal efficiency at the vacancy. • The number of vacancies affects the mercury capture capacity. • Different adsorption behaviors for Hg0 occur due to the presence of FGMs. • SO 2 can significantly improve the capacity of vacancy to capture mercury. [ABSTRACT FROM AUTHOR]

[Display omitted] • LaFeO 3 perovskite was synthesized by sol–gel method and calcination method. • LaFeO 3 has ∼94% removal efficiency at 120 ℃. • LaFeO 3 exhibits excellent simulated flue gas resistance. • Density functional theory was applied to verify the performance of samples. LaFeO 3 perovskite was synthesized by sol–gel method and calcination method and used to remove mercury in flue gas. Three kinds of metal oxides La 2 O 3 , Fe 2 O 3 , and LaFeO 3 were evaluated. The results indicated that the performances for Hg0 removal decreased in the order of LaFeO 3 > Fe 2 O 3 > La 2 O 3. LaFeO 3 has ∼94% removal efficiency at 120 ℃. To explore the temperature response range and the influence of simulated flue gas, the performance of LaFeO 3 to remove Hg0 under O 2 , NO, SO 2 , and different temperature conditions was further examined. Furthermore, LaFeO 3 is repeat-ability. The characterization results showed that the Hg0 transition to HgO is due to the valence change of iron and the release of lattice oxygen. In addition, density functional theory (DFT) was conducted to calculate the density of states to verify the performance of the sample. This work shows that LaFeO 3 is a promising adsorbent for mercury removal from flue gas in coal-fired power plants. [ABSTRACT FROM AUTHOR]

• A simple high-temperature calcination method was used to produce metallic molybdenum disulfide (1 T-Li x MoS 2). • The phase change increases the active site. • ML-100 adsorbent has good mercury removal efficiency and cycle stability. • Density functional theory(DFT) was used to verify the increase in surface activity after 2H-MoS 2 phase changed to 1 T-MoS 2. In this work, a simple high-temperature calcination method was used to produce metallic molybdenum disulfide (1 T-Li x MoS 2). Experiments and simulations show that 1 T-MoS 2 has stronger surface activity and enhances the adsorption capacity of Hg0, thereby effectively removing elemental mercury (Hg0) in coal-fired flue gas. Sample ML-100 could maintain a mercury removal efficiency of approximately 92% after 6-cycle experiments, and approximately 97% efficiency could be maintained throughout a long-term experiment. The proposed method converts the 2H phase to the 1 T phase by doping commercial MoS 2 with lithium ions, thereby improving the removal efficiency of elemental mercury in the flue gas. [ABSTRACT FROM AUTHOR]

Nanosized ZnIn 2 S 4 supported on facet-engineered CeO 2 nanorods were prepared by solvothermal method to effectively capture gaseous elemental mercury from flue gas. The CeO 2 /ZnIn 2 S 4 sorbent exhibited excellent mercury removal performance (>90%) in a wide temperature range from 60 to 240 ℃ and showed much higher mercury adsorption capacity than pure CeO 2 due to the enlarged specific surface area and abundant active oxygen and sulfur sites on the surface. It was found that CeO 2 /ZnIn 2 S 4 has good resistance to SO 2 , NO and H 2 O. At the optimal 120 ℃, the equilibrium Hg0 adsorption capacity of CeO 2 /ZnIn 2 S 4 can reach 19.172 mg/g, which is superior to the reported series of benchmark materials. X-ray photoelectron spectroscopy and temperature programmed desorption of mercury confirmed that the adsorbed mercury existed on the surface as HgO and HgS, indicating that catalytic oxidation and chemisorption occurred on the surface of the adsorbent. The adsorption energy of Hg0 on the CeO 2 (110) and ZnIn 2 S 4 (110) surfaces calculated with density functional theory (DFT), further confirms that the surface activated oxygen and sulfur sites are the most stable adsorption sites. Furthermore, the good regeneration capability of CeO 2 /ZnIn 2 S 4 makes it more promising for Hg0 capture in practical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Estimating mercury adsorption capability plays a vital role in verifying whether fly ash could act as a good sorbent for mercury removal. In this work, mercury retention in fly ash is considered to study its effect on mercury adsorption capacity. Six fly ash samples are collected from six different full-scale coal-fired power plants. The mercury adsorption ratio is measured by adsorption tests to characterize mercury adsorption capability of fly ash. The mercury retention in coals and their corresponding fly ashes are also examined. The results show that there is no linear correlation for fly ash between mercury retention ratio and mercury adsorption ratio Such phenomenon results from the fact that mercury retention ratio is determined by mercury adsorption properties of fly ash and mercury concentration of flue gas. The mercury species adsorbed from flue gas occupy the active sites of fly ash, which decrease the adsorption capability of fly ash. However, each as-received fly ash is surrounded with different mercury concentrations of flue gas. Even though two fly ashes have the same active sites for adsorbing mercury, they have different number of occupied active sites for mercury adsorption after flowing along with flue gas. Hence, evaluating the intrinsic mercury adsorption properties of fly ash should pretreat the fly ash samples before adsorption tests by removing out the adsorbed mercury to recover the occupied active sites, with which it may be reasonable to truly manifest the mercury adsorption properties of fly ash. • Effect of mercury retention on mercury adsorption capability of fly ash is studied. • Adsorption properties is not only one that decides the mercury retention ratio. • Mercury concentration of flue gas affects mercury retention ratio of fly ash. • Removing out adsorbed mercury from fly ash before adsorption test is proposed. [ABSTRACT FROM AUTHOR]