Experimental Study of the Effect of Fly Ash Particle Size on its Mercury Adsorption Capability in the Flue Gas

Wu, Jiang; Wang, Peng; He, Lu Lu; Pan, Wei; Ren, Jian; He, Ping; Wu, Qiang; Zhang, Jin Hong

doi:10.4028/www.scientific.net/amr.356-360.1664

Cited by 3 publications

(8 citation statements)

References 4 publications

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“…The plots of PDOS characterizes the electronic interactions of Hg 0 with Co 3 O 4 (1 1 0) surface in Fig.5. Co 3+ sites of Co (10) and Co (12) have the same PDOS change before and after the interaction. Before adsorption, the s orbitals of Hg locates at 0 Ha and 0.50 Ha.…”

Section: Adsorption Energiesmentioning

confidence: 92%

“…The charge transfer follows the routes below. Co (10) and Co 12 (20) and O (28) atoms obtain 0.014e -, 0.014e -, 0.009 e -, 0.009 e -，0.011 eand 0.004 e -, respectively. The other Co 3+ atoms on the first layer, Co (1) and Co (4), accept 0.024 and 0.025 e -, respectively.…”

Section: Adsorption Energiesmentioning

confidence: 98%

“…As for Co 3 O 4 (1 1 0) surface, all atoms have positive charge transfer. Co (10) and Co (12) obtain the highest electron number of 0.085 and 0.086, respectively. Co (1) and Co (4) accept nearly equal number of electrons (0.024 and 0.025e -).…”

Section: Adsorption Energiesmentioning

confidence: 99%

“…Since the elemental mercury (Hg 0 ) is volatile and water insoluble, removing it from the environment is of great difficulty in all species of mercury [7]. To date, activated carbon [8], calciumbased sorbents [9], fly ash [10], noble metals [11] and metal oxides [12][13][14] have been used for Hg 0 removal. Among these sorbents and catalysts, Co 3 O 4 -based materials capture researchers' attention because of high efficiency on mercury removal [15].…”

Section: Introductionmentioning

confidence: 99%

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A DFT study of Hg0 adsorption on Co3O4 (1 1 0) surface

Shen

Tang

et al. 2016

Chemical Engineering Journal

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Spin polarized density functional theory calculation combined with periodic slabs were employed to reveal the elemental mercury (Hg 0) adsorption mechanism on Co 3 O 4 (1 1 0) surface. The adsorption energies and possible adsorption sites were investigated. To understand the adsorption interaction more directly, the electronic structural changes of before and after adsorption were compared. The hybridization of orbitals was studied by the partial density of states (PDOS) analysis. In addition, the temperature effects toward equilibrium constants of Hg 0-Co 3 O 4 system were taken into consideration. The results manifested that the interaction between Hg 0 and Co 3 O 4 (1 1 0) surface is chemisorption with-74.037kJ/mol. Co 3+ sites, the highest oxidation state of Co atoms, are crucial in this process which can accept the electrons after Hg oxidation. The redundant electrons transfer to O and other Co atoms nearby. PDOS analysis indicates the hybridization of s orbitals (Hg 0) and p, d orbitals (Co atom). And d orbitals of Hg interacts with s, p orbitals of Co atom strongly. The trends of equilibrium constants suggest that Hg 0 adsorption on Co 3 O 4 (1 1 0) surface is favorable at low temperature.

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Section: Adsorption Energiesmentioning

confidence: 92%

Section: Adsorption Energiesmentioning

confidence: 98%

Section: Adsorption Energiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A DFT study of Hg0 adsorption on Co3O4 (1 1 0) surface

Shen

Tang

et al. 2016

Chemical Engineering Journal

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“…Based on Hg contents in different size fractions of fly ash, Hg content first decreased and then increased with the increase in particle size with the minimum Hg content given in the size range 0.048− 0.075 mm. 152 However, only carbon content alone cannot explain Hg retention in fly ash. Different structural morphology of various particle sizes of fly ash may play an important role on Hg retention.…”

Section: Particle Sizementioning

confidence: 99%

Mercury Removal Based on Adsorption and Oxidation by Fly Ash: A Review

Liu

Zhao

et al. 2020

Energy Fuels

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Mercury (Hg), in particular elemental mercury (Hg0) captured from coal-fired power plants, has attracted much attention because of its severe harm to human health and environment. Hg0 can be removed using the technology of adsorbent injection, and one of the promising adsorbents is fly ash. To evaluate the effect of complex multifactors of fly ash on Hg0 removal performance, this review summarizes, analyzes, and evaluates the quantitative effects of fly ash compositions, physical parameters, flue gas components, and modification reagents. The effects of electric field (EF), magnetic field (MF), and ultraviolet (UV) light on Hg0 removal using fly ash are also introduced. Unburned carbon (UBC) and Fe2O3 are two reactive components in fly ash for Hg0 oxidation. Physical parameters including higher specific surface area, larger total pore volume, and wider distribution of pores with well-developed micropores are beneficial for Hg0 retention, and no consistent relationship between particle size and Hg0 retention using fly ash has been obtained. While gas phase components including HCl, NO, and O2 promote the removal of Hg0 using fly ash, no agreement about the effects of SO2 and H2O vapor on Hg0 removal has been reached. The promotion of halogen-modified fly ash on Hg0 removal may be explained by the Langmuir–Hinshelwood mechanism, the Mars–Maessen mechanism, as well as the Eley–Ridel mechanism. The contribution of metal-modified fly ash to Hg0 removal is attributed to the oxidation ability of metal oxides as well as metal positive ions. EF, MF, and UV light enhance the oxidation of Hg0 using fly ash to different degrees. The promotion of EF may be attributed to the formation of more Cl, O, and OH radicals by a series of electron-induced reactions. The enhancement of MF is simultaneously attributed to the energy-level splitting of Hg0 as well as the magnetochemistry effect of magnetic materials in fly ash. The function of fly ash on the photocatalytic oxidation of Hg0 under the UV light has been verified, while relevant studies are still limited. More studies are still needed on the relationship between surface functional groups and carbon types, the control of Hg0 secondary emission from the spent fly ash, the development of fly ash-based products, the compromise between fly ash modification cost and Hg0 removal efficiency, and the effective and economical coremoval of Hg0, NO x , and SO x using fly ash. In particular, the promotional effects of EF, MF, and UV light on Hg0 removal necessitate extensive studies on their underlining mechanisms. This review resolves the existing controversies on the Hg0 removal mechanism and promotes the development of fly ash on Hg0 removal from coal combustion.

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Effect of Mechanical–Chemical Modification Process on Mercury Removal of Bromine Modified Fly Ash

Geng

Duan

et al. 2020

Energy Fuels

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As a new modification method, mechanochemistry features the remarkable advantages of simple operation process, low energy consumption, easy chemical modification, and suitability for industrialization. In this work, the coal-fired byproduct fly ash was modified by a mechanical–chemical method through omnidirectional planetary ball mill. The effect of the mechanical–chemical modification process parameters on the performance of mercury removal and physicochemical properties of the fly ash and the relationship between the mercury removal efficiency and the physicochemical properties were studied. The experimental results showed that, under the condition of single mechanical ball milling, the mercury removal efficiency of fly ash (FA) was slightly higher than that of raw FA. After being modified by NaBr, the mercury removal efficiency of FA increased considerably with the increase of ball milling time and speed and decreased with the increase of the size of the grinding ball. However, it was no longer significantly improved with further increasing the ball milling time and speed owing to the limited unburned carbon content in FA. The best modification process parameters were determined from the ball milling time of 1 h, the ball milling speed of 400 rpm, and the ball size of 5 mm. The characterization results showed that there was no big difference in physical properties of FA between various mechanical–chemical modification processes. However, the content of carbonyl and carboxyl/ester groups and C–Br covalent groups on modified FA demonstrated a key role in promoting mercury removal performance. The contents of carbonyl and carboxyl/ester groups and C–Br covalent groups were positively proportional to the mercury removal rate, and they were consumed during mercury adsorption. The results confirmed that the improvement of mercury removal efficiency of modified FA was dominated mainly by the surface chemical properties. Compared with the carbonyl and carboxyl/ester groups, the C–Br covalent group was the major chemisorption site of Hg0.

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Experimental Study of the Effect of Fly Ash Particle Size on its Mercury Adsorption Capability in the Flue Gas

Cited by 3 publications

References 4 publications

A DFT study of Hg0 adsorption on Co3O4 (1 1 0) surface

A DFT study of Hg0 adsorption on Co3O4 (1 1 0) surface

Mercury Removal Based on Adsorption and Oxidation by Fly Ash: A Review

Effect of Mechanical–Chemical Modification Process on Mercury Removal of Bromine Modified Fly Ash

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