1
|
Zhou L, Zhou J, Zhou Q, Lu Y, Li B, Liu Z, Wang T. Study on the elution mechanism of HgO on mercury-loaded adsorbent in KCl solution via temperature programmed desorption (TPD) method. Sep Purif Technol 2023. [DOI: 10.1016/j.seppur.2023.123636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
|
2
|
Du X, Li C, Zhang J, Zhu Y, Liang C, Huang L, Yang K, Yao C, Ma Y. Tunning active oxygen species for boosting Hg 0 removal and SO 2-resistance of Mn-Fe oxides supported on (NH 4) 2S 2O 8 doping activated coke. JOURNAL OF HAZARDOUS MATERIALS 2023; 441:129882. [PMID: 36087532 DOI: 10.1016/j.jhazmat.2022.129882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 08/06/2022] [Accepted: 08/28/2022] [Indexed: 06/15/2023]
Abstract
Active oxygen species (AOS) play an essential role in modulating the activity of activated coke (AC) based samples. In this paper, AC was endowed with abundant AOS by modifying with (NH4)2S2O8 and MnOx-FeOx for Hg0 removal. (NH4)2S2O8 treatment induced abundant micropores and oxygen-containing functional groups, and thus provided more anchoring sites for the dispersion of MnOx-FeOx. The synergy of MnOx-FeOx and interaction between MnOx-FeOx and NAC support contributed to a larger surface area, highly-dispersed active components, stronger reducibility, and more metal ions with high valence of MnFe/NAC. The optimal MnFe/NAC exhibited superior Hg0 removal efficiency above 90% at 120∼180 ℃, as well as excellent performance for simultaneous removal of Hg0 and NO, and 600 ppm SO2 and 8 vol.% H2O addition led to a slight deterioration. XPS and Hg-TPD revealed that mercury adsorbed on MnFe/NAC included phy-Hg, C=O-Hg, COO-Hg, and OL-HgO. Besides, the priority of AOS for Hg0 chemisorption was C=O > COO- > OL, and Hg2+ was also detected in the outlet. Moreover, the SO2-poisoning effect was ascribed to the sulfation of MnOx and the occupation of COO- and C=O, and FeOx incorporation enhanced the SO2-resistance through weakening SO2 adsorption on C=O and COO-. The motivation of O2 mainly contributed to the regeneration of AOS, especially OL. The excellent regeneration performance and stability further affirmed the application potential of MnFe/NAC for Hg0 capture from coal-fired flue gas.
Collapse
Affiliation(s)
- Xueyu Du
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
| | - Caiting Li
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China.
| | - Jie Zhang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
| | - Youcai Zhu
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
| | - Caixia Liang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
| | - Le Huang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
| | - Kuang Yang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
| | - Chaoliang Yao
- Yonker Environmental Protection Co., Ltd, Changsha 410330, PR China
| | - Ying Ma
- Yonker Environmental Protection Co., Ltd, Changsha 410330, PR China
| |
Collapse
|
3
|
Altaf AR, Adewuyi YG, Teng H, Liu G, Abid F. Elemental mercury (Hg 0) removal from coal syngas using magnetic tea-biochar: Experimental and theoretical insights. J Environ Sci (China) 2022; 122:150-161. [PMID: 35717081 DOI: 10.1016/j.jes.2021.09.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 09/08/2021] [Accepted: 09/26/2021] [Indexed: 06/15/2023]
Abstract
Mercury is ranked 3rd as a global pollutant because of its long persistence in the environment. Approximately 65% of its anthropogenic emission (Hg0) to the atmosphere is from coal-thermal power plants. Thus, the Hg0 emission control from coal-thermal power plants is inevitable. Therefore, multiple sorbent materials were synthesized using a one-step pyrolysis method to capture the Hg0 from simulated coal syngas. Results showed, the Hg0 removal performance of the sorbents increased by the citric acid/ultrasonic application. T5CUF0.3 demonstrated the highest Hg0 capturing performance with an adsorption capacity of 106.81 µg/g within 60 min at 200 °C under complex simulated syngas mixture (20% CO, 20% H2, 10 ppmV HCl, 6% H2O, and 400 ppmV H2S). The Hg0 removal mechanism was proposed, revealing that the chemisorption governs the Hg0 removal process. Besides, the active Hg0 removal performance is attributed to the high dispersion of valence Fe3O4 and lattice oxygen (α) contents over the T5CUF0.3 surface. In addition, the temperature programmed desorption (TPD) and XPS analysis confirmed that H2S/HCl gases generate active sites over the sorbent surface, facilitating high Hg0 adsorption from syngas. This work represented a facile and practical pathway for utilizing cheap and eco-friendly tea waste to control the Hg0 emission.
Collapse
Affiliation(s)
- Adnan Raza Altaf
- School of Chemical Engineering Northwest University, Xi'an 710069, China.
| | - Yusuf G Adewuyi
- Chemical, Biological and Bio Engineering Department, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USA
| | - Haipeng Teng
- School of Chemical Engineering Northwest University, Xi'an 710069, China.
| | - Gang Liu
- State Key Laboratory of Clean Coal-based Energy, China Huaneng Group Clean Energy Research Institute Co., Ltd., Changping District, Beijing 102209, China.
| | - Fazeel Abid
- Department of Information System, Dr Hassan Murad School of Management, University of Management and Technology, Lahore 54770, Pakistan.
| |
Collapse
|
4
|
Mhatre D, Bhatia D. Insights into the Adsorption, Alloy Formation, and Poisoning Effects of Hg on Monometallic and Bimetallic Adsorbents. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:6841-6859. [PMID: 35613429 DOI: 10.1021/acs.langmuir.2c00136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The removal of elemental mercury (Hg0) from coal-derived syngas at high temperatures is desired to improve the thermal efficiency of the coal-to-chemical processes. First-principles density functional theory (DFT) calculations for Hg0 adsorption are performed using different exchange correlation functionals (PBE, optPBE-vdW, and optB88-vdW). Gibbs free energy (ΔG) calculations are further performed to evaluate the feasibility of Hg0 adsorption on various exposed planes of metal nanoparticles and to obtain bimetallic compositions for Hg0 removal at various temperatures. Pd and Pt are shown to be suitable for Hg0 adsorption at high temperatures (473 K), whereas Rh and Ru are effective only until 373 K. The bimetallic adsorbents comprising Ag or Au along with Rh, Ru, Pd, or Pt are identified for Hg0 removal at high temperatures (473 K). The increase in Hg0 adsorption strength on various bimetallic surfaces is correlated to the upward shift in the d-band center. Further, calculations predict the tendency of Hg to segregate toward the surface of amalgams and disturb the perfect planar geometry of the Pd, Pt, Rh, Ru, Ir, Cu, Ag, and Au surfaces to form a noncrystalline Hg-rich amalgam surface. An analysis of the binding of various adsorbates (H, O, N, and S) shows that the adsorption becomes significantly weaker on various sites in close proximity to pre-adsorbed Hg. Moreover, for specific combinations of the adsorbate, surface composition, and the site location, the adsorption does not take place on the proximal sites. These results are complemented by the partial density of states calculations, which show changes in the electronic properties of the amalgam surface, thus explaining the poisoning effect of Hg on metallic catalysts.
Collapse
Affiliation(s)
- Dwijraj Mhatre
- Department of Chemical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Divesh Bhatia
- Department of Chemical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| |
Collapse
|
5
|
Abstract
In this study, the manganese-doped manganese–cobalt–iron spinel was prepared by the sol–gel self-combustion method, and its physical and chemical properties were analyzed by XRD (X-ray diffraction analysis), SEM (scanning electron microscope), and VSM (vibrating sample magnetometer). The mercury removal performance of simulated flue gas was tested on a fixed bed experimental device, and the effects of Mn doping amount, fuel addition amount, reaction temperature, and flue gas composition on its mercury removal capacity were studied. The results showed that the best synthesized product was when the doping amount of Mn was the molar ratio of 0.5, and the average mercury removal efficiency was 87.5% within 120 min. Among the fuel rich, stoichiometric ratio, and fuel lean systems, the stoichiometric ratio system is most conductive to product synthesis, and the mercury removal performance of the obtained product was the best. Moreover, the removal ability of Hg0 was enhanced with the increase in temperature in the test temperature range, and both physical and chemical adsorption play key roles in the spinel adsorption of Hg0 in the medium temperature range. The addition of O2 can promote the removal of Hg0 by adsorbent, but the continuous increase after the volume fraction reached 10% had little effect on the removal efficiency of Hg0. While SO2 inhibited the removal of mercury by adsorbent, the higher the volume fraction, the more obvious the inhibition. In addition, in an oxygen-free environment, the addition of a small amount of HCl can promote the removal of mercury by adsorbent, but the addition of more HCl does not have a better promotion effect. Compared with other reported adsorbents, the adsorbent has better mercury removal performance and magnetic properties, and has a strong recycling performance. The removal efficiency of mercury can always be maintained above 85% in five cycles.
Collapse
|
6
|
Altaf AR, Teng H, Gang L, Adewuyi YG, Zheng M. Effect of Sonochemical Treatment on Thermal Stability, Elemental Mercury (Hg 0) Removal, and Regenerable Performance of Magnetic Tea Biochar. ACS OMEGA 2021; 6:23913-23923. [PMID: 34568670 PMCID: PMC8459432 DOI: 10.1021/acsomega.1c02925] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Indexed: 05/27/2023]
Abstract
Elemental mercury (Hg0) removal from a hot gas is still challenging since high temperature influences the Hg0 removal and regenerable performance of the sorbent. In this work, a facile yet innovative sonochemical method was developed to synthesize a thermally stable magnetic tea biochar to capture the Hg0 from syngas. A sonochemically synthesized magnetic sorbent (TUF0.46) exhibited a more prodigious surface area with developed pore structures, ultra-paramagnetic properties, and high dispersion of Fe3O4/γ-Fe2O3 particles than a simply synthesized magnetic sorbent (TF0.46). The results showed that TUF0.46 demonstrated strong thermostability and attained a high Hg0 removal performance (∼98.6%) at 200 °C. After the 10th adsorption/regeneration cycle, the Hg0 removal efficiency of TUF0.46 was 19% higher than that of TF0.46. Besides, at 23.1% Hg0 breakthrough, TUF0.46 achieved an average Hg0 adsorption capacity of 16.58 mg/g within 24 h under complex syngas (20% CO, 20% H2, 5% H2O, and 400 ppm H2S). In addition, XPS results revealed that surface-active components (Fe+, O2-, O*, C=O) were the key factor for high Hg0 removal performance over TUF0.46 from syngas. Hence, sonochemistry is a promising practical tool for improving the surface morphology, thermal resistance, renewability, and Hg0 removal efficiency of a sorbent.
Collapse
Affiliation(s)
- Adnan Raza Altaf
- School
of Chemical Engineering, Northwest University, Xi’an 710069, China
| | - Haipeng Teng
- School
of Chemical Engineering, Northwest University, Xi’an 710069, China
| | - Liu Gang
- State
Key Laboratory of Clean Coal-based Energy, China Huaneng Group Clean Energy Research Institute Co., Ltd., Changping District, Beijing 102209, China
| | - Yusuf G. Adewuyi
- Chemical,
Biological and Bio Engineering Department, North Carolina Agricultural and Technical State University, Greensboro, North Carolina 27411, United States
| | - Maosheng Zheng
- School
of Chemical Engineering, Northwest University, Xi’an 710069, China
| |
Collapse
|
7
|
Yang Z, Wang S, Li H, Yang J, Zhao J, Qu W, Shih K. Density Functional Theory Study of Elemental Mercury Immobilization on CuSe(001) Surface: Reaction Pathway and Effect of Typical Flue Gas Components. Ind Eng Chem Res 2020. [DOI: 10.1021/acs.iecr.0c02287] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zequn Yang
- School of Energy Science and Engineering, Central South University, Changsha, Hunan 410083, China
- Department of Civil Engineering, The University of Hong Kong, Hong Kong, China
| | - Shengcai Wang
- School of Metallurgy and Environment, Central South University, Changsha, Hunan 410083, China
| | - Hailong Li
- School of Energy Science and Engineering, Central South University, Changsha, Hunan 410083, China
| | - Jianping Yang
- School of Energy Science and Engineering, Central South University, Changsha, Hunan 410083, China
| | - Jiexia Zhao
- School of Energy Science and Engineering, Central South University, Changsha, Hunan 410083, China
| | - Wenqi Qu
- School of Energy Science and Engineering, Central South University, Changsha, Hunan 410083, China
| | - Kaimin Shih
- Department of Civil Engineering, The University of Hong Kong, Hong Kong, China
| |
Collapse
|