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Qiu P, Wang S, Tian C, Lin Z. Adsorption of low-concentration mercury in water by 3D cyclodextrin/graphene composites: Synergistic effect and enhancement mechanism. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 252:1133-1141. [PMID: 31252111 DOI: 10.1016/j.envpol.2019.06.034] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 06/10/2019] [Accepted: 06/10/2019] [Indexed: 06/09/2023]
Abstract
The efficient removal of mercury from aqueous media remains a severe challenge in ensuring environmental safety, especially for low-concentration mercury, which requires adsorbents with high mercury affinity. In this work, we reported a nanocomposite of β-cyclodextrin and three-dimensional graphene (3D CD@RGO) to enhance the adsorption affinity and capacity for mercury with low concentrations. Characterization of the nanocomposite revealed that cyclodextrin was well dispersed on the 3D graphene support structure to provide highly exposed hydroxyl groups. Adsorption experiments showed that CD@RGO exhibited different adsorption behaviors for mercury within different concentration ranges of 0.2-4.0 mg/L and 4.0-10.0 mg/L, and the adsorption affinity for the former range (KL = 10.05 L/mg) was 1.5 times higher than that for the latter range (KL = 6.69 L/mg). Moreover, CD@RGO had a high adsorption efficiency of 96.6% with a superb adsorption affinity (172.09 L/g) at Ce = 0.01 mg/L, which is 6.70 and 41.25 times higher than that of RGO and RCD (physical mixture of RGO and cyclodextrin), respectively, indicating a synergistic effect of CD@RGO for mercury adsorption. This enhancement can be attributed to the transformation of the adsorption mechanism from the outer-sphere force of electrostatic interaction in RGO to the inner-sphere surface complexation in CD@RGO.
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Affiliation(s)
- Peipeng Qiu
- School of Environment and Energy, The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters (Ministry of Education), South China University of Technology, Guangzhou, Guangdong, 510006, China; Guangdong Engineering and Technology Research Center for Environmental Nanomaterials, South China University of Technology, Guangzhou, Guangdong, 510006, China
| | - Shuting Wang
- School of Environment and Energy, The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters (Ministry of Education), South China University of Technology, Guangzhou, Guangdong, 510006, China; Guangdong Engineering and Technology Research Center for Environmental Nanomaterials, South China University of Technology, Guangzhou, Guangdong, 510006, China
| | - Chen Tian
- School of Environment and Energy, The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters (Ministry of Education), South China University of Technology, Guangzhou, Guangdong, 510006, China; Guangdong Engineering and Technology Research Center for Environmental Nanomaterials, South China University of Technology, Guangzhou, Guangdong, 510006, China.
| | - Zhang Lin
- School of Environment and Energy, The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters (Ministry of Education), South China University of Technology, Guangzhou, Guangdong, 510006, China; Guangdong Engineering and Technology Research Center for Environmental Nanomaterials, South China University of Technology, Guangzhou, Guangdong, 510006, China
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Spanu D, Bestetti A, Hildebrand H, Schmuki P, Altomare M, Recchia S. Photocatalytic reduction and scavenging of Hg(ii) over templated-dewetted Au on TiO 2 nanotubes. Photochem Photobiol Sci 2019; 18:1046-1055. [PMID: 30534751 DOI: 10.1039/c8pp00424b] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Gold-decorated TiO2 nanotubes were used for the photocatalytic abatement of Hg(ii) in aqueous solutions. The presence of dewetted Au nanoparticles induces a strong enhancement of photocatalytic reduction and scavenging performances, with respect to naked TiO2. In the presence of chlorides, a massive formation of Hg2Cl2 nanowires, produced from Au nanoparticles, was observed using highly Au loaded photocatalysts to treat a 10 ppm Hg(ii) solution. EDS and XPS confirmed the nature of the photo-produced nanowires. In the absence of chlorides and/or at lower Hg(ii) starting concentrations, the scavenging of mercury proceeds through the formation of Hg-Au amalgams. Solar light driven Hg(ii) abatements up to 90% were observed after 24 h. ICP-MS analysis revealed that the removed Hg(ii) is accumulated on the photocatalyst surface. Regeneration of Hg-loaded exhaust photocatalysts was easily performed by anodic stripping of Hg(0) and Hg(i) to Hg(ii). After four catalytic-regeneration cycles, only a 10% decrease of activity was observed.
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Affiliation(s)
- Davide Spanu
- Department of Science and High Technology, University of Insubria, via Valleggio 11, 22100 Como, Italy.
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Zhao L, Wu Y, Han J, Lu Q, Yang Y, Zhang L. Mechanism of Mercury Adsorption and Oxidation by Oxygen over the CeO₂ (111) Surface: A DFT Study. MATERIALS 2018; 11:ma11040485. [PMID: 29570658 PMCID: PMC5951331 DOI: 10.3390/ma11040485] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 03/20/2018] [Accepted: 03/20/2018] [Indexed: 11/16/2022]
Abstract
CeO2 is a promising catalytic oxidation material for flue gas mercury removal. Density functional theory (DFT) calculations and periodic slab models are employed to investigate mercury adsorption and oxidation by oxygen over the CeO2 (111) surface. DFT calculations indicate that Hg0 is physically adsorbed on the CeO2 (111) surface and the Hg atom interacts strongly with the surface Ce atom according to the partial density of states (PDOS) analysis, whereas, HgO is adsorbed on the CeO2 (111) surface in a chemisorption manner, with its adsorption energy in the range of 69.9–198.37 kJ/mol. Depending on the adsorption methods of Hg0 and HgO, three reaction pathways (pathways I, II, and III) of Hg0 oxidation by oxygen are proposed. Pathway I is the most likely oxidation route on the CeO2 (111) surface due to it having the lowest energy barrier of 20.7 kJ/mol. The formation of the HgO molecule is the rate-determining step, which is also the only energy barrier of the entire process. Compared with energy barriers of Hg0 oxidation on the other catalytic materials, CeO2 is more efficient at mercury removal in flue gas owing to its low energy barrier.
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Affiliation(s)
- Li Zhao
- National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Beijing 102206, China; (L.Z.); (Y.W.); (J.H.); (Y.Y.)
| | - Yangwen Wu
- National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Beijing 102206, China; (L.Z.); (Y.W.); (J.H.); (Y.Y.)
| | - Jian Han
- National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Beijing 102206, China; (L.Z.); (Y.W.); (J.H.); (Y.Y.)
| | - Qiang Lu
- National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Beijing 102206, China; (L.Z.); (Y.W.); (J.H.); (Y.Y.)
- Correspondence: ; Tel.: +86-010-6177-2030
| | - Yongping Yang
- National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, Beijing 102206, China; (L.Z.); (Y.W.); (J.H.); (Y.Y.)
| | - Laibao Zhang
- Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA 70820, USA;
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Ma Q, Zhang H, Cui Y, Deng X, Guo R, Cheng X, Xie M, Cheng Q. Fabrication of Cu 2 O/TiO 2 nano-tube arrays photoelectrode and its enhanced photoelectrocatalytic performance for degradation of 2,4,6-trichlorophenol. J IND ENG CHEM 2018. [DOI: 10.1016/j.jiec.2017.08.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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