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Fang L, Gao B, Li F, Liu K, Chi J. The nature of metal atoms incorporated in hematite determines oxygen activation by surface-bound Fe(II) for As(III) oxidation. WATER RESEARCH 2022; 227:119351. [PMID: 36399840 DOI: 10.1016/j.watres.2022.119351] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 11/06/2022] [Accepted: 11/10/2022] [Indexed: 06/16/2023]
Abstract
The incorporation of secondary metal atoms into iron oxyhydroxides may regulate the surface chemistry of mediating electron transfer (ET) and, therefore, the biogeochemical pollutant processes such as arsenic (As) in the subsurface and soils. The influence of incorporating two typical metals (Cu and Zn) into a specific {001} hematite facet on O2 activation by surface-bound Fe(II) was addressed. The results showed that Cu-incorporated hematite enhances As(III) oxidation in the presence of Fe(II) under oxic conditions and increases with increasing Cu content. Conversely, Zn incorporation leads to the opposite trend. The As(III) oxidation induced by surface-bound Fe(II) is positively related to the Fe(II) content and is favorable under acidic conditions. Reactive oxygen species (ROS), such as superoxide (·O2-) and H2O2, predominantly contribute to As(III) oxidation as a result of 1-electron transfer from bound Fe(II) to surface O2 on hematite and radical propagation. Electrochemical analysis demonstrates that Cu incorporation significantly lower the oxidation potential of Fe(II) on hematite, whereas Zn led to a higher reaction potential for Fe(II) oxidation. Subsequently, distinct surface reactivities of hematite for the activation of O2 to form ROS by surface-bound Fe(II) are evidenced by metal incorporation. Our study provides a new understanding of the changes in the surface chemistry of iron oxyhydroxides because of incorporating metals (Zn and Cu), and therefore impact the biogeochemical processes of pollutants in soils and subsurface environments.
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Affiliation(s)
- Liping Fang
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Baolin Gao
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China; Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, China
| | - Fangbai Li
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Kai Liu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Jialin Chi
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China.
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Ramprasath R, Manikandan V, Aldawood S, Sudha S, Cholan S, Kannadasan N, Sampath S, Gokul B. Polyol-assisted hydrothermal synthesis of Mn-doped α - Fe 2O 3(MFO) nanostructures: Spin disorder-induced magnetism and photocatalytic properties. ENVIRONMENTAL RESEARCH 2022; 214:113866. [PMID: 35952748 DOI: 10.1016/j.envres.2022.113866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 06/10/2022] [Accepted: 07/06/2022] [Indexed: 06/15/2023]
Abstract
Hierarchical nanostructures play an important role in environmental clean-up and sustainability applications. The magnetic and photocatalytic characteristics of flower-like Mn-doped α-Fe2O3 nanostructures were prepared by using a polyol-assisted hydrothermal method. Crystallite sizes are in the range of 35-42 nm, and the existence of 3D hierarchical nanostructures was observed in FESEM pictures. The optical band gap energy varies between 2.08 and 2.16 eV, while XPS examination exposes the ions' charge states and validates Mn3+ inclusion in the Fe3+ lattice. At room temperature, the addition of Mn to α-Fe2O3 results in a spin disorder ferromagnetism and coercivity of about 600 Oe was achieved. Methylene blue (MB) dye solution degraded by 92% when 2.5% Mn doped with α-Fe2O3 under visible conditions for 120 min irradiation time.
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Affiliation(s)
- R Ramprasath
- Department of Physics, Periyar University, Salem, 636 011, Tamil Nadu, India; Department of Physics, P.D.R.T. Padmavathi Arts and Science College (Women), Dharmapuri, 636902, Tamil Nadu, India
| | - Velu Manikandan
- Department of BioNano Technology, Gachon University, 1342 Seongnam-daero, Sujeong-gu, Seongnam-si, Gyeonggi-do, 13120, South Korea
| | - S Aldawood
- Department of Physics and Astronomy, College of Science, P.O. Box 2455, King Saud University, Riyadh, 11451, Saudi Arabia
| | - S Sudha
- Department of Physics, Periyar University, Salem, 636 011, Tamil Nadu, India; Department of Physics, P.D.R.T. Padmavathi Arts and Science College (Women), Dharmapuri, 636902, Tamil Nadu, India
| | - S Cholan
- Department of Physics, Gonzaga College of Arts and Science for Women, Elathagiri, Krishnagiri, 635108, Tamil Nadu, India.
| | - N Kannadasan
- Department of Physics, Sri Sarada Mahavidhyalayam Arts and Science College for Women, Ulunthoorpetai, Vilupuram, 606107, Tamil Nadu, India
| | - Sridhar Sampath
- Department of Physics, Vel Tech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology, Avadi, Chennai, 600062, Tamil Nadu, India
| | - B Gokul
- Department of Physics, Kongunadu Arts and Science College (Autonomous), Coimbatore, 641 029, Tamil Nadu, India
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Gadore V, Ahmaruzzaman M. Fly ash-based nanocomposites: a potential material for effective photocatalytic degradation/elimination of emerging organic pollutants from aqueous stream. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:46910-46933. [PMID: 34263399 DOI: 10.1007/s11356-021-15251-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 06/28/2021] [Indexed: 06/13/2023]
Abstract
Fly ash is readily available and cheaply generated as 47a by-product of the combustion of organic matter. A tremendous amount of fly ash is generated worldwide, and its disposal has imposed 47a severe environmental concern. Its good adsorption capacities attracted several researchers to study the use of fly ash as 47a support for photocatalysts for the degradation of contaminants from wastewater. Undoubtedly the photocatalysts supported on fly ash have represented excellent degradation efficiencies due to the synergistic effect of adsorption and photocatalytic capacity. The utilization of fly ash as 47a precursor has solved the problem of disposal and added value to the waste by-product. Various preparation techniques for fly ash-based nanocomposites such as the sol-gel method, hydrothermal method, solvothermal method, precipitation and co-precipitation, modified metalorganic decomposition, electrospinning, incipient impregnation, and wet chemical synthesis, along with 47a brief study of their characterization using scanning electron microscopy, X-ray diffraction technique and Fourier transform infrared (FTIR) spectroscopy, and the mechanism of photodegradation of dyes have been discussed in this paper. The literature shows that SiO2, TiO2, and Al2O3 present in fly ash play an essential role in the photodegradation of dyes. Factors affecting the degradation of dyes, their kinetic studies, and methods to enhance photodegradation efficiency have also been discussed.
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Affiliation(s)
- Vishal Gadore
- Department of Chemistry, National Institute of Technology, Silchar, Assam, 788010, India
| | - Md Ahmaruzzaman
- Department of Chemistry, National Institute of Technology, Silchar, Assam, 788010, India.
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