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Fan WY, Zhang X, Guo PC, Sheng GP. Highly efficient removal of phosphonates by ferrate-induced oxidation coupled with in situ coagulation. J Hazard Mater 2023; 451:131104. [PMID: 36870127 DOI: 10.1016/j.jhazmat.2023.131104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 01/05/2023] [Accepted: 02/26/2023] [Indexed: 06/18/2023]
Abstract
Phosphonates, as a kind of important organic phosphorus in wastewater, should be removed in terms of their environmental risks. Unfortunately, traditional biological treatments fail to remove phosphonates effectively due to their biological inertness. The reported advanced oxidation processes (AOPs) usually require pH adjustment or coupling with other technologies to achieve high removal efficiency. Thus, a simple and efficient method for phosphonate removal is urgently needed. Herein, ferrate was found to remove phosphonates effectively in one-step under near-neutral circumstances by coupling oxidation and in-situ coagulation. Nitrilotrimethyl-phosphonic acid (NTMP), a typical phosphonate, could be efficiently oxidized by ferrate to release phosphate. The fraction of phosphate release increased with increasing ferrate dosage and reached 43.1% when 0.15 mM ferrate was added. Fe(VI) was responsible for NTMP oxidation, while Fe(V), Fe(IV) and ⋅OH played a minor role. Ferrate-induced phosphate release facilitated total phosphorus (TP) removal, because the phosphate is more easily removed via ferrate-resultant Fe(III) coagulation than the phosphonates. The coagulation removal of TP could reach up to 90% within 10 min. Furthermore, ferrate exerted high removal efficiencies for other commonly used phosphonates with approximately or up to 90% TP removal. This work provides a one-step efficient method to treat phosphonate-containing wastewaters.
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Affiliation(s)
- Wen-Yuan Fan
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, China; USTC-CityU Joint Advanced Research Center, Suzhou Research Institute, University of Science and Technology of China, Suzhou 215123, China
| | - Xin Zhang
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, China.
| | - Pu-Can Guo
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Guo-Ping Sheng
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, China.
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Zeng C, Hu H, Wang C, Shi Q, Zhang Q, Chen M, Wang Q, Zhang T. New insight into the changes in metal-phosphonate complexes from the addition of CaCO 3 to enhance ferric flocculation for efficient phosphonate removal. Chemosphere 2023; 311:137078. [PMID: 36328319 DOI: 10.1016/j.chemosphere.2022.137078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 10/26/2022] [Accepted: 10/28/2022] [Indexed: 06/16/2023]
Abstract
Due to the stable chelating effect of organic phosphonates in wastewater, phosphonates with increasing emission are difficult to be removed effectively by traditional ferric salt flocculation, which has posed tough challenges for reducing total phosphorus pollution in recent years. In this work, calcium carbonate (CaCO3) was introduced to work together with the widely investigated flocculant of ferric chloride (FeCl3) to realize an efficient removal of nitrilotrismethylenephosphonic acid (NTMP) at much lower dosage of FeCl3. With an aid of synergy effect from together use of CaCO3 and FeCl3, the remaining concentration as low as 0.16 mg-P/L, far below the sewage discharge limit (0.5 mg-P/L), was simply obtained with a significantly reduced Fe/P molar ratio at only 4, resulting from calcium source donor to form more stable Fe-Ca-P tridentate bridging complexes, high affinity towards ferric ions on CaCO3 surface and slow-release alkaline from CaCO3. A comparison among sodium hydroxide (NaOH), calcium hydroxide (Ca(OH)2) and CaCO3 as additives, was carried out to highlight the advantages of using CaCO3 and clarify the mechanism for the greatly improved performance by a set of characterizations including XRD, FTIR, Zeta potential, XPS, SEM-EDS and TG analyses. The addition of CaCO3 in ferric flocculation resulted in further obvious advantages such as 75% shortened settling time and only one-third of sludge volume of the precipitant, beneficial to the sample handling in engineering application. The proposed new approach has been further confirmed to work efficiently on real phosphonate-containing wastewater. Discussion on the interaction between CaCO3 and ferric salts in phosphonate solutions shed new insights into the working mechanism of using CaCO3 for the treatment of phosphonates-containing wastewater.
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Affiliation(s)
- Chaocheng Zeng
- School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei, 430070, China
| | - Huimin Hu
- School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei, 430070, China.
| | - Chao Wang
- School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei, 430070, China
| | - Qing Shi
- School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei, 430070, China
| | - Qiwu Zhang
- School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei, 430070, China.
| | - Mengfei Chen
- School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei, 430070, China
| | - Qian Wang
- School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei, 430070, China
| | - Tingting Zhang
- School of Chemical and Environmental Engineering, Wuhan Polytechnic University, Wuhan, Hubei, 430023, China
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