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Fang X, Zhang G, Zhang X, He S, Xu W, Zhang X, Zhong S. Resource utilization of medical waste incineration fly ash to activate peroxydisulfate for tetracycline degradation: Synergy between adsorption and PDS activation. ENVIRONMENTAL RESEARCH 2024; 258:119488. [PMID: 38925468 DOI: 10.1016/j.envres.2024.119488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 06/13/2024] [Accepted: 06/22/2024] [Indexed: 06/28/2024]
Abstract
Medical waste incineration fly ash (MWI FA) is classified as a hazardous solid waste. Therefore, the development of recycling technologies to convert MWI FA into useful products is necessary and challenging. In this study, we developed a sustainable approach for preparing a catalyst through the pyrolysis of water-washed MWI FA (WW FA-x, where x corresponds to the pyrolysis temperature). Subsequently, it was applied as a potent peroxydisulfate (PDS) activator to remove tetracycline (TC) from water. The results showed that the WW FA-800 exhibited remarkable adsorption performance as well as highly efficient catalytic activation of PDS, with a 115 mg/g maximum TC adsorption capacity and 93.5% (reaction kinetic rate = 315 μmol/g/h) TC removal within 60 min. A synergistic effect was achieved by adsorption and PDS activation. TC degradation was primarily driven by non-radical (1O2 and electron transfer) processes. WW FA-800 possesses multiple active sites, including defects, π-π*, O-CO groups, Fe0, and Cu(I). Three possible pathways for TC decomposition have been proposed, with the majority of intermediates exhibiting less toxicity than TC. Furthermore, the WW FA/PDS system exhibited an excellent anti-interference ability, and universality in the degradation of various organic contaminants. Notably, energy consumption was minimal, approximately 2.80 kWh/(g·TC), and the leachability of heavy metals in the WW FA-800 was within acceptable limits. This study provides a MWI FA recycling route for the development of highly active catalysts.
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Affiliation(s)
- Xiaolin Fang
- School of Environment & Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, PR China
| | - Guichang Zhang
- School of Environment & Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, PR China
| | - Xiaoping Zhang
- School of Environment & Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, PR China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters of Ministry of Education, Guangzhou, 510006, PR China; Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, Guangzhou, 510006, PR China; Guangdong Provincial Engineering and Technology Research Center for Environmental Risk Prevention and Emergency Disposal, Guangzhou, 510006, PR China.
| | - Songwen He
- School of Environment & Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, PR China
| | - Wei Xu
- School of Environment & Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, PR China
| | - Xin Zhang
- School of Environment & Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, PR China
| | - Siqi Zhong
- School of Environment & Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, PR China
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Han S, Chen K, Meng F, Gao Y, Li J, Lin L, Qin W, Jiang J. Mitigating heavy metal volatilization during thermal treatment of MSWI fly ash by using iron(III) sulfate as a chlorine depleting agent. JOURNAL OF HAZARDOUS MATERIALS 2024; 465:133185. [PMID: 38064950 DOI: 10.1016/j.jhazmat.2023.133185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 11/23/2023] [Accepted: 12/04/2023] [Indexed: 02/08/2024]
Abstract
In the thermal treatment of municipal solid waste incineration fly ash (FA), the presence of chlorides leads to the pronounced volatilization of heavy metals at high temperature, making heavy metals stabilization challenging. Conventional washing processes struggle to remove chlorides completely, and even minor residual chlorides can lead to significant heavy metal volatilization. This study innovatively applied iron(III) sulfate as a chlorine depleting agent, which can form FeCl3 (boiling point 316 °C) and volatilize to remove the residual chlorides at below 500 °C, thus preventing the chlorination and volatilization of heavy metals at 600-1000 °C. Using water-washed FA to produce lightweight aggregate (LWA) preparation, after adding iron(III) sulfate, the volatilization rates of Pb and Cd at 1140 °C decreased to 5.4% and 9.3%, respectively, a reduction of 82.8% and 84.1% compared to before its addition. The LWA met standard requirements in both performance and heavy metal leaching toxicity. The mechanism was further studied through thermodynamic equilibrium calculations and heating experiments of pure chemicals. This study presents novel approaches and insights for suppressing the volatilization of heavy metals in FA at high temperature, thereby promoting the advancement of thermal treatment techniques and the safe, resourceful disposal of FA.
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Affiliation(s)
- Siyu Han
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Kailun Chen
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Fanzhi Meng
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Yuchen Gao
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Jinglin Li
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Li Lin
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Weikai Qin
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Jianguo Jiang
- School of Environment, Tsinghua University, Beijing 100084, China.
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Chen K, Han S, Meng F, Lin L, Li J, Gao Y, Qin W, Jiang J. Acid controlled washing of municipal solid waste incineration fly ash: Extraction of calcium inhibiting heavy metals and reaction kinetics. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 909:168599. [PMID: 37981132 DOI: 10.1016/j.scitotenv.2023.168599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 11/12/2023] [Accepted: 11/13/2023] [Indexed: 11/21/2023]
Abstract
Washing method has attracted much attention in the research of municipal solid waste incineration (MSWI) fly ash treatment and resource utilization. However, the controlled leaching of heavy metals and the extraction of recyclable calcium in the washing process are still blank. Acid controlled washing was conducted with different acids, concentrations, times and temperatures to extract calcium while inhibiting heavy metals. The mechanism was investigated by reaction kinetics calculation and washed fly ash characterization. The high Ca concentration of 37,420 mg/L while the low heavy metal concentrations of around or <1 mg/L were achieved at 25 °C for 60 min under a liquid-solid ratio (L/S) of 3/1 in 1.5 M HCl. The reaction kinetics of acid controlled washing conformed the layer diffusion control. The results of X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrum (EDS) analysis indicated that the rate-limiting step was the diffusion of ions through the product layer. Simultaneously, the washing solution enriched in Ca, Na and K and the washed fly ash, which met the standard requirements (HJ 1134-2020) for leach toxicity, both had the potential for further resource utilization.
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Affiliation(s)
- Kailun Chen
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Siyu Han
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Fanzhi Meng
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Li Lin
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Jinglin Li
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Yuchen Gao
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Weikai Qin
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Jianguo Jiang
- School of Environment, Tsinghua University, Beijing 100084, China.
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