| 1. |
- Tang, Jinfeng, 1984, et al.
(författare)
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Assessment of heavy metals mobility and correlative recovery and decontamination from MSWI fly ash: Mechanism and hydrometallurgical process evaluation
- 2021
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 768
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Tidskriftsartikel (refereegranskat)abstract
- Fly ash from municipal solid waste incineration (MSWI) enriches many leachable toxic metals which readily migrate into the environment, posing serious risks to the ecosystem and human. In this study, the elements mobility, leaching availability as well as the potential maximum amounts of heavy metals in fly ash were thoroughly evaluated. To decontaminate the toxic elements from resulting fly ash leachates, The aqueous zinc (Zn) was recovered using Cyanex 572, cadmium (Cd) and copper (Cu) were effectively removed through adsorption process by a self-assembled hierarchical hydroxyapatite (HAP) nanostructure. The removal mechanism of Cd, Cu and Zn by leaching, extraction and adsorption was revealed with the results from XRD, ICP-MS and SEM. The results showed that fly ash has a high mobility under maximum availability leaching test (95% of fly ash was dissolved), a recovery rate of 91% for Zn can be obtained using Cyanex 572, and a high adsorption rate (> 95% for both Cu and Cd) was reached using HAP for the pristine fly ash leachate. The outcomes from isothermal and kinetic study revealed that Langmuir isotherm and pseudo-second order model can well describe the Cd and Cu adsorption behavior. Economic assessment suggested that the application of HAP for the removal of Cd and Cu is a technically sound and economically feasible approach. The findings of this study demonstrated that this comprehensive process integrated leaching, solvent extraction and consequential decontamination can be a practical strategy for MSWI fly ash treatment.
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| 2. |
- Tang, Jinfeng, 1984, et al.
(författare)
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Highly efficient recovery and clean-up of four heavy metals from MSWI fly ash by integrating leaching, selective extraction and adsorption
- 2019
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526. ; 234, s. 139-149
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Tidskriftsartikel (refereegranskat)abstract
- Municipal solid waste incineration (MSWI) fly ash contains significant amounts of heavy metals (e.g., Cd, Cu, Pb and Zn) and is therefore considered to be a hazardous waste requiring proper treatment prior to its disposal. In this work, an integrated hydrometallurgical process for treatment of MSWI fly ash was evaluated. Valuable metals, e.g. Cu and Zn, were first recovered by combining leaching and extraction sequentially. In the next step, the t removal of Cd and Pb from the remaining leachate using four types of iron-based adsorbents was evaluated. The leaching was optimized with respect to pH, leaching time and liquid to solid ratio. A test done under optimal conditions gave metal releases of 100% and 80% for Cu and Zn as well as 100% and 85% for Cd and Pb, respectively. The resulting leachate was contacted with organic phases based on kerosene containing the extractants LIX860N–I for Cu extraction and Cyanex 572 for Zn extraction in two consecutive steps. Efficient extractions were achieved, thus demonstrating that the combination of leaching and extraction can be successfully used for the recovery of Cu and Zn. Adsorption of heavy metal ions on various iron based sorbents to detoxify the aqueous effluent from the extraction showed good removal efficiency (more than 95%) for both Cd and Pb. The results of this study show that the proposed integrated process is a promising tool that can be used in the strategy for metal recovery and detoxification of MSWI fly ash.
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| 3. |
- Tang, Jinfeng, 1984, et al.
(författare)
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Optimizing critical metals recovery and correlative decontamination from MSWI fly ash: Evaluation of an integrating two-step leaching hydrometallurgical process
- 2022
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526. ; 368
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Tidskriftsartikel (refereegranskat)abstract
- While municipal solid waste incineration (MSWI) fly ash is classified as hazardous waste, it can also serve as an urban mining source for numerous precious metals. Of particular interest are antimony (Sb) and zinc (Zn); the former of which is a strategic and critical metal that is being rapidly depleted, putting society at high risk for supply shortages. In this work, a two-step leaching method for recovering Sb and Zn from MSWI fly ash is proposed. Furthermore, the leaching behavior and adsorption mechanism of Sb in the MSWI fly ash waste stream were also investigated. Results from the first constant pH leaching tests (CPLT) showed that under diluted acidic condition, the maximum amount of Sb released from fly ash was ∼20%. In addition, at pH 4.0, 67% of the fly ash was dissolved, while 79.3% and 12.1% of the Zn and Sb, respectively, were recovered. After optimizing and executing a second Sb leaching procedure (6 M HCl solution at 60 °C), >80% of the Sb was recovered. Thus, the proposed two-step leaching process, consisting of extraction followed by decontamination using a magnetic HAP@CoFe2O4 adsorbent, can eliminate the Sb in fly ash effluent with a removal efficiency >95%. Moreover, this process produces less toxic products and lowers the effluent residue concentration. As such, the two-step process described herein is suggested for Sb and Zn recovery from fly ash; as it not only enables precious metal recovery, but also aids in treating secondary waste streams produced from urban mining.
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| 4. |
- Tang, Jinfeng, 1984, et al.
(författare)
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Source analysis of municipal solid waste in a mega-city (Guangzhou): Challenges or opportunities?
- 2018
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Ingår i: Waste Management and Research. - 1096-3669 .- 0734-242X. ; 36:12, s. 1166-1176
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Tidskriftsartikel (refereegranskat)abstract
- Rapid economic development accelerates the generation of municipal solid waste (MSW), and thereby calls for an effective and reliable waste management strategy. In the present work, we systematically investigated the status of MSW management in a mega-city of China (Guangzhou). The data were collected from literatures, government statistics and field sampling work. It can be found that a combination of waste sorting by individual residents and a necessary quantity of sanitation workers is one of the most feasible strategies to achieve a sustainable waste management. With implementation of that integrated strategy, approximately 0.03 million tons of metal, 0.24 million tons of paper, as well as 0.46 million tons of plastics can be recycled/recovered for further processing. A cost reduction of 70 million US$ is achieved in comparison with the un-optimized system due to the sale revenue of recyclable materials and the saving from waste disposal fees. The values of environmental assessment were expressed as environmental load units. The developed scenarios could decrease the environmental cost, namely, 0.66 million US$. Based on the studies, waste sorting is urgently needed in Guangzhou. However, to make the proposed strategy to be more economically feasible, the sorting should be performed individually as well as with public participation. The establishment of a win–win situation for all stakeholders is an effective path for the improvement of the integrated waste management system.
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| 5. |
- Dai, Junxi, et al.
(författare)
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Promoted Sb removal with hydrogen production in microbial electrolysis cell by ZIF-67-derived modified sulfate-reducing bacteria bio-cathode
- 2023
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Ingår i: Science of the Total Environment. - : ELSEVIER. - 0048-9697 .- 1879-1026. ; 856
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Tidskriftsartikel (refereegranskat)abstract
- Bio-cathode Microbial electrolysis cell (MEC) has been widely discovered for heavy metals removal and hydrogen production. However, low electron transfer efficiency and heavy metal toxicity limit MEC treatment efficiency. In this study, ZIF-67 was introduced to modify Sulfate-reducing bacteria (SRB) bio-cathode to enhance the bioreduction of sulfate and Antimony (Sb) with hydrogen production in the MEC. ZIF-67 modified bio-cathode was developed from a bio-anode microbial fuel cell (MFC) by operating with an applied voltage of 0.8 V to reverse the polarity. Cyclic voltammetry, linear sweep voltammetry and electrochemical impedance were done to confirm the performance of the ZIF67 modified SRB bio-cathode. The synergy reduction of sulfate and Sb was accomplished by sulfide metal precipitation reaction from SRB itself. Maximum sulfate reduction rate approached 93.37 % and Sb removal efficiency could reach 92 %, which relies on the amount of sulfide concentration generated by sulfate reduction reaction, with 0.923 +/- 0.04 m(3) H-2/m(3) of hydrogen before adding Sb and 0.857 m(3) H-2/m(3) of hydrogen after adding Sb. The hydrogen was mainly produced in this system and the result of gas chromatography (GC) indicated that 73.27 % of hydrogen was produced. Meanwhile the precipitates were analyzed by X-ray diffraction and X-ray photoelectron spectroscopy to confirm Sb2S3 was generated from Sb (V).
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| 6. |
- Tang, Jinfeng, 1984, et al.
(författare)
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Assessment of copper and zinc recovery from MSWI fly ash in Guangzhou based on a hydrometallurgical process
- 2018
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 76, s. 225-233
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Tidskriftsartikel (refereegranskat)abstract
- Fly ash commonly accumulates a significant amount of heavy metals and most of these heavy metals are toxic and easily leached out to the environment, posing risks to human health. Thus, fly ash has been classified as a type of hazardous waste and requires proper treatment before disposal in specific landfill sites for hazardous waste. In this study, a hydrometallurgical process developed to recover copper and zinc performed in pilot scale close to industrial scale followed by a landfill compliance leaching test of the ash residue is evaluated. LIX860N-I and Cyanex 572 gave high selectively for extractions, a yield efficiency of 95% and 61% was achieved for copper and zinc respectively. Results of pilot experiments reveals that the combining metal recovery recycling and landfill disposal of the ash residue in a local regular landfill was demonstrated to be a technically and economically effective strategy. Specifically, the economic and environmental aspects of a scenario, in which the fly ash generated in Guangzhou is processed were systematically assessed. the assessment results show that a 7.15 million US$ of total expense reduction, a less energy cost of 19k GJ as well as 2100 tons less CO2 emissions could be achieved annually comparing to the current alternative, direct disposal of the fly ash as hazardous waste. The results reveal that the hydrometallurgical process has industrial application potential on both economic and environmental aspects and further optimization of the process can give more accurate assessment of the cost and environment effect. In addition, leaching tests and evaluation of solid residue according to the regulations specific to the country should be studied in future.
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| 7. |
- Wang, Yan, et al.
(författare)
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Bimetallic hybrids modified with carbon nanotubes as cathode catalysts for microbial fuel cell: Effective oxygen reduction catalysis and inhibition of biofilm formation
- 2021
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Ingår i: Journal of Power Sources. - Amsterdam, Netherlands : Elsevier. - 0378-7753 .- 1873-2755. ; 485
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Tidskriftsartikel (refereegranskat)abstract
- As a promising energy conversion equipment, the performance of microbial fuel cell (MFC) is affected by slow kinetics of oxygen reduction reaction (ORR). It is of great significance to explore electrocatalysts with high activity for sustainable energy applications. Herein, we synthesize the in-situ grown carbon nanotubes decorated electrocatalyst derived from copper-based metal organic frameworks (MOFs) co-doped with cobalt and nitrogen (CuCo@NCNTs) through straightforward immersion and pyrolysis process. The carbon nanotubes produced by metallic cobalt and high-activity bimetallic active sites formed by nitrogen doping enable CuCo@NCNTs to have the best oxygen reduction reaction (ORR) performance in alkaline electrolyte, with limit current density of 5.88 mA cm-2 and onset potential of 0.91 V (vs. RHE). Moreover, CuCo@NCNTs nanocomposite exhibits obvious antibacterial activity, and inhibiting the biofilm on cathode surface in antibacterial test and biomass quantification. The maximum power density (2757 mW m-3) of MFC modified with CuCo@NCNTs is even higher than Pt/C catalyst (2313 mW m-3). In short, CuCo@NCNTs nanocomposite can be an alternative cathode catalyst for MFC.
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| 8. |
- Wei, Lezhang, et al.
(författare)
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River morphology redistributes potentially toxic elements in acid mine drainage-impacted river sediments: Evidence, causes, and implications
- 2022
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Ingår i: Catena (Cremlingen. Print). - : ELSEVIER. - 0341-8162 .- 1872-6887. ; 214
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Tidskriftsartikel (refereegranskat)abstract
- River morphology plays a vital role in the transport of substance within them. However, our understanding of how natural and artificial morphologies redistribute different potentially toxic elements in acid mine drainage (AMD)-contaminated rivers remains poor. In this study, we linked morphological river features and physicochemical sediment characteristics to trace the redistribution of various potentially toxic elements and elucidate their implications for remediating rivers prone to AMD pollution. A dense network of sediment/soil samples was collected from different river morphological units, such as channels, dam reservoirs, pools, floodplain sandbars and wetlands in an AMD-impacted river. The analyses showed that the contaminant levels in channel generally decreased downstream from the headwater mine site, however, local fluctuations in certain areas were observed due to the trapping effect of various dams along the river. The As and Pb concentrations were higher at floodplain sandbars, while river channels exhibited higher Cd and Zn contamination. The concentrations and geochemical fractions of As, Cd, Cu, Pb and Zn in sediment/soil cores from sandbar and river channel also varied. Additionally, structural equation modeling analysis indicated that spatial variations in contaminant distributions were directly affected by physicochemical properties (such as the soil/sediment Fe, Zn, and S concentrations, and pH), which are indirectly affected by river morphology. The diverse morphology of the river redistributed AMDderived contaminants and could be used to identify contamination hotspots. Our analyses suggested that the feasibility and efficiency of previously proposed countermeasures varied for contaminants in different geomorphological units. In river channels, As uptake from sediments by aquatic plants may be less efficient than Cd, Cu, and Zn uptake due to its lower bioavailability. Moreover, vegetation prevented contaminant enriched soil particle erosion more than it aided in the phytoremediation of As- and Pb-contaminated sandbars. Thus the finding of this study provide a theoretical foundation for further studies on the transport and storage of AMDderived contaminants in similar rivers, along with the development of targeted remediation methods.
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| 9. |
- You, Henghui, et al.
(författare)
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Novel Strontium/Iron Bimetallic Carbon Composites as Synergistic Catalyst for Oxygen Reduction Reaction in Microbial Fuel Cells
- 2021
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Ingår i: Electrocatalysis. - : SPRINGER. - 1868-2529 .- 1868-5994. ; 12:6, s. 759-770
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Tidskriftsartikel (refereegranskat)abstract
- It is critical to develop non-noble metal (NNM) electrocatalysts with excellent stability and innovative activity for oxygen reduction reaction (ORR) in the microbial fuel cells (MFCs), which is a promising energy conversion technology. Herein, the preparation of iron carbide electrocatalysts (SrCO3/Fe3C) by the pyrolysis of a bimetal precursor (Sr and Fe) is proposed as a feasible strategy to realize a highly active electrocatalyst for ORR. Based on the catalytic potential of Sr-based materials, Fe species doping can provide more beneficial active sites for ORR. Concisely, the SrCO3/Fe3C(1:12) catalyst achieves the onset potential of 0.197 V (vs. Ag/AgCl) superior than Pt/C catalyst (0.193 V vs. Ag/AgCl) and the half-wave potential of -0.157 V (vs. Ag/AgCl) in 0.1-M KOH solution. Furthermore, the electrocatalyst exhibits nearly four-electron pathway, and generates less than 3% H2O2. Compared with Pt/C catalyst, it possesses preferable stability and superior methanol tolerance. Moreover, a composite electrode with SrCO3/Fe3C(1:12) as a catalyst on the carbon cloth demonstrated a superb air cathode in MFCs with a power density of 398.98 mW m(-2), which can outperform than 10 wt% Pt/C catalysts (342.13 mW m(-2)) on MFCs.
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| 10. |
- Zhang, Hongguo, et al.
(författare)
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Cu-doped CaFeO3 perovskite oxide as oxygen reduction catalyst in air cathode microbial fuel cells
- 2022
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Ingår i: Environmental Research. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0013-9351 .- 1096-0953. ; 214
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Tidskriftsartikel (refereegranskat)abstract
- Cathode electrocatalyst is quite critical to realize the application of microbial fuel cells (MFCs). Perovskite oxides have been considered as potential MFCs cathode catalysts to replace Pt/C. Herein, Cu-doped perovskite oxide with a stable porous structure and excellent conductivity was successfully prepared through a sol-gel method. Due to the incorporation of Cu, CaFe0.9Cu0.1O3 has more micropores and a larger surface area, which are more conducive to contact with oxygen. Doping Cu resulted in more Fe3+ in B-site and thus enhanced its binding capability to oxygen molecules. The data from electrochemical test demonstrated that the as-prepared catalyst has good conductivity, high stability, and excellent ORR properties. Compared with Pt/C catalyst, CaFe0.9Cu0.1O3 exhibits a lower overpotential, which had an onset potential of 0.195 V and a half-wave potential of 0.224 V, respectively. CaFe0.9Cu0.1O3 displays an outstanding four-electron pathway for ORR mechanism and demonstrates superiors corrosion resistance and stability. The MFC with CaFe0.9Cu0.1O3 has a greater maximum power density (1090 mW m(-3)) rather than that of Pt/C cathode (970 mW m(-3)). This work demonstrated CaFe0.9Cu0.1O3 is an economic and efficient cathodic catalyst for MFCs.
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