CHEMOSPHERE
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2019
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IF 5.108
Yuting Jiang,Shiying Yang,Junqin Liu,Tengfei Ren,Yixuan Zhang,Xinrong Sun
Hexabromocyclododecane (HBCD) has been listed in Annex A of the Stockholm Convention on Persistent Organic Pollutants (POPs) in 2013, but till now there is a lack of efficient methods for its degradation. In this study, nanoscale zero-valent aluminum (nZVAl), an excellent reductant with a very low redox potential of E 0 (Al 3+ /Al 0 ) = −1.662 V and strong electron transfer ability, was used to reductively degrade HBCD. Nearly 100% HBCD was degraded within 8 h reaction at 25 °C in ethanol/water (v/v, 50/50) solution without pH adjustment. And about 67% cyclododecatriene (CDT) was obtained, which is the complete debromination product. What’s more, the yield of Br − could achieve nearly 100% after optimizing conditions. The reaction was strongly promoted by increasing the dosages of nZVAl or decreasing the initial concentration of HBCD. The temperature had the most significant influence and the degradation was completed in 40 min with elevating the reaction temperature to 45 °C. The reaction mechanism was further revealed through the characterization of nZVAl particles before and after the reaction by SEM-EDS, TEM , HRTEM , XRD, and XPS. It was found that, after corrosion of the oxide film on the surface of nZVAl, metallic aluminum inside was exposed. The reactive sites were provided and electrons released were transferred from nZVAl to HBCD, causing HBCD degraded to dibromocyclododecadiene (DBCD) and then CDT by reductive debromination. These findings imply that nZVAl can degrade HBCD efficiently with no extra energy input and this offers a new idea for better treatment of HBCD.
研究领域:
环境科学
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材料科学
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化学工程
✓ 已验证
DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
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2019
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IF 5.589
Rui Wang,Ting Tang,Guining Lu,Zhiqiang Zheng,Kaibo Huang,Huafeng Li,Xueqin Tao,Hua Yin,Zhenqing Shi,Zhang Lin,Fengchang Wu,Zhi Dang
This study investigated the relative significance of electron transfer (e-transfer) and H-atom transfer (H-transfer) in a nanoscale zerovalent iron (n-ZVI) system and six n-ZVI-based bimetallic systems (Fe/Cu, Fe/Ni, Fe/Pd, Fe/Ag, Fe/Pt, and Fe/Au) through a case study of the debromination of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47). The results revealed that the reactivities of these bimetallic particles to BDE-47 decreased in the following order: Fe/Pd > Fe/Ag > Fe/Cu > Fe/Ni > Fe/Au > Fe/Pt ≈ n-ZVI. Debromination of BDE-47 in metal-H 2 systems suggested that Ni, Pd, Pt, Cu and Au can utilize H 2 to debrominate BDE-47. In the H-transfer process, BDE-47 preferentially debrominated the para‑ bromine substituent to generate BDE-17, whereas in the e-transfer process, BDE-47 preferentially debrominate ortho‑ bromine substituent to generate BDE-28. The debromination pathways of BDE-47 in bimetallic and NaBH 4 -metal systems suggested that Fe/Ni, Fe/Pd and Fe/Pt debrominate polybrominated diphenyl ethers (PBDEs) through a H-transfer dominant mechanism, while Fe/Ag debrominate PBDEs through an e-transfer dominant mechanism. In the cases of Fe/Cu and Fe/Au, the e-transfer and H-transfer may be equally involved in the debromination of PBDEs. These results greatly improve our understanding of the relative significance of e-transfer and H-transfer in the dehalogenation of halogenated aromatic compounds (HACs) in various n-ZVI-based bimetallic systems.
研究领域:
环境科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2019
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IF 7.65
Rui Wang,Zhixin Zhu,Shufei Tan,Jie Guo,Zhenming Xu
Degradation of brominated flame retardants (BFRs) in waste printed circuit boards (WPCBs) occurred due to mechanical force during the crushing process. In this study, a planetary ball-milling simulation experiment was designed to explore the mechanochemical debromination process of BFRs in WPCBs. The results showed that CaO had a better debromination performance than MgO and the mixture of Fe + SiO 2 , and high revolution speed and low mass ratio of WPCBs to CaO promoted the degradation of BFRs. After milling for 1 h, the particle size distribution was stable while the debromination efficiency increased with the increase of milling time. Ball milling promoted the migration of bromine from the inside to the new surface of WPCBs powder, and submicron particles adhered to the micron size aggregates. The polybrominated diphenyl ethers (PBDEs) detection showed that the concentrations of most PBDE congeners decreased with the increase of milling time, and a possible degradation pathway was proposed according to the experimental results. All the results provided new data for the mechanism of degradation of BFRs in WPCBs during the mechanical crushing process.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2018
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IF 6.653
Ming Lei,Shun Guo,Zhiying Wang,Lihua Zhu,Heqing Tang
Fast and deep debromination of polybrominated diphenyl ethers (PBDEs) under mild conditions is a challenge in the field of pollution control. A strategy was developed to achieve it by exploiting Cu/TiO2 composites as a noble-metal-free catalyst. Toward the debromination of 2,2′,4,4′-tetrabromodiphenyl ether (BDE47) as a typical PBDE, the use of Cu/TiO2 as a catalyst and hydrazine hydrate (N2H4·H2O) as a reducing agent yielded a degradation removal of 100% and a debromination efficiency of 87.7% in 3 s. A complete debromination of BDE47 at 1500 mg L–1 was possible by successively adding N2H4·H2O. A debromination pathway involving active H atom species was proposed for the catalytic transfer hydrogenation (CTH) of PBDEs according to the identified degradation intermediates. A mechanism was further clarified by density functional theory calculations: electrons are delivered from N2H4·H2O to the metallic Cu atom via a coordination of N in N2H4·H2O with Cu atoms. The electron-trapped Cu atom interacts with adsorbed BDE47 to form a transition complex, and then the debromination of this complex occurs on the surface of Cu nanoparticles due to the hydrogen donation of N2H4·H2O through the CTH process. The new method provides a highly efficient method to remove brominated pollutants.
研究领域:
环境科学
·
污染控制化学
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材料科学
✓ 已验证
DOI
高影响因子
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