Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans(PCDD/Fs)have attracted widespread concern due to their high toxicity,and their difficult manipulation in laboratories has made the research process t...Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans(PCDD/Fs)have attracted widespread concern due to their high toxicity,and their difficult manipulation in laboratories has made the research process tough.Thus,in our work,furan is selected as the model compound owing to the same structure of a central oxygenate ring.Although catalytic oxidation is regarded as an effective and applicable method for the abatement of PCDD/Fs,the synthesis of low-temperature catalysts is still a challenging problem in practical applications.Considering this situation,we prepared a novel V_(2)O_(5)/TiO_(2)catalyst modified with N-doped hierarchical porous carbon(NHPC)via a wet impregnation method.The V/T-1%NHPC catalyst could achieve expectant low-temperature performances with 50%furan conversion at 150℃and a complete conversion at 200℃,which decreased 23℃and 40℃compared to the V/T catalyst respectively.Moreover,the addition of NHPC presented lifting chemical stability during long-time test.The addition of NHPC in V/T catalysts decreased the formation of crystalline V_(2)O_(5) and increased the percentages of V^(5+)and O_(lat),which improved the utilization of vanadium ions and the catalytic activity.Simultaneously,the higher binding energy shift of O_(lat) implied more reaction possibility with other oxidise reactants.Importantly,this work proved the lifting catalytic activity by the interaction between catalysts and NHPC,and proposed the promoting effects of the N element.The results showed that the content of the pyridinic N and graphitic N in NHPC changed after combining with V/T catalyst,which played crucial roles in the excellent catalytic performance.Overall,this work provides comprehensive research of the V/T-1%NHPC catalyst toward furan oxidation at low temperature and explain the effects of N-doped biomass carbon in catalytic activity clearly,which gave a new thought to design low-temperature catalysts in PCDD/Fs degradation.Besides,the internal functional mechanisms of N species are worth further exploration in future studies.展开更多
A field study and theoretical calculations were performed to clarify the levels, profiles, and distributions of polybrominated dibenzo-p-dioxins and dibenzofurans(PBDD/Fs) in a cement kiln co-processing solid waste, w...A field study and theoretical calculations were performed to clarify the levels, profiles, and distributions of polybrominated dibenzo-p-dioxins and dibenzofurans(PBDD/Fs) in a cement kiln co-processing solid waste, with a focus on the PBDF formation mechanism.The raw materials contributed greatly to input of PBDD/Fs into the cement kiln. The PBDD/F concentrations in the raw materials were much higher than those in particle samples from different process stages in the cement kiln. The PBDD/F concentrations in the clinkers were1.40% of the concentrations in the raw materials, which indicated that the high destruction efficiencies for PBDD/Fs by cement kiln. PBDD/F distribution patterns in particle samples collected from different process stages indicated the cement kiln backend was a major site for PBDD/F formation. PBDFs with high levels of halogenation, such as heptabrominated furans(Hp BDF), were the dominant contributors to the total PBDD/F concentrations and accounted for 42%–73% of the total PBDD/F concentrations in the particle samples. Our results showed that co-processing of municipal solid waste in a cement kiln may influence the congener profile of PBDD/Fs, especially for the higher halogenated PBDD fraction. In addition, there were significant correlations between the decabromodiphenyl ether and heptabrominated furan concentrations, which is an indicator of transformation from polybrominated diphenyl ethers to PBDD/Fs. Theoretical calculations were performed and demonstrated that elimination of HBr and Br_2 from polybrominated diphenyl ethers were the dominant formation pathways for PBDD/Fs. These pathways differed from that for polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs).展开更多
Since the 2010 s, the authorities of Guangdong province and local governments have enhanced law enforcement and environmental regulations to abolish open burning, acid washing, and other uncontrolled e-waste recycling...Since the 2010 s, the authorities of Guangdong province and local governments have enhanced law enforcement and environmental regulations to abolish open burning, acid washing, and other uncontrolled e-waste recycling activities. In this study, ambient air and indoor dust near different kinds of e-waste recycling processes were collected in Guiyu and Qingyuan to investigate the pollution status of particles and polychlorinated dibenzo-pdioxins and furans（PCDD/Fs） after stricter environmental regulations. PM_（2.5） and PCDD/Fs both showed significantly reduced levels in the two regions compared with the documented data. The congener distribution and principal component analysis results also confirmed the significant differences between the current PCDD/Fs pollution characterizations and the historical ones. The estimated total intake doses via air inhalation and dust ingestion of children in the recycling region of Guiyu ranged from 10 to 32 pg TEQ/（kg·day）, which far exceeded the tolerable daily intake（TDI） limit（1–4 pg TEQ/（kg·day）. Although the measurements showed a significant reduction of the release of PCDD/Fs, the pollution status was still considered severe in Guiyu town after stricter regulations were implemented.展开更多
Polychlorinated dibenzo-p-dioxins and furans(PCDD/Fs)generated from municipal solid waste(MSW)incineration are considered as the key pollutants,which could pose serious risks to the environment and ecology.This study ...Polychlorinated dibenzo-p-dioxins and furans(PCDD/Fs)generated from municipal solid waste(MSW)incineration are considered as the key pollutants,which could pose serious risks to the environment and ecology.This study comprehensively investigated the effect of selective catalytic reduction(SCR)system on PCDD/F removal,phase distributions,and migrationtransformation characteristics of 17 congeners in a full-scale MSW incinerator.The three flue gas samples and two fly ash samples were separately collected for PCDD/F analysis.The results showed that the SCR system reduced the I-TEQ concentration of PCDD/Fs from 0.135 to 0.010 ng I-TEQ Nm^(−3)with a remarkable toxicity removal efficiency of 92.6%,through oxidation decomposition over V_(2)O_(5)-WO_(3)/TiO_(2)catalysts and chlorination process of low-chlorinated congeners.In addition,the de novo synthesis observed along the flue between SCR system and stack regenerated unexpected PCDD/Fs,which might enhance the PCDD/F emission level.This study verified the three pathways of SCR system on PCDD/F removal and inspired operating suggestions for SCR system,i.e.,keeping SCR system operated in stable and consistent conditions,regularly replacing V_(2)O_(5)-WO_(3)/TiO_(2)catalysts,and timely cleaning the dusts and inlet materials of SCR system,which would be beneficial for achieving the ultra-low emission of PCDD/Fs in full-scale MSW incinerators.展开更多
基金supported by the Natural Science Foundation of Zhejiang Province(No.LY21E060007),the National Natural Science Foundation of China(No.52006191).
文摘Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans(PCDD/Fs)have attracted widespread concern due to their high toxicity,and their difficult manipulation in laboratories has made the research process tough.Thus,in our work,furan is selected as the model compound owing to the same structure of a central oxygenate ring.Although catalytic oxidation is regarded as an effective and applicable method for the abatement of PCDD/Fs,the synthesis of low-temperature catalysts is still a challenging problem in practical applications.Considering this situation,we prepared a novel V_(2)O_(5)/TiO_(2)catalyst modified with N-doped hierarchical porous carbon(NHPC)via a wet impregnation method.The V/T-1%NHPC catalyst could achieve expectant low-temperature performances with 50%furan conversion at 150℃and a complete conversion at 200℃,which decreased 23℃and 40℃compared to the V/T catalyst respectively.Moreover,the addition of NHPC presented lifting chemical stability during long-time test.The addition of NHPC in V/T catalysts decreased the formation of crystalline V_(2)O_(5) and increased the percentages of V^(5+)and O_(lat),which improved the utilization of vanadium ions and the catalytic activity.Simultaneously,the higher binding energy shift of O_(lat) implied more reaction possibility with other oxidise reactants.Importantly,this work proved the lifting catalytic activity by the interaction between catalysts and NHPC,and proposed the promoting effects of the N element.The results showed that the content of the pyridinic N and graphitic N in NHPC changed after combining with V/T catalyst,which played crucial roles in the excellent catalytic performance.Overall,this work provides comprehensive research of the V/T-1%NHPC catalyst toward furan oxidation at low temperature and explain the effects of N-doped biomass carbon in catalytic activity clearly,which gave a new thought to design low-temperature catalysts in PCDD/Fs degradation.Besides,the internal functional mechanisms of N species are worth further exploration in future studies.
基金supported by the National Natural Science Foundation of China(No.21777172)the Collaborative Project supported by Chinese Academy of Sciences and Hebei Academy of Sciences(No.181602)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2016038)
文摘A field study and theoretical calculations were performed to clarify the levels, profiles, and distributions of polybrominated dibenzo-p-dioxins and dibenzofurans(PBDD/Fs) in a cement kiln co-processing solid waste, with a focus on the PBDF formation mechanism.The raw materials contributed greatly to input of PBDD/Fs into the cement kiln. The PBDD/F concentrations in the raw materials were much higher than those in particle samples from different process stages in the cement kiln. The PBDD/F concentrations in the clinkers were1.40% of the concentrations in the raw materials, which indicated that the high destruction efficiencies for PBDD/Fs by cement kiln. PBDD/F distribution patterns in particle samples collected from different process stages indicated the cement kiln backend was a major site for PBDD/F formation. PBDFs with high levels of halogenation, such as heptabrominated furans(Hp BDF), were the dominant contributors to the total PBDD/F concentrations and accounted for 42%–73% of the total PBDD/F concentrations in the particle samples. Our results showed that co-processing of municipal solid waste in a cement kiln may influence the congener profile of PBDD/Fs, especially for the higher halogenated PBDD fraction. In addition, there were significant correlations between the decabromodiphenyl ether and heptabrominated furan concentrations, which is an indicator of transformation from polybrominated diphenyl ethers to PBDD/Fs. Theoretical calculations were performed and demonstrated that elimination of HBr and Br_2 from polybrominated diphenyl ethers were the dominant formation pathways for PBDD/Fs. These pathways differed from that for polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs).
基金supported by the National Natural Science Foundation of China(No.91543202)the Ministry of Environmental Protection of the People's Republic of China(Nos.201409022,201409080 and 201509063)South China Institute of Environmental Science(No.PM-zx021-201510-015)
文摘Since the 2010 s, the authorities of Guangdong province and local governments have enhanced law enforcement and environmental regulations to abolish open burning, acid washing, and other uncontrolled e-waste recycling activities. In this study, ambient air and indoor dust near different kinds of e-waste recycling processes were collected in Guiyu and Qingyuan to investigate the pollution status of particles and polychlorinated dibenzo-pdioxins and furans（PCDD/Fs） after stricter environmental regulations. PM_（2.5） and PCDD/Fs both showed significantly reduced levels in the two regions compared with the documented data. The congener distribution and principal component analysis results also confirmed the significant differences between the current PCDD/Fs pollution characterizations and the historical ones. The estimated total intake doses via air inhalation and dust ingestion of children in the recycling region of Guiyu ranged from 10 to 32 pg TEQ/（kg·day）, which far exceeded the tolerable daily intake（TDI） limit（1–4 pg TEQ/（kg·day）. Although the measurements showed a significant reduction of the release of PCDD/Fs, the pollution status was still considered severe in Guiyu town after stricter regulations were implemented.
基金supported by the National Key R&D Program of China(Grant No. 2018YFC1902904)the National Natural Science Foundation of China (Grant No. 22008104)+4 种基金the Shenzhen Science and Technology Innovation Committee (Grant Nos. JCYJ20200109141642225,JCYJ20200109141227141, and JSGG20210713091810035)the Shenzhen Peacock Plan (Grant No. KQTD20160226195840229)provided by Basic and Applied Basic Research Foundation of Guangdong Province (Grant No. 2021A1515010148)Young S&T Talent Training Program of Guangdong Provincial Association for S&T(Grant No. SKXRC202230)Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme 2018
文摘Polychlorinated dibenzo-p-dioxins and furans(PCDD/Fs)generated from municipal solid waste(MSW)incineration are considered as the key pollutants,which could pose serious risks to the environment and ecology.This study comprehensively investigated the effect of selective catalytic reduction(SCR)system on PCDD/F removal,phase distributions,and migrationtransformation characteristics of 17 congeners in a full-scale MSW incinerator.The three flue gas samples and two fly ash samples were separately collected for PCDD/F analysis.The results showed that the SCR system reduced the I-TEQ concentration of PCDD/Fs from 0.135 to 0.010 ng I-TEQ Nm^(−3)with a remarkable toxicity removal efficiency of 92.6%,through oxidation decomposition over V_(2)O_(5)-WO_(3)/TiO_(2)catalysts and chlorination process of low-chlorinated congeners.In addition,the de novo synthesis observed along the flue between SCR system and stack regenerated unexpected PCDD/Fs,which might enhance the PCDD/F emission level.This study verified the three pathways of SCR system on PCDD/F removal and inspired operating suggestions for SCR system,i.e.,keeping SCR system operated in stable and consistent conditions,regularly replacing V_(2)O_(5)-WO_(3)/TiO_(2)catalysts,and timely cleaning the dusts and inlet materials of SCR system,which would be beneficial for achieving the ultra-low emission of PCDD/Fs in full-scale MSW incinerators.
