An efficient toluene removal in air using a plasma photocatalytic system（PPS） not only needs favorable surface reactions over photocatalysts under the action of plasma,but also requires the photocatalysts to efficie...An efficient toluene removal in air using a plasma photocatalytic system（PPS） not only needs favorable surface reactions over photocatalysts under the action of plasma,but also requires the photocatalysts to efficiently absorb light emitted from the discharge for driving the photocatalytic reactions. We report here that the PPS constructed by integrating a black titania（B-TiO2）photocatalyst with a dielectric barrier discharge（DBD） can effectively remove toluene with above 70% CO2 selectivity and remarkably reduced the concentration of secondary pollutants of ozone and nitrogen oxides at a specific energy input of 1500 J·l-1,while exhibiting good stability. Photocatalyst characterizations suggest that the B-TiO2 provides a high concentration of oxygen vacancies for the surface oxidation of toluene in DBD,and efficiently absorbs ultraviolet–visible light emitted from the discharge to induce plasma photocatalytic oxidation of toluene. The presence of B-TiO2 in the plasma region also results in a high discharge efficiency,facilitating the generation of large numbers of reactive species and thus the oxidation of toluene towards CO2. The greatly enhanced performance of the PPS integrated with B-TiO2 in toluene removal offers a promising approach to efficiently remove refractory volatile organic compounds from air at low temperatures.展开更多
Four pure cultures were isolated from soil samples potentially contaminated with gasoline compounds either at a construction site near a gas station in Fai Chi Kei,Macao SAR or in the northern parts of China（Beijing,...Four pure cultures were isolated from soil samples potentially contaminated with gasoline compounds either at a construction site near a gas station in Fai Chi Kei,Macao SAR or in the northern parts of China（Beijing,and Hebei and Shandong）.The effects of different concentrations of benzene,toluene,ethylbenzene,and three isomers（ortho-,meta-,and para-） of xylene（BTEX）,total petroleum hydrocarbons（TPH）,and trichloroethylene（TCE）,when they were present in mixtures,on the bio-removal effciencies of microbial isolates were investigated,together with their interactions during the bio-removal process.When the isolates were tested for the BTEX（50-350 mg/L）/TPH（2000 mg/L） mixture,BTEoX in BTEoX/TPH mixture was shown with higher bio-removal effciencies,while BTEmX in BTEmX/TPH mixture was shown with the lowest,regardless of isolates.The TPH in BTEmX/TPH mixture,on the other hand,were generally shown with higher bio-removal effciencies compared to when TPH mixed with BTEoX and BTEpX.When these BTEX mixtures（at 350 mg/L） were present with TCE（5-50 mg/L）,the stimulatory effect of TCE toward BTEoX bio-removal was observed for BTEoX/TCE mixture,while the inhibitory effect of TCE toward BTEmX for BTEmX/TCE mixture.The bio-removal effciency for TPH was shown lower in TPH（2000 mg/L）/TCE（5-50 mg/L） mixtures compared to TPH present alone,implying the inhibitory effect of TCE toward TPH bio-removal.For the mixture of BTEX（417 mg/L）,TPH（2000 mg/L） along with TCE（5- 50 mg/L）,TCE was shown co-metabolically removed more effciently at 15 mg/L,probably utilizing BTEX and/or TPH as primary substrates.展开更多
In this study, the improvement in the removal of chlorobenzene （C6H5Cl） in the air was investigated by combining dielectric barrier discharge （DBD） driven by bipolar pulse-power with catalysts. Molecular sieve 4A ...In this study, the improvement in the removal of chlorobenzene （C6H5Cl） in the air was investigated by combining dielectric barrier discharge （DBD） driven by bipolar pulse-power with catalysts. Molecular sieve 4A （MS-4A） and MnO2/γ-Al2O3 （MnO2/ALP） as two kinds of catalysts were tested at different positions in a DBD reactor. Catalysts were located either in the discharging area between two electrodes, or just behind the discharging area （in the afterglow area） closed to the outlet. The results indicated that DBD reactor with a bipolar pulse power-supply produced strong instant discharge and energetic particles, which can effectively activate catalysts of MS-4A and MnO2/ALP located in the afterglow area to achieve the synergistic effects on effective fission of chemical bonds of chlorobenzene. It was considered that the gas-chlorobenzene and the chlorobenzene adsorbed on the catalysts were decomposed simultaneously.展开更多
Dielectric barrier discharge(DBD)has been extensively investigated in the fields of environment and energy,whereas its practical implementation is still limited due to its unsatisfactory energy efficiency.In order to ...Dielectric barrier discharge(DBD)has been extensively investigated in the fields of environment and energy,whereas its practical implementation is still limited due to its unsatisfactory energy efficiency.In order to improve the energy efficiency of DBD,a novel double dielectric barrier discharge(NDDBD)reactor with high field emission and secondary electron emission was developed and compared with traditional DDBD(TDDBD)configuration.Firstly,the discharge characteristics of the two DDBD reactors were analyzed.Compared to TDDBD,the NDDBD reactor exhibited much stronger discharge intensity,higher transferred charge,dissipated power and gas temperature due to the effective utilization of cathode field emission and secondary electron emission.Subsequently,toluene abatement performance of the two reactors was evaluated.The toluene decomposition efficiency and mineralization rate of NDDBD were much higher than that of TDDBD,which were 86.44%-100%versus 28.17%-80.48%and 17.16%-43.42%versus 7.17%-16.44%at 2.17-15.12 W and 1.24-4.90 W respectively.NDDBD also exhibited higher energy yield than TDDBD,whereas the overall energy constant k_(overall)of the two reactors were similar.Finally,plausible toluene decomposition pathway in TDDBD and NDDBD was suggested based on organic intermediates that generated from toluene degradation.The finding of this study is expected to provide reference for the design and optimization of DBD reactor for volatile organic compounds control and other applications.展开更多
We used an impregnation method to prepare CuO/AC(activated carbon) composite materials of different CuO content and characterized them via scanning electron microscope(SEM), Brunauer–Emmett–Teller(BET), and Fourier ...We used an impregnation method to prepare CuO/AC(activated carbon) composite materials of different CuO content and characterized them via scanning electron microscope(SEM), Brunauer–Emmett–Teller(BET), and Fourier transform infrared spectroscopy(FT-IR).The effect of CuO content on toluene adsorption/desorption was evaluated.We explored the reusability of AC and AC03(CuO modified AC with CuO loading 0.3 wt.%) adsorbents via toluene adsorption/desorption cycle testing.We used quasi-firstand quasi-second-order models, the Bangham model, and the Weber–Morris model to fit the toluene adsorption data.The introduction of CuO species evidently improved the adsorption performance of activated carbon toward toluene.The CuO content markedly affected the specific surface area, CuO dispersal, the numbers of oxygen-containing functional groups on the surface, and adsorption performance of the prepared composite adsorbents.Low CuO content was not favorable for the formation of active adsorption sites,while high content greatly reduced the specific surface area, and even covered active adsorption sites.The toluene adsorption performance varied in the order AC03 > AC02 >AC05 > AC08 > AC01(AC03, AC02, AC05, AC08 and AC01 are CuO modifying AC with CuO loading 0.3, 0.2, 0.5 0.8 and 0.1 wt.%, respectively).The breakthrough time and toluene adsorption capacity of the AC03 composite adsorbent were 94 min and 701.8 mg/g,respectively, and the recycling efficiency was 92.8% after thermal desorption at 200°C.The adsorption process was best described by the Bangham model and adsorption could be divided into three stages.展开更多
Nb doped MnCe0.2Ox complex oxides catalysts prepared via a homogeneous precipitation method were investigated for synergistic catalytic removal of NOx and chlorobenzene(CB)at low temperatures.The MnNb0.4Ce0.2Ox cataly...Nb doped MnCe0.2Ox complex oxides catalysts prepared via a homogeneous precipitation method were investigated for synergistic catalytic removal of NOx and chlorobenzene(CB)at low temperatures.The MnNb0.4Ce0.2Ox catalyst with a molar ratio of Nb/Mn=0.4 exhibits excellent activity and the NOx and CB removal efficiency reaches 94.5%and 96%at 220℃,respectively.Furthermore,the NOx and CB removal efficiency of MnNb0.4Ce0.2Ox still remains above 80%after injecting 300 ppm SO2 and 7 vol%H2 O for 36 h.In addition,the presence of CB and NOx+NH3 can improve the NOx and CB removal efficiency of MnNb0.4Ce0.2Ox,respectively.The analysis results from N2-BET,Py-IR,H2-TPR and NH3-TPD reveal that the introduction of Nb increases the average pore size,pore volume and surface area,promoted the growth of Lewis acid amount obviously,and enhances redox ability of MnCe0.2Ox at 100-250℃.Moreover,the molecular migration process of NOx,NH3,CB and SO2 in NH3-SCR and CB oxidation reaction over MnNb0.4Ce0.2Ox catalysts were systematically studied.In situ DRIFTS,FT-IR and XPS also confirm that the adsorption of sulfate species and SO2 on the surface of MnNb0.4Ce0.2Ox is inhibited effectively by the introduction of Nb in the presence of SO2 and H2 O.Moreover,Nb additives also enhance the structural stability of MnNb0.4Ce0.2Ox,due to the interactions among Mn,Nb and Ce.The NH3-TPD,H2-TPR and in situ DRIFTS results also confirm that the MnNb0.4Ce0.2Ox still retains abundant acid sites and high redox ability in the presence of SO2 and H2O.In summary,MnNb0.4Ce0.2Ox catalysts represent a promising and effective candidate for controlling NOx and CB at low temperatures.展开更多
The synergetic abatement of multi-pollutants is one of the development trends of flue gas pollution control technology,which is still in the initial stage and facing many challenges.We developed a V_(2)O_(5)/TiO_(2)gr...The synergetic abatement of multi-pollutants is one of the development trends of flue gas pollution control technology,which is still in the initial stage and facing many challenges.We developed a V_(2)O_(5)/TiO_(2)granular catalyst and established the kinetic model for the simultaneous removal of NO and chlorobenzene(i.e.,an important precursor of dioxins).The granular catalyst synthesized using vanadyl acetylacetonate precursor showed good synergistic catalytic performance and stability.Although the SCR reaction of NO and the oxidation reaction of chlorobenzene mutually inhibited,the reaction order of each reaction was not considerably affected,and the pseudo-first-order reaction kinetics was still followed.The performance prediction of this work is of much value to the understanding and reasonable design of a catalytic system for multi-pollutants(i.e.,NO and dioxins)emission control.展开更多
A biotrickling filter packed with the regular ceramic spheres was designed and fabricated to purify the low toluene-concentration waste gas.Particular attention was made to the study of the start-up behavior of the bi...A biotrickling filter packed with the regular ceramic spheres was designed and fabricated to purify the low toluene-concentration waste gas.Particular attention was made to the study of the start-up behavior of the biotrickling filter.Moreover,the steady performances were investigated to establish the experimental correlation between the operation factors and removal efficiency.It was found that the start-up process of the biotrickling filter exhibited three stages including the biofilm formation,biofilm development,and biofilm stabilization.The OD600 nm of the circulated liquid,gas pressure drop,elimination capacity,and temperature rise maintained at a rather low level in the biofilm formation stage,then increased rapidly in the biofilm development stage,and finally reached a stable value in the biofilm stabilization stage.It was also found that the removal efficiency of the biotrickling filter in the stable period decreased with increase in the waste gas flow rate,circulated liquid flow rate,and diameter of the ceramic sphere.More interestingly,it was revealed the operation modes have a significant influence on the removal efficiency of the biotrickling filter,and the microorganism show a high activity under the operating temperature ranging from 30°C to 40°C.The experimental correlations for describing the effect of operation factors on the removal efficiency of the biotrickling filters under both the co-current and counter-current operation modes were obtained.The correlation results are in good agreement with the experimental data.展开更多
基金supported by National Natural Science Foundation of China (No. 21808024)Fundamental Research Funds for the Central Universities (DMU 3132018175)
文摘An efficient toluene removal in air using a plasma photocatalytic system（PPS） not only needs favorable surface reactions over photocatalysts under the action of plasma,but also requires the photocatalysts to efficiently absorb light emitted from the discharge for driving the photocatalytic reactions. We report here that the PPS constructed by integrating a black titania（B-TiO2）photocatalyst with a dielectric barrier discharge（DBD） can effectively remove toluene with above 70% CO2 selectivity and remarkably reduced the concentration of secondary pollutants of ozone and nitrogen oxides at a specific energy input of 1500 J·l-1,while exhibiting good stability. Photocatalyst characterizations suggest that the B-TiO2 provides a high concentration of oxygen vacancies for the surface oxidation of toluene in DBD,and efficiently absorbs ultraviolet–visible light emitted from the discharge to induce plasma photocatalytic oxidation of toluene. The presence of B-TiO2 in the plasma region also results in a high discharge efficiency,facilitating the generation of large numbers of reactive species and thus the oxidation of toluene towards CO2. The greatly enhanced performance of the PPS integrated with B-TiO2 in toluene removal offers a promising approach to efficiently remove refractory volatile organic compounds from air at low temperatures.
基金supported by the University of Macao Research Committee and the Macao Science and Technology Development Fund
文摘Four pure cultures were isolated from soil samples potentially contaminated with gasoline compounds either at a construction site near a gas station in Fai Chi Kei,Macao SAR or in the northern parts of China（Beijing,and Hebei and Shandong）.The effects of different concentrations of benzene,toluene,ethylbenzene,and three isomers（ortho-,meta-,and para-） of xylene（BTEX）,total petroleum hydrocarbons（TPH）,and trichloroethylene（TCE）,when they were present in mixtures,on the bio-removal effciencies of microbial isolates were investigated,together with their interactions during the bio-removal process.When the isolates were tested for the BTEX（50-350 mg/L）/TPH（2000 mg/L） mixture,BTEoX in BTEoX/TPH mixture was shown with higher bio-removal effciencies,while BTEmX in BTEmX/TPH mixture was shown with the lowest,regardless of isolates.The TPH in BTEmX/TPH mixture,on the other hand,were generally shown with higher bio-removal effciencies compared to when TPH mixed with BTEoX and BTEpX.When these BTEX mixtures（at 350 mg/L） were present with TCE（5-50 mg/L）,the stimulatory effect of TCE toward BTEoX bio-removal was observed for BTEoX/TCE mixture,while the inhibitory effect of TCE toward BTEmX for BTEmX/TCE mixture.The bio-removal effciency for TPH was shown lower in TPH（2000 mg/L）/TCE（5-50 mg/L） mixtures compared to TPH present alone,implying the inhibitory effect of TCE toward TPH bio-removal.For the mixture of BTEX（417 mg/L）,TPH（2000 mg/L） along with TCE（5- 50 mg/L）,TCE was shown co-metabolically removed more effciently at 15 mg/L,probably utilizing BTEX and/or TPH as primary substrates.
基金National Natural Science Foundation of China(No.50678031)
文摘In this study, the improvement in the removal of chlorobenzene （C6H5Cl） in the air was investigated by combining dielectric barrier discharge （DBD） driven by bipolar pulse-power with catalysts. Molecular sieve 4A （MS-4A） and MnO2/γ-Al2O3 （MnO2/ALP） as two kinds of catalysts were tested at different positions in a DBD reactor. Catalysts were located either in the discharging area between two electrodes, or just behind the discharging area （in the afterglow area） closed to the outlet. The results indicated that DBD reactor with a bipolar pulse power-supply produced strong instant discharge and energetic particles, which can effectively activate catalysts of MS-4A and MnO2/ALP located in the afterglow area to achieve the synergistic effects on effective fission of chemical bonds of chlorobenzene. It was considered that the gas-chlorobenzene and the chlorobenzene adsorbed on the catalysts were decomposed simultaneously.
基金financially supported by National Key R&D Program of China(No.2017YFC0212204)Key Research and Development Program of Shaanxi Province(No.2018ZDCXL-SF-02-04)。
文摘Dielectric barrier discharge(DBD)has been extensively investigated in the fields of environment and energy,whereas its practical implementation is still limited due to its unsatisfactory energy efficiency.In order to improve the energy efficiency of DBD,a novel double dielectric barrier discharge(NDDBD)reactor with high field emission and secondary electron emission was developed and compared with traditional DDBD(TDDBD)configuration.Firstly,the discharge characteristics of the two DDBD reactors were analyzed.Compared to TDDBD,the NDDBD reactor exhibited much stronger discharge intensity,higher transferred charge,dissipated power and gas temperature due to the effective utilization of cathode field emission and secondary electron emission.Subsequently,toluene abatement performance of the two reactors was evaluated.The toluene decomposition efficiency and mineralization rate of NDDBD were much higher than that of TDDBD,which were 86.44%-100%versus 28.17%-80.48%and 17.16%-43.42%versus 7.17%-16.44%at 2.17-15.12 W and 1.24-4.90 W respectively.NDDBD also exhibited higher energy yield than TDDBD,whereas the overall energy constant k_(overall)of the two reactors were similar.Finally,plausible toluene decomposition pathway in TDDBD and NDDBD was suggested based on organic intermediates that generated from toluene degradation.The finding of this study is expected to provide reference for the design and optimization of DBD reactor for volatile organic compounds control and other applications.
基金supported by Scientific Platform Project,Ministry of Education(No.fykf201907)Chongqing Feearth Environmental Technology Co.,Ltd.(No.1875029)Student Innovation Fund of Chongqing Technology and Business University(No.193019).
文摘We used an impregnation method to prepare CuO/AC(activated carbon) composite materials of different CuO content and characterized them via scanning electron microscope(SEM), Brunauer–Emmett–Teller(BET), and Fourier transform infrared spectroscopy(FT-IR).The effect of CuO content on toluene adsorption/desorption was evaluated.We explored the reusability of AC and AC03(CuO modified AC with CuO loading 0.3 wt.%) adsorbents via toluene adsorption/desorption cycle testing.We used quasi-firstand quasi-second-order models, the Bangham model, and the Weber–Morris model to fit the toluene adsorption data.The introduction of CuO species evidently improved the adsorption performance of activated carbon toward toluene.The CuO content markedly affected the specific surface area, CuO dispersal, the numbers of oxygen-containing functional groups on the surface, and adsorption performance of the prepared composite adsorbents.Low CuO content was not favorable for the formation of active adsorption sites,while high content greatly reduced the specific surface area, and even covered active adsorption sites.The toluene adsorption performance varied in the order AC03 > AC02 >AC05 > AC08 > AC01(AC03, AC02, AC05, AC08 and AC01 are CuO modifying AC with CuO loading 0.3, 0.2, 0.5 0.8 and 0.1 wt.%, respectively).The breakthrough time and toluene adsorption capacity of the AC03 composite adsorbent were 94 min and 701.8 mg/g,respectively, and the recycling efficiency was 92.8% after thermal desorption at 200°C.The adsorption process was best described by the Bangham model and adsorption could be divided into three stages.
基金Project supported by the National Natural Science Foundation of China(51902166)the Natural Science Foundation of Jiangsu Province(BK20190786+6 种基金BK20170954)the Key Research and Development Program of Jiangsu Province(BE2018074)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(18KJB430019)the Startup Foundation for Introducing Talent of NUIST(2017r073)the USA NIH/NIAID(R21AI107415)the NSF-PREM program(DMR 1827745)the Philadelphia Foundation。
文摘Nb doped MnCe0.2Ox complex oxides catalysts prepared via a homogeneous precipitation method were investigated for synergistic catalytic removal of NOx and chlorobenzene(CB)at low temperatures.The MnNb0.4Ce0.2Ox catalyst with a molar ratio of Nb/Mn=0.4 exhibits excellent activity and the NOx and CB removal efficiency reaches 94.5%and 96%at 220℃,respectively.Furthermore,the NOx and CB removal efficiency of MnNb0.4Ce0.2Ox still remains above 80%after injecting 300 ppm SO2 and 7 vol%H2 O for 36 h.In addition,the presence of CB and NOx+NH3 can improve the NOx and CB removal efficiency of MnNb0.4Ce0.2Ox,respectively.The analysis results from N2-BET,Py-IR,H2-TPR and NH3-TPD reveal that the introduction of Nb increases the average pore size,pore volume and surface area,promoted the growth of Lewis acid amount obviously,and enhances redox ability of MnCe0.2Ox at 100-250℃.Moreover,the molecular migration process of NOx,NH3,CB and SO2 in NH3-SCR and CB oxidation reaction over MnNb0.4Ce0.2Ox catalysts were systematically studied.In situ DRIFTS,FT-IR and XPS also confirm that the adsorption of sulfate species and SO2 on the surface of MnNb0.4Ce0.2Ox is inhibited effectively by the introduction of Nb in the presence of SO2 and H2 O.Moreover,Nb additives also enhance the structural stability of MnNb0.4Ce0.2Ox,due to the interactions among Mn,Nb and Ce.The NH3-TPD,H2-TPR and in situ DRIFTS results also confirm that the MnNb0.4Ce0.2Ox still retains abundant acid sites and high redox ability in the presence of SO2 and H2O.In summary,MnNb0.4Ce0.2Ox catalysts represent a promising and effective candidate for controlling NOx and CB at low temperatures.
基金We gratefully acknowledge the National Natural Science Foundation of China(Grant Nos.21876093 and 21777081).
文摘The synergetic abatement of multi-pollutants is one of the development trends of flue gas pollution control technology,which is still in the initial stage and facing many challenges.We developed a V_(2)O_(5)/TiO_(2)granular catalyst and established the kinetic model for the simultaneous removal of NO and chlorobenzene(i.e.,an important precursor of dioxins).The granular catalyst synthesized using vanadyl acetylacetonate precursor showed good synergistic catalytic performance and stability.Although the SCR reaction of NO and the oxidation reaction of chlorobenzene mutually inhibited,the reaction order of each reaction was not considerably affected,and the pseudo-first-order reaction kinetics was still followed.The performance prediction of this work is of much value to the understanding and reasonable design of a catalytic system for multi-pollutants(i.e.,NO and dioxins)emission control.
基金supported by the National Natural Science Foundation of China (Grant No. 50806086)the National Science Fund of China for Distinguished Young Scholars (Grant No. 50825602)
文摘A biotrickling filter packed with the regular ceramic spheres was designed and fabricated to purify the low toluene-concentration waste gas.Particular attention was made to the study of the start-up behavior of the biotrickling filter.Moreover,the steady performances were investigated to establish the experimental correlation between the operation factors and removal efficiency.It was found that the start-up process of the biotrickling filter exhibited three stages including the biofilm formation,biofilm development,and biofilm stabilization.The OD600 nm of the circulated liquid,gas pressure drop,elimination capacity,and temperature rise maintained at a rather low level in the biofilm formation stage,then increased rapidly in the biofilm development stage,and finally reached a stable value in the biofilm stabilization stage.It was also found that the removal efficiency of the biotrickling filter in the stable period decreased with increase in the waste gas flow rate,circulated liquid flow rate,and diameter of the ceramic sphere.More interestingly,it was revealed the operation modes have a significant influence on the removal efficiency of the biotrickling filter,and the microorganism show a high activity under the operating temperature ranging from 30°C to 40°C.The experimental correlations for describing the effect of operation factors on the removal efficiency of the biotrickling filters under both the co-current and counter-current operation modes were obtained.The correlation results are in good agreement with the experimental data.
