Six Ni-Mo catalysts with different metal contents were prepared and characterized by N2 adsorption and X-ray diffi＇actometry. The active phase microstructure of these catalysts was examined by the Raman spectroscopy,...Six Ni-Mo catalysts with different metal contents were prepared and characterized by N2 adsorption and X-ray diffi＇actometry. The active phase microstructure of these catalysts was examined by the Raman spectroscopy, temperature- programmed reduction （TPR）, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. Hydrodesulfurization （HDS） activity of catalyst samples were analyzed in a flow fixed-bed microreactor. The sulfidation degree of Mo and the length of the MoS2 slab slightly increased with the amount of metal loaded following sulfidation. This small change is attributed to polymolybdate species observed in all the oxidized catalysts. Weak metal-support interactions, as determined by the TPR technique, increased the NiSx sulfidation phase and MoS2 slab stacking. The HDS activity of the catalyst samples increased with the number of active sites. For high metal loading catalysts, their HDS activity was nearly identical because the sulfur atoms cannot easily approach active sites. This change is caused by the large number of stacked layers in the MoS2 slabs as well as the decrease in the specific surface area and pore volume of the catalyst samples with an increasing metal loading.展开更多
Sodium-treated sepiolite(Na Sep)-supported transition metal catalysts(TM/Na Sep;TM = Cu, Fe, Ni, Mn, and Co) were synthesized via a rotary evaporation method. Physicochemical properties of the as-synthesized samples w...Sodium-treated sepiolite(Na Sep)-supported transition metal catalysts(TM/Na Sep;TM = Cu, Fe, Ni, Mn, and Co) were synthesized via a rotary evaporation method. Physicochemical properties of the as-synthesized samples were characterized by means of various techniques, and their catalytic activities for HCHO(0.2%) oxidation were evaluated. Among the samples, Cu/Na Sep exhibited superior performance, and complete HCHO conversion was achieved at 100 ℃(GHSV = 240000 m L/(g·h)). Additionally, the sample retained good catalytic activity during a 42 h stability test. A number of factors, including elevated acidity, the abundance of oxygen species, and favorable low-temperature reducibility, were responsible for the excellent catalytic activity of Cu/Na Sep. According to the results of the in-situ DRIFTS characterization, the HCHO oxidation mechanism was as follows:(i) HCHO was rapidly decomposed into dioxymethylene(DOM) species on the Cu/Na Sep surface;(ii) DOM was then immediately converted to formate species;(iii) the resultant formate species were further oxidized to carbonates;(iv) the carbonate species were eventually converted to CO2 and H2O.展开更多
A metal rubber（MR） dry friction damper was designed based on the load supported by the rotor. An experimental apparatus for obtaining hysteresis loops of support under the precession load was designed. The elastic-d...A metal rubber（MR） dry friction damper was designed based on the load supported by the rotor. An experimental apparatus for obtaining hysteresis loops of support under the precession load was designed. The elastic-damping characteristics of the ring-shaped MR damper used as a rotor support under variable loads were presented by studying the hysteresis loops of the damper. The vibration rigidity and the energy dissipation coefficient were calculated from the hysteresis loops, based on the description of the deformation process of the MR element with simple structure in a dimensionless coordinating system. The calculation results showed that the energy dissipation coefficient in the inner of MR element and on the boundary between the damper and the frame of the rotor support were approximately equal. The comparison of the hysteresis loops for a precession load and a one-axial load indicated a large difference when the coefficient of the energy dissipation and the stiffness of the MR damper were concerned.展开更多
In order to meet the high temperature environment requirement of deep and superdeep well exploitation, a technology of large length-to-diameter ratio metal stator screw lining meshing with rotor is presented. Based on...In order to meet the high temperature environment requirement of deep and superdeep well exploitation, a technology of large length-to-diameter ratio metal stator screw lining meshing with rotor is presented. Based on the elastic-plasticity theory, and under the consideration of the effect of tube size, material mechanical parameters, friction coefficient and loading paths, the external pressure plastic forming mechanical model of metal stator screw lining is established, to study the optimal loading path of metal stator lining tube hydroforming process. The results show that wall thickness reduction of the external pressure tube hydroforming(THF) is about 4%, and three evaluation criteria of metal stator screw lining forming quality are presented: fillet stick mold coefficient, thickness relative error and forming quality coefficient. The smaller the three criteria are, the better the forming quality is.Each indicator has a trend of increase with the loading rate reducing, and the adjustment laws of die arc transition zone equidistance profile curve are acquired for improving tube forming quality. Hence, the research results prove the feasibility of external pressure THF used for processing high-accuracy large length-to-diameter ratio metal stator screw lining, and provide theoretical basis for designing new kind of stator structure which has better performance and longer service life.展开更多
The baseline study profiled Black-chin Tilapia(Sarotherodon.melanotheron),a fish farm pest species in Bataan,Philippines,in terms of yield(processing and fillet),proximate composition(moisture,ash,crude fat,and crude ...The baseline study profiled Black-chin Tilapia(Sarotherodon.melanotheron),a fish farm pest species in Bataan,Philippines,in terms of yield(processing and fillet),proximate composition(moisture,ash,crude fat,and crude protein),heavy metal load(cadmium[Cd],lead[Pb],arsenic[As],and mercury[Hg]),and microbial count(aerobic plate,Escherichia coli,and Staphylococcus aureus counts).The purpose was to establish the species’safety and quality for consumption and potential utilization in the processing of higher value fishery products.A completely randomized experiment using two factors,fish size(standard and small sizes)and collection season(dry and wet seasons),was employed.The collected data were also compared against food consumption and processing standards and/or previous reports on more valuable species.The results showed that the species has a comparable yield and mineral load with the more popular farmed Nile Tilapia(Oreochromis niloticus).It has high moisture and protein compositions.It is a lean fish that can serve as a cheaper functional raw material for processed fishery products.Moreover,the results showed that the species have no As,Cd,and Pb contamination,although traces of Hg,far below the permissible limits,were detected.The Hg load varies across collection season and fish maturity suggesting its manageability.For the microbial contents,the species’aerobic plate,Escherichia coli,and Staphylococcus aureus counts were far below the standard limits,although best post-capture practices are still suggested due to the kind of microbial parameters measured.It was concluded that the Sarotherodon melanotheron infesting Bataan farm ponds can be consumed safely and has the quality of potential raw material for processed fishery products.However,further information is still needed to establish the best post-capture handling on the species.Also,more studies must be done to determine the impact of storage and processing on its stability.展开更多
The current single-atom catalysts(SACs)for medicine still suffer from the limited active site density.Here,we develop a synthetic method capable of increasing both the metal loading and mass-specific activity of SACs ...The current single-atom catalysts(SACs)for medicine still suffer from the limited active site density.Here,we develop a synthetic method capable of increasing both the metal loading and mass-specific activity of SACs by exchanging zinc with iron.The constructed iron SACs(h^(3)-FNC)with a high metal loading of 6.27 wt%and an optimized adjacent Fe distance of~4 A exhibit excellent oxidase-like catalytic performance without significant activity decay after being stored for six months and promising antibacterial effects.Attractively,a“density effect”has been found at a high-enough metal doping amount,at which individual active sites become close enough to interact with each other and alter the electronic structure,resulting in significantly boosted intrinsic activity of single-atomic iron sites in h^(3)-FNCs by 2.3 times compared to low-and medium-loading SACs.Consequently,the overall catalytic activity of h^(3)-FNC is highly improved,with mass activity and metal mass-specific activity that are,respectively,66 and 315 times higher than those of commercial Pt/C.In addition,h^(3)-FNCs demonstrate efficiently enhanced capability in catalyzing oxygen reduction into superoxide anion(O_(2)·^(−))and glutathione(GSH)depletion.Both in vitro and in vivo assays demonstrate the superior antibacterial efficacy of h^(3)-FNCs in promoting wound healing.This work presents an intriguing activity-enhancement effect in catalysts and exhibits impressive therapeutic efficacy in combating bacterial infections.展开更多
This study was aimed at investigating the performance of anaerobic rotating biological cont- reactor treating synthetic wastewater containing a mixture of heavy metals under sulfate redu condition. Statistically valid...This study was aimed at investigating the performance of anaerobic rotating biological cont- reactor treating synthetic wastewater containing a mixture of heavy metals under sulfate redu condition. Statistically valid factorial design of experiments was carried out to understand dynamics of metal removal using this bioreactor system. Copper removal was maximum （〉98% followed by other heavy metals at their respective low inlet concentrations. Metal loading rates than 3.7 mg/L· h in case of Cu（II）; less than 1.69 mg/L· h for Ni（II）, Pb（II）, Zn（II）, Fe（III） and C are favorable to the performance of the An-RBC reactor. Removal efficiency of the heavy metals 1 mixture depended on the metal species and their inlet loading concentrations. Analysis of n precipitates formed in the sulfidogenic bioreactor by field emission scanning electron microscopyalong with energy dispersive X-ray spectroscopy （FESEM-EDX） confirmed metal sulfide precipitationby SRB. All these results clearly revealed that the attached growth biofilm bioreactor is well suited for heavy metal removal from complex mixture.展开更多
The next-generation Euro 7 standard proposed much lower pollutant limits from gasoline vehicles,specifically for CO and NO_(x),which would be challenging for the three-way catalysts(TWCs)utilized commercially to elimi...The next-generation Euro 7 standard proposed much lower pollutant limits from gasoline vehicles,specifically for CO and NO_(x),which would be challenging for the three-way catalysts(TWCs)utilized commercially to eliminate these pollutants.TWCs with reductive(Rh)and oxidative(Pd)active components on gasoline particulate filters(TWC on GPF)play importantly auxiliary roles in the remediation of CO and NO_(x)downstream the close coupled TWCs to meet their emission targets.Here,a low-content Rh-based TWC(0.17 wt%)zoned with a less expensive Pd-based TWC(0.29 wt%)for GPF applications(cGPF)is reported using improved colloidal deposition method.The supporting of Rh on Y-stabilized ZrO_(2)rather than on CeO_(2)-ZrO_(2)inhibits the formation of inactive Ce rhodate species,while Pd on CeO_(2)-ZrO_(2)not only guarantees the high oxygen storage capacity(OSC)but also enhances catalytic activity.The layout of the front one-fifth in volume being 0.29 wt%Pd on Ce_(0.43)Zr_(0.5)7O_(2)and the rear four-fifths being 0.17 wt%Rh on Zr_(0.85)Y_(0.15)O_(2)prevents the possible alloying of Rh with Pd.The highly effective zoned Rh and Pd TWCs show synergistic three-way activity before and after severe hydrothermal aging at 1000℃with 10%water for24 h,which could be potential choices for close coupled GPF application to satisfy the upcoming stringent emission standards,such as Euro 7 and China 6b.展开更多
Two humic acids （HAs） were isolated from contaminated river sediments present under comparative conditions in the Pearl River Basin, China. YFHA （the HA extracted at an open pyrite mining area in Yunfu） exhibited ...Two humic acids （HAs） were isolated from contaminated river sediments present under comparative conditions in the Pearl River Basin, China. YFHA （the HA extracted at an open pyrite mining area in Yunfu） exhibited a lower absorption intensity for certain bands in the Fourier transform infrared spectra, a lower E 4 /E 6 value （the UV absorbances at 465 nm （E 4 ） and 665 nm （E 6 ））, a lower apparent molecular weight, a lower polarity and a lower oxygen functionality in comparison with GZHA （the HA isolated at an urban living area in Guangzhou）. All these differences indicated a higher degree of humification of YFHA than GZHA. Overall, the enrichment patterns of permanent heavy metals in the studied HAs were similar to those in corresponding sediments. In particular, YFHA exhibited high enrichment of trace element Tl, a characteristic concomitant from the mining of the pyrite minerals. The adsorption isotherms of two HAs for goethite and pyrolusite, two representative geological materials, conformed to the Langmuir equation. Based on the qualitative relationships between the Langmuir constants of the adsorption isotherms and the chemical characteristics of HAs, the main mechanism of HA adsorption on these materials was suggested to be hydrophobic interaction. This study highlighted the promising use of HA as a peculiar bio-indicator of uncommon trace metal contaminations. The HA adsorption mechanism on representative geological materials further provided a theoretical basis for the study on the unusual metal behavior in complex environmental settings.展开更多
PtRu supported on TiO2-embedded carbon nanofibers(PtRu/TECNF),which was recently reported as a highly-active catalyst for methanol oxidation,was applied to a direct methanol fuel cell(DMFC),and the power generation pe...PtRu supported on TiO2-embedded carbon nanofibers(PtRu/TECNF),which was recently reported as a highly-active catalyst for methanol oxidation,was applied to a direct methanol fuel cell(DMFC),and the power generation performance was compared to that using the commercial PtRu/C.Before the comparison,the effect of the catalyst loading on the power density of the DMFC was investigated using PtRu(18 wt%)/TECNF.The DMFC power density showed a maximum at about a 1.5 mg cm2 PtRu loading that corresponds to about an 80 mm layer thickness.A catalyst layer thicker than this value reduced the power density probably due to the concentration overvoltage.The PtRu content in the PtRu/TECNF was then increased to 30 wt%or more to reduce the layer thickness and to increase the power density.The DMFC performance was compared to that of different anode catalysts at a 1 mg cm2 PtRu loading.The power density was maximized using the PtRu30 wt%/TECNF,which showed a 173 mW cm2 at 353 K and had 66 mm layer thick,that was 26%higher than that of commercial PtRu/C.The current–voltage curve of the DMFC with the PtRu/TECNF suggested an improved mass transport overvoltage,but a little improvement in the activation one despite using the catalyst with about a 2 times higher activity compared to that of the commercial PtRu/C.This was attributed to the lower Pt utilization of the nanofiber catalyst layer.展开更多
基金SINOPEC for its financial support(No.108012/No.108041)
文摘Six Ni-Mo catalysts with different metal contents were prepared and characterized by N2 adsorption and X-ray diffi＇actometry. The active phase microstructure of these catalysts was examined by the Raman spectroscopy, temperature- programmed reduction （TPR）, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. Hydrodesulfurization （HDS） activity of catalyst samples were analyzed in a flow fixed-bed microreactor. The sulfidation degree of Mo and the length of the MoS2 slab slightly increased with the amount of metal loaded following sulfidation. This small change is attributed to polymolybdate species observed in all the oxidized catalysts. Weak metal-support interactions, as determined by the TPR technique, increased the NiSx sulfidation phase and MoS2 slab stacking. The HDS activity of the catalyst samples increased with the number of active sites. For high metal loading catalysts, their HDS activity was nearly identical because the sulfur atoms cannot easily approach active sites. This change is caused by the large number of stacked layers in the MoS2 slabs as well as the decrease in the specific surface area and pore volume of the catalyst samples with an increasing metal loading.
文摘Sodium-treated sepiolite(Na Sep)-supported transition metal catalysts(TM/Na Sep;TM = Cu, Fe, Ni, Mn, and Co) were synthesized via a rotary evaporation method. Physicochemical properties of the as-synthesized samples were characterized by means of various techniques, and their catalytic activities for HCHO(0.2%) oxidation were evaluated. Among the samples, Cu/Na Sep exhibited superior performance, and complete HCHO conversion was achieved at 100 ℃(GHSV = 240000 m L/(g·h)). Additionally, the sample retained good catalytic activity during a 42 h stability test. A number of factors, including elevated acidity, the abundance of oxygen species, and favorable low-temperature reducibility, were responsible for the excellent catalytic activity of Cu/Na Sep. According to the results of the in-situ DRIFTS characterization, the HCHO oxidation mechanism was as follows:(i) HCHO was rapidly decomposed into dioxymethylene(DOM) species on the Cu/Na Sep surface;(ii) DOM was then immediately converted to formate species;(iii) the resultant formate species were further oxidized to carbonates;(iv) the carbonate species were eventually converted to CO2 and H2O.
基金This project is supported by National Natural Science Foundation of China (No.50675042).
文摘A metal rubber（MR） dry friction damper was designed based on the load supported by the rotor. An experimental apparatus for obtaining hysteresis loops of support under the precession load was designed. The elastic-damping characteristics of the ring-shaped MR damper used as a rotor support under variable loads were presented by studying the hysteresis loops of the damper. The vibration rigidity and the energy dissipation coefficient were calculated from the hysteresis loops, based on the description of the deformation process of the MR element with simple structure in a dimensionless coordinating system. The calculation results showed that the energy dissipation coefficient in the inner of MR element and on the boundary between the damper and the frame of the rotor support were approximately equal. The comparison of the hysteresis loops for a precession load and a one-axial load indicated a large difference when the coefficient of the energy dissipation and the stiffness of the MR damper were concerned.
基金Project(51222406)supported by the National Natural Science Foundation of ChinaProject(NCET-12-1061)supported by the Funds for New Century Excellent Talents in University of China+1 种基金Project(12TD007)supported by the Scientific Research Innovation Team Program of Sichuan Colleges and Universities,ChinaProject(2014TD0025)supported by the Youth Scientific Research Innovation Team Program of Sichuan Province,China
文摘In order to meet the high temperature environment requirement of deep and superdeep well exploitation, a technology of large length-to-diameter ratio metal stator screw lining meshing with rotor is presented. Based on the elastic-plasticity theory, and under the consideration of the effect of tube size, material mechanical parameters, friction coefficient and loading paths, the external pressure plastic forming mechanical model of metal stator screw lining is established, to study the optimal loading path of metal stator lining tube hydroforming process. The results show that wall thickness reduction of the external pressure tube hydroforming(THF) is about 4%, and three evaluation criteria of metal stator screw lining forming quality are presented: fillet stick mold coefficient, thickness relative error and forming quality coefficient. The smaller the three criteria are, the better the forming quality is.Each indicator has a trend of increase with the loading rate reducing, and the adjustment laws of die arc transition zone equidistance profile curve are acquired for improving tube forming quality. Hence, the research results prove the feasibility of external pressure THF used for processing high-accuracy large length-to-diameter ratio metal stator screw lining, and provide theoretical basis for designing new kind of stator structure which has better performance and longer service life.
文摘The baseline study profiled Black-chin Tilapia(Sarotherodon.melanotheron),a fish farm pest species in Bataan,Philippines,in terms of yield(processing and fillet),proximate composition(moisture,ash,crude fat,and crude protein),heavy metal load(cadmium[Cd],lead[Pb],arsenic[As],and mercury[Hg]),and microbial count(aerobic plate,Escherichia coli,and Staphylococcus aureus counts).The purpose was to establish the species’safety and quality for consumption and potential utilization in the processing of higher value fishery products.A completely randomized experiment using two factors,fish size(standard and small sizes)and collection season(dry and wet seasons),was employed.The collected data were also compared against food consumption and processing standards and/or previous reports on more valuable species.The results showed that the species has a comparable yield and mineral load with the more popular farmed Nile Tilapia(Oreochromis niloticus).It has high moisture and protein compositions.It is a lean fish that can serve as a cheaper functional raw material for processed fishery products.Moreover,the results showed that the species have no As,Cd,and Pb contamination,although traces of Hg,far below the permissible limits,were detected.The Hg load varies across collection season and fish maturity suggesting its manageability.For the microbial contents,the species’aerobic plate,Escherichia coli,and Staphylococcus aureus counts were far below the standard limits,although best post-capture practices are still suggested due to the kind of microbial parameters measured.It was concluded that the Sarotherodon melanotheron infesting Bataan farm ponds can be consumed safely and has the quality of potential raw material for processed fishery products.However,further information is still needed to establish the best post-capture handling on the species.Also,more studies must be done to determine the impact of storage and processing on its stability.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFB3804500)the National Natural Science Foundation of China(Grant No.52202352,22335006)+4 种基金the Shanghai Municipal Health Commission(Grant No.20224Y0010)the CAMS Innovation Fund for Medical Sciences(Grant No.2021-I2M-5-012)the Basic Research Program of Shanghai Municipal Government(Grant No.21JC1406000)the Fundamental Research Funds for the Central Universities(Grant No.22120230237,2023-3-YB-11,22120220618)the Basic Research Program of Shanghai Municipal Government(23DX1900200).
文摘The current single-atom catalysts(SACs)for medicine still suffer from the limited active site density.Here,we develop a synthetic method capable of increasing both the metal loading and mass-specific activity of SACs by exchanging zinc with iron.The constructed iron SACs(h^(3)-FNC)with a high metal loading of 6.27 wt%and an optimized adjacent Fe distance of~4 A exhibit excellent oxidase-like catalytic performance without significant activity decay after being stored for six months and promising antibacterial effects.Attractively,a“density effect”has been found at a high-enough metal doping amount,at which individual active sites become close enough to interact with each other and alter the electronic structure,resulting in significantly boosted intrinsic activity of single-atomic iron sites in h^(3)-FNCs by 2.3 times compared to low-and medium-loading SACs.Consequently,the overall catalytic activity of h^(3)-FNC is highly improved,with mass activity and metal mass-specific activity that are,respectively,66 and 315 times higher than those of commercial Pt/C.In addition,h^(3)-FNCs demonstrate efficiently enhanced capability in catalyzing oxygen reduction into superoxide anion(O_(2)·^(−))and glutathione(GSH)depletion.Both in vitro and in vivo assays demonstrate the superior antibacterial efficacy of h^(3)-FNCs in promoting wound healing.This work presents an intriguing activity-enhancement effect in catalysts and exhibits impressive therapeutic efficacy in combating bacterial infections.
文摘This study was aimed at investigating the performance of anaerobic rotating biological cont- reactor treating synthetic wastewater containing a mixture of heavy metals under sulfate redu condition. Statistically valid factorial design of experiments was carried out to understand dynamics of metal removal using this bioreactor system. Copper removal was maximum （〉98% followed by other heavy metals at their respective low inlet concentrations. Metal loading rates than 3.7 mg/L· h in case of Cu（II）; less than 1.69 mg/L· h for Ni（II）, Pb（II）, Zn（II）, Fe（III） and C are favorable to the performance of the An-RBC reactor. Removal efficiency of the heavy metals 1 mixture depended on the metal species and their inlet loading concentrations. Analysis of n precipitates formed in the sulfidogenic bioreactor by field emission scanning electron microscopyalong with energy dispersive X-ray spectroscopy （FESEM-EDX） confirmed metal sulfide precipitationby SRB. All these results clearly revealed that the attached growth biofilm bioreactor is well suited for heavy metal removal from complex mixture.
基金Project supported by the National Natural Science Foundation of China(22076062,22276070)China Postdoctoral Science Foundation(2022M711957)+1 种基金National Engineering Laboratory for Mobile Source Emission Control Technology(NELMS2019A14)Project of Jinan Municipal Bureau of Science and Technology(2020GXRC021).
文摘The next-generation Euro 7 standard proposed much lower pollutant limits from gasoline vehicles,specifically for CO and NO_(x),which would be challenging for the three-way catalysts(TWCs)utilized commercially to eliminate these pollutants.TWCs with reductive(Rh)and oxidative(Pd)active components on gasoline particulate filters(TWC on GPF)play importantly auxiliary roles in the remediation of CO and NO_(x)downstream the close coupled TWCs to meet their emission targets.Here,a low-content Rh-based TWC(0.17 wt%)zoned with a less expensive Pd-based TWC(0.29 wt%)for GPF applications(cGPF)is reported using improved colloidal deposition method.The supporting of Rh on Y-stabilized ZrO_(2)rather than on CeO_(2)-ZrO_(2)inhibits the formation of inactive Ce rhodate species,while Pd on CeO_(2)-ZrO_(2)not only guarantees the high oxygen storage capacity(OSC)but also enhances catalytic activity.The layout of the front one-fifth in volume being 0.29 wt%Pd on Ce_(0.43)Zr_(0.5)7O_(2)and the rear four-fifths being 0.17 wt%Rh on Zr_(0.85)Y_(0.15)O_(2)prevents the possible alloying of Rh with Pd.The highly effective zoned Rh and Pd TWCs show synergistic three-way activity before and after severe hydrothermal aging at 1000℃with 10%water for24 h,which could be potential choices for close coupled GPF application to satisfy the upcoming stringent emission standards,such as Euro 7 and China 6b.
基金supported by the United Foundation of National Natural Science Foundation of China and Guang-dong Provincial Government(No.U0633001)the National Natural Science Foundation of China(No.40930743)
文摘Two humic acids （HAs） were isolated from contaminated river sediments present under comparative conditions in the Pearl River Basin, China. YFHA （the HA extracted at an open pyrite mining area in Yunfu） exhibited a lower absorption intensity for certain bands in the Fourier transform infrared spectra, a lower E 4 /E 6 value （the UV absorbances at 465 nm （E 4 ） and 665 nm （E 6 ））, a lower apparent molecular weight, a lower polarity and a lower oxygen functionality in comparison with GZHA （the HA isolated at an urban living area in Guangzhou）. All these differences indicated a higher degree of humification of YFHA than GZHA. Overall, the enrichment patterns of permanent heavy metals in the studied HAs were similar to those in corresponding sediments. In particular, YFHA exhibited high enrichment of trace element Tl, a characteristic concomitant from the mining of the pyrite minerals. The adsorption isotherms of two HAs for goethite and pyrolusite, two representative geological materials, conformed to the Langmuir equation. Based on the qualitative relationships between the Langmuir constants of the adsorption isotherms and the chemical characteristics of HAs, the main mechanism of HA adsorption on these materials was suggested to be hydrophobic interaction. This study highlighted the promising use of HA as a peculiar bio-indicator of uncommon trace metal contaminations. The HA adsorption mechanism on representative geological materials further provided a theoretical basis for the study on the unusual metal behavior in complex environmental settings.
基金the Element Innovation Project,Ministry of Education,Japan,and by KAKENHI(26289300).
文摘PtRu supported on TiO2-embedded carbon nanofibers(PtRu/TECNF),which was recently reported as a highly-active catalyst for methanol oxidation,was applied to a direct methanol fuel cell(DMFC),and the power generation performance was compared to that using the commercial PtRu/C.Before the comparison,the effect of the catalyst loading on the power density of the DMFC was investigated using PtRu(18 wt%)/TECNF.The DMFC power density showed a maximum at about a 1.5 mg cm2 PtRu loading that corresponds to about an 80 mm layer thickness.A catalyst layer thicker than this value reduced the power density probably due to the concentration overvoltage.The PtRu content in the PtRu/TECNF was then increased to 30 wt%or more to reduce the layer thickness and to increase the power density.The DMFC performance was compared to that of different anode catalysts at a 1 mg cm2 PtRu loading.The power density was maximized using the PtRu30 wt%/TECNF,which showed a 173 mW cm2 at 353 K and had 66 mm layer thick,that was 26%higher than that of commercial PtRu/C.The current–voltage curve of the DMFC with the PtRu/TECNF suggested an improved mass transport overvoltage,but a little improvement in the activation one despite using the catalyst with about a 2 times higher activity compared to that of the commercial PtRu/C.This was attributed to the lower Pt utilization of the nanofiber catalyst layer.
