An innovative process was proposed for recovering lead from spent lead paste, and it produced less pollution and used lessenergy than the traditional process. First, lead dioxide in lead paste was reduced by glucose u...An innovative process was proposed for recovering lead from spent lead paste, and it produced less pollution and used lessenergy than the traditional process. First, lead dioxide in lead paste was reduced by glucose under hydrothermal conditions. Theeffects of the reaction time, glucose excess coefficient, temperature and pH on the hydrothermal reduction were systematicallyinvestigated. Under the optimized reduction conditions （i.e., temperature of 175 ℃, time of 120 min, glucose excess coefficient of3.0 and pH of 5.5）, 99.9% reduction ratio of lead dioxide is achieved, and only the PbO·PbSO4 and PbSO4 phases are observed in thereducing residue. Subsequently, the reducing residue is desulfurized in a NaOH solution, and approximately 99.40% of the sulfur isremoved. The main lead phase in the desulfurization residue is 3PbO·H2O.展开更多
Enzyme activities have the potential to indicate biological functioning of soils. In this study, soil urease, dehydrogenase, acid phosphatase and invertase activities and fluorescein diacetate(FDA) hydrolysis were mea...Enzyme activities have the potential to indicate biological functioning of soils. In this study, soil urease, dehydrogenase, acid phosphatase and invertase activities and fluorescein diacetate(FDA) hydrolysis were measured in two red soils spiked with Pb2+ranging from 0 to 2 400 mg kg-1to relate the enzyme activity values to both plant growth and the levels of available and total Pb2+concentrations in soils, and to examine the potential use of soil enzymes to assess the degrees of Pb contamination. Soil samples were taken for enzyme activities assaying during 3 month's incubation and then after planting of celery(Apium graveolens L.) and Chinese cabbage(Brassica chinensis L.). Enzyme activities in the red soil derived from arenaceous rock(RAR) were generally lower than those in the red soil developed on Quaternary red earths(REQ). At high Pb2+loadings, in both incubation and greenhouse studies, urease activity and FDA hydrolysis were significantly inhibited. But there were no significant relationships between soil dehydrogenase, acid phosphatase or invertase activity and soil Pb2+loadings in both RAR and REQ soils. The growth of celery and Chinese cabbage increased soil urease activity and FDA hydrolysis, but had minimal effect on dehydrogenase and invertase activities. There were positive correlations between celery biomass and soil urease activity and FDA hydrolysis. These results demonstrate that urease activity and FDA hydrolysis are more sensitive to Pb2+than acid phosphatase, dehydrogenase and invertase activities in the RAR and REQ soils.展开更多
Inspired by the great success of ultrathin two-dimensional(2D)layered crystals,more and more attention is being paid to preparing 2D nanostructures from non-layered materials.They can significantly enrich the 2D mater...Inspired by the great success of ultrathin two-dimensional(2D)layered crystals,more and more attention is being paid to preparing 2D nanostructures from non-layered materials.They can significantly enrich the 2D materials and 2D heterostructures family,extend their application prospects,and bring us distinct properties from their bulk counterparts due to the strong 2D confinement effect.However,the realization of 2D non-layered semiconductors with strong light-harvesting capability and the ability to construct high-performance 2D heterostructures is still a critical challenge.Herein,we successfully synthesized 2D PbSe semiconductors with a large lateral dimension and ultrathin thickness via van der Waals epitaxy.The fabricated 2D PbSe device exhibits good electrical conductivity and superior multi-wavelength photoresponse performance with high responsivity(∼10^(3) A/W)and impressive detectivity(∼2×10^(11) Jones).Furthermore,we demonstrate that 2D PbSe nanosheets can serve as component units for constructing high-performance heterostructure devices.With our strategy,ultrahigh current on/off ratio(∼10^(8))and rectification ratio(∼10^()6),as well as high responsivity(∼3×10^(3) A/W)and detectivity(∼7×10^(12) Jones),can be achieved in PbSe/MoS_(2) back-gated transistors.These results indicate that 2D PbSe nanosheets and their heterostructures have tremendous applications potential in electrical and optoelectronic devices.展开更多
基金Project(2016M602427)supported by the Postdoctoral Science Foundation of ChinaProject(51504292)supported by the National Natural Science Foundation of ChinaProject(2016zzts288)supported by Graduate Student Innovation Foundation of Central South University,China
文摘An innovative process was proposed for recovering lead from spent lead paste, and it produced less pollution and used lessenergy than the traditional process. First, lead dioxide in lead paste was reduced by glucose under hydrothermal conditions. Theeffects of the reaction time, glucose excess coefficient, temperature and pH on the hydrothermal reduction were systematicallyinvestigated. Under the optimized reduction conditions （i.e., temperature of 175 ℃, time of 120 min, glucose excess coefficient of3.0 and pH of 5.5）, 99.9% reduction ratio of lead dioxide is achieved, and only the PbO·PbSO4 and PbSO4 phases are observed in thereducing residue. Subsequently, the reducing residue is desulfurized in a NaOH solution, and approximately 99.40% of the sulfur isremoved. The main lead phase in the desulfurization residue is 3PbO·H2O.
基金Supported by the China-EU Science&Technology Cooperation Program(No.2011DFA101222)
文摘Enzyme activities have the potential to indicate biological functioning of soils. In this study, soil urease, dehydrogenase, acid phosphatase and invertase activities and fluorescein diacetate(FDA) hydrolysis were measured in two red soils spiked with Pb2+ranging from 0 to 2 400 mg kg-1to relate the enzyme activity values to both plant growth and the levels of available and total Pb2+concentrations in soils, and to examine the potential use of soil enzymes to assess the degrees of Pb contamination. Soil samples were taken for enzyme activities assaying during 3 month's incubation and then after planting of celery(Apium graveolens L.) and Chinese cabbage(Brassica chinensis L.). Enzyme activities in the red soil derived from arenaceous rock(RAR) were generally lower than those in the red soil developed on Quaternary red earths(REQ). At high Pb2+loadings, in both incubation and greenhouse studies, urease activity and FDA hydrolysis were significantly inhibited. But there were no significant relationships between soil dehydrogenase, acid phosphatase or invertase activity and soil Pb2+loadings in both RAR and REQ soils. The growth of celery and Chinese cabbage increased soil urease activity and FDA hydrolysis, but had minimal effect on dehydrogenase and invertase activities. There were positive correlations between celery biomass and soil urease activity and FDA hydrolysis. These results demonstrate that urease activity and FDA hydrolysis are more sensitive to Pb2+than acid phosphatase, dehydrogenase and invertase activities in the RAR and REQ soils.
基金supported by the National Key R&D Program of China(2018YFA0703700)the National Natural Science Foundation of China(91964203,62104171,62104172,and 62004142)+2 种基金the Natural Science Foundation of Hubei Province(2021CFB037)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB44000000)the Fundamental Research Funds for the Central Universities(2042021kf0067)。
文摘Inspired by the great success of ultrathin two-dimensional(2D)layered crystals,more and more attention is being paid to preparing 2D nanostructures from non-layered materials.They can significantly enrich the 2D materials and 2D heterostructures family,extend their application prospects,and bring us distinct properties from their bulk counterparts due to the strong 2D confinement effect.However,the realization of 2D non-layered semiconductors with strong light-harvesting capability and the ability to construct high-performance 2D heterostructures is still a critical challenge.Herein,we successfully synthesized 2D PbSe semiconductors with a large lateral dimension and ultrathin thickness via van der Waals epitaxy.The fabricated 2D PbSe device exhibits good electrical conductivity and superior multi-wavelength photoresponse performance with high responsivity(∼10^(3) A/W)and impressive detectivity(∼2×10^(11) Jones).Furthermore,we demonstrate that 2D PbSe nanosheets can serve as component units for constructing high-performance heterostructure devices.With our strategy,ultrahigh current on/off ratio(∼10^(8))and rectification ratio(∼10^()6),as well as high responsivity(∼3×10^(3) A/W)and detectivity(∼7×10^(12) Jones),can be achieved in PbSe/MoS_(2) back-gated transistors.These results indicate that 2D PbSe nanosheets and their heterostructures have tremendous applications potential in electrical and optoelectronic devices.
