The change of conductivity and transparency of silver nanowire （AgNW） films by adding silver nano-particles （AgNPs） onto their surface is studied. The results show that the conductivity of the AgNW film is greatly...The change of conductivity and transparency of silver nanowire （AgNW） films by adding silver nano-particles （AgNPs） onto their surface is studied. The results show that the conductivity of the AgNW film is greatly improved with its sheet resistance reduced about 78. 7% to 51.9Ω/sq, and there is no obvious reduction of the transmittance. Further studies show that there is a self-assembling process pushing the AgNPs to concentrate at the intersecting points between AgNWs to weld them, which would reduce the intersection resistance between the AgNWs. This self-assembling behavior is led by the surface interactivities among the dispersing liquid of AgNPs, the surface of the substrate and AgNWs when the dispersing liquid is drying.展开更多
A complex lead-zinc-silver sulfide ore containing 2.98% Pb, 6.49% Zn and 116.32×10-4% Ag (mass fraction) from Yunnan Province, China, was subjected to this work. Research on mineral processing was conducted accor...A complex lead-zinc-silver sulfide ore containing 2.98% Pb, 6.49% Zn and 116.32×10-4% Ag (mass fraction) from Yunnan Province, China, was subjected to this work. Research on mineral processing was conducted according to the properties of the lead-zinc-silver ore. Under low alkalinity condition, the lead minerals are successfully separated from the zinc minerals with new reagent YZN as zinc depressant, new reagent BPB as lead collector, CuSO4 as zinc activator and ethyl xanthate as zinc collector. The associated silver is mostly concentrated to the lead concentrate. With the process utilized in this work, a lead concentrate of 51.90% Pb with a recovery of 82.34% and a zinc concentrate of 56.96% Zn with a recovery of 81.98% are produced. The silver recovery in the lead concentrate is 80.61%. Interactions of flotation reagents with minerals were investigated, of which the results indicate that the presence of proper amount of Na2S can precipitate Pb2+ and has a sulfidation on oxidized lead minerals. The results also show that Na2CO3 and YZN used together as combined depressants for sphalerite can signally improve the depressing effect of new reagent YZN on sphalerite.展开更多
Based on the mineralogical characterization for the polymetallic sulfide ore, the way to improve silver recovery was studied. The results showed that silver was the most valuable metal whose grade was 448.82 g/t Ag, w...Based on the mineralogical characterization for the polymetallic sulfide ore, the way to improve silver recovery was studied. The results showed that silver was the most valuable metal whose grade was 448.82 g/t Ag, while 0.118% Cu, 1.65% Pb and 1.06% Zn may be comprehensively utilizated. The main silver-bearing minerals were argent and aregentite which accounted for 87.18% of total silver. Argentite and other metal minerals were distributed in the gangue minerals in complex forms. Argentite grains of 33.76% minus 50 μm indicated that a fine grinding scheme was necessary to enhance the degree of dissociation, and meanwhile selective grinding must be considered to prevent a complete grinding of coarse grains. The optimum regrinding fineness in the Cu flotation was determined as 73% minus 37 μm, while grains of 68.5% minus 74 μm in one-stage grinding remained unchanged as much as possible. Consequently, silver recovery increased to 2.68%, as well as the content of Pb simultaneously decreased from 7.26% to 2.68% in the Cu concentrate. From the lead pyrometallurgical point of view, recovering larger amounts of silver and lead at the expense of decreasing the grade of lead to a suitable level is not only economically viable for the plant, but also convenient for subsequent processing. Silver and lead recovery increased to 13.18% and 12.58%, respectively, while the Pb grade decreased from 53.1% to 46.12% for the Pb concentrate.展开更多
The effects of silver sulfide (Ag 2S) on the bioleaching of chalcopyrite and pyrite were investigated in this paper. It has been shown that Ag 2S enhanced the yields of bioleaching of chalcopyrite but inhibited the bi...The effects of silver sulfide (Ag 2S) on the bioleaching of chalcopyrite and pyrite were investigated in this paper. It has been shown that Ag 2S enhanced the yields of bioleaching of chalcopyrite but inhibited the bio oxidation of pyrite. The addition of Ag 2S selectively increased the copper dissolution from the chalcopyrite containing ores in shake flasks with a recovery of 85.3% compared with 24.3% without Ag 2S, while slightly decreased the iron yields from 51% to 41.8%. The copper extraction of the chalcoopyrite containing waste rock in column leaching charged with 18 kg mass increased up to 21.7% in the presence of Ag 2S, while only 3.4% in the absence of the catalyst. The mechanism of Ag 2S catalysis could be explained well by the "Mixed potential model".展开更多
Silver nanoparticles (Ag-NPs), one of the most common types of nanomaterials in medical fields and consumer products, are known to have antimicrobial effects;these materials also undergo a series of chemical and biolo...Silver nanoparticles (Ag-NPs), one of the most common types of nanomaterials in medical fields and consumer products, are known to have antimicrobial effects;these materials also undergo a series of chemical and biological transformations in the environment. Although the pristine form of silver nanoparticles has been studied, less is known about the impacts of the transformed Ag-NPs on biological systems. This knowledge gap hinders the progress of effectively assessing the impacts of Ag-NPs on the environment and human health. In this study, we demonstrate that the most common form of transformed Ag-NPs, sulfidized silver nano-particles (Ag2S-NPs), show less damage on established Pseudomonas aeruginosa GFP (ATCC? 10145 GFP?) biofilm than the pristine form of the nanoparticle. At a dosage of 0.625 mg/L, the total biomass in the biofilm decreased 64% after being exposed to Ag-NPs and 44% after exposure to Ag2S-NPs. Live biofilms were also interrogated. We observed high reduction in live population for biofilm exposed to Ag-NPs and relatively low reduction by Ag2S-NPs at exposure concentrations higher than 0.625 mg/L. Compared with Ag-NPs, the lower solubility of Ag2S-NPs results in less Ag+ diffusion into established biofilms. Our results suggest that the sulfidation of Ag-NPs reduces their impacts on established biofilms, indicating that the transformed Ag-NPs may have less environmental or human health risks.展开更多
A cyanidation leaching process for a sulfide concentrate containing gold and silver with ammonia and other complexes was investigated,and its potential in decrease of cyanide consumption was examined.The equilibria be...A cyanidation leaching process for a sulfide concentrate containing gold and silver with ammonia and other complexes was investigated,and its potential in decrease of cyanide consumption was examined.The equilibria behaviors of copper and other metal ions in the CN-NH,-H_(2)0 system and the CN—NH,—EDTA-HjO system were analyzed by a microcomputer program.Experiments revealed that the leaching yield of gold in ammonia-cyanide solutions was raised from 86%to 99%from addition of EDTA in a certain concentration and its cooperative action with ammonia on the cyanidation of gold.Meanwhile,the leaching yield of silver was significantly increased from about 20%to 55%and the consumption of cyanide was decreased.展开更多
Pure and doped Polyvinylidene difluoride (PVDF) films, for the detection of infrared radiation, have been well documented using the mechanism of pyroelectricity. Alternatively, the electrical properties of films made ...Pure and doped Polyvinylidene difluoride (PVDF) films, for the detection of infrared radiation, have been well documented using the mechanism of pyroelectricity. Alternatively, the electrical properties of films made from Polyvinyl Alcohol (PVA) have received considerable attention in recent years. The investigation of surface resistivities of both such films, to this point, has received far less consideration in comparison to pyroelectric effects. In this research, we report temperature dependent surface resistivity measurements of commercial, and of multiwall carbon nanotubes (MWCNT), or Ag-nanoparticle doped PVA films. Without any variation in the temperature range from 22°C to 40°C with controlled humidity, we found that the surface resistivity decreases initially, reaches a minimum, but rises steadily as the temperature continues to increase. This research was conducted with the combined instrumentation of the Keithley Model 6517 Electrometer and Keithley Model 8009 resistivity test fixture using both commercial and in-house produced organic thin films. With the objective to quantify the suitability of PVDF and PVA films as IR detector materials, when using the surface resistivity phenomenon, instead of or in addition to the pyroelectricity, surface resistivity measurements are reported when considering bolometry. We found that the surface resistivity measurements on PVA films were readily implemented.展开更多
A facile and efficient strategy was reported for the preparation of graphene nanosheets-Ag2S hybrid by a simple hydrothermal process. First, Ag2S particles deposited on the surface of graphene oxide（GO） sheet. GO wa...A facile and efficient strategy was reported for the preparation of graphene nanosheets-Ag2S hybrid by a simple hydrothermal process. First, Ag2S particles deposited on the surface of graphene oxide（GO） sheet. GO was then reduced by hydrazine hydrate to graphene. The results of X-ray diffraction（XRD） and Fourier transform infrared（FTIR） demonstrated the efficient reduction of GO to graphene. Transmission electron microscopy（TEM） image of the sample reveals the morphology of the architecture of graphene-Ag2S hybrid. Ultraviolet-visible spectroscopy（UV-Vis） and photoluminescence（PL） measurement were further employed to study the optical properties of the obtained nanocomposite. This work can be extended to design other graphene-based hybrid nanomaterials, and the as-grown architectures may hold promise for many applications.展开更多
文摘The change of conductivity and transparency of silver nanowire （AgNW） films by adding silver nano-particles （AgNPs） onto their surface is studied. The results show that the conductivity of the AgNW film is greatly improved with its sheet resistance reduced about 78. 7% to 51.9Ω/sq, and there is no obvious reduction of the transmittance. Further studies show that there is a self-assembling process pushing the AgNPs to concentrate at the intersecting points between AgNWs to weld them, which would reduce the intersection resistance between the AgNWs. This self-assembling behavior is led by the surface interactivities among the dispersing liquid of AgNPs, the surface of the substrate and AgNWs when the dispersing liquid is drying.
基金Project(50874117) supported by the National Natural Science Foundation of China
文摘A complex lead-zinc-silver sulfide ore containing 2.98% Pb, 6.49% Zn and 116.32×10-4% Ag (mass fraction) from Yunnan Province, China, was subjected to this work. Research on mineral processing was conducted according to the properties of the lead-zinc-silver ore. Under low alkalinity condition, the lead minerals are successfully separated from the zinc minerals with new reagent YZN as zinc depressant, new reagent BPB as lead collector, CuSO4 as zinc activator and ethyl xanthate as zinc collector. The associated silver is mostly concentrated to the lead concentrate. With the process utilized in this work, a lead concentrate of 51.90% Pb with a recovery of 82.34% and a zinc concentrate of 56.96% Zn with a recovery of 81.98% are produced. The silver recovery in the lead concentrate is 80.61%. Interactions of flotation reagents with minerals were investigated, of which the results indicate that the presence of proper amount of Na2S can precipitate Pb2+ and has a sulfidation on oxidized lead minerals. The results also show that Na2CO3 and YZN used together as combined depressants for sphalerite can signally improve the depressing effect of new reagent YZN on sphalerite.
基金Funded by the National Natural Science Foundation of China(No.51374247)
文摘Based on the mineralogical characterization for the polymetallic sulfide ore, the way to improve silver recovery was studied. The results showed that silver was the most valuable metal whose grade was 448.82 g/t Ag, while 0.118% Cu, 1.65% Pb and 1.06% Zn may be comprehensively utilizated. The main silver-bearing minerals were argent and aregentite which accounted for 87.18% of total silver. Argentite and other metal minerals were distributed in the gangue minerals in complex forms. Argentite grains of 33.76% minus 50 μm indicated that a fine grinding scheme was necessary to enhance the degree of dissociation, and meanwhile selective grinding must be considered to prevent a complete grinding of coarse grains. The optimum regrinding fineness in the Cu flotation was determined as 73% minus 37 μm, while grains of 68.5% minus 74 μm in one-stage grinding remained unchanged as much as possible. Consequently, silver recovery increased to 2.68%, as well as the content of Pb simultaneously decreased from 7.26% to 2.68% in the Cu concentrate. From the lead pyrometallurgical point of view, recovering larger amounts of silver and lead at the expense of decreasing the grade of lead to a suitable level is not only economically viable for the plant, but also convenient for subsequent processing. Silver and lead recovery increased to 13.18% and 12.58%, respectively, while the Pb grade decreased from 53.1% to 46.12% for the Pb concentrate.
文摘The effects of silver sulfide (Ag 2S) on the bioleaching of chalcopyrite and pyrite were investigated in this paper. It has been shown that Ag 2S enhanced the yields of bioleaching of chalcopyrite but inhibited the bio oxidation of pyrite. The addition of Ag 2S selectively increased the copper dissolution from the chalcopyrite containing ores in shake flasks with a recovery of 85.3% compared with 24.3% without Ag 2S, while slightly decreased the iron yields from 51% to 41.8%. The copper extraction of the chalcoopyrite containing waste rock in column leaching charged with 18 kg mass increased up to 21.7% in the presence of Ag 2S, while only 3.4% in the absence of the catalyst. The mechanism of Ag 2S catalysis could be explained well by the "Mixed potential model".
文摘Silver nanoparticles (Ag-NPs), one of the most common types of nanomaterials in medical fields and consumer products, are known to have antimicrobial effects;these materials also undergo a series of chemical and biological transformations in the environment. Although the pristine form of silver nanoparticles has been studied, less is known about the impacts of the transformed Ag-NPs on biological systems. This knowledge gap hinders the progress of effectively assessing the impacts of Ag-NPs on the environment and human health. In this study, we demonstrate that the most common form of transformed Ag-NPs, sulfidized silver nano-particles (Ag2S-NPs), show less damage on established Pseudomonas aeruginosa GFP (ATCC? 10145 GFP?) biofilm than the pristine form of the nanoparticle. At a dosage of 0.625 mg/L, the total biomass in the biofilm decreased 64% after being exposed to Ag-NPs and 44% after exposure to Ag2S-NPs. Live biofilms were also interrogated. We observed high reduction in live population for biofilm exposed to Ag-NPs and relatively low reduction by Ag2S-NPs at exposure concentrations higher than 0.625 mg/L. Compared with Ag-NPs, the lower solubility of Ag2S-NPs results in less Ag+ diffusion into established biofilms. Our results suggest that the sulfidation of Ag-NPs reduces their impacts on established biofilms, indicating that the transformed Ag-NPs may have less environmental or human health risks.
文摘A cyanidation leaching process for a sulfide concentrate containing gold and silver with ammonia and other complexes was investigated,and its potential in decrease of cyanide consumption was examined.The equilibria behaviors of copper and other metal ions in the CN-NH,-H_(2)0 system and the CN—NH,—EDTA-HjO system were analyzed by a microcomputer program.Experiments revealed that the leaching yield of gold in ammonia-cyanide solutions was raised from 86%to 99%from addition of EDTA in a certain concentration and its cooperative action with ammonia on the cyanidation of gold.Meanwhile,the leaching yield of silver was significantly increased from about 20%to 55%and the consumption of cyanide was decreased.
文摘Pure and doped Polyvinylidene difluoride (PVDF) films, for the detection of infrared radiation, have been well documented using the mechanism of pyroelectricity. Alternatively, the electrical properties of films made from Polyvinyl Alcohol (PVA) have received considerable attention in recent years. The investigation of surface resistivities of both such films, to this point, has received far less consideration in comparison to pyroelectric effects. In this research, we report temperature dependent surface resistivity measurements of commercial, and of multiwall carbon nanotubes (MWCNT), or Ag-nanoparticle doped PVA films. Without any variation in the temperature range from 22°C to 40°C with controlled humidity, we found that the surface resistivity decreases initially, reaches a minimum, but rises steadily as the temperature continues to increase. This research was conducted with the combined instrumentation of the Keithley Model 6517 Electrometer and Keithley Model 8009 resistivity test fixture using both commercial and in-house produced organic thin films. With the objective to quantify the suitability of PVDF and PVA films as IR detector materials, when using the surface resistivity phenomenon, instead of or in addition to the pyroelectricity, surface resistivity measurements are reported when considering bolometry. We found that the surface resistivity measurements on PVA films were readily implemented.
基金Supported by the National High Technology Research and Development Program of China(No.2009AA03Z319)the Doctor Startup Fundation of Liaoning Province of China(No.20101010)the Fundamental Research Funds for the Central Universities of China(No.DUT12LK04)
文摘A facile and efficient strategy was reported for the preparation of graphene nanosheets-Ag2S hybrid by a simple hydrothermal process. First, Ag2S particles deposited on the surface of graphene oxide（GO） sheet. GO was then reduced by hydrazine hydrate to graphene. The results of X-ray diffraction（XRD） and Fourier transform infrared（FTIR） demonstrated the efficient reduction of GO to graphene. Transmission electron microscopy（TEM） image of the sample reveals the morphology of the architecture of graphene-Ag2S hybrid. Ultraviolet-visible spectroscopy（UV-Vis） and photoluminescence（PL） measurement were further employed to study the optical properties of the obtained nanocomposite. This work can be extended to design other graphene-based hybrid nanomaterials, and the as-grown architectures may hold promise for many applications.
