The effects of fly ash with different mixing volume and different particle sizes on pore solution of cement-based materials were studied. The pore solution was extracted by squeezing at scheduled ages. The particle si...The effects of fly ash with different mixing volume and different particle sizes on pore solution of cement-based materials were studied. The pore solution was extracted by squeezing at scheduled ages. The particle size distribution of fly ash was classified as smaller than 45 μm and 45～80 μm,and the mixing volume was classified as 10% and 20%. The concentrations of K+,Na+ and Ca2+ were measured using Inductively Coupled Plasma Emission Spectrometer (ICP),and the pH was measured by acid-base titration. The results indicate that the concentrations of various ions were prompted at the initial time of the hydration. With further hydration,ion concentrations of K+ and Na+ raise again and finally stabilized,but there is a certain decline on Ca2+ later on. It also shows that fly ash exhibited great effect on the hydration of cement,it can lower the concentration of Ca2+ and pH of the pore solution,but raise the concentrations of K+ and Na+. More importantly,ion concentrations of K+,Na+ and Ca2+ reduced with smaller particle sizes of fly ash.展开更多
The reservoirs of the Songliao Basin are Composed of typical unstable sandstones,with high percentages of volcanic fragments and feldspar. In the course of sedimentation andburying, a series of physical and chemical r...The reservoirs of the Songliao Basin are Composed of typical unstable sandstones,with high percentages of volcanic fragments and feldspar. In the course of sedimentation andburying, a series of physical and chemical reactions took place between minerals and pete waterand water-rock reactions and ion exchange caused changes in ion assemblage of pore water. Hydration-hydrolysis, dissolution and the albitization of feldspar made many ions free from theirframework and inter into the pore water, and induced the precipitation of a large amount of authigenic minerals such as smectite and chlorite. DUring the diagenesis of sandstone, diageneticreactions involved several stages with increasing depth, and so did the precipitation of authigenic minerals and the transformation of minerals. The migration of ions is related with theprecipitation, transformation and dissolution of authigenic minerals. Thus, to deepen our studyon sandstone diagenesis is an important link for the analysis of ion migration in the evolution ofpore water. The origin and evolution of Pore water could be tracked in terms of the geochemistry of fluid inclusions in authigenic minerals. And the isotopic composition of the authigenicmineral calcite can provide its genetic information.展开更多
Isotopic and chemical compositions of pore water(PW) are highly relevant to environmental and forensic study. Five lake water(LW)samples and five sediment samples were collected to investigate the effects of pore size...Isotopic and chemical compositions of pore water(PW) are highly relevant to environmental and forensic study. Five lake water(LW)samples and five sediment samples were collected to investigate the effects of pore sizes of sediments on PW chemistry and stable isotopes and determine mechanisms controlling their variations. Six pore water fractions were extracted from different-sized pores in each sediment sample at six sequential centrifugal speeds for chemical and isotopic analysis. The sediments consisted mainly of quartz, feldspar, and clay minerals. The hydrogen and oxygen isotopic compositions of PW are mainly controlled by the overlying LW, although the lag effect of exchange between overlying LW and PW results in isotopic differences when recharge of LW is quicker than isotopic exchange in PW. Identical isotopic compositions of PW from sediments with different pore sizes indicate that isotopic exchange of water molecules with different pore sizes is a quick process. The ratio of average total dissolved solid(TDS) concentration of PW to TDS concentration of LW shows a strong relationship with adsorption capacity of sediments, demonstrating that remobilization of ions bound to sediments mainly causes a chemical shift from LW to PW.Concentrations of Ca^(2+), Mg^(2+),and Cl^-in PW remain unchanged,while concentrations of Na^+,K^+,and SO_4^(2-) slightly increase with decreasing pore size. Chemical differences of PW from sediments with different pore sizes are governed by ion adsorption properties and surface characteristics of different-si zed particles.展开更多
As the key component of electrochemical energy storage devices, an electrode with superior ions transport pores is the important premise for high electrochemical performance. In this paper, we developed a unique solut...As the key component of electrochemical energy storage devices, an electrode with superior ions transport pores is the important premise for high electrochemical performance. In this paper, we developed a unique solution process to prepare freestanding TiO_2/graphene hydrogel electrode with tunable density and porous structures. By incorporating room temperature ionic liquids（RTILs）, even upon drying, the non-volatile RTILs that remained in the gel film would preserve the efficient ion transport channels and prevent the electrode from closely stacking, to develop dense yet porous structures. As a result, the dense TiO_2/graphene gel film as an electrode for lithium ion battery displayed a good gravimetric electrochemical performance and more importantly a high volumetric performance.展开更多
Nuclear track pores were develop and observed in polycarbonate and LR-115 membranes. The polymer membranes were irradiated by swift heavy ions (SHI) and etched chemically. The stopping range of heavy ion is larger tha...Nuclear track pores were develop and observed in polycarbonate and LR-115 membranes. The polymer membranes were irradiated by swift heavy ions (SHI) and etched chemically. The stopping range of heavy ion is larger than the thickness of the membrane. The fluence of ions was changes from 103 to 107 ions-cm-2. The etching time was increased till pore size reaches up to micron range. The etching conditions were set to develop the porous tracks. The tracks are revealed under optical microscope as the size reaches up to micron or sub-micron size. The size was measured using standard electron diffraction grid. Results show that the porous tracks having average size of 2.4 micron can be developed in polycarbonate, while 5 - 10 micron porous tracks can be developed in LR-115.展开更多
Pore size and distribution in carbon-based materials are regarded to be a key factor to affect the electrochemical capacitive performances of the resultant electrodes.In this study,nitrogen and oxygen codoped porous c...Pore size and distribution in carbon-based materials are regarded to be a key factor to affect the electrochemical capacitive performances of the resultant electrodes.In this study,nitrogen and oxygen codoped porous carbons(NOPCs) are fabricated based on a simple Schiff-base reaction between m-phenylenediamine and terephthalaldehyde.The NOPCs have tunable morphologies,high surface areas,abundant heteroatom doping.More importantly,the carbons show a dominant micropores of 0.5-0.8 nm,comparable to the ionic sizes of LiTFSI(Li^+0.069 nm;TFSI-0.79 nm) water-in-salt electrolyte with a high potential window of 2.2 V.Consequently,the fabricated symmetric supercapacitor gives a high energy output of 30.5 Wh/kg at 1 kW/kg,and high stability after successive 10,000 cycles with ^96.8% retention.This study provides promising potential to develop high-energy supercapacitors.展开更多
Ion transport of sandwich cementitious materials（SCM） exposed to chloride environment was investigated by accelerated diffusion method and natural diffusion method. Pore structure and micromorphology of SCM were inv...Ion transport of sandwich cementitious materials（SCM） exposed to chloride environment was investigated by accelerated diffusion method and natural diffusion method. Pore structure and micromorphology of SCM were investigated by MIP and SEM-EDS. In comparison with the monolayer structural high performance concrete（HPC）, conductive charge for 6 hours, chloride diffusion coefficient, and apparent chloride diffusion coeffi cient of SCM were decreased by 30%-40%, two orders of magnitude and 40%-50%, respectively. Pore structure of ultra low ion permeability cementitious materials（ULIPCM） prepared for the facesheet is superior to that of HPC prepared for the core. As for porosity, the most probable pore radius, the content of pores with radius 50 nm and the surface area of pores, the order is ULIPCM展开更多
基金supported by the National Fundamental Scientific Research Project (PR China),relevant to"Basic research in Environmentally Friendly Concrete (2009CB623201)"research Project 50802067 supported by National Natural Science Foundation of China
文摘The effects of fly ash with different mixing volume and different particle sizes on pore solution of cement-based materials were studied. The pore solution was extracted by squeezing at scheduled ages. The particle size distribution of fly ash was classified as smaller than 45 μm and 45～80 μm,and the mixing volume was classified as 10% and 20%. The concentrations of K+,Na+ and Ca2+ were measured using Inductively Coupled Plasma Emission Spectrometer (ICP),and the pH was measured by acid-base titration. The results indicate that the concentrations of various ions were prompted at the initial time of the hydration. With further hydration,ion concentrations of K+ and Na+ raise again and finally stabilized,but there is a certain decline on Ca2+ later on. It also shows that fly ash exhibited great effect on the hydration of cement,it can lower the concentration of Ca2+ and pH of the pore solution,but raise the concentrations of K+ and Na+. More importantly,ion concentrations of K+,Na+ and Ca2+ reduced with smaller particle sizes of fly ash.
文摘The reservoirs of the Songliao Basin are Composed of typical unstable sandstones,with high percentages of volcanic fragments and feldspar. In the course of sedimentation andburying, a series of physical and chemical reactions took place between minerals and pete waterand water-rock reactions and ion exchange caused changes in ion assemblage of pore water. Hydration-hydrolysis, dissolution and the albitization of feldspar made many ions free from theirframework and inter into the pore water, and induced the precipitation of a large amount of authigenic minerals such as smectite and chlorite. DUring the diagenesis of sandstone, diageneticreactions involved several stages with increasing depth, and so did the precipitation of authigenic minerals and the transformation of minerals. The migration of ions is related with theprecipitation, transformation and dissolution of authigenic minerals. Thus, to deepen our studyon sandstone diagenesis is an important link for the analysis of ion migration in the evolution ofpore water. The origin and evolution of Pore water could be tracked in terms of the geochemistry of fluid inclusions in authigenic minerals. And the isotopic composition of the authigenicmineral calcite can provide its genetic information.
基金supported by the National Natural Science Foundation of China(Grants No.41672225 and 41222020)the Program of the China Geology Survey(Grant No.12120113103700)the Fundamental Research Funds for the Central Universities(Grant No.2652013028)
文摘Isotopic and chemical compositions of pore water(PW) are highly relevant to environmental and forensic study. Five lake water(LW)samples and five sediment samples were collected to investigate the effects of pore sizes of sediments on PW chemistry and stable isotopes and determine mechanisms controlling their variations. Six pore water fractions were extracted from different-sized pores in each sediment sample at six sequential centrifugal speeds for chemical and isotopic analysis. The sediments consisted mainly of quartz, feldspar, and clay minerals. The hydrogen and oxygen isotopic compositions of PW are mainly controlled by the overlying LW, although the lag effect of exchange between overlying LW and PW results in isotopic differences when recharge of LW is quicker than isotopic exchange in PW. Identical isotopic compositions of PW from sediments with different pore sizes indicate that isotopic exchange of water molecules with different pore sizes is a quick process. The ratio of average total dissolved solid(TDS) concentration of PW to TDS concentration of LW shows a strong relationship with adsorption capacity of sediments, demonstrating that remobilization of ions bound to sediments mainly causes a chemical shift from LW to PW.Concentrations of Ca^(2+), Mg^(2+),and Cl^-in PW remain unchanged,while concentrations of Na^+,K^+,and SO_4^(2-) slightly increase with decreasing pore size. Chemical differences of PW from sediments with different pore sizes are governed by ion adsorption properties and surface characteristics of different-si zed particles.
基金supported by grants from the National Natural Science Foundation of China(21303251)Innovation Program of Shanghai Municipal Education Commission(16SG17)the Shenzhen Science and Technology Foundation(JCYJ201419122040621)
文摘As the key component of electrochemical energy storage devices, an electrode with superior ions transport pores is the important premise for high electrochemical performance. In this paper, we developed a unique solution process to prepare freestanding TiO_2/graphene hydrogel electrode with tunable density and porous structures. By incorporating room temperature ionic liquids（RTILs）, even upon drying, the non-volatile RTILs that remained in the gel film would preserve the efficient ion transport channels and prevent the electrode from closely stacking, to develop dense yet porous structures. As a result, the dense TiO_2/graphene gel film as an electrode for lithium ion battery displayed a good gravimetric electrochemical performance and more importantly a high volumetric performance.
文摘Nuclear track pores were develop and observed in polycarbonate and LR-115 membranes. The polymer membranes were irradiated by swift heavy ions (SHI) and etched chemically. The stopping range of heavy ion is larger than the thickness of the membrane. The fluence of ions was changes from 103 to 107 ions-cm-2. The etching time was increased till pore size reaches up to micron range. The etching conditions were set to develop the porous tracks. The tracks are revealed under optical microscope as the size reaches up to micron or sub-micron size. The size was measured using standard electron diffraction grid. Results show that the porous tracks having average size of 2.4 micron can be developed in polycarbonate, while 5 - 10 micron porous tracks can be developed in LR-115.
基金financially supported by the National Natural Science Foundation of China(Nos.21875165,51772216 and 21703161)the Science and Technology Commission of Shanghai Municipality,China(No.14DZ2261100)the Fundamental Research Funds for the Central Universities。
文摘Pore size and distribution in carbon-based materials are regarded to be a key factor to affect the electrochemical capacitive performances of the resultant electrodes.In this study,nitrogen and oxygen codoped porous carbons(NOPCs) are fabricated based on a simple Schiff-base reaction between m-phenylenediamine and terephthalaldehyde.The NOPCs have tunable morphologies,high surface areas,abundant heteroatom doping.More importantly,the carbons show a dominant micropores of 0.5-0.8 nm,comparable to the ionic sizes of LiTFSI(Li^+0.069 nm;TFSI-0.79 nm) water-in-salt electrolyte with a high potential window of 2.2 V.Consequently,the fabricated symmetric supercapacitor gives a high energy output of 30.5 Wh/kg at 1 kW/kg,and high stability after successive 10,000 cycles with ^96.8% retention.This study provides promising potential to develop high-energy supercapacitors.
基金Funded by the National Natural Science Foundation of China(Nos.51002072 and 51562024)the Jiangxi Science and Technology Support Project(Nos.20133BBE50027 and 20143BBM26055)
文摘Ion transport of sandwich cementitious materials（SCM） exposed to chloride environment was investigated by accelerated diffusion method and natural diffusion method. Pore structure and micromorphology of SCM were investigated by MIP and SEM-EDS. In comparison with the monolayer structural high performance concrete（HPC）, conductive charge for 6 hours, chloride diffusion coefficient, and apparent chloride diffusion coeffi cient of SCM were decreased by 30%-40%, two orders of magnitude and 40%-50%, respectively. Pore structure of ultra low ion permeability cementitious materials（ULIPCM） prepared for the facesheet is superior to that of HPC prepared for the core. As for porosity, the most probable pore radius, the content of pores with radius 50 nm and the surface area of pores, the order is ULIPCM
