Pure water has been characterized for nearly a century, by its dissociation into hydronium （H3O）1＋ and hydroxide （HO）1- ions. As a chemical equilibrium reaction, the equilibrium constant, known as the ion product...Pure water has been characterized for nearly a century, by its dissociation into hydronium （H3O）1＋ and hydroxide （HO）1- ions. As a chemical equilibrium reaction, the equilibrium constant, known as the ion product or the product of the equilibrium concentration of the two ion species, has been extensively measured by chemists over the liquid water temperature and pressure range. The experimental data have been nonlinear least-squares fitted to chemical thermodynamic-based equilibrium equations, which have been accepted as the industrial standard for 35 years. In this study, a new and statistical-physics-based water ion product equation is presented, in which, the ions are the positively charged protons and the negatively charged proton-holes or prohols. Nonlinear least squares fits of our equation to the experimental data in the 0-100℃ pure liquid water range, give a factor of two better precision than the 35-year industrial standard.展开更多
Samples of fog water collected in the area of Guangzhou during February, March and April of 2005 are used in this work to study the chemical composition of fog water in polluting fog there. Three typical episodes of p...Samples of fog water collected in the area of Guangzhou during February, March and April of 2005 are used in this work to study the chemical composition of fog water in polluting fog there. Three typical episodes of polluting fog are analyzed in terms of ionic concentration and their possible sources. It is found that the concentration of various ions in fog water is much higher than those in rainwater. Fog not only blocks visual range but contains liquid particles that result in high degree of pollution and are very harmful to human health. SO4= is the anion with the highest concentration in fog water, followed by NO3-. For the cation, Ca++ and NH4+ are the highest in concentration. It is then known that rainwater is more acidic than fog water, indicating that ionic concentration of fog water is much higher than that of rainwater, but there are much more buffering materials in fog water, like NH4+ and Ca++. There is significant enrichment of Ca++, SO4=, and Mg++ in fog water. In the Guangzhou area, fog water from polluting fog is mainly influenced continental environment and human activity. The episodes of serious fog pollution during the time have immediate relationships with the presence of abundant water vapor and large amount of polluting aerosol particles.展开更多
Activated carbons were prepared by two chemical methods and the adsorption of Cu(II) on activated carbons from aqueous solution containing amino groups was studied. The first method involved the chlorination of activa...Activated carbons were prepared by two chemical methods and the adsorption of Cu(II) on activated carbons from aqueous solution containing amino groups was studied. The first method involved the chlorination of activated carbon following by substitution of chloride groups with amino groups, and the second involved the nitrilation of activated carbon with reduction of nitro groups to amino groups. Resultant activated carbons were characterized in terms of porous structure, elemental analysis, FTIR spectroscopy, XPS, Boehm titration,and p Hzpc. Kinetic and equilibrium tests were performed for copper adsorption in the batch mode. Also,adsorption mechanism and effect of p H on the adsorption of Cu(II) ions were discussed. Adsorption study shows enhanced adsorption for copper on the modified activated carbons, mainly by the presence of amino groups, and the Freundlich model is applicable for the activated carbons. It is suggested that binding of nitrogen atoms with Cu(II) ions is stronger than that with H+ions due to relatively higher divalent charge or stronger electrostatic force.展开更多
This paper presents an assessment of the hydrochemical characteristics of groundwater in Northern Gezira State, Central Sudan. The approaches followed here include the chemical analyses for major ions chemistry and co...This paper presents an assessment of the hydrochemical characteristics of groundwater in Northern Gezira State, Central Sudan. The approaches followed here include the chemical analyses for major ions chemistry and construction of hydrochemical maps of total dissolved solids (TDS), sodium (Na +), bicarbonate (HCO 3 -), and chloride (Cl -) ions. The hydrochemical characteristics of the groundwater in each aquifer and management consideration are discussed. Sources of major ions in groundwater are analyzed. The hydrochemical maps of important species are constructed. The relationship of groundwater to use is elaborated. High concentrations of the chemical and hydrochemical constituents and the occurrence of calcretes (CaCO 3) in upper zones suggest a long history of evaporation and increasing leachates.展开更多
To realize highly selective relay recognition of Fe3＋ and H2PO4^- ions, a simple benzimidazole-based fluorescent chemosensor （L） was designed and synthesized. Sensor L displays rapid, highly selective, and sensitiv...To realize highly selective relay recognition of Fe3＋ and H2PO4^- ions, a simple benzimidazole-based fluorescent chemosensor （L） was designed and synthesized. Sensor L displays rapid, highly selective, and sensitive recognition to Fe^3＋ in H2O/DMSO （1：1, v/v） solutions. The in stitu-generated L-Fe^3＋ complex solution exhibits a fast response and high selectivity toward dihydrogen phosphate anion via the Fe^3＋ displacement approach. The detection limits of sensor L to Fe^3＋ and L-Fe^3＋complex to H2PO4 anion were estimated to be 1.0 × 10^-9 mol/L. Notably, the sensor was retrievable to indicate dihydrogen phosphate an- ions with Fe^3＋, and HePO4 , in turn, increased. This successive recognition feature of sensor L makes it a potential utility for Fe^3＋ and H2PO4 anion detection in aqueous media.展开更多
SnO2 hollow spheres have been synthesized via a facile hydrothermal method using sulfonated polystyrene beads as a template followed by a calcination process in air.X-ray diffraction,scanning electron microscopy,and t...SnO2 hollow spheres have been synthesized via a facile hydrothermal method using sulfonated polystyrene beads as a template followed by a calcination process in air.X-ray diffraction,scanning electron microscopy,and transmission electron microscopy show that the as-obtained SnO2 hollow spheres have a wall thickness of about 50 nm,and consist of nanosized SnO2 particles with a mean diameter of about 15 nm.Electrochemical measurements indicate that the SnO2 hollow spheres exhibit improved electrochemical performance in terms of specific capacity and rate capability in comparison with commercial SnO2 when used as anode materials for lithium-ion batteries.The enhanced performance may be attributed to the spherical and hollow structure,as well as the building blocks of SnO2 nanoparticles.展开更多
High yields of CoFe204, NiFe204 and CdFe204 hierarchical porous ball-in-ball hollow spheres have been achieved using hydrothermal synthesis followed by calcination. The mechanism of formation is shown to involve an in...High yields of CoFe204, NiFe204 and CdFe204 hierarchical porous ball-in-ball hollow spheres have been achieved using hydrothermal synthesis followed by calcination. The mechanism of formation is shown to involve an in situ carbonaceous-template process. Hierarchical porous CoFe2O4 hollow spheres with different numbers of shells can be obtained by altering the synthesis conditions. The electrochemical properties of the resulting CoFe2O4 electrodes have been compared, using different binders. The as-obtained CoFe2O4 and NiFe2O4 have relatively high reversible discharge capacity and good rate retention performance which make them promising materials for use as anode materials in lithium ion batteries.展开更多
文摘Pure water has been characterized for nearly a century, by its dissociation into hydronium （H3O）1＋ and hydroxide （HO）1- ions. As a chemical equilibrium reaction, the equilibrium constant, known as the ion product or the product of the equilibrium concentration of the two ion species, has been extensively measured by chemists over the liquid water temperature and pressure range. The experimental data have been nonlinear least-squares fitted to chemical thermodynamic-based equilibrium equations, which have been accepted as the industrial standard for 35 years. In this study, a new and statistical-physics-based water ion product equation is presented, in which, the ions are the positively charged protons and the negatively charged proton-holes or prohols. Nonlinear least squares fits of our equation to the experimental data in the 0-100℃ pure liquid water range, give a factor of two better precision than the 35-year industrial standard.
基金Natural Science Foundation of China (40375002, 40418008, 40775011, U0733004)Project 863 (2006AA06A306, 2006AA06A308)+3 种基金National Basic Research Program of China (973 Program):2005CB422207Natural Science Foundation of Guangdong Province (033029)Project of Key Scientific Research of Guangdong Province (2004A30401002, 2005B32601011)Project of Applied Fundamental Research of Guangzhou (2004J1-0021)
文摘Samples of fog water collected in the area of Guangzhou during February, March and April of 2005 are used in this work to study the chemical composition of fog water in polluting fog there. Three typical episodes of polluting fog are analyzed in terms of ionic concentration and their possible sources. It is found that the concentration of various ions in fog water is much higher than those in rainwater. Fog not only blocks visual range but contains liquid particles that result in high degree of pollution and are very harmful to human health. SO4= is the anion with the highest concentration in fog water, followed by NO3-. For the cation, Ca++ and NH4+ are the highest in concentration. It is then known that rainwater is more acidic than fog water, indicating that ionic concentration of fog water is much higher than that of rainwater, but there are much more buffering materials in fog water, like NH4+ and Ca++. There is significant enrichment of Ca++, SO4=, and Mg++ in fog water. In the Guangzhou area, fog water from polluting fog is mainly influenced continental environment and human activity. The episodes of serious fog pollution during the time have immediate relationships with the presence of abundant water vapor and large amount of polluting aerosol particles.
文摘Activated carbons were prepared by two chemical methods and the adsorption of Cu(II) on activated carbons from aqueous solution containing amino groups was studied. The first method involved the chlorination of activated carbon following by substitution of chloride groups with amino groups, and the second involved the nitrilation of activated carbon with reduction of nitro groups to amino groups. Resultant activated carbons were characterized in terms of porous structure, elemental analysis, FTIR spectroscopy, XPS, Boehm titration,and p Hzpc. Kinetic and equilibrium tests were performed for copper adsorption in the batch mode. Also,adsorption mechanism and effect of p H on the adsorption of Cu(II) ions were discussed. Adsorption study shows enhanced adsorption for copper on the modified activated carbons, mainly by the presence of amino groups, and the Freundlich model is applicable for the activated carbons. It is suggested that binding of nitrogen atoms with Cu(II) ions is stronger than that with H+ions due to relatively higher divalent charge or stronger electrostatic force.
文摘This paper presents an assessment of the hydrochemical characteristics of groundwater in Northern Gezira State, Central Sudan. The approaches followed here include the chemical analyses for major ions chemistry and construction of hydrochemical maps of total dissolved solids (TDS), sodium (Na +), bicarbonate (HCO 3 -), and chloride (Cl -) ions. The hydrochemical characteristics of the groundwater in each aquifer and management consideration are discussed. Sources of major ions in groundwater are analyzed. The hydrochemical maps of important species are constructed. The relationship of groundwater to use is elaborated. High concentrations of the chemical and hydrochemical constituents and the occurrence of calcretes (CaCO 3) in upper zones suggest a long history of evaporation and increasing leachates.
基金supported by the National Natural Science Foundation of China(21064006,21161018,21262032)the Natural Science Foundation of Gansu Province(1010RJZA018)+1 种基金the Program for Changjiang ScholarsInnovative Research Teams in Universities of the Ministry of Education of China(IRT1177)
文摘To realize highly selective relay recognition of Fe3＋ and H2PO4^- ions, a simple benzimidazole-based fluorescent chemosensor （L） was designed and synthesized. Sensor L displays rapid, highly selective, and sensitive recognition to Fe^3＋ in H2O/DMSO （1：1, v/v） solutions. The in stitu-generated L-Fe^3＋ complex solution exhibits a fast response and high selectivity toward dihydrogen phosphate anion via the Fe^3＋ displacement approach. The detection limits of sensor L to Fe^3＋ and L-Fe^3＋complex to H2PO4 anion were estimated to be 1.0 × 10^-9 mol/L. Notably, the sensor was retrievable to indicate dihydrogen phosphate an- ions with Fe^3＋, and HePO4 , in turn, increased. This successive recognition feature of sensor L makes it a potential utility for Fe^3＋ and H2PO4 anion detection in aqueous media.
基金supported by the National Natural Science Foundation of China (21121063)the National Key Project on Basic Research(2011CB935700 and 2009CB930400)the Chinese Academy of Sciences
文摘SnO2 hollow spheres have been synthesized via a facile hydrothermal method using sulfonated polystyrene beads as a template followed by a calcination process in air.X-ray diffraction,scanning electron microscopy,and transmission electron microscopy show that the as-obtained SnO2 hollow spheres have a wall thickness of about 50 nm,and consist of nanosized SnO2 particles with a mean diameter of about 15 nm.Electrochemical measurements indicate that the SnO2 hollow spheres exhibit improved electrochemical performance in terms of specific capacity and rate capability in comparison with commercial SnO2 when used as anode materials for lithium-ion batteries.The enhanced performance may be attributed to the spherical and hollow structure,as well as the building blocks of SnO2 nanoparticles.
文摘High yields of CoFe204, NiFe204 and CdFe204 hierarchical porous ball-in-ball hollow spheres have been achieved using hydrothermal synthesis followed by calcination. The mechanism of formation is shown to involve an in situ carbonaceous-template process. Hierarchical porous CoFe2O4 hollow spheres with different numbers of shells can be obtained by altering the synthesis conditions. The electrochemical properties of the resulting CoFe2O4 electrodes have been compared, using different binders. The as-obtained CoFe2O4 and NiFe2O4 have relatively high reversible discharge capacity and good rate retention performance which make them promising materials for use as anode materials in lithium ion batteries.
