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2001 Volume 17 Issue 8
2001, 17(08): 673-675
doi: 10.3866/PKU.WHXB20010801
Abstract:
The valence electron structure of cyclopentane was measured by using high resolution(ΔE=1.16 eV,ΔP=0.1 au) (e,2e) spectrometer.The impact energy was 1200 eV plus binding energy (i.e.1206 to 1224 eV) and a symmetric non-coplannar kinematics was employed.The measured binding energies agree with the data obtained by photoelectron spectra (PES).The experimental momentum profiles have been compared with those calculated using the Hartree-Fock method and the density function theory(DFT) method.The measured momentum distributions are consistent with the theoretical calculations.
The valence electron structure of cyclopentane was measured by using high resolution(ΔE=1.16 eV,ΔP=0.1 au) (e,2e) spectrometer.The impact energy was 1200 eV plus binding energy (i.e.1206 to 1224 eV) and a symmetric non-coplannar kinematics was employed.The measured binding energies agree with the data obtained by photoelectron spectra (PES).The experimental momentum profiles have been compared with those calculated using the Hartree-Fock method and the density function theory(DFT) method.The measured momentum distributions are consistent with the theoretical calculations.
2001, 17(08): 676-681
doi: 10.3866/PKU.WHXB20010802
Abstract:
Based on the BrO-3--H＋-KMnO4 pH oscillation system ,the effect of changing the reaction parameters on the properties of the oscillation system was studied.Some new phenomena,such as the color oscillation of MnO(OH)＋ and the appearance of MnO2 precipitation were found.These phenomena by our modified reaction mechanism including an autocatalytic process of MnO(OH)＋ were explained,and its phase diagram on the [KMnO4]-Kf plane was drawn( see Fig.7).
Based on the BrO-3--H＋-KMnO4 pH oscillation system ,the effect of changing the reaction parameters on the properties of the oscillation system was studied.Some new phenomena,such as the color oscillation of MnO(OH)＋ and the appearance of MnO2 precipitation were found.These phenomena by our modified reaction mechanism including an autocatalytic process of MnO(OH)＋ were explained,and its phase diagram on the [KMnO4]-Kf plane was drawn( see Fig.7).
2001, 17(08): 682-686
doi: 10.3866/PKU.WHXB20010803
Abstract:
A statistical model,the two-dimensional Ising model,combined with Monte Carlo method,is applied to analyze quantitatively the wetting behavior of liquid in fibrous assemblies,which is regarded as the space between fibers changed from gas dominant state to liquid dominant state. Such change is driven by the difference in energy between the two states and finally terminated by the balance of surface tension and gravity. To accommodate the Ising model to the process of liquid wetting in fibrous assemblies,new sets of variables,si=1(liquid cell) or 0(gas cell),Fi=1(fiber cell) or 0(cell without fiber),are adopted to study the wetting dynamics. Characteristics of interacting fiber materials and liquid can be represented in the coefficients of the adhesive energy between fiber and liquid and cohesive energy within liquid. Work of extrinsic force,the surface tension,has been taken into account for its contribution to the energy of the system derived from liquid and the fibrous assemblies. Results of simulation are in od agreements with wicking experiments,indicating od prospect of the method to be used in this area. The model can be modified to adapt to wetting process of liquid on more complex pattern of structures by altering the initial configuration of fiber assemblies. For example,it is used to simulate the wetting process in an isotropic fiber network and the wetting process in a filament bundle. The results are showed in Fig.2～3.
A statistical model,the two-dimensional Ising model,combined with Monte Carlo method,is applied to analyze quantitatively the wetting behavior of liquid in fibrous assemblies,which is regarded as the space between fibers changed from gas dominant state to liquid dominant state. Such change is driven by the difference in energy between the two states and finally terminated by the balance of surface tension and gravity. To accommodate the Ising model to the process of liquid wetting in fibrous assemblies,new sets of variables,si=1(liquid cell) or 0(gas cell),Fi=1(fiber cell) or 0(cell without fiber),are adopted to study the wetting dynamics. Characteristics of interacting fiber materials and liquid can be represented in the coefficients of the adhesive energy between fiber and liquid and cohesive energy within liquid. Work of extrinsic force,the surface tension,has been taken into account for its contribution to the energy of the system derived from liquid and the fibrous assemblies. Results of simulation are in od agreements with wicking experiments,indicating od prospect of the method to be used in this area. The model can be modified to adapt to wetting process of liquid on more complex pattern of structures by altering the initial configuration of fiber assemblies. For example,it is used to simulate the wetting process in an isotropic fiber network and the wetting process in a filament bundle. The results are showed in Fig.2～3.
2001, 17(08): 687-691
doi: 10.3866/PKU.WHXB20010804
Abstract:
Short single walled carbon nanotubes (SWNTs) were prepared by shortening CVD growth time and by postsynthesis chemical oxidation with ultrasonication. Most of the SWNTs could be controlled to be shorter than 500 nm by both the two methods. However, Raman spectra show that shortening CVD time results in the decrease of amorphous carbon impurities, but in the oxidation process the damage of SWNTs occurred and amorphous carbon impurities increased. The short SWNTs directly synthesized by CVD have higher purity than that by chemical oxidation.
Short single walled carbon nanotubes (SWNTs) were prepared by shortening CVD growth time and by postsynthesis chemical oxidation with ultrasonication. Most of the SWNTs could be controlled to be shorter than 500 nm by both the two methods. However, Raman spectra show that shortening CVD time results in the decrease of amorphous carbon impurities, but in the oxidation process the damage of SWNTs occurred and amorphous carbon impurities increased. The short SWNTs directly synthesized by CVD have higher purity than that by chemical oxidation.
2001, 17(08): 692-695
doi: 10.3866/PKU.WHXB20010805
Abstract:
The formation and structural variation of lyotropic liquid crystal in mixed cationic surfactants (alkyl (C8,C12,C14)trimethylamonium bromide,alkyl (C12,C14)pyridinium bromide)and anionic surfactants (sodium alkyl(C8,C12) sulfate ) systems were studied.When the molar ratio of cationic to anionic surfactant was close to 1,the liquid crystal changed from hexan nal structure to lamellar or cubic structure in concentrated aqueous solution.Variation of nonpolar chain lengthes of surfactants has obvious effects on the phase behavior.When both of cationic and anionic surfactants have short carbon chain length at equimolar mixed ratio,a mixture of large amount of lamellar or cubic liquid crystal and small amount of precipitate was obtained.With the carbon chain length increasing amount of precipitate increased.The amount of coexisted liquid crystal decreased,and even disappeared as well.The alkyltrimethylamonium interacted with sodium alkylsulfate more intensively than with alkyl pyridinium.Therefore,the insoluble mixture produced at wider molar ratio of the two surfactants.
The formation and structural variation of lyotropic liquid crystal in mixed cationic surfactants (alkyl (C8,C12,C14)trimethylamonium bromide,alkyl (C12,C14)pyridinium bromide)and anionic surfactants (sodium alkyl(C8,C12) sulfate ) systems were studied.When the molar ratio of cationic to anionic surfactant was close to 1,the liquid crystal changed from hexan nal structure to lamellar or cubic structure in concentrated aqueous solution.Variation of nonpolar chain lengthes of surfactants has obvious effects on the phase behavior.When both of cationic and anionic surfactants have short carbon chain length at equimolar mixed ratio,a mixture of large amount of lamellar or cubic liquid crystal and small amount of precipitate was obtained.With the carbon chain length increasing amount of precipitate increased.The amount of coexisted liquid crystal decreased,and even disappeared as well.The alkyltrimethylamonium interacted with sodium alkylsulfate more intensively than with alkyl pyridinium.Therefore,the insoluble mixture produced at wider molar ratio of the two surfactants.
2001, 17(08): 696-701
doi: 10.3866/PKU.WHXB20010806
Abstract:
Decomposition of Nnitrosodimethylamine (NDMA) and Nnitrosopyrrolidine (NPYR) on zeolite Y and ZSM5 was investigated by means of temperature programmed surface reaction(TPSR) combined with GCMSD and IR techniques. Degradation of Nnitrosamine strongly depended on the activity of zeolite and was accelerated by acid sites. Products of Nnitrosamines degradation were changed by zeolite catalysis, cyano derivative appeared as the main product on NaZSM5 and NaY zeolites similar to that in pyrolysis while dimethylamine became the dominant one on HZSM5 and HY. Different reactions are thus proposed: on the latter the Bronsted acid sites probably play the role of main catalytic sites, hence Nnitrosamines degrades to amines while on the former Nnitrosamines may decompose through radical reaction process, similar to the process of pyrolysis. Protonation of zeolite NaY or NaZSM5 is proved not to be necessary for decomposition of Nnitrosamines. Zeolites are proved to be the novel materials for removing Nnitrosamines pollutants from environment.
Decomposition of Nnitrosodimethylamine (NDMA) and Nnitrosopyrrolidine (NPYR) on zeolite Y and ZSM5 was investigated by means of temperature programmed surface reaction(TPSR) combined with GCMSD and IR techniques. Degradation of Nnitrosamine strongly depended on the activity of zeolite and was accelerated by acid sites. Products of Nnitrosamines degradation were changed by zeolite catalysis, cyano derivative appeared as the main product on NaZSM5 and NaY zeolites similar to that in pyrolysis while dimethylamine became the dominant one on HZSM5 and HY. Different reactions are thus proposed: on the latter the Bronsted acid sites probably play the role of main catalytic sites, hence Nnitrosamines degrades to amines while on the former Nnitrosamines may decompose through radical reaction process, similar to the process of pyrolysis. Protonation of zeolite NaY or NaZSM5 is proved not to be necessary for decomposition of Nnitrosamines. Zeolites are proved to be the novel materials for removing Nnitrosamines pollutants from environment.
2001, 17(08): 702-707
doi: 10.3866/PKU.WHXB20010807
Abstract:
Chemosynthesis in microwave field, was employed to obtain the electrode materials for LiMnO system by using different mixture of x=Li/Mn, Li2CO3 and MnO2 as raw materials. The reaction time in microwave field where the ratio of 2Li to Mn was important, was much shorter than that in conventional solid reaction. Several techniques such as XRD, SEM, XPS were used to explore the microstructure of products.
Chemosynthesis in microwave field, was employed to obtain the electrode materials for LiMnO system by using different mixture of x=Li/Mn, Li2CO3 and MnO2 as raw materials. The reaction time in microwave field where the ratio of 2Li to Mn was important, was much shorter than that in conventional solid reaction. Several techniques such as XRD, SEM, XPS were used to explore the microstructure of products.
2001, 17(08): 708-712
doi: 10.3866/PKU.WHXB20010808
Abstract:
Using Xray diffraction, the structure factors of molten Cu12％(mass fraction)Al alloys and pure copper have been investigated. Distinct prepeak(the prepeak occurs at values of scattering vector Q=18.5 nm－1) has been found in the structure factor of Cu12％Al alloys melt at 1250 ℃. The prepeak in the liquid alloy increases with decreasing temperature. The prepeak is a sign of mediumrange order. Rapid solidified ribbons prepared by the single roller meltspinning technique have been investigated with Xray scattering. The phase in the ribbons is Cu3Al with superstructure. The structural unit size of mediumrange order clusters in liquid equals to intercrystal face distance d111 of Cu3Al. According to the nearest neighbor distance and coordination number, obtained from the pair correlation function, and basic unit model of cluster, the length of cubic edge can be calculated, which meets the parameter of the crystalline structure given by literature. So it is speculated that there are DO3 structure clusters in the liquid Cu12％Al alloy. This stable mediumrange order can exist up to nearly 200 ℃ above liquidus and the structural correlation length increases with decreasing temperature.
Using Xray diffraction, the structure factors of molten Cu12％(mass fraction)Al alloys and pure copper have been investigated. Distinct prepeak(the prepeak occurs at values of scattering vector Q=18.5 nm－1) has been found in the structure factor of Cu12％Al alloys melt at 1250 ℃. The prepeak in the liquid alloy increases with decreasing temperature. The prepeak is a sign of mediumrange order. Rapid solidified ribbons prepared by the single roller meltspinning technique have been investigated with Xray scattering. The phase in the ribbons is Cu3Al with superstructure. The structural unit size of mediumrange order clusters in liquid equals to intercrystal face distance d111 of Cu3Al. According to the nearest neighbor distance and coordination number, obtained from the pair correlation function, and basic unit model of cluster, the length of cubic edge can be calculated, which meets the parameter of the crystalline structure given by literature. So it is speculated that there are DO3 structure clusters in the liquid Cu12％Al alloy. This stable mediumrange order can exist up to nearly 200 ℃ above liquidus and the structural correlation length increases with decreasing temperature.
2001, 17(08): 713-717
doi: 10.3866/PKU.WHXB20010809
Abstract:
Titanium tetrachloride reacted with triethanolamine to form soluble titanium compound. The compound was aged at 145 ℃ for 48 h forming monodispersed titanium dioxide particles. The formation and hydrolysis of the compound were discussed. Change of the pH value of the aging solution between 0.9 and 10.5 great influences the particle size and shape, the higher the acidity, the less the particles size. Rod particles are formed at pH 10.5 and spherelike particles are formed at the pH less than 10.0. The particle size can also be controlled by adding seeds. In the case of adding seeds at pH 10.5, the shape of the particles keeps rod. Crystal habits of the particles were detected by TEM and XRD etc.
Titanium tetrachloride reacted with triethanolamine to form soluble titanium compound. The compound was aged at 145 ℃ for 48 h forming monodispersed titanium dioxide particles. The formation and hydrolysis of the compound were discussed. Change of the pH value of the aging solution between 0.9 and 10.5 great influences the particle size and shape, the higher the acidity, the less the particles size. Rod particles are formed at pH 10.5 and spherelike particles are formed at the pH less than 10.0. The particle size can also be controlled by adding seeds. In the case of adding seeds at pH 10.5, the shape of the particles keeps rod. Crystal habits of the particles were detected by TEM and XRD etc.
2001, 17(08): 718-722
doi: 10.3866/PKU.WHXB20010810
Abstract:
Singlewalled carbon nanotubes (SWNTs) were synthesized by the decomposition of methane on Al2O3 supported Fe,Co,Ni,Ru catalysts at 850 ℃. The diameters of the single walled carbon nanotubes were in the range of 0.8～5 nm. The amorphous carbon impurity could be reduced by pretreatment of catalysts at 1100 ℃. Raman spectra showed that the diameter distributions of the SWNTs were mainly influenced by the reaction temperature. At lower temperature small diameter nanotubes were favored and better selectivity of diameter could be achieved.
Singlewalled carbon nanotubes (SWNTs) were synthesized by the decomposition of methane on Al2O3 supported Fe,Co,Ni,Ru catalysts at 850 ℃. The diameters of the single walled carbon nanotubes were in the range of 0.8～5 nm. The amorphous carbon impurity could be reduced by pretreatment of catalysts at 1100 ℃. Raman spectra showed that the diameter distributions of the SWNTs were mainly influenced by the reaction temperature. At lower temperature small diameter nanotubes were favored and better selectivity of diameter could be achieved.
2001, 17(08): 723-727
doi: 10.3866/PKU.WHXB20010811
Abstract:
The adsorption equilibrium of methane in activated carbon was simulated by the Gibbs ensemble Monte Carlo(GEMC) method.A modified GEMC method was proposed to simulate the adsorption equilibrium at a specified pressure.The excess adsorption at 263 K is larger than that at 298 K or 313 K.There exists a maximum excess adsorption at each temperature.At 263 K,the excess adsorption reaches the maximum at 5.0 MPa; while at 298 K or 313 K,the excess adsorption reaches the maximum at about 7.0 MPa.
The adsorption equilibrium of methane in activated carbon was simulated by the Gibbs ensemble Monte Carlo(GEMC) method.A modified GEMC method was proposed to simulate the adsorption equilibrium at a specified pressure.The excess adsorption at 263 K is larger than that at 298 K or 313 K.There exists a maximum excess adsorption at each temperature.At 263 K,the excess adsorption reaches the maximum at 5.0 MPa; while at 298 K or 313 K,the excess adsorption reaches the maximum at about 7.0 MPa.
2001, 17(08): 728-732
doi: 10.3866/PKU.WHXB20010812
Abstract:
The electrochemical behavior of mononuclear and symmetrical binuclear ruthenium（Ⅱ） complexes [Ru1:Ru(bpy)2DIPB(ClO4)2,Ru2:(bpy)2 Ru(DIPB)Ru(bpy)2(ClO4)4,Ru3:Ru(phen)2DIPB(ClO4)2 and Ru4:(phen)2 Ru(DIPB)Ru (phen)2(ClO4)4] containing binuclear ligand 2,2′-bipyridine(bpy)，1,10-phenanthroline(phen) and bridging ligand 1,4-di-[2-imidazo[4,5-f][1,10] phenanthroine benzene(DIPB) on a platinum electrode and the intermetallic interaction of binuclear complexes have been investigated using cyclic voltammetry,cyclic ac voltammetry and differential capacitance techniques,etc.In acetonitrile solution with a concentration of 0.1 mol穌m-3 TBAP,the central ions in four complexes all display single 1e and 2e reversible oxidation- reduction waves on the cyclic voltammograms,with apparent diffusion coefficients of the mononuclear complexed cations being larger than that of the binuclear ones.The apparent diffusion coefficients for complexed cations with auxiliary ligands bpy are also found to be larger than that with ligands phen.It appears that the overlapping of two continuous single-electron processes by cyclic ac voltammetry and differential capacitance techniques occurs during the redox processes of the central ions binuclear complexes.The results show that a weak electronic interaction exits between the two central ruthenium ions in binuclear complexes.
The electrochemical behavior of mononuclear and symmetrical binuclear ruthenium（Ⅱ） complexes [Ru1:Ru(bpy)2DIPB(ClO4)2,Ru2:(bpy)2 Ru(DIPB)Ru(bpy)2(ClO4)4,Ru3:Ru(phen)2DIPB(ClO4)2 and Ru4:(phen)2 Ru(DIPB)Ru (phen)2(ClO4)4] containing binuclear ligand 2,2′-bipyridine(bpy)，1,10-phenanthroline(phen) and bridging ligand 1,4-di-[2-imidazo[4,5-f][1,10] phenanthroine benzene(DIPB) on a platinum electrode and the intermetallic interaction of binuclear complexes have been investigated using cyclic voltammetry,cyclic ac voltammetry and differential capacitance techniques,etc.In acetonitrile solution with a concentration of 0.1 mol穌m-3 TBAP,the central ions in four complexes all display single 1e and 2e reversible oxidation- reduction waves on the cyclic voltammograms,with apparent diffusion coefficients of the mononuclear complexed cations being larger than that of the binuclear ones.The apparent diffusion coefficients for complexed cations with auxiliary ligands bpy are also found to be larger than that with ligands phen.It appears that the overlapping of two continuous single-electron processes by cyclic ac voltammetry and differential capacitance techniques occurs during the redox processes of the central ions binuclear complexes.The results show that a weak electronic interaction exits between the two central ruthenium ions in binuclear complexes.
2001, 17(08): 733-738
doi: 10.3866/PKU.WHXB20010813
Abstract:
The reactions of methane partial oxidation (POM) and methane reforming with CO2 to produce synthetic gas over Ni/TiO2 catalyst were studied.The catalyst shows od catalytic performance with high H2 selectivity for the POM reaction and od low temperature activity for the reaction of methane reforming with CO2.The activation of methane over Ni/TiO2 catalysts was investigated using MS-pulse technique in the absence of gaseous oxygen.It was found that methane activation and its oxidation products were determined by the concentration of surface oxygen species of the catalyst.Both oxygen and hydrogen spillover phenomena were observed during the interaction of methane with Ni/TiO2.The spillover oxygen and hydrogen species over the catalyst may be responsible for the od activity and carbon resistance ability of the Ni/TiO2 catalyst.
The reactions of methane partial oxidation (POM) and methane reforming with CO2 to produce synthetic gas over Ni/TiO2 catalyst were studied.The catalyst shows od catalytic performance with high H2 selectivity for the POM reaction and od low temperature activity for the reaction of methane reforming with CO2.The activation of methane over Ni/TiO2 catalysts was investigated using MS-pulse technique in the absence of gaseous oxygen.It was found that methane activation and its oxidation products were determined by the concentration of surface oxygen species of the catalyst.Both oxygen and hydrogen spillover phenomena were observed during the interaction of methane with Ni/TiO2.The spillover oxygen and hydrogen species over the catalyst may be responsible for the od activity and carbon resistance ability of the Ni/TiO2 catalyst.
2001, 17(08): 739-742
doi: 10.3866/PKU.WHXB20010814
Abstract:
Nanometer-sized CeO2/polystyrene hybrid material was prepared using reversed micelles microemulsion method. XRD analysis revealed that the CeO2 nanoparticles in polystyrene were amorphous. XPS patterns indicated that the hybrid material was not a simply physical mixture,but a certain strength of chemical bond between CeO2 nanoparticles and polystyrene existed. FTIR patterns revealed that the absorption of Ce-O bond in hybrid material was blue-shifted.
Nanometer-sized CeO2/polystyrene hybrid material was prepared using reversed micelles microemulsion method. XRD analysis revealed that the CeO2 nanoparticles in polystyrene were amorphous. XPS patterns indicated that the hybrid material was not a simply physical mixture,but a certain strength of chemical bond between CeO2 nanoparticles and polystyrene existed. FTIR patterns revealed that the absorption of Ce-O bond in hybrid material was blue-shifted.
2001, 17(08): 743-746
doi: 10.3866/PKU.WHXB20010815
Abstract:
The behavior of a novel amphiphilic block copolymer,Dendr.PE-PAA,in aqueous solution was studied by 1H NMR.The self-diffusion,spin-lattice relaxation time,spin-spin relaxation time and NOESY spectra were obtained.The results suggest that the amphiphilic block copolymer forms self-assembly in aqueous solution,and reveal that the shapes of self-assembly change with different concentration of the solution.
The behavior of a novel amphiphilic block copolymer,Dendr.PE-PAA,in aqueous solution was studied by 1H NMR.The self-diffusion,spin-lattice relaxation time,spin-spin relaxation time and NOESY spectra were obtained.The results suggest that the amphiphilic block copolymer forms self-assembly in aqueous solution,and reveal that the shapes of self-assembly change with different concentration of the solution.
2001, 17(08): 747-749
doi: 10.3866/PKU.WHXB20010816
Abstract:
A tantalate Ba3TiTa4O15 was synthesized by doping Ti4＋ in the binary system BaOTa2O5. The crystal structure was determined by Xray powder diffraction, and it belongs to paraelectric phase of tetra nal tungsten bronze structure at room temperature with unit cell parameters : a=1.256 27(6)nm, c=0.395 86(4)nm. Dielectric measurements showed that the phase transition of Ba3TiTa4O15 from ferroelectric to paraelectric occurred at －35 ℃, lower than that of Ba6Ti2Nb8O30. The dielectric constant of Ba3TiTa4O15 ceramic was stable at room temperature with the frequency increasing from 1 kHz to 1 MHz, while the dielectric loss was as low as 0.002. Ba3TiTa4O15 might be a suitable candidate for microwave dielectric ceramics.
A tantalate Ba3TiTa4O15 was synthesized by doping Ti4＋ in the binary system BaOTa2O5. The crystal structure was determined by Xray powder diffraction, and it belongs to paraelectric phase of tetra nal tungsten bronze structure at room temperature with unit cell parameters : a=1.256 27(6)nm, c=0.395 86(4)nm. Dielectric measurements showed that the phase transition of Ba3TiTa4O15 from ferroelectric to paraelectric occurred at －35 ℃, lower than that of Ba6Ti2Nb8O30. The dielectric constant of Ba3TiTa4O15 ceramic was stable at room temperature with the frequency increasing from 1 kHz to 1 MHz, while the dielectric loss was as low as 0.002. Ba3TiTa4O15 might be a suitable candidate for microwave dielectric ceramics.
2001, 17(08): 750-752
doi: 10.3866/PKU.WHXB20010817
Abstract:
Xray absorption fine structure (XAFS) and Xray diffraction (XRD) have been combined to investigate the structure of NiB ultrafine amorphous alloy prepared by chemical reduction during the crystallization process. The results demonstrate that a fcclike nanocrystalline Ni phase with a mediumrange order and a nanocrystalline Ni3B alloy are formed at 573 K where the first exothermic process is observed. At annealing temperature of 773 K, large amount of NiB ultrafine amorphous alloy decomposes into metal Ni.
Xray absorption fine structure (XAFS) and Xray diffraction (XRD) have been combined to investigate the structure of NiB ultrafine amorphous alloy prepared by chemical reduction during the crystallization process. The results demonstrate that a fcclike nanocrystalline Ni phase with a mediumrange order and a nanocrystalline Ni3B alloy are formed at 573 K where the first exothermic process is observed. At annealing temperature of 773 K, large amount of NiB ultrafine amorphous alloy decomposes into metal Ni.
2001, 17(08): 753-756
doi: 10.3866/PKU.WHXB20010818
Abstract:
The Mixedligands complexes of Lglutamic acid and Larginine with Cu(Ⅱ) was synthesized. The composition of the complex was determined by chemical analysis, element analysis and thermal gravity analysis. By solution calorimetry in a reaction calorimeter at 298.2 K,the dissolution enthalpy for the reactant, CuSO4 5H2O(s), LGlutamic acid(s) and LArginine(s), and the product, Cu稧lu稟rg稴O4 5H2O(s), were determined. They were dissolved in 2 mol稬－1 H2SO4 solution, respectively. A themochemistry cycle was designed, to obtain the coordinate reaction enthalpy change,=(19.745 0.033) kJ穖ol－1, and the standard formation enthalpy of the mixedligands complex was calculated,=(－3923.145 3.768)kJ穖ol－1. This result offers a basic thermochemistry parameter for the further research of this kind of compounds.
The Mixedligands complexes of Lglutamic acid and Larginine with Cu(Ⅱ) was synthesized. The composition of the complex was determined by chemical analysis, element analysis and thermal gravity analysis. By solution calorimetry in a reaction calorimeter at 298.2 K,the dissolution enthalpy for the reactant, CuSO4 5H2O(s), LGlutamic acid(s) and LArginine(s), and the product, Cu稧lu稟rg稴O4 5H2O(s), were determined. They were dissolved in 2 mol稬－1 H2SO4 solution, respectively. A themochemistry cycle was designed, to obtain the coordinate reaction enthalpy change,=(19.745 0.033) kJ穖ol－1, and the standard formation enthalpy of the mixedligands complex was calculated,=(－3923.145 3.768)kJ穖ol－1. This result offers a basic thermochemistry parameter for the further research of this kind of compounds.
2001, 17(08): 757-760
doi: 10.3866/PKU.WHXB20010819
Abstract:
The solubility of polymer-supercritical CO2 binary systems was studied, and the effects of co-solvent on the solubility were discussed. The polymers used in this experiment were from commercial coating resins,and AR toluene and cyclohexane produced domestically were used as co-solvent. The results show that the addition of co-solvent increases the solubility remarkably (see Tab. 1).The high-pressure phase behavior of polymer-solvent-supercritical CO2 ternary systems was also investigated experimentally. The effects of component's character and their concentration on p-T phase diagram were discussed. It was found that as CO2 concentration increases, the diagram changed from L-LV boundary to steeper L-LL boundary. the L-LV boundary was not sensitive to different polymers.
The solubility of polymer-supercritical CO2 binary systems was studied, and the effects of co-solvent on the solubility were discussed. The polymers used in this experiment were from commercial coating resins,and AR toluene and cyclohexane produced domestically were used as co-solvent. The results show that the addition of co-solvent increases the solubility remarkably (see Tab. 1).The high-pressure phase behavior of polymer-solvent-supercritical CO2 ternary systems was also investigated experimentally. The effects of component's character and their concentration on p-T phase diagram were discussed. It was found that as CO2 concentration increases, the diagram changed from L-LV boundary to steeper L-LL boundary. the L-LV boundary was not sensitive to different polymers.
2001, 17(08): 761-764
doi: 10.3866/PKU.WHXB20010820
Abstract:
Based on Hartree-Fock and DFT theories,steric models of NO,CO and O2 adsorbed on Cu+ in Cu+ zeolite have obtained.The results show that the most stable structures are formed in linear adsorption of small molecules on Cu+ which can make steric hindrance least and energy minimum,while the other structuresof non-linear adsorption can also exist but are much less stable.Potential energy curve and effect of temperature on the adsorption are also computed.At lower temperature the adsorption is more stable in the reaction temperature ranging from 500 to 800 K.Two NO molecules can be stably adsorbed on one Cu+ to form Cu+ (NO)(ON) structure and lead to NO reduction.
Based on Hartree-Fock and DFT theories,steric models of NO,CO and O2 adsorbed on Cu+ in Cu+ zeolite have obtained.The results show that the most stable structures are formed in linear adsorption of small molecules on Cu+ which can make steric hindrance least and energy minimum,while the other structuresof non-linear adsorption can also exist but are much less stable.Potential energy curve and effect of temperature on the adsorption are also computed.At lower temperature the adsorption is more stable in the reaction temperature ranging from 500 to 800 K.Two NO molecules can be stably adsorbed on one Cu+ to form Cu+ (NO)(ON) structure and lead to NO reduction.
2001, 17(08): 765-768
doi: 10.3866/PKU.WHXB20010821
Abstract:
Bolaamphiphile, in which two head groups are linked by one or two hydrophobic chains,has been attracting much interest in recent years. The structures of the Langmuir films spread from two novel bolaamphiphiles containing α-naphthyl and β-naphthyl groups at the air/water interface have been investigated. Surface pressure -area isotherms,AFM and XRD measurements reveal that when spreading at the air/water surface,the molecule containing α-naphthyl forms a triple-layer Langmuir film,while the one containing β-naphthyl forms a stretched monolayer.
Bolaamphiphile, in which two head groups are linked by one or two hydrophobic chains,has been attracting much interest in recent years. The structures of the Langmuir films spread from two novel bolaamphiphiles containing α-naphthyl and β-naphthyl groups at the air/water interface have been investigated. Surface pressure -area isotherms,AFM and XRD measurements reveal that when spreading at the air/water surface,the molecule containing α-naphthyl forms a triple-layer Langmuir film,while the one containing β-naphthyl forms a stretched monolayer.
