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2003 Volume 19 Issue 7
2003, 19(07): 577-579
doi: 10.3866/PKU.WHXB20030701
Abstract:
The equimolar mixed system of decyltriethylammonium bromide and sodium decylsulfonate, which was homogeneous solution even with the total surfactant concentration increasing up to 0.2 mol•L－1, formed aqueous two-phase system(ATPS) when salts, such as NaF, Na2SO4 or Na3PO4, were added. The phase behavior and partitioning of BSA in this saltinduced ATPS were studied. Compared with the usual ATPS of catanionic surfactant mixtures, this salt-induced ATPS exhibited some special advantages, and overcame some shortcomings of the usual ATPS. It was shown that the phase behavior of this salt-induced ATPS could be adjusted by adding salts and the partition coefficient of BSA could be altered and optimized by salt species.
The equimolar mixed system of decyltriethylammonium bromide and sodium decylsulfonate, which was homogeneous solution even with the total surfactant concentration increasing up to 0.2 mol•L－1, formed aqueous two-phase system(ATPS) when salts, such as NaF, Na2SO4 or Na3PO4, were added. The phase behavior and partitioning of BSA in this saltinduced ATPS were studied. Compared with the usual ATPS of catanionic surfactant mixtures, this salt-induced ATPS exhibited some special advantages, and overcame some shortcomings of the usual ATPS. It was shown that the phase behavior of this salt-induced ATPS could be adjusted by adding salts and the partition coefficient of BSA could be altered and optimized by salt species.
2003, 19(07): 580-583
doi: 10.3866/PKU.WHXB20030702
Abstract:
The product of oxidative polymerization of aniline using dichromate as oxidant was proved to be polyaniline/Cr(OH)3 composites by methods of IR, XRD, elemental analysis and pyrolysis experiment.This conclusion is different from the idea in the literature that when aniline is oxidized the product of the reduction of dichromate is soluble Cr3＋ that would not remain in the polyaniline product.The Cr(OH)3 content in the composites decreased from 38.4％ to 1.3％ along with the growth of solution acidity,as shown in Fig.1.The reduction Cr2O72－ of was supposed to be composed of two steps:the reduction of Cr2O72－ to Cr(OH)3 followed by the dissolution of Cr(OH)3 into acidic solution.The standard Gibbs free energy of the first step was calculated to be －582.11 kJ•mol－1,which is a very large negative value.The second step being the adsorption of polyaniline onto Cr(OH)3 retards its dissolution and leads to the formation of polyaniline/Cr(OH)3 composites.
The product of oxidative polymerization of aniline using dichromate as oxidant was proved to be polyaniline/Cr(OH)3 composites by methods of IR, XRD, elemental analysis and pyrolysis experiment.This conclusion is different from the idea in the literature that when aniline is oxidized the product of the reduction of dichromate is soluble Cr3＋ that would not remain in the polyaniline product.The Cr(OH)3 content in the composites decreased from 38.4％ to 1.3％ along with the growth of solution acidity,as shown in Fig.1.The reduction Cr2O72－ of was supposed to be composed of two steps:the reduction of Cr2O72－ to Cr(OH)3 followed by the dissolution of Cr(OH)3 into acidic solution.The standard Gibbs free energy of the first step was calculated to be －582.11 kJ•mol－1,which is a very large negative value.The second step being the adsorption of polyaniline onto Cr(OH)3 retards its dissolution and leads to the formation of polyaniline/Cr(OH)3 composites.
2003, 19(07): 584-587
doi: 10.3866/PKU.WHXB20030703
Abstract:
The kinetics of dissolution and transformation processes of 2M •2B2O3•MgCl2•14H2O in 4.5％ H3BO3 aqueous solution at 40 ℃ was studied. The liquid samples were taken at different times for chemical analysis. And the solid phase at different stages was separated and identified. The experimental results showed that 2M •2B2O3•MgCl2•14H2O dissolved congruently in 4.5％ H3BO3 aqueous solution, which was different from the process of the dissolution of 2M •2B2O3•MgCl2•14H2O in water. The final crystal solid phase was kurnakovite(2M •3B2O3•15H2O). The kinetic equations of the crystallization reaction were given with the aid of Simplex Optimum Method and Runge-Kutta digital solution of differential equation system, a mechanism of dissolution and transformation and the formation condition of kurnakovite in Qinghai-Tibetan plateau were proposed and discussed.
The kinetics of dissolution and transformation processes of 2M •2B2O3•MgCl2•14H2O in 4.5％ H3BO3 aqueous solution at 40 ℃ was studied. The liquid samples were taken at different times for chemical analysis. And the solid phase at different stages was separated and identified. The experimental results showed that 2M •2B2O3•MgCl2•14H2O dissolved congruently in 4.5％ H3BO3 aqueous solution, which was different from the process of the dissolution of 2M •2B2O3•MgCl2•14H2O in water. The final crystal solid phase was kurnakovite(2M •3B2O3•15H2O). The kinetic equations of the crystallization reaction were given with the aid of Simplex Optimum Method and Runge-Kutta digital solution of differential equation system, a mechanism of dissolution and transformation and the formation condition of kurnakovite in Qinghai-Tibetan plateau were proposed and discussed.
The Electrocatalytic Oxidation of Hydrogen Peroxide on Polyaniline Doped with Ferrocenesulfonic Acid
2003, 19(07): 588-592
doi: 10.3866/PKU.WHXB20030704
Abstract:
Polyaniline（PAnFc） synthesized in a presence of ferrocenesulfonic acid and polyaniline（PAn） synthesized in the absence of ferrocenesulfonic acid can catalyze the electrochemical oxidation of hydrogen peroxide in a buffer solution with pH 5.0, but the catalytic activity of PAnFc is higher than that of PAn.Evidence for this catalytic effect is that the oxidation potential of hydrogen peroxide shifts from 0.59 V on the bare platinum electrode to 0.48 V （vs SCE） on the PAnFc electrode, and the anodic peak current of hydrogen peroxide on the PAnFc electrode is 5.3 times as high as that on the bare platinum electrode. Based on this catalytic property, both PAn and PAnFc were used for immobilization of glucose oxidase to fabricate the enzyme electrodes. The experimental results indicate that the response current of the PAnFc enzyme electrode is much higher than that of the PAn enzyme electrode, the response time of PAnFc enzyme electrode is shorter than that of the PAn enzyme electrode. This is due to the fact that the electrochemical activity of PAnFc is higher than that of PAn in the buffer solution with pH 5.0 and ferrocenesulfonic acid doped into polyaniline plays an important role in the charge transfer.
Polyaniline（PAnFc） synthesized in a presence of ferrocenesulfonic acid and polyaniline（PAn） synthesized in the absence of ferrocenesulfonic acid can catalyze the electrochemical oxidation of hydrogen peroxide in a buffer solution with pH 5.0, but the catalytic activity of PAnFc is higher than that of PAn.Evidence for this catalytic effect is that the oxidation potential of hydrogen peroxide shifts from 0.59 V on the bare platinum electrode to 0.48 V （vs SCE） on the PAnFc electrode, and the anodic peak current of hydrogen peroxide on the PAnFc electrode is 5.3 times as high as that on the bare platinum electrode. Based on this catalytic property, both PAn and PAnFc were used for immobilization of glucose oxidase to fabricate the enzyme electrodes. The experimental results indicate that the response current of the PAnFc enzyme electrode is much higher than that of the PAn enzyme electrode, the response time of PAnFc enzyme electrode is shorter than that of the PAn enzyme electrode. This is due to the fact that the electrochemical activity of PAnFc is higher than that of PAn in the buffer solution with pH 5.0 and ferrocenesulfonic acid doped into polyaniline plays an important role in the charge transfer.
2003, 19(07): 593-596
doi: 10.3866/PKU.WHXB20030705
Abstract:
Nanocrystalline PbTiO3 powder was obtained by melting appropriate amount of stearic acid at 70 ℃, into which tetrabutyl titanate and lead acetate were added while stirring. Then the solution was cooled in cool water to form a gel and the gel was calcined at different temperatures. The products were characterized by X-ray powder diffraction and infrared spectra analysis. The surface state was analyzed by means of X-ray photoelectron spectroscopy and surface photovoltage spectroscopy (SPS). The results show that the surface structure of nanocrystalline PbTiO3 is not integrate mainly due to the existence of oxygen cavities and most of the exposing atoms on the grain surface are metal ions. With the reducing of grain size, the oxygen cavity defect increases, the photovoltage effect on the surface enhances and the width of SPS becomes wider. The surface states of nanocrystalline materials have important influence on their dielectric properties and make the static state dielectric constant much bigger than that of bulk material.
Nanocrystalline PbTiO3 powder was obtained by melting appropriate amount of stearic acid at 70 ℃, into which tetrabutyl titanate and lead acetate were added while stirring. Then the solution was cooled in cool water to form a gel and the gel was calcined at different temperatures. The products were characterized by X-ray powder diffraction and infrared spectra analysis. The surface state was analyzed by means of X-ray photoelectron spectroscopy and surface photovoltage spectroscopy (SPS). The results show that the surface structure of nanocrystalline PbTiO3 is not integrate mainly due to the existence of oxygen cavities and most of the exposing atoms on the grain surface are metal ions. With the reducing of grain size, the oxygen cavity defect increases, the photovoltage effect on the surface enhances and the width of SPS becomes wider. The surface states of nanocrystalline materials have important influence on their dielectric properties and make the static state dielectric constant much bigger than that of bulk material.
2003, 19(07): 597-600
doi: 10.3866/PKU.WHXB20030706
Abstract:
Highly ordered ternary alloy nanowire arrays have been fabricated within nanochannels of anodic alumina membrane by electrochemical deposition. Scanning electron microscopy and transmission electron microscopy observations show that the nanowires are smooth, uniform and straight. The XRD gives the microstructure information on samples annealed at different temperatures under Ar atmosphere. Magnetic measurement shows that the nanowire arrays have higher coercivity than that of the thin magnetic film with similar composition. Meanwhile, the relation between the coercivity and annealing temperature has been studied.
Highly ordered ternary alloy nanowire arrays have been fabricated within nanochannels of anodic alumina membrane by electrochemical deposition. Scanning electron microscopy and transmission electron microscopy observations show that the nanowires are smooth, uniform and straight. The XRD gives the microstructure information on samples annealed at different temperatures under Ar atmosphere. Magnetic measurement shows that the nanowire arrays have higher coercivity than that of the thin magnetic film with similar composition. Meanwhile, the relation between the coercivity and annealing temperature has been studied.
2003, 19(07): 601-604
doi: 10.3866/PKU.WHXB20030707
Abstract:
Industrial crystallizers have to be operated at the optimum supersaturation which is less than the metastable zone width to obtain a desired product quality, such as median article size,crystal size distribution, shape and purity. Due to the time-consuming experimental determination of metastable zone width, the theoretical calculation method was studied in this paper. According to the nuclear theory and the dynamics of crystal growth, a theory model based on the model of Mersmann’s was suggested for calculating the metastable zone width of organic system with high viscosity. Also, its computation program was suggested. Combining with the parameters of crystallization process of monomehypo pesticide, the metastable zone width of industrial crystallization process was calculated, and its result is close to the experimental value. This method could be as a model for choosing the supersaturation of industrial crystallization.
Industrial crystallizers have to be operated at the optimum supersaturation which is less than the metastable zone width to obtain a desired product quality, such as median article size,crystal size distribution, shape and purity. Due to the time-consuming experimental determination of metastable zone width, the theoretical calculation method was studied in this paper. According to the nuclear theory and the dynamics of crystal growth, a theory model based on the model of Mersmann’s was suggested for calculating the metastable zone width of organic system with high viscosity. Also, its computation program was suggested. Combining with the parameters of crystallization process of monomehypo pesticide, the metastable zone width of industrial crystallization process was calculated, and its result is close to the experimental value. This method could be as a model for choosing the supersaturation of industrial crystallization.
2003, 19(07): 605-609
doi: 10.3866/PKU.WHXB20030708
Abstract:
Principles of aerosol transport mechanics are widely used to describe the performance of various sampling,filtration and aerosol processing devices, and to the prediction of their main parameters of engineering interest. Previous studies have aimed at the transport of aerosol flow in tubes, there are few studies of aerosol transport mechanics in packed columns. In this paper, the experimental method used in the investigation was the real-time measurements of the time-dependent aerosol particles concentration at the outlet of the packed columns, when submicrometer monodispersed solid spherical polystyrene aerosol particles were instantaneously introduced at the inlet to clean nitrogen flowing through the irregular-shaped quartz random-packed columns. The mean retention time and penetration were derived from the distribution of retention time. The results showed that flow velocity of the carrier gas, packed column length, aerosol particles size and quartz size effected the mean retention time and penetration of aerosols. The longer the packed column, the slower the flow velocity and the smaller aerosol particles size and quartz size, the lower the penetration coefficients. The mean retention time of aerosol particles increased with packed column length, decreased with the flow velocity increased, and was almost independent of the quartz size. The results obtained can be used to filtration and purification of aerosol particles.
Principles of aerosol transport mechanics are widely used to describe the performance of various sampling,filtration and aerosol processing devices, and to the prediction of their main parameters of engineering interest. Previous studies have aimed at the transport of aerosol flow in tubes, there are few studies of aerosol transport mechanics in packed columns. In this paper, the experimental method used in the investigation was the real-time measurements of the time-dependent aerosol particles concentration at the outlet of the packed columns, when submicrometer monodispersed solid spherical polystyrene aerosol particles were instantaneously introduced at the inlet to clean nitrogen flowing through the irregular-shaped quartz random-packed columns. The mean retention time and penetration were derived from the distribution of retention time. The results showed that flow velocity of the carrier gas, packed column length, aerosol particles size and quartz size effected the mean retention time and penetration of aerosols. The longer the packed column, the slower the flow velocity and the smaller aerosol particles size and quartz size, the lower the penetration coefficients. The mean retention time of aerosol particles increased with packed column length, decreased with the flow velocity increased, and was almost independent of the quartz size. The results obtained can be used to filtration and purification of aerosol particles.
2003, 19(07): 610-615
doi: 10.3866/PKU.WHXB20030709
Abstract:
Two new ternary complexes La(Ala)3Im(ClO4)3•3H2O (La1) and La(Ala)3BenIm(ClO4)3•H2O (La2) of lanthanum perchlorate and DL-α-alanine (Ala),imidazole (Im) or benzimidazole (BenIm) have been synthesized.In methanol, the composition of the complexes is determined by EDTA capacity analysis and elemental analysis. The characters and thermostability have been studied by IR, UV, X-ray, and TG-DTG, DSC analysis. Bioactivity experiments show that the complexes have bacteriostasis effect for five variety of microbe.
Two new ternary complexes La(Ala)3Im(ClO4)3•3H2O (La1) and La(Ala)3BenIm(ClO4)3•H2O (La2) of lanthanum perchlorate and DL-α-alanine (Ala),imidazole (Im) or benzimidazole (BenIm) have been synthesized.In methanol, the composition of the complexes is determined by EDTA capacity analysis and elemental analysis. The characters and thermostability have been studied by IR, UV, X-ray, and TG-DTG, DSC analysis. Bioactivity experiments show that the complexes have bacteriostasis effect for five variety of microbe.
2003, 19(07): 616-620
doi: 10.3866/PKU.WHXB20030710
Abstract:
On the basis of the model of slip-bare metal dissolution-repassivation and crack-tip strain analysis, a theoretical equation of stress corrosion crack propagation rate as a function of crack-tip strain rate and potential for 304L stainless steel in acidic chloride solution was deduced. The theoretical prediction showed that there are two regions in the curve of crack propagation rate with the crack-tip strain rate. In region I, the crack growth rate increases with increasing crack-tip strain rate. In region II, the crack propagation rate is independence of the crack-tip strain rate. The crack propagation rate of 304L stainless steel in acidic chloride solution has been measured by slow strain rate testing (SSRT) technique. The crack propagation rate calculated theoretically was consistent with the experimental results in region II when potential was controlled in anodic region. Fig.8Ref.12
On the basis of the model of slip-bare metal dissolution-repassivation and crack-tip strain analysis, a theoretical equation of stress corrosion crack propagation rate as a function of crack-tip strain rate and potential for 304L stainless steel in acidic chloride solution was deduced. The theoretical prediction showed that there are two regions in the curve of crack propagation rate with the crack-tip strain rate. In region I, the crack growth rate increases with increasing crack-tip strain rate. In region II, the crack propagation rate is independence of the crack-tip strain rate. The crack propagation rate of 304L stainless steel in acidic chloride solution has been measured by slow strain rate testing (SSRT) technique. The crack propagation rate calculated theoretically was consistent with the experimental results in region II when potential was controlled in anodic region. Fig.8Ref.12
2003, 19(07): 621-625
doi: 10.3866/PKU.WHXB20030711
Abstract:
The surface-modified SnO2 nanocrystals were prepared from SnO2 nanoparticles and silane coupling reagent KH-570 (γ-methacryloxy propyl trimethoxy silane). The chemical structure and surface characteristics of the sample were studied by FT-IR, XPS, TEM and TG-DTA techniques. The results indicate that the chemical binding and the physical adsorption between KH-570 and SnO2 have occured during the modification reaction. And the following items have also been obtained in this paper: (a)the characteristic absorption bands of some organic functional groups of KH-570 on the surface of SnO2 such as C=O and －C－O－ were observed by FT-IR; (b) the silicon 2s and 2p spectra of silicon in silane coupling reagent on the surface of the post-modified SnO2 were detected with XPS; (c)the dispersivity and hydrophobicity in water were enhanced. Finally, the influence factors of the quantity of KH-570 on the surface of SnO2 were discussed on the basis of the investigatied results with XPS and TG.
The surface-modified SnO2 nanocrystals were prepared from SnO2 nanoparticles and silane coupling reagent KH-570 (γ-methacryloxy propyl trimethoxy silane). The chemical structure and surface characteristics of the sample were studied by FT-IR, XPS, TEM and TG-DTA techniques. The results indicate that the chemical binding and the physical adsorption between KH-570 and SnO2 have occured during the modification reaction. And the following items have also been obtained in this paper: (a)the characteristic absorption bands of some organic functional groups of KH-570 on the surface of SnO2 such as C=O and －C－O－ were observed by FT-IR; (b) the silicon 2s and 2p spectra of silicon in silane coupling reagent on the surface of the post-modified SnO2 were detected with XPS; (c)the dispersivity and hydrophobicity in water were enhanced. Finally, the influence factors of the quantity of KH-570 on the surface of SnO2 were discussed on the basis of the investigatied results with XPS and TG.
2003, 19(07): 626-629
doi: 10.3866/PKU.WHXB20030712
Abstract:
The geometries of reactants, transition states, intermediates and products on the reaction of CH3(2A′)＋O3 have been optimized at the UMP2/6-31++G** level. The transition states and intermediates of the reactions were verified by frequency analysis. The relative single-point energies were further calculated at the UQCISD(T)/6-311++G** level, based on the UMP2/6-311++G** optimized structures. The zero point energy (ZPE) corrections and reaction’s rate constants were also obtained. We used the classic transition state theory to compute the rate constants of the CH3(2A′)＋O3 reaction (k=4.73×10－14 cm3•molecule－1•s－1). Compared with the experimental values (k=2.52×10－14 cm3•molecule－1•s－1), our calculated result is in od agreement with experimental datum.
The geometries of reactants, transition states, intermediates and products on the reaction of CH3(2A′)＋O3 have been optimized at the UMP2/6-31++G** level. The transition states and intermediates of the reactions were verified by frequency analysis. The relative single-point energies were further calculated at the UQCISD(T)/6-311++G** level, based on the UMP2/6-311++G** optimized structures. The zero point energy (ZPE) corrections and reaction’s rate constants were also obtained. We used the classic transition state theory to compute the rate constants of the CH3(2A′)＋O3 reaction (k=4.73×10－14 cm3•molecule－1•s－1). Compared with the experimental values (k=2.52×10－14 cm3•molecule－1•s－1), our calculated result is in od agreement with experimental datum.
2003, 19(07): 630-634
doi: 10.3866/PKU.WHXB20030713
Abstract:
Cyclic voltammetry and potentiostatic electrolysis were used to investigate the preparation of Er-Bi alloy films in LiCl-DMSO system.The effects of several factors including the potential and current density of deposition and concentrations of main salts were studied.Experimental results indicate that Er-Bi alloy films containing Er 24.09％～46.56％ could be prepared in ErCl3-Bi(NO3)3-LiCl-DMSO system by controlling the composition and deposition conditions of the system.They are gray, uniform, of metallic luster and adhere firmly to the copper substrates showed by SEM, EDS, XRD and DSC. After heating at 723 K for 1 h, the crystallized alloy phase of Er-Bi could be found in XRD patterns.
Cyclic voltammetry and potentiostatic electrolysis were used to investigate the preparation of Er-Bi alloy films in LiCl-DMSO system.The effects of several factors including the potential and current density of deposition and concentrations of main salts were studied.Experimental results indicate that Er-Bi alloy films containing Er 24.09％～46.56％ could be prepared in ErCl3-Bi(NO3)3-LiCl-DMSO system by controlling the composition and deposition conditions of the system.They are gray, uniform, of metallic luster and adhere firmly to the copper substrates showed by SEM, EDS, XRD and DSC. After heating at 723 K for 1 h, the crystallized alloy phase of Er-Bi could be found in XRD patterns.
2003, 19(07): 635-640
doi: 10.3866/PKU.WHXB20030714
Abstract:
Four hemicyanine derivatives, (E)-N-(4-sulfobutyl)-4-[2-(4-N, N-dimethylamino- phenyl) ethenyl] pyridinium(P1), (E)-N-(4-sulfobutyl)-4-[2-(4-N, N-dimethylaminophenyl)-1,3- butenyl]pyridinium(P2), (E)-N-(4-sulfobutyl)-4-[2-(4-N,N-dimethylaminophenyl)ethenyl] quinol- inium (Q1) and (E)-N-(4-sulfobutyl)-4- [2-(4-N,N- dimethylaminophenyl)-1,3- butenyl] quinolinium(Q2), with different conjugated bridge and acceptor groups, have been synthesized and characterized with regard to their photophysical and photoelectrochemical properties. Experiments show that with extended π-conjugation bridge, the λmax of P2 and Q2 both red shifted and their absorption spectra broadened, which is advantageous for photoelectric conversion. Photoelectric properties of the four dye sensitized TiO2 electrodes were investigated in standard two-electrode system, and the data obtained show that Q1 has the best photo-to-electron conversion among the four dyes.
Four hemicyanine derivatives, (E)-N-(4-sulfobutyl)-4-[2-(4-N, N-dimethylamino- phenyl) ethenyl] pyridinium(P1), (E)-N-(4-sulfobutyl)-4-[2-(4-N, N-dimethylaminophenyl)-1,3- butenyl]pyridinium(P2), (E)-N-(4-sulfobutyl)-4-[2-(4-N,N-dimethylaminophenyl)ethenyl] quinol- inium (Q1) and (E)-N-(4-sulfobutyl)-4- [2-(4-N,N- dimethylaminophenyl)-1,3- butenyl] quinolinium(Q2), with different conjugated bridge and acceptor groups, have been synthesized and characterized with regard to their photophysical and photoelectrochemical properties. Experiments show that with extended π-conjugation bridge, the λmax of P2 and Q2 both red shifted and their absorption spectra broadened, which is advantageous for photoelectric conversion. Photoelectric properties of the four dye sensitized TiO2 electrodes were investigated in standard two-electrode system, and the data obtained show that Q1 has the best photo-to-electron conversion among the four dyes.
2003, 19(07): 641-646
doi: 10.3866/PKU.WHXB20030715
Abstract:
Ti/ZrN2 multiplayer was deposited on silicon wafer using DC magnetron sputtering method. Interface diffusion and chemical states at interfaces were investigated using line shape analysis along with depth profile analysis of Auger electron spectroscopy (AES). Interface diffusion was performed during deposition of thin film and can be intensified by thermal treatment in vacuum. Interface reaction also can be promoted by thermal treatment, and TiNx and SiNx species were formed at interface respectively.
Ti/ZrN2 multiplayer was deposited on silicon wafer using DC magnetron sputtering method. Interface diffusion and chemical states at interfaces were investigated using line shape analysis along with depth profile analysis of Auger electron spectroscopy (AES). Interface diffusion was performed during deposition of thin film and can be intensified by thermal treatment in vacuum. Interface reaction also can be promoted by thermal treatment, and TiNx and SiNx species were formed at interface respectively.
2003, 19(07): 647-650
doi: 10.3866/PKU.WHXB20030716
Abstract:
A novel composite material consisting of nano-colloidal silver and zirconium phosphate was synthesized and applied for the preparation of modified electrodes. The electrochemical property of the modified electrode was studied by the cyclic voltammetry. The nature of nano size particles of silver and the ability of zirconium phosphate to tune the potential were retained in this complex film. The ability of zirconium phosphate to adsorb neutral red and the redox reaction activity of neutral red were enhanced significantly in the composite film. The composite film modified electrode showed greater response. The composite film presents better mechanic strength and the modified electrode shows better stability.
A novel composite material consisting of nano-colloidal silver and zirconium phosphate was synthesized and applied for the preparation of modified electrodes. The electrochemical property of the modified electrode was studied by the cyclic voltammetry. The nature of nano size particles of silver and the ability of zirconium phosphate to tune the potential were retained in this complex film. The ability of zirconium phosphate to adsorb neutral red and the redox reaction activity of neutral red were enhanced significantly in the composite film. The composite film modified electrode showed greater response. The composite film presents better mechanic strength and the modified electrode shows better stability.
2003, 19(07): 651-653
doi: 10.3866/PKU.WHXB20030717
Abstract:
The structure parameters and some thermodynamic functions for UO2, UC2, UCO are calculated using ab initio method. The vibration energies Ev, vibration and electronic entropies Sev for solid U are calculated based on Debye’s theories for crystal vibration. Thus the formation thermodynamic functions ΔHfΘ、ΔSfΘ and ΔGfΘ for UO2, UC2 and UCO compound are obtained. Results show that UO2 is stable, while UC2 and UCO are unstable.
The structure parameters and some thermodynamic functions for UO2, UC2, UCO are calculated using ab initio method. The vibration energies Ev, vibration and electronic entropies Sev for solid U are calculated based on Debye’s theories for crystal vibration. Thus the formation thermodynamic functions ΔHfΘ、ΔSfΘ and ΔGfΘ for UO2, UC2 and UCO compound are obtained. Results show that UO2 is stable, while UC2 and UCO are unstable.
2003, 19(07): 654-656
doi: 10.3866/PKU.WHXB20030718
Abstract:
A new solid acid resin catalyst with high thermal stability——sulfonated poly (phthalazinone ether sulfone ketone) (S-PPESK) resin was prepared through sulfonation method and applied to isobutene oli merization. S-PPESK showed high catalytic activity and excellent dimerization selectivity under low reaction temperature conditions. The thermal stability of S-PPESK was measured by pretreatment method, the pretreatment temperature was 180 ℃ which was about 40 ℃ higher than that for with commercial sulphuric acid resin catalyst. S-PPESK exhibits od catalytic activity, excellent dimerization selectivity and high thermal stability in isobutene oli merization. It is a promising resin catalyst.
A new solid acid resin catalyst with high thermal stability——sulfonated poly (phthalazinone ether sulfone ketone) (S-PPESK) resin was prepared through sulfonation method and applied to isobutene oli merization. S-PPESK showed high catalytic activity and excellent dimerization selectivity under low reaction temperature conditions. The thermal stability of S-PPESK was measured by pretreatment method, the pretreatment temperature was 180 ℃ which was about 40 ℃ higher than that for with commercial sulphuric acid resin catalyst. S-PPESK exhibits od catalytic activity, excellent dimerization selectivity and high thermal stability in isobutene oli merization. It is a promising resin catalyst.
2003, 19(07): 657-660
doi: 10.3866/PKU.WHXB20030719
Abstract:
By using modified sol-gel method, BaTiO3 nano-films were coated on the surface of polyaniline particles. The structure and morphology of coated powders were characterized by TEM and FT-IR, the electrorheological effects were also investigated. The infrared spectrogram shows that there is N－O hydrogen-bond forming between PAn and BaTiO3 in coated particle. TEM results show that the diameters of the coated particles are 1.0～1.5 μm.In addition, the dielectric properties and electrorheological effects are improved greatly by the coating process. It has provided us a new method for the preparation of excellent ER materials and further studies should be continued.
By using modified sol-gel method, BaTiO3 nano-films were coated on the surface of polyaniline particles. The structure and morphology of coated powders were characterized by TEM and FT-IR, the electrorheological effects were also investigated. The infrared spectrogram shows that there is N－O hydrogen-bond forming between PAn and BaTiO3 in coated particle. TEM results show that the diameters of the coated particles are 1.0～1.5 μm.In addition, the dielectric properties and electrorheological effects are improved greatly by the coating process. It has provided us a new method for the preparation of excellent ER materials and further studies should be continued.
2003, 19(07): 661-665
doi: 10.3866/PKU.WHXB20030720
Abstract:
Methane molecules were irradiated by a laser beam in the intensity range of 7.6 ×1013～1.4×1014 W•cm－2 (800 nm, 160 fs). A time of flight mass spectrometer was coupled to the laser system. The parent ions can be seen at low laser intensity of 7.6×1013 W•cm－2. When the laser intensity increases to 8 .0×1013 W•cm－2, CH3＋ ions appear. The appearance of the CH2＋, CH＋, C＋ ions are at the laser intensities of 1.0×1014 W•cm－2, 1.4×1014 W•cm－2 and 1.4×1014 W•cm－2, respectively. The facts show that dissociation of methane is a step-wise process. Coulomb explosion does not happen during the dissociation because no multi-electron ions are found in the mass spectra. Only H＋ ion yield has anisotropic angular distribution when methane is irradiated by a linearly polarized laser. This fact implies that the chemical bonds in the molecule are pulled off by the laser field and that the H＋ ion flies along the direction of the laser electronic field. The quasi-diatomic molecule model we proposed can explain the experimental results satisfactorily.
Methane molecules were irradiated by a laser beam in the intensity range of 7.6 ×1013～1.4×1014 W•cm－2 (800 nm, 160 fs). A time of flight mass spectrometer was coupled to the laser system. The parent ions can be seen at low laser intensity of 7.6×1013 W•cm－2. When the laser intensity increases to 8 .0×1013 W•cm－2, CH3＋ ions appear. The appearance of the CH2＋, CH＋, C＋ ions are at the laser intensities of 1.0×1014 W•cm－2, 1.4×1014 W•cm－2 and 1.4×1014 W•cm－2, respectively. The facts show that dissociation of methane is a step-wise process. Coulomb explosion does not happen during the dissociation because no multi-electron ions are found in the mass spectra. Only H＋ ion yield has anisotropic angular distribution when methane is irradiated by a linearly polarized laser. This fact implies that the chemical bonds in the molecule are pulled off by the laser field and that the H＋ ion flies along the direction of the laser electronic field. The quasi-diatomic molecule model we proposed can explain the experimental results satisfactorily.
2003, 19(07): 666-669
doi: 10.3866/PKU.WHXB20030721
Abstract:
The supported catalyst LaCoO3/γ-Al2O3 was prepared by ultrasound during the impregnating preparation steps and the effects of ultrasound with various frequencies on the properties of catalyst were investigated in this paper. For the preparation of LaCoO3/γ-Al2O3, 5 g ofγ-Al2O3 ( 20 mesh) was added to 20 mL of molar ratio 1:1 mixture of aqueous solution of La(NO3)3 and Co(NO3)2. Ultrasonic irradiation was performed with direct immersion horn (with various frequencies i.e. 33, 40, 50 and 70 kHz) at 20 ℃. The precursors were filtered off, washed with water, dried for 2 h at 120 ℃ and were calcined for 5 h at 850 ℃. The formation of LaCoO3 was determined by XRD. Another sample (O＃ sample) for comparision LaCoO3/γ-Al2O3 was prepared under the same experimental conditions and steps except ultrasonic irradiation was replaced by mechanical stirring for 2 h in impregnating step. The effects of ultrasonic irradiation frequencies and irradiation time in impregnating step on loading of LaCoO3 were studied. The results showed that ultrasonic irradiation could decrease impregnating time and increase loading of LaCoO3. And ultrasonic irradiation with 50 kHz frequencies showed the best experimental result. The loading of LaCoO3 of LaCoO3/γ-Al2O3 ( 1＃ sample ), prepared by ultrasonic irradiation ( with 50 kHz for 5 min), was 25％ more than that of 0＃ sample. Transmission electron micrograph showed that on the support surface of 1＃ sample, the average particle size of LaCoO3 was 8 nm. The scanning electron micrographs and electron microprobe analyzer scans showed that on the support surface of 1＃ sample, distribution of LaCoO3 particles was better compared with that on the support surface of 0＃ sample. Using the BET method, surface area and pore distribution were determined. They were 133.17 m2•g－1(1＃ sample) and 114.71 m2•g－1 (0＃ sample )respectirely. 1＃ sample have more micropores than 0＃ sample. According to the results of activities evaluation of decomposition of NO, the catalytic activity of 1＃ sample was higher than that of 0＃ sample. Therefore, using ultrasonic irradiation in the impregnating step of catalyst preparation is an effective method for enhancing catalytic activity of the catalyst.
The supported catalyst LaCoO3/γ-Al2O3 was prepared by ultrasound during the impregnating preparation steps and the effects of ultrasound with various frequencies on the properties of catalyst were investigated in this paper. For the preparation of LaCoO3/γ-Al2O3, 5 g ofγ-Al2O3 ( 20 mesh) was added to 20 mL of molar ratio 1:1 mixture of aqueous solution of La(NO3)3 and Co(NO3)2. Ultrasonic irradiation was performed with direct immersion horn (with various frequencies i.e. 33, 40, 50 and 70 kHz) at 20 ℃. The precursors were filtered off, washed with water, dried for 2 h at 120 ℃ and were calcined for 5 h at 850 ℃. The formation of LaCoO3 was determined by XRD. Another sample (O＃ sample) for comparision LaCoO3/γ-Al2O3 was prepared under the same experimental conditions and steps except ultrasonic irradiation was replaced by mechanical stirring for 2 h in impregnating step. The effects of ultrasonic irradiation frequencies and irradiation time in impregnating step on loading of LaCoO3 were studied. The results showed that ultrasonic irradiation could decrease impregnating time and increase loading of LaCoO3. And ultrasonic irradiation with 50 kHz frequencies showed the best experimental result. The loading of LaCoO3 of LaCoO3/γ-Al2O3 ( 1＃ sample ), prepared by ultrasonic irradiation ( with 50 kHz for 5 min), was 25％ more than that of 0＃ sample. Transmission electron micrograph showed that on the support surface of 1＃ sample, the average particle size of LaCoO3 was 8 nm. The scanning electron micrographs and electron microprobe analyzer scans showed that on the support surface of 1＃ sample, distribution of LaCoO3 particles was better compared with that on the support surface of 0＃ sample. Using the BET method, surface area and pore distribution were determined. They were 133.17 m2•g－1(1＃ sample) and 114.71 m2•g－1 (0＃ sample )respectirely. 1＃ sample have more micropores than 0＃ sample. According to the results of activities evaluation of decomposition of NO, the catalytic activity of 1＃ sample was higher than that of 0＃ sample. Therefore, using ultrasonic irradiation in the impregnating step of catalyst preparation is an effective method for enhancing catalytic activity of the catalyst.
2003, 19(07): 670-674
doi: 10.3866/PKU.WHXB20030722
Abstract:
Two kinds of intra-molecular conjugated charge transfer compounds 2,3-dicyano-5,7-bis[2-[4-dimethylamino-phenyl]ethenyl]-6H-1,4-diazepine(1) and 2,3-dicyano-5- phenyl-7-[2-(4-dimethylamino-phenyl)ethenyl]-6H-1,4-diazepine(2) are synthesized and studied in this work. From the literature it is well known by the calculation of quantum chemistry that the molecular structure of these compounds is the non-planar one. The solvato-chromic behaviors of these compounds are studied in solvents with different polarity in detail. Results indicate that the peak wavelengths of fluorescence spectra of these compounds in solution are linear related with the empirical parameter of solvent polarity ET(30) in certain kinds of solvents. Compared with the double arm’s conjugated compound (1), the single arm’s conjugated compound (2) shows itself the larger Stoke’s shift and larger dipole moment difference. The results have been discussed preliminary.
Two kinds of intra-molecular conjugated charge transfer compounds 2,3-dicyano-5,7-bis[2-[4-dimethylamino-phenyl]ethenyl]-6H-1,4-diazepine(1) and 2,3-dicyano-5- phenyl-7-[2-(4-dimethylamino-phenyl)ethenyl]-6H-1,4-diazepine(2) are synthesized and studied in this work. From the literature it is well known by the calculation of quantum chemistry that the molecular structure of these compounds is the non-planar one. The solvato-chromic behaviors of these compounds are studied in solvents with different polarity in detail. Results indicate that the peak wavelengths of fluorescence spectra of these compounds in solution are linear related with the empirical parameter of solvent polarity ET(30) in certain kinds of solvents. Compared with the double arm’s conjugated compound (1), the single arm’s conjugated compound (2) shows itself the larger Stoke’s shift and larger dipole moment difference. The results have been discussed preliminary.
2003, 19(07): 675-680
doi: 10.3866/PKU.WHXB20030723
Abstract:
Surfactant is a substance that lowers the surface tension of the medium in which it is dissolved. They form oriented colloidal aggregates, micelles, when a specific concentration is exceeded and abrupt changes in physical properties of the solution will be observed. Surfactant systems have been proved to be very useful in many biological and industrial processes. Properties of these systems have been intensively investigated by many spectroscopy methods, especially proton nuclear magnetic resonance (1H NMR). It has played more and more important role in the continued development of NMR new techniques. Characterization of micellization processes, physical properties of micelles, e.g. structure, size and shape, hydration of micelles, solubilization by micelles, interaction between micelles of different kinds of surfactants, and that with biological compounds and with polymers were studied by the existing sophisticated NMR techniques. These investigations demonstrate that NMR spectroscopy is a versatile technique for the study of surfactants. It provides information at a molecular level that is not available by other spectroscopic methods. Chemical shift changes, relaxation experiments and NMR self-diffusion measurements are almost used routinely. The use of two-dimensional NMR spectroscopy, 2D NOESY and HOESY is a growing trend in studying the chain packing in micelles as well as interactions between micelles with other molecules, biological and polymeric. These methods provide a deeper insight into the relative arrangement of surfactant molecules in an associated assembly.
Surfactant is a substance that lowers the surface tension of the medium in which it is dissolved. They form oriented colloidal aggregates, micelles, when a specific concentration is exceeded and abrupt changes in physical properties of the solution will be observed. Surfactant systems have been proved to be very useful in many biological and industrial processes. Properties of these systems have been intensively investigated by many spectroscopy methods, especially proton nuclear magnetic resonance (1H NMR). It has played more and more important role in the continued development of NMR new techniques. Characterization of micellization processes, physical properties of micelles, e.g. structure, size and shape, hydration of micelles, solubilization by micelles, interaction between micelles of different kinds of surfactants, and that with biological compounds and with polymers were studied by the existing sophisticated NMR techniques. These investigations demonstrate that NMR spectroscopy is a versatile technique for the study of surfactants. It provides information at a molecular level that is not available by other spectroscopic methods. Chemical shift changes, relaxation experiments and NMR self-diffusion measurements are almost used routinely. The use of two-dimensional NMR spectroscopy, 2D NOESY and HOESY is a growing trend in studying the chain packing in micelles as well as interactions between micelles with other molecules, biological and polymeric. These methods provide a deeper insight into the relative arrangement of surfactant molecules in an associated assembly.
