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2005 Volume 22 Issue 7
2005, 22(7): 697-702
Abstract:
Nanoscience and nanotechnology is recognized as the base of high-tech in the 21st century.During the process of application of nanoparticles,their assembly is crucial.So what challenges us is how to control and assemble nanoparticles efficiently.This review comments on the role of Langmuir-Blodgett in the assembly of nanoparticles:its status and future development.
Nanoscience and nanotechnology is recognized as the base of high-tech in the 21st century.During the process of application of nanoparticles,their assembly is crucial.So what challenges us is how to control and assemble nanoparticles efficiently.This review comments on the role of Langmuir-Blodgett in the assembly of nanoparticles:its status and future development.
2005, 22(7): 703-708
Abstract:
The promoters Ce0.6Zr0.4-xTbxO2-y of three-way catalysts (TWCs) were prepared by coprecipitation and sol-gel methods.The XRD and Raman spectra confirm that the Ce0.6Zr0.4-xTbxO2-y cubic solid solution is formed,and the XPS analysis indicates that the valences of Ce and Tb are maily in the forms of Ce4+ and Tb3+ on the surface of samples.The particle size distribution and TEM show that the solid solution particles are in the form of agglomerate in the liquid.The catalytic performance was also measured for the fully formulated Pt,Rh and Pd TWCs (high ratio of Pd) containing this kind of promoters.The results indicate that the introduction of Tb ions into CeO2-ZrO2 solid solution lowers the ligh-off temperature of fresh TWCs.Among TWCs containing the promoters which prepared via coprecipitation method,the sample containing 15% Tb exhibits the lowest ligh-off temperature,that is,18℃,21℃ and 27℃ for CO,C3H6 and NOx conversion,while for those containing the promoters prepared by sol-gel method,the ligh-off temperature does not depend on Tb content,the sol-gel method is better than the coprecipitation method.For the aged samples which have been calcined at 900℃ for 2 h,the optimum Tb content is 5%.
The promoters Ce0.6Zr0.4-xTbxO2-y of three-way catalysts (TWCs) were prepared by coprecipitation and sol-gel methods.The XRD and Raman spectra confirm that the Ce0.6Zr0.4-xTbxO2-y cubic solid solution is formed,and the XPS analysis indicates that the valences of Ce and Tb are maily in the forms of Ce4+ and Tb3+ on the surface of samples.The particle size distribution and TEM show that the solid solution particles are in the form of agglomerate in the liquid.The catalytic performance was also measured for the fully formulated Pt,Rh and Pd TWCs (high ratio of Pd) containing this kind of promoters.The results indicate that the introduction of Tb ions into CeO2-ZrO2 solid solution lowers the ligh-off temperature of fresh TWCs.Among TWCs containing the promoters which prepared via coprecipitation method,the sample containing 15% Tb exhibits the lowest ligh-off temperature,that is,18℃,21℃ and 27℃ for CO,C3H6 and NOx conversion,while for those containing the promoters prepared by sol-gel method,the ligh-off temperature does not depend on Tb content,the sol-gel method is better than the coprecipitation method.For the aged samples which have been calcined at 900℃ for 2 h,the optimum Tb content is 5%.
2005, 22(7): 709-714
Abstract:
A medium-scale smoke chamber,a thermal image formation analyzer and a Fourier transform infrared spectrometer etc.were used to measure the camouflaging mass and extinction coefficient of red phosphorous smoke screen.When the target was covered completely,the camouflaging mass was 3.58 g/m2.The extinction coefficient was 0.14 m2/g in the range of 3~5 μm or 0.078 m2/g in the range of 8~12 μm at 23℃ and relative humidity 60%.According to the Mie scattering theory,the extinction efficiency of red phosphorous smoke screen was calculated.By comparing the result of the theoretical data with the result of the experiment,it is shown that the two kinds of results are rather analogical in the wave band form 8 to 12 μm.The extinction of particle (2.5 μm) is worked out via analyzing key extinction factors,such as time,particle size and conductance.At the beginning of smoke screen is released,the extinction coefficient is increased.With the time going on,it falls down fast because of the sedimentation and cohesion of the small grains.The conductance of RP is little.The deepness of radiation is great while the reflection of radiation is small.So,the main extinction ability of RP is absorption.
A medium-scale smoke chamber,a thermal image formation analyzer and a Fourier transform infrared spectrometer etc.were used to measure the camouflaging mass and extinction coefficient of red phosphorous smoke screen.When the target was covered completely,the camouflaging mass was 3.58 g/m2.The extinction coefficient was 0.14 m2/g in the range of 3~5 μm or 0.078 m2/g in the range of 8~12 μm at 23℃ and relative humidity 60%.According to the Mie scattering theory,the extinction efficiency of red phosphorous smoke screen was calculated.By comparing the result of the theoretical data with the result of the experiment,it is shown that the two kinds of results are rather analogical in the wave band form 8 to 12 μm.The extinction of particle (2.5 μm) is worked out via analyzing key extinction factors,such as time,particle size and conductance.At the beginning of smoke screen is released,the extinction coefficient is increased.With the time going on,it falls down fast because of the sedimentation and cohesion of the small grains.The conductance of RP is little.The deepness of radiation is great while the reflection of radiation is small.So,the main extinction ability of RP is absorption.
2005, 22(7): 715-721
Abstract:
Isotactic polypropylene grafted with maleic anhydride (PP-g-MAH) and PP-g-MAH filled with Nd2O3 or CeO2 (REOs) were prepared by means of reactive extrusion.The crystallization behavior and crystal structure of PP,PP-g-MAH and PP-g-MAH filled with REOs were studied by DSC,PLM and WAXD techniques.The results show that the crystallization rate of the grafted polypropylene is higher than that of blank polypropylene.Furthermore,the addition of the REO can accelerate the crystallization rate of the grafted polypropylene.After introducing the REO into PP-g-MAH,the heterogeneous nucleation dominates the process of crystallization,and the low active energy for crystallization increases the crystallization rate.In particular,PP-g-MAH filled with CeO2 has the lowest active energy and the highest crystallization rate.The addition of REOs does not influence notably the nucleation mechanism and growth mode of the crystallization of i-PP,whereas it enhances the equilibrium melting point and equilibrium melting enthalpy of PP-g-MAH.The WAXD analysis indicates that the addition of the REO can increase the crystallite size of the α-form crystal.
Isotactic polypropylene grafted with maleic anhydride (PP-g-MAH) and PP-g-MAH filled with Nd2O3 or CeO2 (REOs) were prepared by means of reactive extrusion.The crystallization behavior and crystal structure of PP,PP-g-MAH and PP-g-MAH filled with REOs were studied by DSC,PLM and WAXD techniques.The results show that the crystallization rate of the grafted polypropylene is higher than that of blank polypropylene.Furthermore,the addition of the REO can accelerate the crystallization rate of the grafted polypropylene.After introducing the REO into PP-g-MAH,the heterogeneous nucleation dominates the process of crystallization,and the low active energy for crystallization increases the crystallization rate.In particular,PP-g-MAH filled with CeO2 has the lowest active energy and the highest crystallization rate.The addition of REOs does not influence notably the nucleation mechanism and growth mode of the crystallization of i-PP,whereas it enhances the equilibrium melting point and equilibrium melting enthalpy of PP-g-MAH.The WAXD analysis indicates that the addition of the REO can increase the crystallite size of the α-form crystal.
2005, 22(7): 722-725
Abstract:
Mn3O4 nanoparticles were prepared at low temperatures with KMnO4 and ethanol as reactants via a solvothermal method.With the help of spectrophotometer and X-ray diffractometer,the influences of temperature,reaction time and water content in the solvent on the reaction process as well as the product were investigated.Experiments showed that increasing reaction temperature accelerated the reaction rate,improved the crystallinity of Mn3O4 and made its particles grow larger.When reaction temperature was blow 100℃,the reaction slowed down.Water in the solvent can accelerate the reaction rate of KMnO4,but higher water content leads to a new phase MnO(OH).Based on the experiments,the controllable synthesis of nanocrystalline Mn3O4 has been achieved.Nanocrystalline Mn3O4 powders with average particle sizes of 10 nm and 60 nm were obtained,respectively at 100℃ and 160℃.The products were characterized with X-ray powder diffraction and transmission electron microscopy.
Mn3O4 nanoparticles were prepared at low temperatures with KMnO4 and ethanol as reactants via a solvothermal method.With the help of spectrophotometer and X-ray diffractometer,the influences of temperature,reaction time and water content in the solvent on the reaction process as well as the product were investigated.Experiments showed that increasing reaction temperature accelerated the reaction rate,improved the crystallinity of Mn3O4 and made its particles grow larger.When reaction temperature was blow 100℃,the reaction slowed down.Water in the solvent can accelerate the reaction rate of KMnO4,but higher water content leads to a new phase MnO(OH).Based on the experiments,the controllable synthesis of nanocrystalline Mn3O4 has been achieved.Nanocrystalline Mn3O4 powders with average particle sizes of 10 nm and 60 nm were obtained,respectively at 100℃ and 160℃.The products were characterized with X-ray powder diffraction and transmission electron microscopy.
2005, 22(7): 726-729
Abstract:
In a 0.2 mol/L NaOH solution,KIO3 can yield two peaks at -0.6 V(vs.SCE) and -1.6 V on the cathode of oscillogram.The reduction at -1.6 V is quite sensitive,its depth would get shallow with the increase of Vc because of the reaction between Vc and KIO3.Based on this oscillographic character,a new method,second order differential simple oscillographic voltammetry for the determination of Vc in a troche and a drink containing Vc is established in this paper.Under the optimal experimental condition,a linear response was observed in the range 3.0×10-6~4.5×10-5 mol/L with a correlation coefficient R=0.995 4 and a detection limit 2.0×10-6 mol/L for Vc.The relative standard deviation (RSD) and average recovery for the determination of 3.0×10-5 mol/L Vc are 2.9% and 98.9%(n=5),respec-tively.Thus,the oscillographic determination method in a redox system can be applied to the determination of some non-active substances in oscillographic analysis,and so it is an actually useful approach for enlarging the application field of oscillographic analysis.
In a 0.2 mol/L NaOH solution,KIO3 can yield two peaks at -0.6 V(vs.SCE) and -1.6 V on the cathode of oscillogram.The reduction at -1.6 V is quite sensitive,its depth would get shallow with the increase of Vc because of the reaction between Vc and KIO3.Based on this oscillographic character,a new method,second order differential simple oscillographic voltammetry for the determination of Vc in a troche and a drink containing Vc is established in this paper.Under the optimal experimental condition,a linear response was observed in the range 3.0×10-6~4.5×10-5 mol/L with a correlation coefficient R=0.995 4 and a detection limit 2.0×10-6 mol/L for Vc.The relative standard deviation (RSD) and average recovery for the determination of 3.0×10-5 mol/L Vc are 2.9% and 98.9%(n=5),respec-tively.Thus,the oscillographic determination method in a redox system can be applied to the determination of some non-active substances in oscillographic analysis,and so it is an actually useful approach for enlarging the application field of oscillographic analysis.
2005, 22(7): 730-733
Abstract:
A one-dimensional coordination polymer of Ag(Ⅰ) with 2-aminobenzothiazole,[Ag(C7H6N2S)(NO3)]∞(1) was synthesized and characterized by means of elemental analysis,IR spectrum and fluorescence spectrum.Its crystal structure was determined by virture of X-ray single crystal diffraction method.The title compound,C7H6AgN3O3S,Mr=320.08,crystallized in the monoclinic system with space group P2(1)/c,a=0.683 4(1),b=1.541 6(2),c=0.906 9(1) nm,β=90.05(1)°,Z=4,Dc=(2.225 Mg/m3),V=0.955 4(2) nm3,F(000)=624 and R1=0.036 2,wR2=0.070 2(I>2σ(I)).In compound 1,the 2-aminobenzothiazole coordinates to silver (Ⅰ) via its thiazole N atoms,and NO3- bridges the adjacent silver (Ⅰ) via its' two O atoms to form a one-dimensional chain structure.The antibacterial activity test result shows that the ligand and complex possess strong inhibition activity to Staphylococcus aureus,escherichia coli,Candida albicans in the concentration range of 5.0×10-1~6.25×10-2 g/mL (DMSO as solvent).
A one-dimensional coordination polymer of Ag(Ⅰ) with 2-aminobenzothiazole,[Ag(C7H6N2S)(NO3)]∞(1) was synthesized and characterized by means of elemental analysis,IR spectrum and fluorescence spectrum.Its crystal structure was determined by virture of X-ray single crystal diffraction method.The title compound,C7H6AgN3O3S,Mr=320.08,crystallized in the monoclinic system with space group P2(1)/c,a=0.683 4(1),b=1.541 6(2),c=0.906 9(1) nm,β=90.05(1)°,Z=4,Dc=(2.225 Mg/m3),V=0.955 4(2) nm3,F(000)=624 and R1=0.036 2,wR2=0.070 2(I>2σ(I)).In compound 1,the 2-aminobenzothiazole coordinates to silver (Ⅰ) via its thiazole N atoms,and NO3- bridges the adjacent silver (Ⅰ) via its' two O atoms to form a one-dimensional chain structure.The antibacterial activity test result shows that the ligand and complex possess strong inhibition activity to Staphylococcus aureus,escherichia coli,Candida albicans in the concentration range of 5.0×10-1~6.25×10-2 g/mL (DMSO as solvent).
2005, 22(7): 734-738
Abstract:
A W/O microemulsion was prepared with Span80-PS (petroleum sulfonate) as composite emulsi-fier,isopropanol as cosurfactant and kerosene as oil phase.The optimal microemulsion conditions were found from pseudoternary phase diagrams,i.e.,the mass ratio of Span80 to PS is 4:1 and that of composite emulsifier to cosurfactant is 1:1.The Fe3O4 fluid was obtained by one-step method with the W/O micro-emulsion as microreactor to synthesize magnetic nanoparticles (reaction temperature is 30℃ and reaction time is 5 h) and kerosene as carrier liquid.The magnetic fluid was investigated by means of TEM,XRD and fluorescence microscopy.The magnetism of Fe3O4 fluid was determined by virtue of a Gouy magnetic balance.The average particle size is 7.4 nm,and magnetic particles are well-dispersed.The stable Fe3O4 magnetic fluid with good magnetism may be prepared by one-step method in the microemulsion.Accordingly,the traditional preparation method of magnetic fluid can be simplified greatly.
A W/O microemulsion was prepared with Span80-PS (petroleum sulfonate) as composite emulsi-fier,isopropanol as cosurfactant and kerosene as oil phase.The optimal microemulsion conditions were found from pseudoternary phase diagrams,i.e.,the mass ratio of Span80 to PS is 4:1 and that of composite emulsifier to cosurfactant is 1:1.The Fe3O4 fluid was obtained by one-step method with the W/O micro-emulsion as microreactor to synthesize magnetic nanoparticles (reaction temperature is 30℃ and reaction time is 5 h) and kerosene as carrier liquid.The magnetic fluid was investigated by means of TEM,XRD and fluorescence microscopy.The magnetism of Fe3O4 fluid was determined by virtue of a Gouy magnetic balance.The average particle size is 7.4 nm,and magnetic particles are well-dispersed.The stable Fe3O4 magnetic fluid with good magnetism may be prepared by one-step method in the microemulsion.Accordingly,the traditional preparation method of magnetic fluid can be simplified greatly.
2005, 22(7): 739-743
Abstract:
Resveratrol,a promising anti-cancer agent,is an important active ingredent in Polygonum cuspidatum Sieb.et Zucc.A molecular imprinted polymer was prepared by virtue of molecular imprinting technique,with trans-resveratrol as the template molecular,acrylamide as the functional monomer,EGDMA as the cross-linking agent.The molecular imprinted polymer was investigated with the aid of equilibrium binding experiments to evaluate the molecular recognition and binding characteristics of the trans-resveratrol molecularly imprinted polymer.The scatchard analysis showed that two kinds of binding sites were produced in the polymer matrix and their dissociation constants were calculated to be 9.9×10-5 mol/L,1.7×10-3 mol/L,respec-tively.The results show that compared with non-imprinted polymer,the imprinted polymer exhibits a much higher affinity for trans-resveratrol among the tested compounds Res,Pol and BPA.Also,the imprinted polymer was applied to separate resveratrol from Polygonum cuspidatum Sieb.et Zucc.extracts and good results were obtained.
Resveratrol,a promising anti-cancer agent,is an important active ingredent in Polygonum cuspidatum Sieb.et Zucc.A molecular imprinted polymer was prepared by virtue of molecular imprinting technique,with trans-resveratrol as the template molecular,acrylamide as the functional monomer,EGDMA as the cross-linking agent.The molecular imprinted polymer was investigated with the aid of equilibrium binding experiments to evaluate the molecular recognition and binding characteristics of the trans-resveratrol molecularly imprinted polymer.The scatchard analysis showed that two kinds of binding sites were produced in the polymer matrix and their dissociation constants were calculated to be 9.9×10-5 mol/L,1.7×10-3 mol/L,respec-tively.The results show that compared with non-imprinted polymer,the imprinted polymer exhibits a much higher affinity for trans-resveratrol among the tested compounds Res,Pol and BPA.Also,the imprinted polymer was applied to separate resveratrol from Polygonum cuspidatum Sieb.et Zucc.extracts and good results were obtained.
2005, 22(7): 744-748
Abstract:
The two-step reaction for the preparation of methyl methacrylate (MMA) from methacrolein (MAL) via oxidative esterification was simplified to one-stage reaction.The catalysts were prepared by means of impregnation and applied to the oxidative esterification reaction of MAL.The results show that the catalytic activity of catalyst mainly containing Pd is increased by adding one,two or a combination of Pb,Bi and Fe.The yield of MMA can reach to 62.4% in the presence of catalyst Pd5Bi2PbFe carried on CaCO3;the catalyst carried on SiO2 or ZnO has a good activity;while the catalyst carried on MgCO3 or ZrO2 has no activity.When catalyst Pd5Bi2PbFe carried on CaCO3 with loading metal order:Pd,Pb,Bi,Fe was used in the reaction,the yield of MMA was 86.9%.The selectivity to methacrolein was improved observably when rare earth elements were added to catalysts Pd5Bi2PbFe.When catalyst Pd5Bi2PbFePr/CaCO3 was used to oxidative-esterification reaction of methacrolein,the yield of MMA could reach to 90.4%.
The two-step reaction for the preparation of methyl methacrylate (MMA) from methacrolein (MAL) via oxidative esterification was simplified to one-stage reaction.The catalysts were prepared by means of impregnation and applied to the oxidative esterification reaction of MAL.The results show that the catalytic activity of catalyst mainly containing Pd is increased by adding one,two or a combination of Pb,Bi and Fe.The yield of MMA can reach to 62.4% in the presence of catalyst Pd5Bi2PbFe carried on CaCO3;the catalyst carried on SiO2 or ZnO has a good activity;while the catalyst carried on MgCO3 or ZrO2 has no activity.When catalyst Pd5Bi2PbFe carried on CaCO3 with loading metal order:Pd,Pb,Bi,Fe was used in the reaction,the yield of MMA was 86.9%.The selectivity to methacrolein was improved observably when rare earth elements were added to catalysts Pd5Bi2PbFe.When catalyst Pd5Bi2PbFePr/CaCO3 was used to oxidative-esterification reaction of methacrolein,the yield of MMA could reach to 90.4%.
2005, 22(7): 749-753
Abstract:
Copolymerization of dimethyl diallyl ammonium chloride (DMDAAC) and acrylamide (AM) was initiated by adding a NaHSO3 solution to the reaction system that contained AIBA·2HCl initiator.By means of AIBA·2HCl-NaHSO3 initiation system,a series of high intrinsic viscosity copolymers was prepared in water medium under different conditions.Effects of various factors such as mass fraction of monomer,mass fraction of initiator,pH of solution,the mole ratio of AM to DMDAAC and the feeding way of AM etc.were studied.The results indicate that the copolymerization can be initiated at low temperatures.At the conditions of 30℃,n(AM):n(DMDAAC)=4:1,ω(monomer)=30%,ω(AIBA·2HCl-RH)=0.01%,the copolymer obtained had a high intrinsic viscosity and yield.When the monomers solution was copolymerized at pH=7.0,the intrinsic viscosity of PDMDAAC-AM was 11.56 dL/g,while monomers DMDAAC and AM were copolymerized at pH=10.0,the intrinsic viscosity of copolymer was up to 13.60 dL/g.When the mole ratio of AM to DMDAAC was equal to 1:1,the cationicity and intrinsic viscosity of the copolymer were 38.8% and 11.61 dL/g,respectively,by adopting the continuous feeding way of AM.
Copolymerization of dimethyl diallyl ammonium chloride (DMDAAC) and acrylamide (AM) was initiated by adding a NaHSO3 solution to the reaction system that contained AIBA·2HCl initiator.By means of AIBA·2HCl-NaHSO3 initiation system,a series of high intrinsic viscosity copolymers was prepared in water medium under different conditions.Effects of various factors such as mass fraction of monomer,mass fraction of initiator,pH of solution,the mole ratio of AM to DMDAAC and the feeding way of AM etc.were studied.The results indicate that the copolymerization can be initiated at low temperatures.At the conditions of 30℃,n(AM):n(DMDAAC)=4:1,ω(monomer)=30%,ω(AIBA·2HCl-RH)=0.01%,the copolymer obtained had a high intrinsic viscosity and yield.When the monomers solution was copolymerized at pH=7.0,the intrinsic viscosity of PDMDAAC-AM was 11.56 dL/g,while monomers DMDAAC and AM were copolymerized at pH=10.0,the intrinsic viscosity of copolymer was up to 13.60 dL/g.When the mole ratio of AM to DMDAAC was equal to 1:1,the cationicity and intrinsic viscosity of the copolymer were 38.8% and 11.61 dL/g,respectively,by adopting the continuous feeding way of AM.
2005, 22(7): 754-758
Abstract:
The ion-exchanger LiAlTiO4 of spinel type was prepared by means of the common precipitation/hydrothermal crystallization method,then was acid-modified.Its ion-exchange proporties for alkali ions such as saturation capacity of exchange,distribution coefficient and the pH titration curve were determind.LiAlTiO4 was characterized by virtue of X-ray diffraction method.The acid treatment of LiAlTiO4 causes Li+ extraction ratio to change from 28% to 72%,while the dissolution of Al is less than 6.8%.This inorgnic ion-exchanger (LiAlTiO4-700) has the saturation capacity of exchange for Li higher than those for other alkali ions,the saturation capacity of exchange for Li+ reaches to 4.29 mmol/g (30.03 mg/g);LiAlTiO4-700(H) has a higher selectivity of ion exchange for Li+ than for other alkali ions.These result show LiAlTiO4-700(H) has better memory and selectivity of ion exchange,and higher capacity of ion exchange for Li+.It is a kind of prospective ionic sieve for Li+.
The ion-exchanger LiAlTiO4 of spinel type was prepared by means of the common precipitation/hydrothermal crystallization method,then was acid-modified.Its ion-exchange proporties for alkali ions such as saturation capacity of exchange,distribution coefficient and the pH titration curve were determind.LiAlTiO4 was characterized by virtue of X-ray diffraction method.The acid treatment of LiAlTiO4 causes Li+ extraction ratio to change from 28% to 72%,while the dissolution of Al is less than 6.8%.This inorgnic ion-exchanger (LiAlTiO4-700) has the saturation capacity of exchange for Li higher than those for other alkali ions,the saturation capacity of exchange for Li+ reaches to 4.29 mmol/g (30.03 mg/g);LiAlTiO4-700(H) has a higher selectivity of ion exchange for Li+ than for other alkali ions.These result show LiAlTiO4-700(H) has better memory and selectivity of ion exchange,and higher capacity of ion exchange for Li+.It is a kind of prospective ionic sieve for Li+.
2005, 22(7): 759-763
Abstract:
Nanosized TiO2 in the rutile phase was coated with aluminum hydroxide obtained from the hydrolysis of aluminium sulfate as source material.The nanosized TiO2 was characterize by means of XRD,XPS,Zeta potential,TEM and BET techniques.The photostability of nanosized TiO2 was evaluated.The results reveal that the coating layer of aluminum hydroxide is loose and porous.Aluminum hydroxide is amorphous structure when m(Al2O3):m(TiO2)=1:10,while m(Al2O3):m(TiO2)≥1:5,bayerite structure appears and the crystal size of bayerite is 20~25 nm.According to the difference of electron binding energy,it can be inferred that Al atoms in the coating layer are attached to TiO2 surface via Al-O-Ti bond.The Zeta potentials and BET surface areas show that along with the increase of m(Al2O3):m(TiO2) the isoelectric point of nanosized TiO2 shifts from pH=4.2 to pH=8.0 and BET surface area drops slowly.
Nanosized TiO2 in the rutile phase was coated with aluminum hydroxide obtained from the hydrolysis of aluminium sulfate as source material.The nanosized TiO2 was characterize by means of XRD,XPS,Zeta potential,TEM and BET techniques.The photostability of nanosized TiO2 was evaluated.The results reveal that the coating layer of aluminum hydroxide is loose and porous.Aluminum hydroxide is amorphous structure when m(Al2O3):m(TiO2)=1:10,while m(Al2O3):m(TiO2)≥1:5,bayerite structure appears and the crystal size of bayerite is 20~25 nm.According to the difference of electron binding energy,it can be inferred that Al atoms in the coating layer are attached to TiO2 surface via Al-O-Ti bond.The Zeta potentials and BET surface areas show that along with the increase of m(Al2O3):m(TiO2) the isoelectric point of nanosized TiO2 shifts from pH=4.2 to pH=8.0 and BET surface area drops slowly.
2005, 22(7): 764-767
Abstract:
The influence of water mass fraction on the performance of Lithium-ion batteries was studied.The results show that the comprehensive electrochemical performance of Lithium-ion batteries is the best with the first discharging capacity (125±2) minutes at 300 mA,discharging time (48±3) minutes at 600 mA and 3.6 V cut-off voltage,resistance (38±3) mΩ,thickness (4.25±0.05) mm,capacity attenuation of 100 cycles (7.8±0.5)% when the water mass fraction is controlled within 0.015%.The experimental results were analyzed by the formation mechanism of negative SEI film and the reaction process of water in the electrolyte.
The influence of water mass fraction on the performance of Lithium-ion batteries was studied.The results show that the comprehensive electrochemical performance of Lithium-ion batteries is the best with the first discharging capacity (125±2) minutes at 300 mA,discharging time (48±3) minutes at 600 mA and 3.6 V cut-off voltage,resistance (38±3) mΩ,thickness (4.25±0.05) mm,capacity attenuation of 100 cycles (7.8±0.5)% when the water mass fraction is controlled within 0.015%.The experimental results were analyzed by the formation mechanism of negative SEI film and the reaction process of water in the electrolyte.
2005, 22(7): 768-771
Abstract:
Ferrocene was condensed with aldehyde in toluene with the mixture of methanol and concentrated sulfuric acid as the catalyst.The condensation reactions of ferrocene with aldehyde acetal and with the mixture of aldehyde,methanol and micro-amount of concentrated sulfuric acid were compared.It was found that the results of the two methods were similar.However,the process of synthesizing aldehyde acetal was not necessary in the later method.After the unreacted ferrocene was removed via vacuum sublimation,eight 1,1-bisferrocenylalkanes were obtained with chromatography.The structures of these compounds were characterized by means of elemental analysis,IR and 1H NMR spectra.The characteristic bands of these compounds are in the range of 3 080~3 096 cm-1 for νC-H(Fc-H) in IR spectra.In the 1H NMR spectra,the peaks of the protons attached to the bridge carbon atoms are shifted to lower field and their chemical shifts (δ) are about 3.0.The mass spectra and electrochemical properties of 1,1-bisferrocenylhexane were also determined.Both molecular ion peak at m/z=454.1 and fragment ion peak of (Fc)2CH+at m/z=383.0 are base peaks.The electrochemical properties of 1,1-bisferrocenylhexane show that there are two pairs of oxidation and reduction peaks,corresponding to Fe(Ⅱ)Fe(Ⅱ)↔Fe(Ⅱ)Fe(Ⅲ) and Fe(Ⅱ)Fe(Ⅲ)↔Fe(Ⅲ)Fe(Ⅲ) respectively.The two electrochemical reactions are reversible.
Ferrocene was condensed with aldehyde in toluene with the mixture of methanol and concentrated sulfuric acid as the catalyst.The condensation reactions of ferrocene with aldehyde acetal and with the mixture of aldehyde,methanol and micro-amount of concentrated sulfuric acid were compared.It was found that the results of the two methods were similar.However,the process of synthesizing aldehyde acetal was not necessary in the later method.After the unreacted ferrocene was removed via vacuum sublimation,eight 1,1-bisferrocenylalkanes were obtained with chromatography.The structures of these compounds were characterized by means of elemental analysis,IR and 1H NMR spectra.The characteristic bands of these compounds are in the range of 3 080~3 096 cm-1 for νC-H(Fc-H) in IR spectra.In the 1H NMR spectra,the peaks of the protons attached to the bridge carbon atoms are shifted to lower field and their chemical shifts (δ) are about 3.0.The mass spectra and electrochemical properties of 1,1-bisferrocenylhexane were also determined.Both molecular ion peak at m/z=454.1 and fragment ion peak of (Fc)2CH+at m/z=383.0 are base peaks.The electrochemical properties of 1,1-bisferrocenylhexane show that there are two pairs of oxidation and reduction peaks,corresponding to Fe(Ⅱ)Fe(Ⅱ)↔Fe(Ⅱ)Fe(Ⅲ) and Fe(Ⅱ)Fe(Ⅲ)↔Fe(Ⅲ)Fe(Ⅲ) respectively.The two electrochemical reactions are reversible.
2005, 22(7): 772-775
Abstract:
A kind of insoluble chitosan linked β-cyclodextrin (CTS-β-CD) was prepared,which has property to form host-guest complexes with various organic compounds.The isothermal sorption kinetics of CTS-β-CD for p-nitrophenol was investigated by spectrophotometry.The result is satisfied with the Langmuir equation.In pH=11.2 media,at 35℃,when p-nitrophenol (pNP) initial concentration is 150 mg/L,the adsorption capacity of CTS-β-CD for p-nitrophenol is 83.76 mg/g,54.56 mg/g higher than that of CTS,which is only 29.20 mg/g.
A kind of insoluble chitosan linked β-cyclodextrin (CTS-β-CD) was prepared,which has property to form host-guest complexes with various organic compounds.The isothermal sorption kinetics of CTS-β-CD for p-nitrophenol was investigated by spectrophotometry.The result is satisfied with the Langmuir equation.In pH=11.2 media,at 35℃,when p-nitrophenol (pNP) initial concentration is 150 mg/L,the adsorption capacity of CTS-β-CD for p-nitrophenol is 83.76 mg/g,54.56 mg/g higher than that of CTS,which is only 29.20 mg/g.
2005, 22(7): 776-779
Abstract:
A novel gold electrode modified with Fe3O4 nanoparticles was constructed and characterized by means of electrochemical impedance spectroscopy and cyclic voltammertry.The modified electrode exhibits strong promoting effect and high stability toward the electrochemical oxidation of dopamine (DA),which gives reversible redox peaks at a formal potential of 0.192 V (vs.Ag/AgCl) in a pH=7.0 phosphate buffer solution.The anodic peak current (measured with constant potential amperometry) increass linearly with the increased concentration of dopamine in the range of 1.5×10-7 to 4.0×10-4 mol/L and the linear regression equation is ip(μA)=0.715+0.272 c(μmol/L).The detection limit (S/N=3) obtained was 3.0×10-8 mol/L.The relative standard deviation (RSD) of 8 successive scans is 3.4% for 1.5×10-6 mol/L DA.The interference of ascorbic acid with the determination of DA could be eliminated efficiently.The proposed method shows excellent sensitivity and recovery.
A novel gold electrode modified with Fe3O4 nanoparticles was constructed and characterized by means of electrochemical impedance spectroscopy and cyclic voltammertry.The modified electrode exhibits strong promoting effect and high stability toward the electrochemical oxidation of dopamine (DA),which gives reversible redox peaks at a formal potential of 0.192 V (vs.Ag/AgCl) in a pH=7.0 phosphate buffer solution.The anodic peak current (measured with constant potential amperometry) increass linearly with the increased concentration of dopamine in the range of 1.5×10-7 to 4.0×10-4 mol/L and the linear regression equation is ip(μA)=0.715+0.272 c(μmol/L).The detection limit (S/N=3) obtained was 3.0×10-8 mol/L.The relative standard deviation (RSD) of 8 successive scans is 3.4% for 1.5×10-6 mol/L DA.The interference of ascorbic acid with the determination of DA could be eliminated efficiently.The proposed method shows excellent sensitivity and recovery.
2005, 22(7): 780-783
Abstract:
Pseudo ternary phase diagrams of fenvalerate microemulsion are presented.The mechanism of fenvalerate microemulsion formation was studied,with the particular emphasis on the effects of different temperature and different alcohols on fenvalerate microemulsion formation.It has been found that the type and area of microemulsion region vary with the length of carbon chain of alcohol molecules.The microemulsion region increases with the increase of temperature for the same cosurfactant (n-butanol).Microstructure was studied by means of conductivity measurement.When the mass ratio of surfactant solution (S+A) to fenvalerate solution (O+A) was 4:1,the microstructure changed from W/O structure through bicontinuous structure to O/W structure.When the mass ratio of (S+A) to (O+A) was 6:4,there was a liquid crystal region before bicontinuous structure.
Pseudo ternary phase diagrams of fenvalerate microemulsion are presented.The mechanism of fenvalerate microemulsion formation was studied,with the particular emphasis on the effects of different temperature and different alcohols on fenvalerate microemulsion formation.It has been found that the type and area of microemulsion region vary with the length of carbon chain of alcohol molecules.The microemulsion region increases with the increase of temperature for the same cosurfactant (n-butanol).Microstructure was studied by means of conductivity measurement.When the mass ratio of surfactant solution (S+A) to fenvalerate solution (O+A) was 4:1,the microstructure changed from W/O structure through bicontinuous structure to O/W structure.When the mass ratio of (S+A) to (O+A) was 6:4,there was a liquid crystal region before bicontinuous structure.
2005, 22(7): 784-787
Abstract:
Layered crystalline zirconium (glycine-N,N-dimethylenephosphonate-phosphate)(α-ZGDMPP) was prepared (interlayer distance is 1.52 nm).The intercalation complex of n-butylamine into α-ZGDMPP was also investigated.α-ZGDMPP and its intercalation complex were characterized by elemental analysis,XRD,IR,13C CP/MAS NMR and TG methods.The results show that the intercalation behavior of layered α-ZGDMPP is different from that of α-ZP with the formation of host-guest compound.The interlayer distance of α-ZGDMPP is enlarged 1.02 nm,n-butylamine molecules intercalated form bilayers and the carbon chains incline at rough 55°to α-ZGDMPP layers,the intercalated n-butylamine is lost in the temperature range of 150~250℃.
Layered crystalline zirconium (glycine-N,N-dimethylenephosphonate-phosphate)(α-ZGDMPP) was prepared (interlayer distance is 1.52 nm).The intercalation complex of n-butylamine into α-ZGDMPP was also investigated.α-ZGDMPP and its intercalation complex were characterized by elemental analysis,XRD,IR,13C CP/MAS NMR and TG methods.The results show that the intercalation behavior of layered α-ZGDMPP is different from that of α-ZP with the formation of host-guest compound.The interlayer distance of α-ZGDMPP is enlarged 1.02 nm,n-butylamine molecules intercalated form bilayers and the carbon chains incline at rough 55°to α-ZGDMPP layers,the intercalated n-butylamine is lost in the temperature range of 150~250℃.
2005, 22(7): 788-791
Abstract:
The production of biodiesel from rapeseed oil and methanol was performed under the catalysis of immobilized Candida antarctica lipase.The effects of the preincubation of the enzyme,water content,the molar ratio of the oil to methanol and the way for addition of methanol on the methanolysis reaction rate were investigated.The experiment showed that the methanolysis progressed much faster when immobilized lipase was preincubated in methyl oleate for 2 h and subsequently in rapeseed oil for 12 h.Trace water contained in rapeseed oil and methanol increased the methanolysis reaction rate,but adding water in the reaction mixture was found to suppress the methanolysis reaction catalyzed by immobilized lipase.The suitable molar ratio of methanol to the oil is 3:1,lipase inactivation is avoided by three-step addition of methanol.A high methyl ester content above 99% can be achieved.
The production of biodiesel from rapeseed oil and methanol was performed under the catalysis of immobilized Candida antarctica lipase.The effects of the preincubation of the enzyme,water content,the molar ratio of the oil to methanol and the way for addition of methanol on the methanolysis reaction rate were investigated.The experiment showed that the methanolysis progressed much faster when immobilized lipase was preincubated in methyl oleate for 2 h and subsequently in rapeseed oil for 12 h.Trace water contained in rapeseed oil and methanol increased the methanolysis reaction rate,but adding water in the reaction mixture was found to suppress the methanolysis reaction catalyzed by immobilized lipase.The suitable molar ratio of methanol to the oil is 3:1,lipase inactivation is avoided by three-step addition of methanol.A high methyl ester content above 99% can be achieved.
2005, 22(7): 792-795
Abstract:
Anionic Gemini surfactant system were investigated in this paper.The results reveal that the critical micella concentration (CMC) of Gemini surfactant has a much lower value compared with that of conventional monomeric one and CMC is decreased upon increasing spacer length.Surface tensions of Gemini surfactants were studied by means of the drop volume method.The surface tension of Gemini surfactant with c20 is two orders of magnitude lower than that of monomeric surfactant,indicating that Gemini surfactant is more efficient in declining the surface tension of water.The interfacial tensions of crude oil and water systems were measured by virtue of the pendant drop method.The surface tension of the crude oil and water system is ultra-low when the system contains 0.1% Gemini D which indicates that Gemini surfactants show a great effect on declining the interfacial tensions between oil and water.
Anionic Gemini surfactant system were investigated in this paper.The results reveal that the critical micella concentration (CMC) of Gemini surfactant has a much lower value compared with that of conventional monomeric one and CMC is decreased upon increasing spacer length.Surface tensions of Gemini surfactants were studied by means of the drop volume method.The surface tension of Gemini surfactant with c20 is two orders of magnitude lower than that of monomeric surfactant,indicating that Gemini surfactant is more efficient in declining the surface tension of water.The interfacial tensions of crude oil and water systems were measured by virtue of the pendant drop method.The surface tension of the crude oil and water system is ultra-low when the system contains 0.1% Gemini D which indicates that Gemini surfactants show a great effect on declining the interfacial tensions between oil and water.
2005, 22(7): 796-799
Abstract:
Via the melt-grafted reaction of low density polyethylene (LDPE) with multimonomer,we successfully introduced Glycidyl methylacrylate and Styrene onto the macromolecular chain of LDPE.The grafting degree of gLDPE reached to 3% approximately.Two analytic methods were employed to study the different processes of the non-isothermal crystallization for LDPE and gLDPE.Crystal of the grafted LDPE was observed by means of a polarized optical microscope.The investigation showed that compared to that of LDPE,the crysallization temperature (Tc) of gLDPE has shifted to higher temperature slightly and the range of crystallization temperature has become wider.The exponent n of Avrami equation was about 4,indicating that gLDPE and LDPE have a similar model of non-isothermal crystallization.
Via the melt-grafted reaction of low density polyethylene (LDPE) with multimonomer,we successfully introduced Glycidyl methylacrylate and Styrene onto the macromolecular chain of LDPE.The grafting degree of gLDPE reached to 3% approximately.Two analytic methods were employed to study the different processes of the non-isothermal crystallization for LDPE and gLDPE.Crystal of the grafted LDPE was observed by means of a polarized optical microscope.The investigation showed that compared to that of LDPE,the crysallization temperature (Tc) of gLDPE has shifted to higher temperature slightly and the range of crystallization temperature has become wider.The exponent n of Avrami equation was about 4,indicating that gLDPE and LDPE have a similar model of non-isothermal crystallization.
2005, 22(7): 800-803
Abstract:
2-Benzoylamino-3-phenyl-propionic acid methyl ester was enantioseparated by HPLC with a chiral stationary phase (CSP) commercially named Kromasil CHI-DMB.This CSP contained a chiral immobilized network polymer derived from L-tartaric acid.The effects of the amount of polar modifier in the mobile phase on the chiral resolution and associated thermodynamic parameters were studied.The interactions,which involve hydrogen bonding principally,are believed to be important for the chiral recognition.The slow adsorption/desorption sites are released in low 2-propanol concentration.The separation factor was 1.661 for this amino acid derivative when n-hexane/2-propanol (volume ratio 99:1) was used as mobile phase at a flow rate of 1.0 mL/min and 25℃ with retention time being within 14 minutes.Benzoin was successfully enantio-separated when non-protonic modifier (THF) was used.The separation factor could reach to 1.168.
2-Benzoylamino-3-phenyl-propionic acid methyl ester was enantioseparated by HPLC with a chiral stationary phase (CSP) commercially named Kromasil CHI-DMB.This CSP contained a chiral immobilized network polymer derived from L-tartaric acid.The effects of the amount of polar modifier in the mobile phase on the chiral resolution and associated thermodynamic parameters were studied.The interactions,which involve hydrogen bonding principally,are believed to be important for the chiral recognition.The slow adsorption/desorption sites are released in low 2-propanol concentration.The separation factor was 1.661 for this amino acid derivative when n-hexane/2-propanol (volume ratio 99:1) was used as mobile phase at a flow rate of 1.0 mL/min and 25℃ with retention time being within 14 minutes.Benzoin was successfully enantio-separated when non-protonic modifier (THF) was used.The separation factor could reach to 1.168.
2005, 22(7): 804-807
Abstract:
The synthesis technology for mono-alkyl phosphate reactive surfactants was studied and the optimum conditions of preparation were determined on the basis of experimental results.Firstly,ω-hydroxy-decyl-methacrylate (compound Ⅰ) was synthesized when the mole ratio of methacrylic acid to 1,10-decanediol was 1:1.75 with p-toluene sulphonic acid as catalyst and at 80℃ for 5 h.Secondly,ω-phosphate-decylmethacrylate (compound Ⅱ) was obtained by the reaction of compound Ⅰ with P2O5 at the mole ratio of 2:3,the reaction temperature was 60~70℃,the reaction time was 5 h;and then,the hydrolysis reaction time was 1 h.Finally,the product was got by neutralizing the compound Ⅱ with KOH.The yield of alkyl monophosphate reaches to 97.91%.It was found that the emulsifying power of the product was better than those of SDS and DNS-86,the critical micell concentration of the product was 0.036 mol/L.
The synthesis technology for mono-alkyl phosphate reactive surfactants was studied and the optimum conditions of preparation were determined on the basis of experimental results.Firstly,ω-hydroxy-decyl-methacrylate (compound Ⅰ) was synthesized when the mole ratio of methacrylic acid to 1,10-decanediol was 1:1.75 with p-toluene sulphonic acid as catalyst and at 80℃ for 5 h.Secondly,ω-phosphate-decylmethacrylate (compound Ⅱ) was obtained by the reaction of compound Ⅰ with P2O5 at the mole ratio of 2:3,the reaction temperature was 60~70℃,the reaction time was 5 h;and then,the hydrolysis reaction time was 1 h.Finally,the product was got by neutralizing the compound Ⅱ with KOH.The yield of alkyl monophosphate reaches to 97.91%.It was found that the emulsifying power of the product was better than those of SDS and DNS-86,the critical micell concentration of the product was 0.036 mol/L.
2005, 22(7): 808-810
Abstract:
The adsorption characteristics of (+)-Catechin on self-prepared polypropylene-based anion exchange fiber under static conditions were studied and the adsorption isotherms at different temperatures were also determined.The results show that the adsorption behavior of (+)-Catechin in dilute solution on the anion exchange fiber basically obeys in the Freundlich equation.Based on infinitesimal calculation the reaction order is 1.When the initial concentration is 44.60 mg/L,the values of the apparent rate constants at 286 K,303 K,323 K and 338 K are 0.016 7,0.039 4,0.054 5 and 0.094 4 min-1 respectively,and the rate constant values increase with the rise of temperature.
The adsorption characteristics of (+)-Catechin on self-prepared polypropylene-based anion exchange fiber under static conditions were studied and the adsorption isotherms at different temperatures were also determined.The results show that the adsorption behavior of (+)-Catechin in dilute solution on the anion exchange fiber basically obeys in the Freundlich equation.Based on infinitesimal calculation the reaction order is 1.When the initial concentration is 44.60 mg/L,the values of the apparent rate constants at 286 K,303 K,323 K and 338 K are 0.016 7,0.039 4,0.054 5 and 0.094 4 min-1 respectively,and the rate constant values increase with the rise of temperature.
2005, 22(7): 811-812
Abstract:
Triaryl cyanurates,2,4,6-tris (phenyoxy)-1,3,5-triazine derivatives,were prepared by solid-state reaction,which was carried out between cyanuric chloride and phenols with the molar ratio of 1:3 in the presence of potassium hydroxide as catalyst at room temperature.It is shown that the yields of the products are mainly affected by the reactivity of phenols due to the substituted group and its position.Under the same conditions,2,4,6-tris (p-methoxyphenyoxy)-1,3,5-triazine was synthesized from p-methoxyphenol in the yield of 89% and 2,4,6-tris (o-chlorophenyoxy)-1,3,5-triazine was synthesized from o-chlorophenol in the yield of 30%.
Triaryl cyanurates,2,4,6-tris (phenyoxy)-1,3,5-triazine derivatives,were prepared by solid-state reaction,which was carried out between cyanuric chloride and phenols with the molar ratio of 1:3 in the presence of potassium hydroxide as catalyst at room temperature.It is shown that the yields of the products are mainly affected by the reactivity of phenols due to the substituted group and its position.Under the same conditions,2,4,6-tris (p-methoxyphenyoxy)-1,3,5-triazine was synthesized from p-methoxyphenol in the yield of 89% and 2,4,6-tris (o-chlorophenyoxy)-1,3,5-triazine was synthesized from o-chlorophenol in the yield of 30%.
