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2008 Volume 25 Issue 10
2008, 25(10): 1125-1129
Abstract:
The studies on the methanol-alternative fuels for direct methanol fuel cells(DMFC) have received much attention due to the problems of the direct methanol fuel cells.In this paper,the recent progress in the methanol-alternative fuels,such as ethanol and formic acid,is introduced.Compared with methanol,formic acid as the fuel has many advantages.For example,formic acid is non-toxic and inflammable.Thus,its storage and transportation is safe.It has low penetration rate through the Nafion membrane and excellent oxidation performance.During oxidation,it does not produce the CO intermediate,which can poison the catalyst.Therefore,among the numerous methanol-alternative fuels studied,formic acid is most likely to replace methanol as the fuel in DMFC.
The studies on the methanol-alternative fuels for direct methanol fuel cells(DMFC) have received much attention due to the problems of the direct methanol fuel cells.In this paper,the recent progress in the methanol-alternative fuels,such as ethanol and formic acid,is introduced.Compared with methanol,formic acid as the fuel has many advantages.For example,formic acid is non-toxic and inflammable.Thus,its storage and transportation is safe.It has low penetration rate through the Nafion membrane and excellent oxidation performance.During oxidation,it does not produce the CO intermediate,which can poison the catalyst.Therefore,among the numerous methanol-alternative fuels studied,formic acid is most likely to replace methanol as the fuel in DMFC.
2008, 25(10): 1130-1133
Abstract:
The photo conversion of parachlorophenol(4-CP) in the presence of ice and nitrite under UV radiation in a temperature range of-14~-12℃ was investigated.According to the results,the conversion of 4-CP in the presence of ice reached 80% within 180 min.Under the conditions mentioned above,four photoproducts:5-chlorobiphenyl-2,4'-diol,phenol,4-(4-chloro-2-nitrophenoxy)phenol and 4-chloro-2-nitrophenol were identified,which was a little different from that of the photoreaction in solution.The presence of nitrite could change the products and mechanism of the photoconnersion of 4-CP in ice.
The photo conversion of parachlorophenol(4-CP) in the presence of ice and nitrite under UV radiation in a temperature range of-14~-12℃ was investigated.According to the results,the conversion of 4-CP in the presence of ice reached 80% within 180 min.Under the conditions mentioned above,four photoproducts:5-chlorobiphenyl-2,4'-diol,phenol,4-(4-chloro-2-nitrophenoxy)phenol and 4-chloro-2-nitrophenol were identified,which was a little different from that of the photoreaction in solution.The presence of nitrite could change the products and mechanism of the photoconnersion of 4-CP in ice.
2008, 25(10): 1134-1137
Abstract:
A new composite material,poly(ethylene terephthalate)-polymeric thiourea resin,was prepared by dipping method.The adsorption of Au(Ⅲ) was studied by batch method.Maximum adsorption capacity of PET-PDTU for Au(Ⅲ) reached 4.24 mmol/g,and the rate constant k=0.004 04 min-1;G.E.Boyd Equation adequately fits the sorption rate before equilibrium,which confirms that the film diffusion controlls the sorption process.The equilibrium sorption data can be described by the Langmuir isotherm equation,which implies the monomolecular sorption in these systems.It was also proved from the thermodynamics that the sorption process was endothermal,and the enthalpy change ΔH calculated was 40.00 kJ/mol.
A new composite material,poly(ethylene terephthalate)-polymeric thiourea resin,was prepared by dipping method.The adsorption of Au(Ⅲ) was studied by batch method.Maximum adsorption capacity of PET-PDTU for Au(Ⅲ) reached 4.24 mmol/g,and the rate constant k=0.004 04 min-1;G.E.Boyd Equation adequately fits the sorption rate before equilibrium,which confirms that the film diffusion controlls the sorption process.The equilibrium sorption data can be described by the Langmuir isotherm equation,which implies the monomolecular sorption in these systems.It was also proved from the thermodynamics that the sorption process was endothermal,and the enthalpy change ΔH calculated was 40.00 kJ/mol.
2008, 25(10): 1138-1141
Abstract:
1-Butyl-3-methyl imidazolium salts with hexafluorophosphate,tetrafluoroborate,perfluorobutyl sulphonate,and chloride anions and eight kinds of alkylimidazolium bromide salts with different alkyl chain length were prepared.The Blanc chloromethylation of o-xylene with hydrogen chloride and paraformaldehyde was investigated in the presence of the above ionic liquids as catalysts.The influence of the type and the amount of the ionic liquid,reaction temperature,and reaction time on the chloromethylation was investigated.The products were analyzed by GC-MS.The results showed that 1-dodecyl-3-methylimidazolium bromide([C12mim]Br) was the best one among the catalysts for the reaction.The optimum reaction conditions were 4%(the molar ratio of ionic liquid to o-xylene) ionic liquid,70℃ reaction temperature and 10 h reaction time.Under the above reaction conditions,the yield was 89.8%,and the turnover number was 22.4.
1-Butyl-3-methyl imidazolium salts with hexafluorophosphate,tetrafluoroborate,perfluorobutyl sulphonate,and chloride anions and eight kinds of alkylimidazolium bromide salts with different alkyl chain length were prepared.The Blanc chloromethylation of o-xylene with hydrogen chloride and paraformaldehyde was investigated in the presence of the above ionic liquids as catalysts.The influence of the type and the amount of the ionic liquid,reaction temperature,and reaction time on the chloromethylation was investigated.The products were analyzed by GC-MS.The results showed that 1-dodecyl-3-methylimidazolium bromide([C12mim]Br) was the best one among the catalysts for the reaction.The optimum reaction conditions were 4%(the molar ratio of ionic liquid to o-xylene) ionic liquid,70℃ reaction temperature and 10 h reaction time.Under the above reaction conditions,the yield was 89.8%,and the turnover number was 22.4.
2008, 25(10): 1142-1145
Abstract:
N-methyl-2-(3,4-dihydroxyphenyl)[60] fullerene pyrrolidine was synthesized by the 1,3-dipolar cycloaddition reaction of fullerene(C60) and azomethine ylide(prepared from N-methylglycine and 3,4-dihydroxybenzaldehyde).The product was characterized by UV-Vis,FI-IR,1H NMR and MS.The reaction conditions affecting the yield were investigated and the optimum reaction conditions which afforded 66%(based on consumed C60) of the product were:molar ratio of C60:N-methylglycine:3,4-dihydroxybenzaldehyde 1:2:5,reaction temperature 95℃,reaction time 28 h.
N-methyl-2-(3,4-dihydroxyphenyl)[60] fullerene pyrrolidine was synthesized by the 1,3-dipolar cycloaddition reaction of fullerene(C60) and azomethine ylide(prepared from N-methylglycine and 3,4-dihydroxybenzaldehyde).The product was characterized by UV-Vis,FI-IR,1H NMR and MS.The reaction conditions affecting the yield were investigated and the optimum reaction conditions which afforded 66%(based on consumed C60) of the product were:molar ratio of C60:N-methylglycine:3,4-dihydroxybenzaldehyde 1:2:5,reaction temperature 95℃,reaction time 28 h.
2008, 25(10): 1146-1150
Abstract:
An acrylate polymer,P(BA/LMA),with soft core-soft shell structure was synthesized by semi-continuous emulsion polymerization under monomer starved condition.Butyl acrylate was used as the monomer for the core and for lauryl methacrylate as the monomer for the shell.Ethylene glycol dimethacrylate was used as the crosslinking agent for the core.The result indicated that the system was stabilized at a ratio(OP-10/SDS) of 2:1 and an emulsifier concentration of 4%.The monomer had a high rate of conversion at an addition rate of 8 mL/h.The structure of P(BA/LMA) was analysed by FT-IR.Presence of the crosslinking agent at different places led to different morphologies such as spheres(without crosslinking agent),core-shell structure(with crosslinking agent in the core),cinquefoil(with cosslinking agent in the core and the shell).DSC indicated that the polymer had two Tg at -64℃ and -51℃,respectively.
An acrylate polymer,P(BA/LMA),with soft core-soft shell structure was synthesized by semi-continuous emulsion polymerization under monomer starved condition.Butyl acrylate was used as the monomer for the core and for lauryl methacrylate as the monomer for the shell.Ethylene glycol dimethacrylate was used as the crosslinking agent for the core.The result indicated that the system was stabilized at a ratio(OP-10/SDS) of 2:1 and an emulsifier concentration of 4%.The monomer had a high rate of conversion at an addition rate of 8 mL/h.The structure of P(BA/LMA) was analysed by FT-IR.Presence of the crosslinking agent at different places led to different morphologies such as spheres(without crosslinking agent),core-shell structure(with crosslinking agent in the core),cinquefoil(with cosslinking agent in the core and the shell).DSC indicated that the polymer had two Tg at -64℃ and -51℃,respectively.
2008, 25(10): 1151-1155
Abstract:
Nanostructured ε-MnO2 made up of its nanowhiskers was successfully prepared with KMnO4 and MnSO4 as the raw materials at room temperature.X-ray diffraction(XRD),transmission electron microscopy(TEM) and specific surface area(BET) were used to characterize the product.The as-prepared nano-structured ε-MnO2 was used as a catalyst to decompose simulated phenol wastewater.This catalytic reaction was mild and required any oxidant.Based on fluorescence spectroscopy(FL) results,the removal of phenol was up to 80.4% within 80 min.The intermediate products during the degradation process of phenol were investigated with high performance liquid chromatography(HPLC).The possible decomposition path of phenol was proposed.Kinetic study of the catalytic reaction showed that the reaction kinetics order was 1.64 and the reaction rate constant was 0.007 5(mg·L-1)-0.64/min.
Nanostructured ε-MnO2 made up of its nanowhiskers was successfully prepared with KMnO4 and MnSO4 as the raw materials at room temperature.X-ray diffraction(XRD),transmission electron microscopy(TEM) and specific surface area(BET) were used to characterize the product.The as-prepared nano-structured ε-MnO2 was used as a catalyst to decompose simulated phenol wastewater.This catalytic reaction was mild and required any oxidant.Based on fluorescence spectroscopy(FL) results,the removal of phenol was up to 80.4% within 80 min.The intermediate products during the degradation process of phenol were investigated with high performance liquid chromatography(HPLC).The possible decomposition path of phenol was proposed.Kinetic study of the catalytic reaction showed that the reaction kinetics order was 1.64 and the reaction rate constant was 0.007 5(mg·L-1)-0.64/min.
2008, 25(10): 1156-1160
Abstract:
A series of new chiral liquid crystalline elastomers was prepared by graft polymerization of a nematic monomer,4-allyloxybiphenyl-4'-hexyloxybenzoate,with a chiral crosslinking agent,isosorbide 4-allyloxybenzoyl bisate,using poly(methyl hydrosiloxane) as the backbone.The chemical structures of the monomers and the polymers obtained were confirmed by FTIR,1H NMR and elemental analysies.The mesomorphic properties were investigated by differential scanning calorimetry,polarizing optical microscopy,and X-ray diffraction.Polymer P1 and elatomers P1~P2 exhibited smectic phase,while elastomers P4~P7 showed cholesteric phase,and P8 displayed no liquid crystal phase.It was found that the glass transition temperatures reduced first and then increased,the isotropization temperatures and the mesophase temperature ranges decreased with increasing the content of the crosslinking unit.The thermal decomposition temperature(at 5% mass loss) of the polymers were greater than 300℃.
A series of new chiral liquid crystalline elastomers was prepared by graft polymerization of a nematic monomer,4-allyloxybiphenyl-4'-hexyloxybenzoate,with a chiral crosslinking agent,isosorbide 4-allyloxybenzoyl bisate,using poly(methyl hydrosiloxane) as the backbone.The chemical structures of the monomers and the polymers obtained were confirmed by FTIR,1H NMR and elemental analysies.The mesomorphic properties were investigated by differential scanning calorimetry,polarizing optical microscopy,and X-ray diffraction.Polymer P1 and elatomers P1~P2 exhibited smectic phase,while elastomers P4~P7 showed cholesteric phase,and P8 displayed no liquid crystal phase.It was found that the glass transition temperatures reduced first and then increased,the isotropization temperatures and the mesophase temperature ranges decreased with increasing the content of the crosslinking unit.The thermal decomposition temperature(at 5% mass loss) of the polymers were greater than 300℃.
2008, 25(10): 1161-1165
Abstract:
Ni-Cu-P coatings were obtained by electroless plating.The effects of CuSO4·5H2O concentration in bath on the deposition rate and composition of Ni-Cu-P coatings were investigated.Microstructures and morphologies of Ni-Cu-P coatings obtained at various CuSO4·5H2O concentrations were analyzed via XRD and SEM.Corrosion resistances of Ni-Cu-P coatings were evaluated via polarization curves in 3.5% NaCl solution.The results show the deposition rate and P content of coatings decrease with the increasing of CuSO4·5H2O concentration in bath.P mass content in Ni-P coating was 14.98%.P mass content in coating was 4.21% when CuSO4·5H2O concentration in bath was 1.0 g/L.Crystallinity of coatings grows with the increasing of Cu content in electroless coatings.Addition of Cu in electroless bath makes the morphology of electroless coatings much smooth.Corrosion resistance of coatings first increased and then decreased with the increasing of CuSO4·5H2O concentration in bath.Ni-Cu-P coating obtained at 0.4 g/L CuSO4 concentration in bath performs optimal corrosion resistance.
Ni-Cu-P coatings were obtained by electroless plating.The effects of CuSO4·5H2O concentration in bath on the deposition rate and composition of Ni-Cu-P coatings were investigated.Microstructures and morphologies of Ni-Cu-P coatings obtained at various CuSO4·5H2O concentrations were analyzed via XRD and SEM.Corrosion resistances of Ni-Cu-P coatings were evaluated via polarization curves in 3.5% NaCl solution.The results show the deposition rate and P content of coatings decrease with the increasing of CuSO4·5H2O concentration in bath.P mass content in Ni-P coating was 14.98%.P mass content in coating was 4.21% when CuSO4·5H2O concentration in bath was 1.0 g/L.Crystallinity of coatings grows with the increasing of Cu content in electroless coatings.Addition of Cu in electroless bath makes the morphology of electroless coatings much smooth.Corrosion resistance of coatings first increased and then decreased with the increasing of CuSO4·5H2O concentration in bath.Ni-Cu-P coating obtained at 0.4 g/L CuSO4 concentration in bath performs optimal corrosion resistance.
2008, 25(10): 1166-1170
Abstract:
Critical aggregation numbers of micelle(Nm) of quaternary ammonium gemini surfactants containing modified rosin,DDMPDAB,DDMHPDAC,and DDMHDAB,were determined by steady-state fluorescence probe method in which pyrene was used as the fluorescence probe and cetylpyridinium chloride(CPC) as the quencher.According to the change of fluorescence intensity ratio of pyrene I1/I3 with the change of surfactant concentration of aqueous solution,critical micelle concentration(CMC) was investigated by steady-state fluorescence probe and compared with that determined by surface tension method.The results showed that CMC determined by steady-state fluorescence probe was in agreement with that determined by surface tension method.CMC values for DDMPDAB,DDMHPDAC and DDMHDAB were 2×10-5,8×10-5 and 6×10-5 mol/L,respectively.Satisfactory results were obtained when the surfactant solution was prepared with saturated aqueous solution of pyrene and the optimum concentration of CPC was selected at 0.04~0.06 mmol/L.The experimental results showed that N increased linearly with the increase of the surfactant concentration in a range of 5~15 times CMC and Nm can be extrapolated from the N-C curve,which were 10,19,and 20,respectively.
Critical aggregation numbers of micelle(Nm) of quaternary ammonium gemini surfactants containing modified rosin,DDMPDAB,DDMHPDAC,and DDMHDAB,were determined by steady-state fluorescence probe method in which pyrene was used as the fluorescence probe and cetylpyridinium chloride(CPC) as the quencher.According to the change of fluorescence intensity ratio of pyrene I1/I3 with the change of surfactant concentration of aqueous solution,critical micelle concentration(CMC) was investigated by steady-state fluorescence probe and compared with that determined by surface tension method.The results showed that CMC determined by steady-state fluorescence probe was in agreement with that determined by surface tension method.CMC values for DDMPDAB,DDMHPDAC and DDMHDAB were 2×10-5,8×10-5 and 6×10-5 mol/L,respectively.Satisfactory results were obtained when the surfactant solution was prepared with saturated aqueous solution of pyrene and the optimum concentration of CPC was selected at 0.04~0.06 mmol/L.The experimental results showed that N increased linearly with the increase of the surfactant concentration in a range of 5~15 times CMC and Nm can be extrapolated from the N-C curve,which were 10,19,and 20,respectively.
2008, 25(10): 1171-1175
Abstract:
Electro-synthesis of adipic acid from cyclohexanol in alkaline solution was investigated.Before electrolysis,the Ni electrode was activated by voltammetric technique to form NiOOH on its surface.Cyclo-hexanol was first oxidized to cyclohexanone and then to adipic acid on the activated Ni electrode.Orthogonal tests showed that the maximum yield of adipic acid was 42.59% under the optimum conditions of current density of 6×10-3 A/cm2,reaction temperature of 60℃,reaction time of 16 F/mol,and c(NaOH)=1.0 mol/L.Results of the kinetic study on the cyclohexanol oxidation show that the reaction obeys the consecutive reaction mechanism,and the formation of cyclohexanone is a fast step and the formation of adipic acid is a slower and rate-determining step.The corresponding kinetic equations of cycylohexanol oxidation were derived.The proposed kinetic model gave a satisfactory description for the electro-oxidation of cyclohe-xanol in 1 mol/L NaOH.
Electro-synthesis of adipic acid from cyclohexanol in alkaline solution was investigated.Before electrolysis,the Ni electrode was activated by voltammetric technique to form NiOOH on its surface.Cyclo-hexanol was first oxidized to cyclohexanone and then to adipic acid on the activated Ni electrode.Orthogonal tests showed that the maximum yield of adipic acid was 42.59% under the optimum conditions of current density of 6×10-3 A/cm2,reaction temperature of 60℃,reaction time of 16 F/mol,and c(NaOH)=1.0 mol/L.Results of the kinetic study on the cyclohexanol oxidation show that the reaction obeys the consecutive reaction mechanism,and the formation of cyclohexanone is a fast step and the formation of adipic acid is a slower and rate-determining step.The corresponding kinetic equations of cycylohexanol oxidation were derived.The proposed kinetic model gave a satisfactory description for the electro-oxidation of cyclohe-xanol in 1 mol/L NaOH.
2008, 25(10): 1176-1180
Abstract:
Surface Acoustic Wave(SAW) chemical sensor for the detection of organophosphorus compounds was prepared on the SAW gold delayline by molecular imprinting technology(MIT) and self-assembly(SAWS) technology with 25-(thioalkyl-alkoxy)-p-tertbutylcalix[4] arene self-assembled monolayers as the sensitive coating and GB as the template reagent.The sensor has special response to target organophosphorus compounds and the response of this sensor to organophosphorus compounds under 0.1 mg/m3 is 350 Hz.The response frequency increases linearly with the increase of the concentration of DMMP and GB in a range of 0.1 to 0.6 mg/m3.Possible explanation of interactions between the coatings and the organophosphorus compounds is discussed.
Surface Acoustic Wave(SAW) chemical sensor for the detection of organophosphorus compounds was prepared on the SAW gold delayline by molecular imprinting technology(MIT) and self-assembly(SAWS) technology with 25-(thioalkyl-alkoxy)-p-tertbutylcalix[4] arene self-assembled monolayers as the sensitive coating and GB as the template reagent.The sensor has special response to target organophosphorus compounds and the response of this sensor to organophosphorus compounds under 0.1 mg/m3 is 350 Hz.The response frequency increases linearly with the increase of the concentration of DMMP and GB in a range of 0.1 to 0.6 mg/m3.Possible explanation of interactions between the coatings and the organophosphorus compounds is discussed.
2008, 25(10): 1181-1185
Abstract:
CeO2 promoted Pd/Al2O3 catalyst was prepared by impregnation method.Its activity and sulfur tolerance was investigated in the hydrodesulfurization of thiophene.CO adsorption,FT-IR and TG were used to characterize the catalyst.The results of deactivity with time and sulfide degree showed that Pd-CeO2/Al2O3 catalyst had much better sulfur tolerance than Pd/Al2O3 catalyst.The FT-IR results indicated the addition of CeO2 caused the bond energy of Pd-S to weaken and H2S to be adsorbed on CeO2.TG revealed that H2S was mainly adsorbed on CeO2 and not on Pd.Enhanced sulfur tolerance of Pd-CeO2/Al2O3 was attributed to the Pd electron deficient state which inhibitd the formation of sulfided palladium.In addition,competitive adsorption of H2S on CeO2 resulted in the lowering of partial pressure of H2S around the Pd phase in close contact with CeO2.
CeO2 promoted Pd/Al2O3 catalyst was prepared by impregnation method.Its activity and sulfur tolerance was investigated in the hydrodesulfurization of thiophene.CO adsorption,FT-IR and TG were used to characterize the catalyst.The results of deactivity with time and sulfide degree showed that Pd-CeO2/Al2O3 catalyst had much better sulfur tolerance than Pd/Al2O3 catalyst.The FT-IR results indicated the addition of CeO2 caused the bond energy of Pd-S to weaken and H2S to be adsorbed on CeO2.TG revealed that H2S was mainly adsorbed on CeO2 and not on Pd.Enhanced sulfur tolerance of Pd-CeO2/Al2O3 was attributed to the Pd electron deficient state which inhibitd the formation of sulfided palladium.In addition,competitive adsorption of H2S on CeO2 resulted in the lowering of partial pressure of H2S around the Pd phase in close contact with CeO2.
2008, 25(10): 1186-1192
Abstract:
The interaction between N,N'-bis(2-hydroxy-1-naphthaldehyde)-2,6-pyridyenediimine and DNA was studied by cyclic voltammetry(CV) and UV-Vis spectrometry(UV).The oxidation peak potential(Ep) and the wavelength of absorption shifted positively,meanwhile the peak current(Ip) and the absorbance value declined,indicating strong intercalation between the complex and DNA.The complex ratio and stability constant of the complex combined with DNA were 0.966 and 3.05×104 L/mol by electrochemical method,respectively,which agreed with the values from UV-Vis spectra.Oxidation peak current of the complex decreased with the addition of DNA and the decreasing in peak current was proportional to the DNA concentration in the range of 2.0×10-5 mol/L to 1.0×10-3 mol/L.The linear regression equation was ΔIp(μA)=5.516 1×103cDNA(mol/L)+0.253 1 with a correlation coefficient was 0.996 0.This method can be used for DNA determination.
The interaction between N,N'-bis(2-hydroxy-1-naphthaldehyde)-2,6-pyridyenediimine and DNA was studied by cyclic voltammetry(CV) and UV-Vis spectrometry(UV).The oxidation peak potential(Ep) and the wavelength of absorption shifted positively,meanwhile the peak current(Ip) and the absorbance value declined,indicating strong intercalation between the complex and DNA.The complex ratio and stability constant of the complex combined with DNA were 0.966 and 3.05×104 L/mol by electrochemical method,respectively,which agreed with the values from UV-Vis spectra.Oxidation peak current of the complex decreased with the addition of DNA and the decreasing in peak current was proportional to the DNA concentration in the range of 2.0×10-5 mol/L to 1.0×10-3 mol/L.The linear regression equation was ΔIp(μA)=5.516 1×103cDNA(mol/L)+0.253 1 with a correlation coefficient was 0.996 0.This method can be used for DNA determination.
2008, 25(10): 1193-1196
Abstract:
The synthesis of a tripod Schiff-base ligand and its complexes with five rare earth nitrates are reported.All the compounds were characterized by elemental analysis,IR,TG-DTA,and molar-conductance measurement.The results showed that in the complexes the Ln:L ratio is 1:1,one nitrate group is free,the other two nitrate groups monodentately coordinate to the Ln(Ⅲ) ion,and the coordination number of the rare earth ion is 8.The interactions of the complexes with DNA were investigated by fluorescent spectroscopy,which showed that the complexes could be bound to DNA,and the binding mode of the complexes with DNA was intercalation.
The synthesis of a tripod Schiff-base ligand and its complexes with five rare earth nitrates are reported.All the compounds were characterized by elemental analysis,IR,TG-DTA,and molar-conductance measurement.The results showed that in the complexes the Ln:L ratio is 1:1,one nitrate group is free,the other two nitrate groups monodentately coordinate to the Ln(Ⅲ) ion,and the coordination number of the rare earth ion is 8.The interactions of the complexes with DNA were investigated by fluorescent spectroscopy,which showed that the complexes could be bound to DNA,and the binding mode of the complexes with DNA was intercalation.
2008, 25(10): 1197-1200
Abstract:
K6SiW11O39SnⅡ(SiW11Sn) was prepared and fixed on the mesoporous molecular sieve of SiO2(SBA-15),and SiW11Sn-SBA-15 composite was obtained.Using the liquid phase reduction method,SiW11Sn-SBA-15 supported Pd(Pd/SiW11Sn-SBA-15) catalyst as the anodic catalyst in the direct formic acid fuel cell(DFAFC) was prepared.It was found that the electrocatalytic activity and stability of the Pd/SiW11Sn-SBA-15 catalyst for the oxidation of formic acid are better than that of the Pd/C catalyst,although the average size of the particles and the Pd content in the two catalysts were similar.This is because that formic acid is oxidized at the Pd/SiW11Sn-SBA-15 catalyst mainly through the expected direct pathway due to the dehydrogen action of SiW11Sn.
K6SiW11O39SnⅡ(SiW11Sn) was prepared and fixed on the mesoporous molecular sieve of SiO2(SBA-15),and SiW11Sn-SBA-15 composite was obtained.Using the liquid phase reduction method,SiW11Sn-SBA-15 supported Pd(Pd/SiW11Sn-SBA-15) catalyst as the anodic catalyst in the direct formic acid fuel cell(DFAFC) was prepared.It was found that the electrocatalytic activity and stability of the Pd/SiW11Sn-SBA-15 catalyst for the oxidation of formic acid are better than that of the Pd/C catalyst,although the average size of the particles and the Pd content in the two catalysts were similar.This is because that formic acid is oxidized at the Pd/SiW11Sn-SBA-15 catalyst mainly through the expected direct pathway due to the dehydrogen action of SiW11Sn.
2008, 25(10): 1201-1204
Abstract:
N-alkyl chitosan derivatives were synthesized by reducing Schiff` base formed from the reaction of aldehyde and chitosan.The degree of substitution of the modified chitosan was characterized by elemental analysis.The effects of preparation conditions on the degree of substitution and the adsorption of N-alkyl chitosan derivatives were studied.The results showed that reaction time,aldehyde/CTS ratio and reaction temperature were main factors to influence the substitution degree of the N-alkyl chitosan derivatives.Under conditions of aldehyde/CTS of 4/1,reaction temperature of 100℃ and reaction time of 8 h,the substitution degree of the N-alkyl chitosan reached the maximum.It was found that the higher the substituted degree,the better the adsorption capability.In addition,with increasing the N-alkyl chain length,the adsorption capability of the N-alkyl chitosan derivatives for 2,4-dichlorophenol improved until the carbon number of the N-alkyl chain reached seven and then declined after wards.The N-heptaldehyde chitosan exhibited the best adsorption capability.
N-alkyl chitosan derivatives were synthesized by reducing Schiff` base formed from the reaction of aldehyde and chitosan.The degree of substitution of the modified chitosan was characterized by elemental analysis.The effects of preparation conditions on the degree of substitution and the adsorption of N-alkyl chitosan derivatives were studied.The results showed that reaction time,aldehyde/CTS ratio and reaction temperature were main factors to influence the substitution degree of the N-alkyl chitosan derivatives.Under conditions of aldehyde/CTS of 4/1,reaction temperature of 100℃ and reaction time of 8 h,the substitution degree of the N-alkyl chitosan reached the maximum.It was found that the higher the substituted degree,the better the adsorption capability.In addition,with increasing the N-alkyl chain length,the adsorption capability of the N-alkyl chitosan derivatives for 2,4-dichlorophenol improved until the carbon number of the N-alkyl chain reached seven and then declined after wards.The N-heptaldehyde chitosan exhibited the best adsorption capability.
2008, 25(10): 1205-1208
Abstract:
The extract from the bark of Juglans mandshurica Maxim.was extracted again with chloroform or acetic ether.The active components in the chloroform part and the acetic ether part of the alcohol extract(separated with chloroform and acetic ether from the alcohol extract) were analyzed for by GC-MS.The major active components in the chloroform part of the alcohol extract from the bark might be 5-hydroxy-1,4-naphthalenedione(juglone,36.65%),4-hydroxy-2-methoxycinnamaldehyde,2,3-dihydro-benzofuran,vanillin,and 2-methoxy-4-vinylphenol.The major active components in the acetic ether part of the alcohol extract from the bark of Juglans mandshurica might be 1,2,3-benzenetriol(42.31%),juglone(12.33%),7-methoxy-1-tetralone(11.26%),5-(hydroxymethyl)-2-furancarboxaldehyde,3,4-dihydro-6,7-dihydroxy-1(2H)-naphthalenone,4-hydroxy-2-methoxycinnamaldehyde,and D-allose.
The extract from the bark of Juglans mandshurica Maxim.was extracted again with chloroform or acetic ether.The active components in the chloroform part and the acetic ether part of the alcohol extract(separated with chloroform and acetic ether from the alcohol extract) were analyzed for by GC-MS.The major active components in the chloroform part of the alcohol extract from the bark might be 5-hydroxy-1,4-naphthalenedione(juglone,36.65%),4-hydroxy-2-methoxycinnamaldehyde,2,3-dihydro-benzofuran,vanillin,and 2-methoxy-4-vinylphenol.The major active components in the acetic ether part of the alcohol extract from the bark of Juglans mandshurica might be 1,2,3-benzenetriol(42.31%),juglone(12.33%),7-methoxy-1-tetralone(11.26%),5-(hydroxymethyl)-2-furancarboxaldehyde,3,4-dihydro-6,7-dihydroxy-1(2H)-naphthalenone,4-hydroxy-2-methoxycinnamaldehyde,and D-allose.
2008, 25(10): 1209-1212
Abstract:
Polyurea microcapsules containing a phase change material,n-eicosane,were synthesized by means of interfacial polymerization method with toluene-2,4-diisocyanate(TDI) and 1,6-hexane diamine(HDA) as the monomers in an emulsion system.Poly(ethylene glycol) octyl-phenyl ether(OP),a nonionic surfactant,was the emulsifier for the system.TDI reacted with HDA at a mass ratio of 1.5 to 0.8.The sizes of microcapsules were analyzed with TEM and a laser particle analyzer.The hollow microcapsules were about 0.2 μm in diameter and those containing n-eicosane were about 2~6 μm in diameter.FT-IR spectra proved the formation of the wall material,polyurea,from the two monomers,TDI and HDA.Encapsulation efficiency of n-eicosane was about 65%~80%.Microcapsule of n-eicosane melted at a temperature close to that of n-eicosane,while its stored heat energy varied with the amount of n-eicosane when the wall material was fixed.Thermo-gravimetric analysis showed that core material n-eicosane,micro-n-eicosane and wall material polyurea can withstand temperatures of up to 130℃,165℃,and 250℃,respectively.
Polyurea microcapsules containing a phase change material,n-eicosane,were synthesized by means of interfacial polymerization method with toluene-2,4-diisocyanate(TDI) and 1,6-hexane diamine(HDA) as the monomers in an emulsion system.Poly(ethylene glycol) octyl-phenyl ether(OP),a nonionic surfactant,was the emulsifier for the system.TDI reacted with HDA at a mass ratio of 1.5 to 0.8.The sizes of microcapsules were analyzed with TEM and a laser particle analyzer.The hollow microcapsules were about 0.2 μm in diameter and those containing n-eicosane were about 2~6 μm in diameter.FT-IR spectra proved the formation of the wall material,polyurea,from the two monomers,TDI and HDA.Encapsulation efficiency of n-eicosane was about 65%~80%.Microcapsule of n-eicosane melted at a temperature close to that of n-eicosane,while its stored heat energy varied with the amount of n-eicosane when the wall material was fixed.Thermo-gravimetric analysis showed that core material n-eicosane,micro-n-eicosane and wall material polyurea can withstand temperatures of up to 130℃,165℃,and 250℃,respectively.
2008, 25(10): 1213-1216
Abstract:
A complex extraction was used for the treatment of wastewater containing dimethylamine(DMA).The effects of the diluent and complexing agent and their concentrations,solution pH,and the volume ratio of oil to water on the equilibrium distribution coefficient were systematically studied.The results showed that the extraction was a rapid and exothermal reaction,and the enthalpy of the extraction reaction ΔH was-6.50 kJ/mol with di(2-ethylhexyl)phosphoric acid as the complexing agent and hexahydrobenzene as the diluent.The composition of the extracted species was deduced,and the ratio of P204:DMA was 1:1.The maximum removal rate of DMA was 93.0% by one stage extraction under the conditions of pH=11.87,oil to water volume ratio of 0.25,and a volume ratio of 0.1 of the extractant to the diluent in oil phase.The mechanism of complexation reaction was investigated by infrared,and there were hydrogen bonding and ion-association reaction.
A complex extraction was used for the treatment of wastewater containing dimethylamine(DMA).The effects of the diluent and complexing agent and their concentrations,solution pH,and the volume ratio of oil to water on the equilibrium distribution coefficient were systematically studied.The results showed that the extraction was a rapid and exothermal reaction,and the enthalpy of the extraction reaction ΔH was-6.50 kJ/mol with di(2-ethylhexyl)phosphoric acid as the complexing agent and hexahydrobenzene as the diluent.The composition of the extracted species was deduced,and the ratio of P204:DMA was 1:1.The maximum removal rate of DMA was 93.0% by one stage extraction under the conditions of pH=11.87,oil to water volume ratio of 0.25,and a volume ratio of 0.1 of the extractant to the diluent in oil phase.The mechanism of complexation reaction was investigated by infrared,and there were hydrogen bonding and ion-association reaction.
2008, 25(10): 1217-1220
Abstract:
Polystyrene nanoparticles were prepared by dispersion polymerization under ultrasonic irradiation.The morphologies and sizes of the latex particles were characterized with the transmission electron microscopy(TEM);the conversion of the monomer was determined by gravimetry.The results show that the polymerization under ultrasonic irradiation showed a faster reaction rate and higher conversion compared with conventional heating method.The conversion of St under ultrasonic irradiation was 63% within 1 h.The latex particle diameter was about 80 nm by means of dispersion polymerization under ultrasonic irradiation,which was smaller than that prepared by conventional heating method.Raising temperature was a useful way to promote the reaction.
Polystyrene nanoparticles were prepared by dispersion polymerization under ultrasonic irradiation.The morphologies and sizes of the latex particles were characterized with the transmission electron microscopy(TEM);the conversion of the monomer was determined by gravimetry.The results show that the polymerization under ultrasonic irradiation showed a faster reaction rate and higher conversion compared with conventional heating method.The conversion of St under ultrasonic irradiation was 63% within 1 h.The latex particle diameter was about 80 nm by means of dispersion polymerization under ultrasonic irradiation,which was smaller than that prepared by conventional heating method.Raising temperature was a useful way to promote the reaction.
2008, 25(10): 1221-1224
Abstract:
In phosphate buffer midia the inclusion behavior beween meloxicam and β-cyclodextrin(β-CD),hydroxyproyl-β-cyclodextrin(HP-β-CD) and sulfobutyl ether-β-cyclodextrin(SBE-β-CD) was studied by fluorescence spectroscopy.It showed that 1:1 inclusion complexes were formed beween meloxicam and the three kinds of CDs,because the emission maximum shifted by 7,9,and 14 nm,respectively and the reciprocal of change in fluorescence intensity(ΔF) was directly proportional to the reciprocal of the CD concentration(CCD).The binding ability was SBE-β-CD > HP-β-CD > β-CD in acidic and neutral media based on the formation constants.There were not only hydrophobic but also electrostatic forces involved.
In phosphate buffer midia the inclusion behavior beween meloxicam and β-cyclodextrin(β-CD),hydroxyproyl-β-cyclodextrin(HP-β-CD) and sulfobutyl ether-β-cyclodextrin(SBE-β-CD) was studied by fluorescence spectroscopy.It showed that 1:1 inclusion complexes were formed beween meloxicam and the three kinds of CDs,because the emission maximum shifted by 7,9,and 14 nm,respectively and the reciprocal of change in fluorescence intensity(ΔF) was directly proportional to the reciprocal of the CD concentration(CCD).The binding ability was SBE-β-CD > HP-β-CD > β-CD in acidic and neutral media based on the formation constants.There were not only hydrophobic but also electrostatic forces involved.
2008, 25(10): 1225-1228
Abstract:
The enzymatically degradable poly(N-isopropylacrylamide-co-acrylic acid) hydrogels were prepared with 4,4'-bis(methacryloylamino)azobenzene(BMAAB) as a crosslinker.It was found that the hydrogels exhibited a phase transition temperature between 4℃(refrigerator temperature) and 37℃(human body temperature).Bovine Serum albumin(BSA) as a model drug was loaded into the hydrogels.The loading capability was 144.5 mg BSA/g gel in buffer solution(pH=7.4) at 4℃,while it was 14.8 mg BSA/g gel at 37℃.The hydrogels can be degraded by cecal bacteria and cumulative release may be 100 mg BSA/g gel 4 days after enzymatic degradation of hydrogel in pH=7.4 buffer solution containing cecal bacteria at 37℃.
The enzymatically degradable poly(N-isopropylacrylamide-co-acrylic acid) hydrogels were prepared with 4,4'-bis(methacryloylamino)azobenzene(BMAAB) as a crosslinker.It was found that the hydrogels exhibited a phase transition temperature between 4℃(refrigerator temperature) and 37℃(human body temperature).Bovine Serum albumin(BSA) as a model drug was loaded into the hydrogels.The loading capability was 144.5 mg BSA/g gel in buffer solution(pH=7.4) at 4℃,while it was 14.8 mg BSA/g gel at 37℃.The hydrogels can be degraded by cecal bacteria and cumulative release may be 100 mg BSA/g gel 4 days after enzymatic degradation of hydrogel in pH=7.4 buffer solution containing cecal bacteria at 37℃.
2008, 25(10): 1229-1232
Abstract:
Four viscoelastic surfactants(N-alkyl-N,N-hydroxyethyl octadecyl bromine ammonium) were synthesized.SEM was used to analyze the structure of the four surfactants.The influence of R4 on cmc was studied.The more the number of carbons in R4,the higher the surface activity of the surfactant,the higher the viscoelasticity,and the higher the temperature resistance.The cmc can reach 1.87 mmol/L,and the consistency coefficient increased by a factor of 1.7.
Four viscoelastic surfactants(N-alkyl-N,N-hydroxyethyl octadecyl bromine ammonium) were synthesized.SEM was used to analyze the structure of the four surfactants.The influence of R4 on cmc was studied.The more the number of carbons in R4,the higher the surface activity of the surfactant,the higher the viscoelasticity,and the higher the temperature resistance.The cmc can reach 1.87 mmol/L,and the consistency coefficient increased by a factor of 1.7.
2008, 25(10): 1233-1236
Abstract:
The isothermal crystallization process and subsequent melting behavior of a cis-1,4-polybutadiene(PB) sample were investigated by differential scanning calorimetry(DSC).It was found that there existed a perfection process of crystals at the late stage of the isothermal crystallization process.In addition,the rate of crystallization decreased with an increase of the crystallization temperature.Melting of the PB crystals always starts at about 2℃ above the crystallization temperature.At a heating rate of 10℃/min,DSC thermogram shows a broad distribution of melting temperatures with a smaller shoulder on the low-temperature side,indicating that this sample possesses crystallites with different stabilities after isothermal crystallization.By extrapolating the melting points to zero crystallinity(Xc=0) or infinite long crystallization time(tc-1=0),we determined the equilibrium melting point Tm∞ of this PB specimen to be in between 9 and 17.6℃ according to the Hoffman-Weeks approach.
The isothermal crystallization process and subsequent melting behavior of a cis-1,4-polybutadiene(PB) sample were investigated by differential scanning calorimetry(DSC).It was found that there existed a perfection process of crystals at the late stage of the isothermal crystallization process.In addition,the rate of crystallization decreased with an increase of the crystallization temperature.Melting of the PB crystals always starts at about 2℃ above the crystallization temperature.At a heating rate of 10℃/min,DSC thermogram shows a broad distribution of melting temperatures with a smaller shoulder on the low-temperature side,indicating that this sample possesses crystallites with different stabilities after isothermal crystallization.By extrapolating the melting points to zero crystallinity(Xc=0) or infinite long crystallization time(tc-1=0),we determined the equilibrium melting point Tm∞ of this PB specimen to be in between 9 and 17.6℃ according to the Hoffman-Weeks approach.
2008, 25(10): 1237-1239
Abstract:
Enantiomeric separation of simeconazole was performed by high performance liquid chromatography with the coating-type amylose-tris[(s)-α-methyphenylcarbamate] as the chiral stationary phase(CSP).The chromatographic conditions were optimized by studying the influence of the mobile phase composition including the concentration and type of the alcohol modifier in hexane on enantiomers separation.The data indicated that simeconazole was best separated with the resolutions of 1.39 and 3.75 by 2% iso-propanol or ethanol as the mobile phase respectively,ethanol had a higher separation efficiency than isopropanol.The effect of temperature on chiral separation was investigated,and it was found that lower column temperatures resulted in better separation of simeconazole.
Enantiomeric separation of simeconazole was performed by high performance liquid chromatography with the coating-type amylose-tris[(s)-α-methyphenylcarbamate] as the chiral stationary phase(CSP).The chromatographic conditions were optimized by studying the influence of the mobile phase composition including the concentration and type of the alcohol modifier in hexane on enantiomers separation.The data indicated that simeconazole was best separated with the resolutions of 1.39 and 3.75 by 2% iso-propanol or ethanol as the mobile phase respectively,ethanol had a higher separation efficiency than isopropanol.The effect of temperature on chiral separation was investigated,and it was found that lower column temperatures resulted in better separation of simeconazole.
2008, 25(10): 1240-1242
Abstract:
SiO2/sucrose hybrid sol was prepared from sol-gel of TEOS and sucrose,and SiO2/sucrose hybrid ferbers were prepared by drawing method.The change in viscosity and the spinnablity of the hybrid sols were studied.The morphology of the hybrid fibers was characterized by SEM;the thermal properties of the hybrid fibers were characterized by TG and DSC,and the crystalline property of the hybrid fibers was characterized by XRD.The results showed that the SiO2/sucrose hybrid sols had good spinnability,and the hybrid fibers had excellent appearance.The heat resistance of sucrose was improved in the hybrid.The hybrid fibers were amorphous and some micro-crystals of graphite were formed after they had been heated to 800℃.
SiO2/sucrose hybrid sol was prepared from sol-gel of TEOS and sucrose,and SiO2/sucrose hybrid ferbers were prepared by drawing method.The change in viscosity and the spinnablity of the hybrid sols were studied.The morphology of the hybrid fibers was characterized by SEM;the thermal properties of the hybrid fibers were characterized by TG and DSC,and the crystalline property of the hybrid fibers was characterized by XRD.The results showed that the SiO2/sucrose hybrid sols had good spinnability,and the hybrid fibers had excellent appearance.The heat resistance of sucrose was improved in the hybrid.The hybrid fibers were amorphous and some micro-crystals of graphite were formed after they had been heated to 800℃.
2008, 25(10): 1243-1245
Abstract:
Nine new water soluble α-amino phosphonate esters were synthesized from the addition reaction of salicylaldehyde amino acid Schiff base with dialkylphosphite.The structures of the compounds were confirmed by elemental analysis,IR and 1H NMR,and preliminary biological activity tests showed that the compound f had notable positive effect on sterilization and promoting plant growth.
Nine new water soluble α-amino phosphonate esters were synthesized from the addition reaction of salicylaldehyde amino acid Schiff base with dialkylphosphite.The structures of the compounds were confirmed by elemental analysis,IR and 1H NMR,and preliminary biological activity tests showed that the compound f had notable positive effect on sterilization and promoting plant growth.
2008, 25(10): 1246-1248
Abstract:
Analysis of multi-brighteners in Ni-plating bath for sintered NdFeB magnets plating by HPLC-DAD-ELSD method is reported.The method is fast and easy to be operated,with broad linear range,good reprodu-cibility,and low interference.Overall recoveries of all the studied brighteners were 92%~101% with RSD values less than 10%.The present method was used for quality control of the plating bath in the production process with favorable results and accurate information.
Analysis of multi-brighteners in Ni-plating bath for sintered NdFeB magnets plating by HPLC-DAD-ELSD method is reported.The method is fast and easy to be operated,with broad linear range,good reprodu-cibility,and low interference.Overall recoveries of all the studied brighteners were 92%~101% with RSD values less than 10%.The present method was used for quality control of the plating bath in the production process with favorable results and accurate information.
