Login In
2006 Volume 23 Issue 4
2006, 23(4): 349-352
Abstract:
Vapor phase grafting of vinyltrimethoxysilane(VTMS) onto polypropylene(PP) powders and its subsequent hydrolysis crosslinking were studied in this work.The vapor grafting mechanism of VTMS onto PP through free radical was studied.The effects of the VTMS monomer and initiator concentrations on the grafting degree of the silane and gel content of the crosslinked samples were investigated.FTIR and FTIR-PAS were used to analyze the grafted materials.The result shows that the diffusion conditions of the monomer and the initiator in the PP have significant influence on the VTMS grafting degree.The grafting degree of VTMS increases with increasing monomer and initiator concentrations,and this trend slows down when the concentrations of the monomer and the initiator are over 0.026 mol/L and 0.6%,respectively.
Vapor phase grafting of vinyltrimethoxysilane(VTMS) onto polypropylene(PP) powders and its subsequent hydrolysis crosslinking were studied in this work.The vapor grafting mechanism of VTMS onto PP through free radical was studied.The effects of the VTMS monomer and initiator concentrations on the grafting degree of the silane and gel content of the crosslinked samples were investigated.FTIR and FTIR-PAS were used to analyze the grafted materials.The result shows that the diffusion conditions of the monomer and the initiator in the PP have significant influence on the VTMS grafting degree.The grafting degree of VTMS increases with increasing monomer and initiator concentrations,and this trend slows down when the concentrations of the monomer and the initiator are over 0.026 mol/L and 0.6%,respectively.
2006, 23(4): 353-356
Abstract:
Non-covalent molecular imprinted polymers(MIP) of cholesterol were prepared from its reaction with methacrylic acid(MAA),ethylene glycol dimethacrylate(EGDMA) and azobisisobutyronitrile(AIBN) via thermal and UV polymerization.The binding capability and selectivity of the different polymers for cholesterol were studied.The polymers were used as immunosorbents for the selective enrichment of cholesterol in different biological samples(serum,milk and yolk) under optimal loading,washing and eluting conditions.Results show that MIPs can selectively recognize and separate cholesterol in all three biological samples.The rate of recovery of cholesterol from serum was the highest,while that from yolk was the lowest.Co MPared with C18 SPE,the UV initiated MIPs show higher recovery than C18 for cholesterol in the sample.
Non-covalent molecular imprinted polymers(MIP) of cholesterol were prepared from its reaction with methacrylic acid(MAA),ethylene glycol dimethacrylate(EGDMA) and azobisisobutyronitrile(AIBN) via thermal and UV polymerization.The binding capability and selectivity of the different polymers for cholesterol were studied.The polymers were used as immunosorbents for the selective enrichment of cholesterol in different biological samples(serum,milk and yolk) under optimal loading,washing and eluting conditions.Results show that MIPs can selectively recognize and separate cholesterol in all three biological samples.The rate of recovery of cholesterol from serum was the highest,while that from yolk was the lowest.Co MPared with C18 SPE,the UV initiated MIPs show higher recovery than C18 for cholesterol in the sample.
2006, 23(4): 357-361
Abstract:
The inorganic ion-exchanger Li4Mn0.5Ti0.5O4 of spinal type was prepared by the coprecipitation/thermal crystallization method,and was modified by impregnation in an acid.Its ion-exchange properties for alkali ions such as saturation capacity of exchange,distribution coefficient,the pH titration curve and service cycles were determined.Li4Mn0.5Ti0.5O4 was characterized by X-ray diffraction.These results show that this inorganic ion-sieve has better memory effect and exchange selectivity,and higher exchange capacity for Li+,with a saturation exchange capacity for Li+ of 5.96 mmol/g.At the same time,lower extration ratios for Mn4+ and Ti4+ were maintained.
The inorganic ion-exchanger Li4Mn0.5Ti0.5O4 of spinal type was prepared by the coprecipitation/thermal crystallization method,and was modified by impregnation in an acid.Its ion-exchange properties for alkali ions such as saturation capacity of exchange,distribution coefficient,the pH titration curve and service cycles were determined.Li4Mn0.5Ti0.5O4 was characterized by X-ray diffraction.These results show that this inorganic ion-sieve has better memory effect and exchange selectivity,and higher exchange capacity for Li+,with a saturation exchange capacity for Li+ of 5.96 mmol/g.At the same time,lower extration ratios for Mn4+ and Ti4+ were maintained.
2006, 23(4): 362-365
Abstract:
The sodium salts of (S)-2-(1-imidazolyl)alkanoic acids(2) were prepared by the cyclization of natural amino acids with formaldehyde aqueous solution and glyoxal aqueous solution under basic condition.The sodium salts(2) were esterified to form (S)-2-(1-imidazolyl)alkanoates(3a~3g).The (S)-2-(1-imidazolyl)alkanols(4a~4e) were obtaind by reduction of 3a~3e via NaBH4 with satisfactory yields.The structures of the compounds(3a~3g,4a~4e) were confirmed by IR,1H NMR,MS,and elemental analysis.
The sodium salts of (S)-2-(1-imidazolyl)alkanoic acids(2) were prepared by the cyclization of natural amino acids with formaldehyde aqueous solution and glyoxal aqueous solution under basic condition.The sodium salts(2) were esterified to form (S)-2-(1-imidazolyl)alkanoates(3a~3g).The (S)-2-(1-imidazolyl)alkanols(4a~4e) were obtaind by reduction of 3a~3e via NaBH4 with satisfactory yields.The structures of the compounds(3a~3g,4a~4e) were confirmed by IR,1H NMR,MS,and elemental analysis.
2006, 23(4): 366-369
Abstract:
By means of pH potentiometric titration,the dissociation equilibrium of polyaspartic acid(PASP) and its complexation with two divalent cations(Ca2+,Mg2+) were studied.Considering the complexity of the dissociation of polyaspartic acid in aqueous solution,a proper model of PASP(H4L) was constructed to simulate the dissociation process of PASP.The computer program BEST developed by A.E Martell was used to determine the dissociation constants of PASP and the stability constants of the related PASP complexes with Ca2+ or Mg2+.According to the experimental and computation results,the distributions of PASP complex species in aqueous solution at different pH values were given out.The dissociation constants pKai of PASP were 2.27,3.66,4.22,and 5.40 respectively with an erroe of 0.006 1.The stability constants (lgβ) of PASP with Ca2+ or Mg2+ ranged from 2.97 to 13.15.The results show that PASP is a good ligand for forming different complexes with Ca2+ or Mg2+ under a wider range pH.
By means of pH potentiometric titration,the dissociation equilibrium of polyaspartic acid(PASP) and its complexation with two divalent cations(Ca2+,Mg2+) were studied.Considering the complexity of the dissociation of polyaspartic acid in aqueous solution,a proper model of PASP(H4L) was constructed to simulate the dissociation process of PASP.The computer program BEST developed by A.E Martell was used to determine the dissociation constants of PASP and the stability constants of the related PASP complexes with Ca2+ or Mg2+.According to the experimental and computation results,the distributions of PASP complex species in aqueous solution at different pH values were given out.The dissociation constants pKai of PASP were 2.27,3.66,4.22,and 5.40 respectively with an erroe of 0.006 1.The stability constants (lgβ) of PASP with Ca2+ or Mg2+ ranged from 2.97 to 13.15.The results show that PASP is a good ligand for forming different complexes with Ca2+ or Mg2+ under a wider range pH.
2006, 23(4): 370-373
Abstract:
BaW4 nanoparticles of wire,rod,and hollow spherical shapes were prepared in different microemulsion systems with octane as the oil,and undecylenic acid and/or dodecylamine as the surfactants.The powder was characterized by XRD,TEM and HRTEM.The Raman spectra of the BaWO4 nanowires and hollow BaWO4 spherical particles were also presented.This method may be extended to prepare novel nanostructures of other tungstates.
BaW4 nanoparticles of wire,rod,and hollow spherical shapes were prepared in different microemulsion systems with octane as the oil,and undecylenic acid and/or dodecylamine as the surfactants.The powder was characterized by XRD,TEM and HRTEM.The Raman spectra of the BaWO4 nanowires and hollow BaWO4 spherical particles were also presented.This method may be extended to prepare novel nanostructures of other tungstates.
2006, 23(4): 374-377
Abstract:
WO3 electrochromic films were prepared on ITO glass substrates by the sol-gel method.The precursor sodium tungstate was converted into tungstenic acid by cation-exchange.Ethanol and PVA were used as additives to improve the performance of the film.The effects of additives and annealing temperature were discussed.The experimental results indicate that the film annealed at 75℃ show predominant electrochromic performance.The film has the advantages of distinct color change,short response time,excellent stability and long cycle life.It is in prospect of being used in electrochromic devices.
WO3 electrochromic films were prepared on ITO glass substrates by the sol-gel method.The precursor sodium tungstate was converted into tungstenic acid by cation-exchange.Ethanol and PVA were used as additives to improve the performance of the film.The effects of additives and annealing temperature were discussed.The experimental results indicate that the film annealed at 75℃ show predominant electrochromic performance.The film has the advantages of distinct color change,short response time,excellent stability and long cycle life.It is in prospect of being used in electrochromic devices.
2006, 23(4): 378-381
Abstract:
In order to improve electrochemical performance of LiMn2O4 as a cathode material for lithium ion batteries at a high temperature(55℃),a stable SiO2 film was coated on the surface of LiMn2O4 cathode material by sol-gel method from Si(OCH2CH3)4.The structures of the coated and uncoated LiMn2O4 were characterized by XRD and SEM. The results show that the SiO2 layer can reduce the direct contact between LiMn2O4 and the electrolyte,and thus effectively suppress the undesirable interactions between them at elevated temperatures.At 55℃,the surface modified LiMn2O4 cathode material can stabilize the cycling performance and largely reduce the self-discharge of the battery.
In order to improve electrochemical performance of LiMn2O4 as a cathode material for lithium ion batteries at a high temperature(55℃),a stable SiO2 film was coated on the surface of LiMn2O4 cathode material by sol-gel method from Si(OCH2CH3)4.The structures of the coated and uncoated LiMn2O4 were characterized by XRD and SEM. The results show that the SiO2 layer can reduce the direct contact between LiMn2O4 and the electrolyte,and thus effectively suppress the undesirable interactions between them at elevated temperatures.At 55℃,the surface modified LiMn2O4 cathode material can stabilize the cycling performance and largely reduce the self-discharge of the battery.
2006, 23(4): 382-385
Abstract:
The preparation of microcapsules of bio-pesticide rotenone by means of in-situ polymerization,with melamine formaldehyde resin(MF) as the shell material, is discussed in this paper.The results show that MF resin is a superior shell material for controlled release bio-pesticide microcapsules.The production process of this resin is simple and it has good stability.The microcapsules did not break and the encapsulation efficiency did not changed obviously after they were preserved at 0℃,(25℃),50℃ for 14 d,respectively.When the stirring rate was is 500 r/min,the size of the microcapsule was 10~60 μm,meeting the standard of pesticide microcapsules.The controlled release times of the product is about 7 d or more,and the encapsulation efficiency is 68.55%±5.0%.
The preparation of microcapsules of bio-pesticide rotenone by means of in-situ polymerization,with melamine formaldehyde resin(MF) as the shell material, is discussed in this paper.The results show that MF resin is a superior shell material for controlled release bio-pesticide microcapsules.The production process of this resin is simple and it has good stability.The microcapsules did not break and the encapsulation efficiency did not changed obviously after they were preserved at 0℃,(25℃),50℃ for 14 d,respectively.When the stirring rate was is 500 r/min,the size of the microcapsule was 10~60 μm,meeting the standard of pesticide microcapsules.The controlled release times of the product is about 7 d or more,and the encapsulation efficiency is 68.55%±5.0%.
2006, 23(4): 386-389
Abstract:
A method for the analysis of 4 organic acids(aminoacetic acid,lactic acid,acetic acid, citric acid) in electroless plating solutions was developed.The analysis could be finished within 6 min.It is based on an ion suppression chromatographic separation under the conditions of isocratic elution with 25 m mol/L phosphate buffer solution(pH=2.1) on a Hypersil ODS column,and UV detection at 210 nm.Linear calibrations were obtained within 0.05×10-3~5×10-3 g/mL(r>0.999 4).The limits of detection(mg/L) were 6 of aminoacetic acid,20 for lactic acid,14 for acetic acid and 9 for citric acid,respectively.The average recovery rate was(n=6) 98.12%~102.60%,and the relative standard deviation(n=6) 0.31%~0.98%.Through the formula for distribution coefficient,and with the pH value of the original solution,the contents of different forms of each organic acid were figured out.
A method for the analysis of 4 organic acids(aminoacetic acid,lactic acid,acetic acid, citric acid) in electroless plating solutions was developed.The analysis could be finished within 6 min.It is based on an ion suppression chromatographic separation under the conditions of isocratic elution with 25 m mol/L phosphate buffer solution(pH=2.1) on a Hypersil ODS column,and UV detection at 210 nm.Linear calibrations were obtained within 0.05×10-3~5×10-3 g/mL(r>0.999 4).The limits of detection(mg/L) were 6 of aminoacetic acid,20 for lactic acid,14 for acetic acid and 9 for citric acid,respectively.The average recovery rate was(n=6) 98.12%~102.60%,and the relative standard deviation(n=6) 0.31%~0.98%.Through the formula for distribution coefficient,and with the pH value of the original solution,the contents of different forms of each organic acid were figured out.
2006, 23(4): 390-393
Abstract:
The used perfluorosulfonic acid ion-exchange membrane was treated in a solvent to recycle the perfluorosulfonic acid resin.The perfluorosulfonic acid resin/silica composite catalysts were prepared by the sol-gel method and the impregnation method,respectively,and characterized by FTIR,TG,BET,and SEM.For co MParison,catalysts such as an impregnated perfluorosulfonic acid resin/SiO2,Nafion SAC-13,SO42-/TiO2 solid acid and p-toluenesulfonic acid were also studied.The composite catalysts obtained were used in the esterification of phthalic anhydride with 2-ethyl hexanol.The results show that under the conditions of n(phthalic anhydride):n(2-ethyl hexanol)=1:3,4.4%(mass fraction) catalyst,170℃ and 4 h, dioctyl phthalate could be obtained in a yield of 97.06%.
The used perfluorosulfonic acid ion-exchange membrane was treated in a solvent to recycle the perfluorosulfonic acid resin.The perfluorosulfonic acid resin/silica composite catalysts were prepared by the sol-gel method and the impregnation method,respectively,and characterized by FTIR,TG,BET,and SEM.For co MParison,catalysts such as an impregnated perfluorosulfonic acid resin/SiO2,Nafion SAC-13,SO42-/TiO2 solid acid and p-toluenesulfonic acid were also studied.The composite catalysts obtained were used in the esterification of phthalic anhydride with 2-ethyl hexanol.The results show that under the conditions of n(phthalic anhydride):n(2-ethyl hexanol)=1:3,4.4%(mass fraction) catalyst,170℃ and 4 h, dioctyl phthalate could be obtained in a yield of 97.06%.
2006, 23(4): 394-398
Abstract:
Three solid complexes of Schiff base C16H15N3O2(L) derived from Furfural and 4-aminoantipyrine with each of 3 lanthanide nitrates were synthesized and characterized by elemental analysis,IR,UV,TG-DTG and molar conductivity analysis.The compositions of the complexes were confirmed to be[LnL(NO3)3(CH3-OH)]·H2O(Ln=Pr,La,Eu).The third-stage thermal decomposition kinetics of the complexes was studied under non-isothermal condition by TG and DTG methods.The kinetic equation may be expressed as:dα/dt=A·e-E/RT·3/2[(1-α)-1/3-1)]-1.The kinetic parameters(E,A),activation entropy ΔS≠ and activation free-energy △G≠ were also obtained.
Three solid complexes of Schiff base C16H15N3O2(L) derived from Furfural and 4-aminoantipyrine with each of 3 lanthanide nitrates were synthesized and characterized by elemental analysis,IR,UV,TG-DTG and molar conductivity analysis.The compositions of the complexes were confirmed to be[LnL(NO3)3(CH3-OH)]·H2O(Ln=Pr,La,Eu).The third-stage thermal decomposition kinetics of the complexes was studied under non-isothermal condition by TG and DTG methods.The kinetic equation may be expressed as:dα/dt=A·e-E/RT·3/2[(1-α)-1/3-1)]-1.The kinetic parameters(E,A),activation entropy ΔS≠ and activation free-energy △G≠ were also obtained.
2006, 23(4): 399-403
Abstract:
A stable enzyme-modified electrode was made by immobilizing horseradish peroxidase(HRP) on edge-plane pyrolytic graphite(EPG) electrode with sodium alginate hydrogel.The entrapped HRP underwent a fast direct electron-transfer reaction in both phosphate buffer and phosphate-ethanol buffer.The formal potential(-0.364 V vs SCE) indicates the redox of HRPFe(Ⅲ)/(Ⅱ) couple.The Eo' is linearly dependent on solution pH,suggesting that electron transfer is proton-coupled.The catalytic reductions of oxygen,hydrogen peroxide,nitric oxide and the dehalogenation of hexachloroethane by HRP were also explored.
A stable enzyme-modified electrode was made by immobilizing horseradish peroxidase(HRP) on edge-plane pyrolytic graphite(EPG) electrode with sodium alginate hydrogel.The entrapped HRP underwent a fast direct electron-transfer reaction in both phosphate buffer and phosphate-ethanol buffer.The formal potential(-0.364 V vs SCE) indicates the redox of HRPFe(Ⅲ)/(Ⅱ) couple.The Eo' is linearly dependent on solution pH,suggesting that electron transfer is proton-coupled.The catalytic reductions of oxygen,hydrogen peroxide,nitric oxide and the dehalogenation of hexachloroethane by HRP were also explored.
2006, 23(4): 404-408
Abstract:
A parathion(PT) imprinted sensor was prepared on nano-TiO2 thin film by the liquid phase deposition method with p-tert-butylcalix\arene as the functional monomer.The experimental results indicate that PT gives an irreversible reduction peak(Ep=-0.706 V) and a pair of reversible peaks(Ep=-0.067 2 V and-0.169 9 V) in phosphate buffer solution(pH=5.5).The oxidation peak current increases linearly with the increase of the concentration PT in the range of 5.0×10-8 to 1.0×10-5 mol/L(r=0.996 5).The detection limit is 1.0×10-8 mol/L.The selectivity of the imprinted sensors was also studied.It was found that the current responses of some similar compounds of parathion were much smaller than that of parathion.This method was applied in the determination of PT in some vegetables and a good recovery of added PT in the vegetable samples was demonstrated.
A parathion(PT) imprinted sensor was prepared on nano-TiO2 thin film by the liquid phase deposition method with p-tert-butylcalix\arene as the functional monomer.The experimental results indicate that PT gives an irreversible reduction peak(Ep=-0.706 V) and a pair of reversible peaks(Ep=-0.067 2 V and-0.169 9 V) in phosphate buffer solution(pH=5.5).The oxidation peak current increases linearly with the increase of the concentration PT in the range of 5.0×10-8 to 1.0×10-5 mol/L(r=0.996 5).The detection limit is 1.0×10-8 mol/L.The selectivity of the imprinted sensors was also studied.It was found that the current responses of some similar compounds of parathion were much smaller than that of parathion.This method was applied in the determination of PT in some vegetables and a good recovery of added PT in the vegetable samples was demonstrated.
2006, 23(4): 409-413
Abstract:
Dimethylopropionic acid(DMPa) was used as a chain extender to extend the isocyanate-terminated PDMS-modified polyurethane prepolymer,and isocyanate-terminated PDMS-modified polyurethane oligomers containing carboxyl groups were obtained.Then a novel type of PU/EP IPN was prepared by the reaction of the oligomers with the epoxy resin monomers(E-51),which was cured by 3,3'-dichloro-4,4'-diaminodiphenyl methane(MOCA).The kinetics of the IPN formation and the microphase separation were analyzed by means of FTIR and SEM.The mechnical properties of the IPN with different PU/EP ratios were investigated by DMA.The thermal stability was also studied by TGA.The experimental results showed that when the amount of PU oligomer was 25%(mass fraction),the impact strength and modulus of the resulted material in glassy state were 23.58 kg/m2 and 103 MPa,respectively.Co MPared with that of the control epoxy resin,the impact strength of the resulted material increased by 116.7%,and the modulus increased almost by 100%;while the 5% weight loss temperature remained almost the same,the synergism of IPN occurred,and accordingly the composite material obtained exhibited excellent compositive properties.
Dimethylopropionic acid(DMPa) was used as a chain extender to extend the isocyanate-terminated PDMS-modified polyurethane prepolymer,and isocyanate-terminated PDMS-modified polyurethane oligomers containing carboxyl groups were obtained.Then a novel type of PU/EP IPN was prepared by the reaction of the oligomers with the epoxy resin monomers(E-51),which was cured by 3,3'-dichloro-4,4'-diaminodiphenyl methane(MOCA).The kinetics of the IPN formation and the microphase separation were analyzed by means of FTIR and SEM.The mechnical properties of the IPN with different PU/EP ratios were investigated by DMA.The thermal stability was also studied by TGA.The experimental results showed that when the amount of PU oligomer was 25%(mass fraction),the impact strength and modulus of the resulted material in glassy state were 23.58 kg/m2 and 103 MPa,respectively.Co MPared with that of the control epoxy resin,the impact strength of the resulted material increased by 116.7%,and the modulus increased almost by 100%;while the 5% weight loss temperature remained almost the same,the synergism of IPN occurred,and accordingly the composite material obtained exhibited excellent compositive properties.
2006, 23(4): 414-418
Abstract:
A series of biodegradable crosslinkers terminated by double epoxy groups was prepared from epoxypropane chloride and the intermediates of poly(lactic acid)-poly(ethylene glycol)(PLA-PEG-PLA) in the presence of NaH.The molecular weights of the intermediates were measured with GPC.The optimized process parameters were obtained by orthogonal trials.The crosslinker terminated with active epoxy groups was used to react with chitosan which has many amido and hydroxy groups.The crosslinked materials were characterized by water absorbency,surface contact angle and mechanical property analyses.The results of the orthogonal trials indicated that the crosslinker was best prepared at 40℃ for 4 h in a reactant ratio of 1:2,and the epoxy value was 1.034 mmol/g.The test of water absorption and surface contact angles and tensile tests showed that both the hydrophilicity and the mechanical properties of the crosslinked chitosan had been improved.
A series of biodegradable crosslinkers terminated by double epoxy groups was prepared from epoxypropane chloride and the intermediates of poly(lactic acid)-poly(ethylene glycol)(PLA-PEG-PLA) in the presence of NaH.The molecular weights of the intermediates were measured with GPC.The optimized process parameters were obtained by orthogonal trials.The crosslinker terminated with active epoxy groups was used to react with chitosan which has many amido and hydroxy groups.The crosslinked materials were characterized by water absorbency,surface contact angle and mechanical property analyses.The results of the orthogonal trials indicated that the crosslinker was best prepared at 40℃ for 4 h in a reactant ratio of 1:2,and the epoxy value was 1.034 mmol/g.The test of water absorption and surface contact angles and tensile tests showed that both the hydrophilicity and the mechanical properties of the crosslinked chitosan had been improved.
2006, 23(4): 419-423
Abstract:
With biochemical sludges from sewage and petrochemistry and surplus sludge as raw materials 3 kinds of adsorbents were prepared via chemical activation. Contrasted with active carbon,the adsorbents made from sludges were studied by SEM,pore characteristics and elemental analysis.The results showed that for all the sludges,the adsorbents made by the complex of ZnCl2 and H2SO4 were better,and the optimum ratio of 5 mol/L ZnCl2 and 5 mol/L H2SO4 solution was 2:1.By application of those adsorbents to the treatment of wastewater and oil-bearing sewage from oilfield,the removal rates of COD and P were better than that for active carbon,and the chromaticity color of the wastewater improved.The adsorbent made from the sludge of petrochemistry was better for the treatment of oil-bearing sewage.
With biochemical sludges from sewage and petrochemistry and surplus sludge as raw materials 3 kinds of adsorbents were prepared via chemical activation. Contrasted with active carbon,the adsorbents made from sludges were studied by SEM,pore characteristics and elemental analysis.The results showed that for all the sludges,the adsorbents made by the complex of ZnCl2 and H2SO4 were better,and the optimum ratio of 5 mol/L ZnCl2 and 5 mol/L H2SO4 solution was 2:1.By application of those adsorbents to the treatment of wastewater and oil-bearing sewage from oilfield,the removal rates of COD and P were better than that for active carbon,and the chromaticity color of the wastewater improved.The adsorbent made from the sludge of petrochemistry was better for the treatment of oil-bearing sewage.
2006, 23(4): 424-428
Abstract:
A high substitution cationic starch was prepared by a damp-dry process from starch and 2,3-epoxypropyl-trimethylammonium chloride(EPTMAC).The effects of the amounts of water and alkaline catalyst as well as reaction temperature,reaction time on the substitution and reaction efficiency were studied.When the amount of starch and that of EPTMAC were 25 g and 13.1 g,respectively,the optimum reaction conditions were that ω(NaOH) was 1.2%,reaction temperature 80℃,reaction time 5 h and the amount of water 25.0%.The performance of the cationic starch as a filtrate reducer was evaluated in the laboratory.The experimental results show that the cationic starch has very good capacities of depressing the filter loss,salt-resistance and anti-caving.
A high substitution cationic starch was prepared by a damp-dry process from starch and 2,3-epoxypropyl-trimethylammonium chloride(EPTMAC).The effects of the amounts of water and alkaline catalyst as well as reaction temperature,reaction time on the substitution and reaction efficiency were studied.When the amount of starch and that of EPTMAC were 25 g and 13.1 g,respectively,the optimum reaction conditions were that ω(NaOH) was 1.2%,reaction temperature 80℃,reaction time 5 h and the amount of water 25.0%.The performance of the cationic starch as a filtrate reducer was evaluated in the laboratory.The experimental results show that the cationic starch has very good capacities of depressing the filter loss,salt-resistance and anti-caving.
2006, 23(4): 429-431
Abstract:
After the Pt/C electrode is treated with a mixed solvent of tetrahydrofuran and acetone,its electrocatalytic activity for ethanol oxidation is significantly increased.The main reason is that the treatment can remove the impurities,such as the surfactant introduced during the preparation of the Pt/C electrode,change the surface structure of the electrode to a certain extent and increase the exposed surface area of Pt.In addition,the treatment of the Pt/C electrode can decrease the adsorption strength of CO,the intermediate of the ethanol oxidation,and hence decrease the poisoning effect of the adsorbed CO on the Pt/C electrode.The treatment method is simple and effective,and may be used in the preparation of DMFC.
After the Pt/C electrode is treated with a mixed solvent of tetrahydrofuran and acetone,its electrocatalytic activity for ethanol oxidation is significantly increased.The main reason is that the treatment can remove the impurities,such as the surfactant introduced during the preparation of the Pt/C electrode,change the surface structure of the electrode to a certain extent and increase the exposed surface area of Pt.In addition,the treatment of the Pt/C electrode can decrease the adsorption strength of CO,the intermediate of the ethanol oxidation,and hence decrease the poisoning effect of the adsorbed CO on the Pt/C electrode.The treatment method is simple and effective,and may be used in the preparation of DMFC.
2006, 23(4): 432-434
Abstract:
Porous microspheres of cardanol-aldehyde resin were prepared by suspension condensation polymerization,and the morphologies of the microspheres were observed by SEM.The preliminary results show that the size of the microspheres is about 1 mm,and the pore size is in the range of 1~4 μm.The microspheres are infusible,insoluble,and adsorptive.The adsorption capacities of the microspheres towards Cd2+,Pb2+,ethylenediamine and diethylene triamine were 5.87,16.21,32.24 and 354.04 mg/g,resperctively.
Porous microspheres of cardanol-aldehyde resin were prepared by suspension condensation polymerization,and the morphologies of the microspheres were observed by SEM.The preliminary results show that the size of the microspheres is about 1 mm,and the pore size is in the range of 1~4 μm.The microspheres are infusible,insoluble,and adsorptive.The adsorption capacities of the microspheres towards Cd2+,Pb2+,ethylenediamine and diethylene triamine were 5.87,16.21,32.24 and 354.04 mg/g,resperctively.
2006, 23(4): 435-437
Abstract:
CdTe semiconductor nanocrystals were synthesized in aqueous solution by using thioglycolic acid (HSCH2COOH) as the stabilizer.Obtained samples were characterized by means of Scanning Tunneling Microscopy(STM),UV-Vis,and PL emission.The size of the CdTe semiconductor nanocrystals was controlled by the reflux time.The PL spectra peaks and absorption spectra peaks shifted to longer wavelengths with the growth of the CdTe nanocrystals,and the colors of PL changed from green to red gradually.
CdTe semiconductor nanocrystals were synthesized in aqueous solution by using thioglycolic acid (HSCH2COOH) as the stabilizer.Obtained samples were characterized by means of Scanning Tunneling Microscopy(STM),UV-Vis,and PL emission.The size of the CdTe semiconductor nanocrystals was controlled by the reflux time.The PL spectra peaks and absorption spectra peaks shifted to longer wavelengths with the growth of the CdTe nanocrystals,and the colors of PL changed from green to red gradually.
2006, 23(4): 438-440
Abstract:
Silver nanoparticles of controlled shapes were prepared in an AgNO3-TSC systerm by a simple photoreduction technique.The growth mechanism was investigated via UV-Vis and TEM techniques.The result indicates that UV radiation was necessary to reduce Ag+ from the solution and the particle morphologies strongly depended on the wavelength of the irradiation light.Sliver nanorods and nanoprisms were obtained under 253.7 nm and 365 nm ultraviolet irradiations,respectively,while nanoprisms, nanorods,nanocubes and nanospheres coinstantaneous appeared under 200~2 000 nm broad band irradiation.
Silver nanoparticles of controlled shapes were prepared in an AgNO3-TSC systerm by a simple photoreduction technique.The growth mechanism was investigated via UV-Vis and TEM techniques.The result indicates that UV radiation was necessary to reduce Ag+ from the solution and the particle morphologies strongly depended on the wavelength of the irradiation light.Sliver nanorods and nanoprisms were obtained under 253.7 nm and 365 nm ultraviolet irradiations,respectively,while nanoprisms, nanorods,nanocubes and nanospheres coinstantaneous appeared under 200~2 000 nm broad band irradiation.
2006, 23(4): 441-443
Abstract:
A waterborne aliphatic polyurethane(WPU) dispersion was synthesized by the reaction of epoxy resin with polyester-diol,glycerol,dimethoxypropionic acid(DMPa) and isophorone diisocyanate(IPDI).The effect of the epoxy value and the amount of epoxy resin,the kind and the amount of the chain-extender and n(NCO)/n(OH) on the properties of the WPU were investigated.The results showed that when the amount of E-44 was 6%~8%,the amount of EDA was 1%,n(NCO):n(OH)=(1.5~1.8):1,the WPU with good water-resistance,stability and mechanical properties could be prepared.
A waterborne aliphatic polyurethane(WPU) dispersion was synthesized by the reaction of epoxy resin with polyester-diol,glycerol,dimethoxypropionic acid(DMPa) and isophorone diisocyanate(IPDI).The effect of the epoxy value and the amount of epoxy resin,the kind and the amount of the chain-extender and n(NCO)/n(OH) on the properties of the WPU were investigated.The results showed that when the amount of E-44 was 6%~8%,the amount of EDA was 1%,n(NCO):n(OH)=(1.5~1.8):1,the WPU with good water-resistance,stability and mechanical properties could be prepared.
2006, 23(4): 444-446
Abstract:
Thirteen new aroyl ureas were synthesized by the reaction of 2-amino-5-(1-o-chlorophenoxyethyl)-1,3,4-thiodiazole with aroyl isocyanates,and their structures were confirmend by IR,1H NMR and elemental analysis.Preliminary biological activity test results show that the target compounds 2c,2d and 2h have a relatively good activicy of auxin,and the promoting rates of them are 30.1%,32.5% and 29.9%,respectively.
Thirteen new aroyl ureas were synthesized by the reaction of 2-amino-5-(1-o-chlorophenoxyethyl)-1,3,4-thiodiazole with aroyl isocyanates,and their structures were confirmend by IR,1H NMR and elemental analysis.Preliminary biological activity test results show that the target compounds 2c,2d and 2h have a relatively good activicy of auxin,and the promoting rates of them are 30.1%,32.5% and 29.9%,respectively.
2006, 23(4): 447-449
Abstract:
3,3'-Dinitrochalcone was synthesized by the Claisen-Schmidt condensation of nitrobenzaldehyde and nitroacetophenone,which was reduced to 3,3'-diaminochalcone by 85% hydrazine hydration with FeCl3·6H2O/C.The product was characterized by elemental analysis,melting point,IR,and 1H NMR measurements.The factors influencing the product yield were also discussed.Co MPared with previous methods in the literature,the present procedure has the advantages of milder conditions,lower cost,easier work-up,high product yield(78.6%) and is environmental friendly.
3,3'-Dinitrochalcone was synthesized by the Claisen-Schmidt condensation of nitrobenzaldehyde and nitroacetophenone,which was reduced to 3,3'-diaminochalcone by 85% hydrazine hydration with FeCl3·6H2O/C.The product was characterized by elemental analysis,melting point,IR,and 1H NMR measurements.The factors influencing the product yield were also discussed.Co MPared with previous methods in the literature,the present procedure has the advantages of milder conditions,lower cost,easier work-up,high product yield(78.6%) and is environmental friendly.
2006, 23(4): 450-452
Abstract:
A new schiff base ligand was synthesized by the condensation reaction of methyl 3-formyl-4-hydroxybenzoate with 1,2-diaminocyclohexane under N2 in absolute ethanol.The ligand first reacted with Mn(OAc)2·4H2O,and then the mixture was exposed to air and treated by LiCl in absolute ethanol to obtained a Mn(Ⅲ) complex.Two Fe(Ⅲ) and Ni(Ⅱ) complexes were also prepared by the reaction of the ligand with the corresponding metal chloride salts.The new ligand and the complexes were characterized by elemental analysis,1H NMR and IR.
A new schiff base ligand was synthesized by the condensation reaction of methyl 3-formyl-4-hydroxybenzoate with 1,2-diaminocyclohexane under N2 in absolute ethanol.The ligand first reacted with Mn(OAc)2·4H2O,and then the mixture was exposed to air and treated by LiCl in absolute ethanol to obtained a Mn(Ⅲ) complex.Two Fe(Ⅲ) and Ni(Ⅱ) complexes were also prepared by the reaction of the ligand with the corresponding metal chloride salts.The new ligand and the complexes were characterized by elemental analysis,1H NMR and IR.
2006, 23(4): 453-455
Abstract:
A fluorescent dye light green SF(LGSF) can produce its characteristic fluorescence peak in diluted sulfuric acid at 312 nm.The fluorescence can be quenched by the hydroxyl radical OH produced by Fenton reaction.By measuring the change of the fluorescence intensity of LGSF,the OH content can be determined indirectly under optimum experimental conditions.The results show that this method is stable,simple and rapid.The method can be used as a convenient way for the selection of hydroxyl radical scavengers for its good stability,and can be applied to determine and monitor hydroxyl radicals on line.
A fluorescent dye light green SF(LGSF) can produce its characteristic fluorescence peak in diluted sulfuric acid at 312 nm.The fluorescence can be quenched by the hydroxyl radical OH produced by Fenton reaction.By measuring the change of the fluorescence intensity of LGSF,the OH content can be determined indirectly under optimum experimental conditions.The results show that this method is stable,simple and rapid.The method can be used as a convenient way for the selection of hydroxyl radical scavengers for its good stability,and can be applied to determine and monitor hydroxyl radicals on line.
2006, 23(4): 456-458
Abstract:
The porous Co(OH)2 was synthesized with SDS(Sodium dodecyl Sulfate) as the soft template and urea as the hydrolysis agent.XRD and SEM were used to characterize the synthesized porous Co(OH)2,which possesse a layered structure with a pore-size of 20~30 nm.All electrochemical tests show that the porous Co(OH)2 has a good capacity due to its unique porous structure and a high surface area of 283 m2/g.The highest specific capacitance of 320 F/g was obtained for the as-prepared Co(OH)2 at a current density of 5×103 A/cm2.
The porous Co(OH)2 was synthesized with SDS(Sodium dodecyl Sulfate) as the soft template and urea as the hydrolysis agent.XRD and SEM were used to characterize the synthesized porous Co(OH)2,which possesse a layered structure with a pore-size of 20~30 nm.All electrochemical tests show that the porous Co(OH)2 has a good capacity due to its unique porous structure and a high surface area of 283 m2/g.The highest specific capacitance of 320 F/g was obtained for the as-prepared Co(OH)2 at a current density of 5×103 A/cm2.
2006, 23(4): 459-461
Abstract:
In the processing of Lingtou Dancong tea,27 factors were optimized by the pattern recognition method.From the 27 factors,5 major ones which affected tea quality were identified.These 5 factors were the time of sun-withering t1,the number of green-making N,the first time for green-making Z1,the laying time after last green-making t10 and temperature for destroying enzyme t1.The technic parameters of the 5 factors were that:t1 was 10~45 min;N was 4~8;Z1 was 5~20;t10 was 60~120 min;t1 was 120~200℃.The pattern recognition model on tea quality was built on the basis of the 5 factors.The quality of 17 tea samples was predicted by the pattern recognition model.The result shows that the prediction values of 17 tea samples were basically accordant with the experimental values.The 5 factors are key factors that affect tea quality and the quality of Lingtou Dancong tea can be improved by controlling the 5 key factors.
In the processing of Lingtou Dancong tea,27 factors were optimized by the pattern recognition method.From the 27 factors,5 major ones which affected tea quality were identified.These 5 factors were the time of sun-withering t1,the number of green-making N,the first time for green-making Z1,the laying time after last green-making t10 and temperature for destroying enzyme t1.The technic parameters of the 5 factors were that:t1 was 10~45 min;N was 4~8;Z1 was 5~20;t10 was 60~120 min;t1 was 120~200℃.The pattern recognition model on tea quality was built on the basis of the 5 factors.The quality of 17 tea samples was predicted by the pattern recognition model.The result shows that the prediction values of 17 tea samples were basically accordant with the experimental values.The 5 factors are key factors that affect tea quality and the quality of Lingtou Dancong tea can be improved by controlling the 5 key factors.
2006, 23(4): 462-464
Abstract:
Soybean oligosaccharides were analyzed via high performance liquid chromatography with gradient elution of acetonitril-water and an evaporative light-scattering detector.The three important components, sucrose,raffinose,stachyose of soybean oilgosaccharides were separated completely from other components within twenty minutes.The quantitative analysis results of the three components were achieved with the external standard method,and the linear relations were good.The recovery of this method is 96.5%~99.1%,the relative standard deviations are in a range of 0.18%~4.67%.Operation of the method is simple and fast,applicable to the routine analysis of industrial products.
Soybean oligosaccharides were analyzed via high performance liquid chromatography with gradient elution of acetonitril-water and an evaporative light-scattering detector.The three important components, sucrose,raffinose,stachyose of soybean oilgosaccharides were separated completely from other components within twenty minutes.The quantitative analysis results of the three components were achieved with the external standard method,and the linear relations were good.The recovery of this method is 96.5%~99.1%,the relative standard deviations are in a range of 0.18%~4.67%.Operation of the method is simple and fast,applicable to the routine analysis of industrial products.
