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2011 Volume 28 Issue 7
2011, 28(7): 733-738
doi: 10.3724/SP.J.1095.2011.00475
Abstract:
Biodiesel,an environment-friendly fuel,has attracted considerable attention due to the fact that it can be used as an alternative fuel for fossil diesel,which is in favor of resolving the depletion of fossil fuel,and reducing some environmental problems caused by the combustion of fossil fuel.In this article,the methods used to produce biodiesel with transesterification are reviewed.Both the advantages and disadvantages of methods are discussed in detail.Furthermore,the developing trends and corresponding advances in catalytic transesterification for biodiesel production in the future are summarized.
Biodiesel,an environment-friendly fuel,has attracted considerable attention due to the fact that it can be used as an alternative fuel for fossil diesel,which is in favor of resolving the depletion of fossil fuel,and reducing some environmental problems caused by the combustion of fossil fuel.In this article,the methods used to produce biodiesel with transesterification are reviewed.Both the advantages and disadvantages of methods are discussed in detail.Furthermore,the developing trends and corresponding advances in catalytic transesterification for biodiesel production in the future are summarized.
2011, 28(7): 739-746
doi: 10.3724/SP.J.1095.2011.00641
Abstract:
In the synthesis of pyrrole 2-ethoxycarbonyl-3-trifluoromethyl-4-methylpyrrole(1) from 2-acetoxy-3-nitro-1,1,1-trifluorobutane(1b) and ethyl isocyanoacetate according to the Barton-Zard reaction,the organic base 1,8-diazabicyclo undec-7-ene(DBU) and the solvent tetrahydrofuran(THF) were replaced with K2CO3 and ethanol,respectively.The improved Barton-Zard procedure had advantages such as less expensive and safe reagents,higher yield and more convenient operation procedures than original Barton-Zard method.Moreover,the preparation of the intermediate 1b from compound 1a by acetylation reaction was carried out by employing acetyl chloride in boiling toluene solution instead of acetic anhydride and the catalyst concentrated sulfuric acid.Its optimum reaction conditions were that the molar ratio of acetyl chloride to compound 1a and reaction time were set as 1.2:1 and 3~3.5 h,respectively.After treatment of compound 1 with excess LiAlH4 at low temperature,it affords the crude product α-(hydroxymethyl)-3-trifluoromethyl-4-methylpyrrole(1c),which immediately reacted via a tetramerization in the presence of the catalyst BF3·OEt2 and in CHCl3,followed by oxidation of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone(DDQ) to provide the corresponding trifluoromethylated porphyrin derivative 2.The results indicate that using boron trifluoride diethyl etherate(BF3·OEt2) as catalyst instead of p-toluenesulphonic acid(p-TsOH) in the synthesis of compound 2 from compound 1c can significantly increases the yield of product 2 up to 50% from 14%.
In the synthesis of pyrrole 2-ethoxycarbonyl-3-trifluoromethyl-4-methylpyrrole(1) from 2-acetoxy-3-nitro-1,1,1-trifluorobutane(1b) and ethyl isocyanoacetate according to the Barton-Zard reaction,the organic base 1,8-diazabicyclo undec-7-ene(DBU) and the solvent tetrahydrofuran(THF) were replaced with K2CO3 and ethanol,respectively.The improved Barton-Zard procedure had advantages such as less expensive and safe reagents,higher yield and more convenient operation procedures than original Barton-Zard method.Moreover,the preparation of the intermediate 1b from compound 1a by acetylation reaction was carried out by employing acetyl chloride in boiling toluene solution instead of acetic anhydride and the catalyst concentrated sulfuric acid.Its optimum reaction conditions were that the molar ratio of acetyl chloride to compound 1a and reaction time were set as 1.2:1 and 3~3.5 h,respectively.After treatment of compound 1 with excess LiAlH4 at low temperature,it affords the crude product α-(hydroxymethyl)-3-trifluoromethyl-4-methylpyrrole(1c),which immediately reacted via a tetramerization in the presence of the catalyst BF3·OEt2 and in CHCl3,followed by oxidation of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone(DDQ) to provide the corresponding trifluoromethylated porphyrin derivative 2.The results indicate that using boron trifluoride diethyl etherate(BF3·OEt2) as catalyst instead of p-toluenesulphonic acid(p-TsOH) in the synthesis of compound 2 from compound 1c can significantly increases the yield of product 2 up to 50% from 14%.
2011, 28(7): 747-752
doi: 10.3724/SP.J.1095.2011.00496
Abstract:
Using 4,6-dichlorin-5-amino-pyrimidine as a starting material,a serials of 6-chlorin-8-alkyl-9-aryl-purine derivatives have been designed and synthesized via N-alkylation,condensation and chloridization.All synthesized compounds were confirmed by elemental analysis,MS and 1H NMR techniques.The effects of catalyst on N-alkylation,the amounts of polyphosphoric acid(PPA) on condensation,the microwave heating process on chloridization were investigated.
Using 4,6-dichlorin-5-amino-pyrimidine as a starting material,a serials of 6-chlorin-8-alkyl-9-aryl-purine derivatives have been designed and synthesized via N-alkylation,condensation and chloridization.All synthesized compounds were confirmed by elemental analysis,MS and 1H NMR techniques.The effects of catalyst on N-alkylation,the amounts of polyphosphoric acid(PPA) on condensation,the microwave heating process on chloridization were investigated.
2011, 28(7): 753-758
doi: 10.3724/SP.J.1095.2011.00441
Abstract:
Organosilixane prepolymer derived from methyltriethoxylsilane was synthesized,and characterized by IR and 1H NMR.The hydrolysis and condensation of the methyltriethoxylsilane were carried out in the presence of a catalytic amount of hydrochloric acid.Using 0.60% NaOH-CH3OH solution as curing agent,the curing performance of the prepolymer at various temperature was investigated.The curing time was 9 min at 30℃,and 4 min at 50℃,when 0.05 mL 0.60% NaOH-CH3OH was added to prepolymer-industrial ethanol solution with the volume ratio of the prepolymer to industrial ethanol at 1:1.The mixture of organosilixane prepolymer and polyvinyl alcohol(PVA) was used as chemical sand-fixing material for the first time.The crust,which was formed by using this material,had good water resistance,ageing resistance(under 16 h ultraviolet irradiation),and shear strength value.The cohesion value was 483.7 kPa,and the angle of internal friction was 68.39°,when the mass ratio of polyvinyl ethanol to organosilixane prepolymer was 1:4.
Organosilixane prepolymer derived from methyltriethoxylsilane was synthesized,and characterized by IR and 1H NMR.The hydrolysis and condensation of the methyltriethoxylsilane were carried out in the presence of a catalytic amount of hydrochloric acid.Using 0.60% NaOH-CH3OH solution as curing agent,the curing performance of the prepolymer at various temperature was investigated.The curing time was 9 min at 30℃,and 4 min at 50℃,when 0.05 mL 0.60% NaOH-CH3OH was added to prepolymer-industrial ethanol solution with the volume ratio of the prepolymer to industrial ethanol at 1:1.The mixture of organosilixane prepolymer and polyvinyl alcohol(PVA) was used as chemical sand-fixing material for the first time.The crust,which was formed by using this material,had good water resistance,ageing resistance(under 16 h ultraviolet irradiation),and shear strength value.The cohesion value was 483.7 kPa,and the angle of internal friction was 68.39°,when the mass ratio of polyvinyl ethanol to organosilixane prepolymer was 1:4.
2011, 28(7): 759-763
doi: 10.3724/SP.J.1095.2011.00480
Abstract:
Epoxidations of styrene and unsaturated fatty acid methyl esters(FAMEs) were studied using bicarbonate-activated hydrogen peroxide(BAP) system.The effects of bicarbonate,surfactants,adding modes of feedstocks,reaction time,the amount of H2O2 and reaction temperature on H2O2 decomposition and olefin epoxidation were investigated,respectively.When the molar ratio of n(styrene):n(H2O2):n(NaHCO3) is 1:10:0.25,the adding amount of cation surfactant cetyl trimethylammonium bromide(CTAB) is 1% mass fraction,the reaction temperature is less than 35℃,the reaction time is 6 h with slowly adding 30% H2O2 under stirring,the yield and selectivity of styrene oxide were up to 85% and 96%,respectively,and only a minor amount of benzaldehyde was formed.Cation surfactant CTAB,which carries active oxygen species HCO4-,can significantly promote the styrene conversion.However,the electrophilicity of active oxygen species HCO4- is not enough to epoxide unsaturated FAMEs molecules with straight chains or containing an electron-defect C=C bond.
Epoxidations of styrene and unsaturated fatty acid methyl esters(FAMEs) were studied using bicarbonate-activated hydrogen peroxide(BAP) system.The effects of bicarbonate,surfactants,adding modes of feedstocks,reaction time,the amount of H2O2 and reaction temperature on H2O2 decomposition and olefin epoxidation were investigated,respectively.When the molar ratio of n(styrene):n(H2O2):n(NaHCO3) is 1:10:0.25,the adding amount of cation surfactant cetyl trimethylammonium bromide(CTAB) is 1% mass fraction,the reaction temperature is less than 35℃,the reaction time is 6 h with slowly adding 30% H2O2 under stirring,the yield and selectivity of styrene oxide were up to 85% and 96%,respectively,and only a minor amount of benzaldehyde was formed.Cation surfactant CTAB,which carries active oxygen species HCO4-,can significantly promote the styrene conversion.However,the electrophilicity of active oxygen species HCO4- is not enough to epoxide unsaturated FAMEs molecules with straight chains or containing an electron-defect C=C bond.
2011, 28(7): 764-769
doi: 10.3724/SP.J.1095.2011.00530
Abstract:
Melt extrusion method was adopted to produce thermoplastic starch(TPS)/polyvinyl alcohol(PVA)/montmorillonite(MMT) nanocomposites.The mechanical properties of TPS were improved effectively by adding certain amount of MMT and PVA.Under a relative humidity of 50%,the X-ray diffraction and transmission electron microscopy of the composites showed that MMT was exfoliated and well dispersed in TPS/PVA matrix.Mechanical property test showed that the mechanical property of the composites[w(MMT)=0% to 5%]was obviously improved.The tensile strength of the composite[w(MMT)=3%]reached 13.24 MPa and the Young's modulus reached 61.46 MPa.This indicates that MMT is likely to play a role of physical crosslinking to improve the mechanical properties of composites.
Melt extrusion method was adopted to produce thermoplastic starch(TPS)/polyvinyl alcohol(PVA)/montmorillonite(MMT) nanocomposites.The mechanical properties of TPS were improved effectively by adding certain amount of MMT and PVA.Under a relative humidity of 50%,the X-ray diffraction and transmission electron microscopy of the composites showed that MMT was exfoliated and well dispersed in TPS/PVA matrix.Mechanical property test showed that the mechanical property of the composites[w(MMT)=0% to 5%]was obviously improved.The tensile strength of the composite[w(MMT)=3%]reached 13.24 MPa and the Young's modulus reached 61.46 MPa.This indicates that MMT is likely to play a role of physical crosslinking to improve the mechanical properties of composites.
2011, 28(7): 770-776
doi: 10.3724/SP.J.1095.2011.00492
Abstract:
A series of waterborne polyurethanes(WPU) were prepared from isophorone diisocyanate(IPDI) and dimethylolpropionic acid(DMPA),which acted as the hard segment.Effects of the hard segment content on the emulsion stability,thermostability and mechanical properties of WPU had been studied.When the mass fraction of the hard segment was below 26%,the emulsion stability was poor.With the increase of hard segment content,the tensile strength of the resultant film prepared from WPU increased quickly,and the breaking elongation decreased slightly;FTIR spectra showed that the intensity of free N——H stretching vibration peaks dropped,while the intensity of hydrogen bonded N——H stretching vibration peaks increased.At the same time,the peak shape of C=O stretching vibration changed obviously and shifted to lower wave numbers.It is shown that the hydrogen bonds disaggregated evidently and the intensity of endothermic peak strengthened from 50℃ to 125℃ according to DSC analysis,suggesting that the hydrogen bonding strengthened gradually as the hard segment content increased.The TG curves indicated that the thermal decomposition of WPU was mainly a step-by-step decomposition of the hard and soft segments.The decomposition temperature of the hard segment and the thermostability of WPU decreased with the increase of hard segment content.
A series of waterborne polyurethanes(WPU) were prepared from isophorone diisocyanate(IPDI) and dimethylolpropionic acid(DMPA),which acted as the hard segment.Effects of the hard segment content on the emulsion stability,thermostability and mechanical properties of WPU had been studied.When the mass fraction of the hard segment was below 26%,the emulsion stability was poor.With the increase of hard segment content,the tensile strength of the resultant film prepared from WPU increased quickly,and the breaking elongation decreased slightly;FTIR spectra showed that the intensity of free N——H stretching vibration peaks dropped,while the intensity of hydrogen bonded N——H stretching vibration peaks increased.At the same time,the peak shape of C=O stretching vibration changed obviously and shifted to lower wave numbers.It is shown that the hydrogen bonds disaggregated evidently and the intensity of endothermic peak strengthened from 50℃ to 125℃ according to DSC analysis,suggesting that the hydrogen bonding strengthened gradually as the hard segment content increased.The TG curves indicated that the thermal decomposition of WPU was mainly a step-by-step decomposition of the hard and soft segments.The decomposition temperature of the hard segment and the thermostability of WPU decreased with the increase of hard segment content.
2011, 28(7): 777-784
doi: 10.3724/SP.J.1095.2011.00723
Abstract:
Poly(diallylmethylbenzylammonium chloride)(PDAMABC) was synthesized using methylamine,allyl chloride,NaOH,benzyl chloride and 2,2'-azobis[2-(2-imidazolin-2-yl) propane]dihydrochloride as raw materials.The structure of PDAMABC was characterized by FT-IR,1H NMR and elemental analysis.The viscosity behaviors of the polymer in sodium chloride,potassium chloride,potassium bromide,calcium chloride,magnesium chloride,magnesium sulfate and sodium sulfate solutions were investigated.The results show that the yield of diallylmethylamine increases from 72.79% to 83.41% by reusing the water phase and the collected distillate with low boiling point;the yield of diallylmethylbenzylammonium chloride is high and the product has a good water-solubility using the mixed solvents with a volume ratio in the range of 1:3~2:3 as solvents.The reduced viscosity of PDAMABC decreases with increasing the concentration of added salt.In 0.1 mol/L NaCl solution,it behaves as a polyelectrolyte with a mass concentration below 0.031 25 g/L,and a neutral polymer when the concentration is above 0.125 g/L.The influence order of added salts is as follows:Na2SO4< NaCl< KCl< MgSO4< MgCl2< CaCl2 KBr.The shielding effect of anion to quaternary ammonium cation is the main reason for the decrease of reduced viscosity.
Poly(diallylmethylbenzylammonium chloride)(PDAMABC) was synthesized using methylamine,allyl chloride,NaOH,benzyl chloride and 2,2'-azobis[2-(2-imidazolin-2-yl) propane]dihydrochloride as raw materials.The structure of PDAMABC was characterized by FT-IR,1H NMR and elemental analysis.The viscosity behaviors of the polymer in sodium chloride,potassium chloride,potassium bromide,calcium chloride,magnesium chloride,magnesium sulfate and sodium sulfate solutions were investigated.The results show that the yield of diallylmethylamine increases from 72.79% to 83.41% by reusing the water phase and the collected distillate with low boiling point;the yield of diallylmethylbenzylammonium chloride is high and the product has a good water-solubility using the mixed solvents with a volume ratio in the range of 1:3~2:3 as solvents.The reduced viscosity of PDAMABC decreases with increasing the concentration of added salt.In 0.1 mol/L NaCl solution,it behaves as a polyelectrolyte with a mass concentration below 0.031 25 g/L,and a neutral polymer when the concentration is above 0.125 g/L.The influence order of added salts is as follows:Na2SO4< NaCl< KCl< MgSO4< MgCl2< CaCl2 KBr.The shielding effect of anion to quaternary ammonium cation is the main reason for the decrease of reduced viscosity.
2011, 28(7): 785-790
doi: 10.3724/SP.J.1095.2011.00531
Abstract:
The static adsorption properties of several water soluble polymers,including different kinds of partially hydrolyzed polyacryamide(HPAM) and hydrophobically associative water soluble polymers(HAWSPs),have been studied at 45℃,55℃ and 65℃.The results show that the maximum adsorption of HAWSPs on sand is affected by the hydrophobe contents and the lengths of micro-block,with the former one playing the major role.The isothermal adsorption curves show two platform areas.The maximum adsorption of HPAM rises with the increase of temperature,but the situation for HAWSPs is in the contrary.It indicates that the hydrophobe contents and the lengths of micro-block may affect the adsorption.
The static adsorption properties of several water soluble polymers,including different kinds of partially hydrolyzed polyacryamide(HPAM) and hydrophobically associative water soluble polymers(HAWSPs),have been studied at 45℃,55℃ and 65℃.The results show that the maximum adsorption of HAWSPs on sand is affected by the hydrophobe contents and the lengths of micro-block,with the former one playing the major role.The isothermal adsorption curves show two platform areas.The maximum adsorption of HPAM rises with the increase of temperature,but the situation for HAWSPs is in the contrary.It indicates that the hydrophobe contents and the lengths of micro-block may affect the adsorption.
2011, 28(7): 791-797
doi: 10.3724/SP.J.1095.2011.00545
Abstract:
Immobilized AlCl3 catalyst(AlCl3/ATP) was prepared through solvent refluxing and adsorption method with attapulgite as the support and then used in the synthesis of aspirin.The catalyst was characterized by Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD),specific surface area(BET),X-ray energy dispersive spectrometry(EDS) and Hammett indicators.Factors influencing the catalytic properties such as concentration of hydrochloric acid,heat-treated temperature,AlCl3 loading and amount of catalyst were optimized according to the yield of aspirin.The catalytic properties of the catalysts and the support were compared before and after loading.The results show that the amount of AlCl3 loading on ATP reached 1.18 mmol/g after ATP acidified with 10 mol/L HCl for 12 h at room temperature and then heat-treated under 300℃ for 2 h.The yield of aspirin catalyzed by AlCl3/ATP reaches 92.5% when the dosage of the AlCl3/ATP is 5% mass fraction of salicylic acid,which is higher than that of unloaded AlCl3 and the support itself.The catalyst also exhibits excellent catalytic stability within 5 times reused.
Immobilized AlCl3 catalyst(AlCl3/ATP) was prepared through solvent refluxing and adsorption method with attapulgite as the support and then used in the synthesis of aspirin.The catalyst was characterized by Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD),specific surface area(BET),X-ray energy dispersive spectrometry(EDS) and Hammett indicators.Factors influencing the catalytic properties such as concentration of hydrochloric acid,heat-treated temperature,AlCl3 loading and amount of catalyst were optimized according to the yield of aspirin.The catalytic properties of the catalysts and the support were compared before and after loading.The results show that the amount of AlCl3 loading on ATP reached 1.18 mmol/g after ATP acidified with 10 mol/L HCl for 12 h at room temperature and then heat-treated under 300℃ for 2 h.The yield of aspirin catalyzed by AlCl3/ATP reaches 92.5% when the dosage of the AlCl3/ATP is 5% mass fraction of salicylic acid,which is higher than that of unloaded AlCl3 and the support itself.The catalyst also exhibits excellent catalytic stability within 5 times reused.
2011, 28(7): 798-803
doi: 10.3724/SP.J.1095.2011.00494
Abstract:
Calcium carbonate(CC) with calcite structure was efficiently synthesized using collodion membrane as an active template.Then,the CaCO3/Ni composite was obtained through in situ reaction on the CC surface.The morphologies,structures,and thermal stability of the composite were studied by TEM,XRD,FT-IR and TG-DTA,etc.The composite was added to the antistatic-coating system,which shows the same antistatic ability(electrical resitivity:1.2×106 Ω·cm) as that of Ni powders,and saves about 60% Ni.The composite can be applied in the fields of conductive,antistatic,etc.,to replace Ni materials.
Calcium carbonate(CC) with calcite structure was efficiently synthesized using collodion membrane as an active template.Then,the CaCO3/Ni composite was obtained through in situ reaction on the CC surface.The morphologies,structures,and thermal stability of the composite were studied by TEM,XRD,FT-IR and TG-DTA,etc.The composite was added to the antistatic-coating system,which shows the same antistatic ability(electrical resitivity:1.2×106 Ω·cm) as that of Ni powders,and saves about 60% Ni.The composite can be applied in the fields of conductive,antistatic,etc.,to replace Ni materials.
2011, 28(7): 804-808
doi: 10.3724/SP.J.1095.2011.00529
Abstract:
By adjusting the pH of the H2SO4 leaching liquor of fly ash,Ti4+ and Fe3+ were extract-separated with trioctylphosphineoxide(TOPO)-kerosene and di(2-ethylhexyl) phosphoric acid(P204)-kerosene,respectively.Effects of the extractants,the concentration of the cations,pH of the aqueous solution,extracting temperature,and extracting time on the extracting efficiency were investigated.Effect of the recycle conditions of the loaded extractants on the recovery yield and the purity of recovered products were discussed as well.The phase of the precursor and its calcined products were characterized by X-ray diffraction(XRD).The purity of the TiO2 and Fe2O3 were determined by X-ray fluorescence(XRF).The analysis results show that the extracting-titanium efficiency and the extracting-iron efficiency were as high as 97%.The extraction yields of ferric oxide and titanium dioxide are 96% and greater than 92%,respectively.The purities of TiO2 and Fe2O3 are 98% and 97%,respectively,which can be used as a white pigment or iron oxide red pigment in the production of paints,respectively.
By adjusting the pH of the H2SO4 leaching liquor of fly ash,Ti4+ and Fe3+ were extract-separated with trioctylphosphineoxide(TOPO)-kerosene and di(2-ethylhexyl) phosphoric acid(P204)-kerosene,respectively.Effects of the extractants,the concentration of the cations,pH of the aqueous solution,extracting temperature,and extracting time on the extracting efficiency were investigated.Effect of the recycle conditions of the loaded extractants on the recovery yield and the purity of recovered products were discussed as well.The phase of the precursor and its calcined products were characterized by X-ray diffraction(XRD).The purity of the TiO2 and Fe2O3 were determined by X-ray fluorescence(XRF).The analysis results show that the extracting-titanium efficiency and the extracting-iron efficiency were as high as 97%.The extraction yields of ferric oxide and titanium dioxide are 96% and greater than 92%,respectively.The purities of TiO2 and Fe2O3 are 98% and 97%,respectively,which can be used as a white pigment or iron oxide red pigment in the production of paints,respectively.
2011, 28(7): 809-814
doi: 10.3724/SP.J.1095.2011.00444
Abstract:
The adsorption capability of 16 alkyl-guanidine modified attapulgite for methyl orange was studied.The effects of adsorption time,the amount of adsorbent,and the concentration of the dyes were also studied.The results showed that the adsorption capacity of the modified attapulgite clay was improved obviously,and the decolorization rate of methyl orange simulated wastewater dyes was higher than 98%.The relationship between adsorpting capacity(qe) and equilibrum mass concentration(ρe) was in accordance with the isothermal adsorption Langmuir equations.The adsorption heat is less than 40 kJ/mol.The adsorption exhibits a physical adsorption.
The adsorption capability of 16 alkyl-guanidine modified attapulgite for methyl orange was studied.The effects of adsorption time,the amount of adsorbent,and the concentration of the dyes were also studied.The results showed that the adsorption capacity of the modified attapulgite clay was improved obviously,and the decolorization rate of methyl orange simulated wastewater dyes was higher than 98%.The relationship between adsorpting capacity(qe) and equilibrum mass concentration(ρe) was in accordance with the isothermal adsorption Langmuir equations.The adsorption heat is less than 40 kJ/mol.The adsorption exhibits a physical adsorption.
2011, 28(7): 815-820
doi: 10.3724/SP.J.1095.2011.00500
Abstract:
One porous stainless steel-supported manganese dioxide thin film electrode,fabricated by electrochemical method was evaluated as a potential electrode for electrochemical capacitors.The porous stainless steel substrate electrode was obtained by mask electrolysis in the sodium chloride solution containing a lyotropic liquid crystalline phase of p-tert-alkylphenoxy poly(oxyethylene) ether(Triton X-100).Manganese dioxide film was electrodeposited on porous stainless steel substrate under a potentiostatic mode.Liquid crystalline phases were examined using XP-330C polarizing microscope at room temperature.The surface morphologies of the electrode were characterized by SEM.The capacity of manganese oxide film electrode was investigated by cycle voltammetry and constant-current charge-discharge method in potassium sulfate solutions.The results showed that stainless steel exhibited a highly porous surface morphology with an irregular pore size in a range of tens nanometer to hundreds nanometer after electrochemical erosion with liquid crystal mask.The deposited manganese oxide film consisted of spherical particles with an average size of 80~90 nm.The manganese oxide film electrode presents a specific capacitance of 400 F/g when the charge consumed is 0.4 C/cm2 in electro deposition.The highest capacitance of 320×10-3 F/cm2 could be obtained by cycle voltammetry at a scan rate of 20 mV/s,corresponding to a specific capacitance of 200 F/g.The porous stainless steel-supported manganese dioxide electrode shows promising applications in electrochemical super capacitors.
One porous stainless steel-supported manganese dioxide thin film electrode,fabricated by electrochemical method was evaluated as a potential electrode for electrochemical capacitors.The porous stainless steel substrate electrode was obtained by mask electrolysis in the sodium chloride solution containing a lyotropic liquid crystalline phase of p-tert-alkylphenoxy poly(oxyethylene) ether(Triton X-100).Manganese dioxide film was electrodeposited on porous stainless steel substrate under a potentiostatic mode.Liquid crystalline phases were examined using XP-330C polarizing microscope at room temperature.The surface morphologies of the electrode were characterized by SEM.The capacity of manganese oxide film electrode was investigated by cycle voltammetry and constant-current charge-discharge method in potassium sulfate solutions.The results showed that stainless steel exhibited a highly porous surface morphology with an irregular pore size in a range of tens nanometer to hundreds nanometer after electrochemical erosion with liquid crystal mask.The deposited manganese oxide film consisted of spherical particles with an average size of 80~90 nm.The manganese oxide film electrode presents a specific capacitance of 400 F/g when the charge consumed is 0.4 C/cm2 in electro deposition.The highest capacitance of 320×10-3 F/cm2 could be obtained by cycle voltammetry at a scan rate of 20 mV/s,corresponding to a specific capacitance of 200 F/g.The porous stainless steel-supported manganese dioxide electrode shows promising applications in electrochemical super capacitors.
2011, 28(7): 821-825
doi: 10.3724/SP.J.1095.2011.00522
Abstract:
The LiFeBO3 cathode materials for Li-ion batteries were prepared by means of solid reaction using lithium metaborate and ferrous oxalate as raw materials.The LiFeBO3 cathode materials were further coated by ethylene propylene copolymer(EPM).The samples were characterized by X-ray diffraction,scanning electron microscopy,and titration analysis.Electrochemical tests of materials showed that LiFeBO3 exhibited a higher discharge mass specific capacity.The electrochemical performance of the coated samples was demonstrated to be improved.Sample coated with 5% EPM had an initial capacity of 190 mA·h/g.It was found that only 4.2% capacity was lost after 50 charge/discharge cyclings at 0.5C.
The LiFeBO3 cathode materials for Li-ion batteries were prepared by means of solid reaction using lithium metaborate and ferrous oxalate as raw materials.The LiFeBO3 cathode materials were further coated by ethylene propylene copolymer(EPM).The samples were characterized by X-ray diffraction,scanning electron microscopy,and titration analysis.Electrochemical tests of materials showed that LiFeBO3 exhibited a higher discharge mass specific capacity.The electrochemical performance of the coated samples was demonstrated to be improved.Sample coated with 5% EPM had an initial capacity of 190 mA·h/g.It was found that only 4.2% capacity was lost after 50 charge/discharge cyclings at 0.5C.
2011, 28(7): 826-830
doi: 10.3724/SP.J.1095.2011.00534
Abstract:
An ion selective electrode of quaternary-ammonium gemini surfactant C12-3-C12·2Br has been fabricated.The variation of electromotive force(EMF) of the systems of C12-3-C12·2Br and bovine serum albumin(BSA) with the concentration of C12-3-C12·2Br has been studied.The binding isotherms and Scatchard plots of the interaction of C12-3-C12·2Br with BSA molecules have been obtained.The numbers of binding sites,Hill coefficient and Hill binding constant have been calculated on the basis of the binding capacity.The results show that the interaction of C12-3-C12·2Br with BSA molecules behaved a positive cooperativity in the binding process.There are two types of binding sites on BSA for C12-3-C12·2Br.One is high-affinity binding site at which the essential role of the interaction is electrostatic force,and the other is low-affinity binding site at which the essential role of interaction is hydrophobic force.
An ion selective electrode of quaternary-ammonium gemini surfactant C12-3-C12·2Br has been fabricated.The variation of electromotive force(EMF) of the systems of C12-3-C12·2Br and bovine serum albumin(BSA) with the concentration of C12-3-C12·2Br has been studied.The binding isotherms and Scatchard plots of the interaction of C12-3-C12·2Br with BSA molecules have been obtained.The numbers of binding sites,Hill coefficient and Hill binding constant have been calculated on the basis of the binding capacity.The results show that the interaction of C12-3-C12·2Br with BSA molecules behaved a positive cooperativity in the binding process.There are two types of binding sites on BSA for C12-3-C12·2Br.One is high-affinity binding site at which the essential role of the interaction is electrostatic force,and the other is low-affinity binding site at which the essential role of interaction is hydrophobic force.
2011, 28(7): 831-835
doi: 10.3724/SP.J.1095.2011.00517
Abstract:
The critical micelle concentrations(cmc,1×10-5 mol/L) and the surface tensions(γcmc,mN/m) of nine alkyl aryl sulfonate composite systems were measured at 25℃.The relationship between composite system relative molecular mass and its distribution and surface properties was studied.The γcmc and cmc values of five distributions with the average relative molecular mass of 432 were determined as 2.341 and 28.96 for the incremental type molecular mass distribution;2.458 and 32.56 for the descending type distribution;3.667 and 36.14 for the normal type distribution;2.201 and 27.55 reverse normal type distribution;and 2.761 and 33.54 for the uniform type distribution,respectively.Moreover,the γcmc and cmc values for the descending distribution with four average relative molecular masses were determined as 3.786 and 29.54,3.530 and 29.81,2.458 and 32.56,8.337 and 29.54 for average relative molecular mass of 390,418,432 and 446,respectively.The adsorption capacity,Γmax,the saturated adsorption area,Am,and the surfactant concentration needed in order to reduce surface tension by 20 mN/m(pC20) were calculated according to Gibbs adsorption equation and a reasonable explanation was also presented.
The critical micelle concentrations(cmc,1×10-5 mol/L) and the surface tensions(γcmc,mN/m) of nine alkyl aryl sulfonate composite systems were measured at 25℃.The relationship between composite system relative molecular mass and its distribution and surface properties was studied.The γcmc and cmc values of five distributions with the average relative molecular mass of 432 were determined as 2.341 and 28.96 for the incremental type molecular mass distribution;2.458 and 32.56 for the descending type distribution;3.667 and 36.14 for the normal type distribution;2.201 and 27.55 reverse normal type distribution;and 2.761 and 33.54 for the uniform type distribution,respectively.Moreover,the γcmc and cmc values for the descending distribution with four average relative molecular masses were determined as 3.786 and 29.54,3.530 and 29.81,2.458 and 32.56,8.337 and 29.54 for average relative molecular mass of 390,418,432 and 446,respectively.The adsorption capacity,Γmax,the saturated adsorption area,Am,and the surfactant concentration needed in order to reduce surface tension by 20 mN/m(pC20) were calculated according to Gibbs adsorption equation and a reasonable explanation was also presented.
2011, 28(7): 836-841
doi: 10.3724/SP.J.1095.2011.00497
Abstract:
The interaction of diacerein with human serum albumin(HSA) in physiological solution was studied by fluorescence spectroscopy.The result shows that diacerein quenches the fluorescence of HSA in a static quenching mode.The binding equilibrium constant KA and numbers of binding site n at different temperatures were calculated using two methods,which were compared in the work.The thermodynamic parameters obtained from measured data showed that the binding of diacerein to HSA involved hydrogen bonding and van der Waals interactions.According to the theory of energy transfer,the binding distance(r=2.88 nm) and transfer efficiency of energy(E=0.273 8) between diacerein and HSA were determined.The effect of diacerein on the conformation of HSA was also analyzed by synchronous fluorescence spectrometry.
The interaction of diacerein with human serum albumin(HSA) in physiological solution was studied by fluorescence spectroscopy.The result shows that diacerein quenches the fluorescence of HSA in a static quenching mode.The binding equilibrium constant KA and numbers of binding site n at different temperatures were calculated using two methods,which were compared in the work.The thermodynamic parameters obtained from measured data showed that the binding of diacerein to HSA involved hydrogen bonding and van der Waals interactions.According to the theory of energy transfer,the binding distance(r=2.88 nm) and transfer efficiency of energy(E=0.273 8) between diacerein and HSA were determined.The effect of diacerein on the conformation of HSA was also analyzed by synchronous fluorescence spectrometry.
2011, 28(7): 842-848
doi: 10.3724/SP.J.1095.2011.00546
Abstract:
A new protocol for the determination of copper was developed based on the fluorescence quenching of carboxymethyl cellulose(CMC) coated CdS quantum dots(QDs),which were synthesized in aqueous solution using environmental benign carboxymethyl cellulose as stabilizer.The method has a relatively high selectivity,and no obvious interference on the determination of copper from other coexisting metal ions is observed except Co2+ and Hg2+ ions.Some influencing factors,including the buffer system,pH of the solution,concentration of QDs,reacting time and the temperature of reaction have also been investigated to obtain the optimal conditions for copper determination.When the concentration of QDs was 2×10-4 mol/L,the concentration of KH2PO4-Na2HPO4 is 0.033 mol/L at pH=5.6,the relative fluorescence intensity of QDs was linearly proportional to copper(Ⅱ) ion concentration in the range from 5×10-8 to 2×10-5 mol/L.The linear equation was F0/F=1.0150+100791.6c,and the detection limit was 8×10-9 mol/L.This method is simple and rapid.Compared with the methods reported using QDs as fluorescence probes,this method has a higher selectivity and a wider linear range.The proposed method has been applied to the determination of trace copper in water and human hair with satisfactory results.
A new protocol for the determination of copper was developed based on the fluorescence quenching of carboxymethyl cellulose(CMC) coated CdS quantum dots(QDs),which were synthesized in aqueous solution using environmental benign carboxymethyl cellulose as stabilizer.The method has a relatively high selectivity,and no obvious interference on the determination of copper from other coexisting metal ions is observed except Co2+ and Hg2+ ions.Some influencing factors,including the buffer system,pH of the solution,concentration of QDs,reacting time and the temperature of reaction have also been investigated to obtain the optimal conditions for copper determination.When the concentration of QDs was 2×10-4 mol/L,the concentration of KH2PO4-Na2HPO4 is 0.033 mol/L at pH=5.6,the relative fluorescence intensity of QDs was linearly proportional to copper(Ⅱ) ion concentration in the range from 5×10-8 to 2×10-5 mol/L.The linear equation was F0/F=1.0150+100791.6c,and the detection limit was 8×10-9 mol/L.This method is simple and rapid.Compared with the methods reported using QDs as fluorescence probes,this method has a higher selectivity and a wider linear range.The proposed method has been applied to the determination of trace copper in water and human hair with satisfactory results.
2011, 28(7): 849-854
doi: 10.3724/SP.J.1095.2011.00446
Abstract:
The three-dimensional spectra combined with fluorescence spectroscopy under simulative physiological conditions were used to investigate the interaction between resveratrol and human serum albumin.With the presence of Tris-HCl,the endogenous fluorescence was quenched by resveratrol and the three-dimensional spectra also changed when resveratrol exsited in the system.The synchronous fluorescence intensity and the concentration of serum albumin solution have a good linear relationship.A new synchronous fluorescence method for the determination of trace proteins was developed.The spectral characterization and intensity of synchronous fluorescence were related to the value of Δλ,reaction medium and so on.Under optimized conditions,the fluorescence intensity(I) of the system was proportional to the concentration of protein in the range of 1.380~276.0 mg/L,with the detection limit of 1.037 mg/L for human serum albumin(HSA).This method was applied to the determination of proteins in human serum,urine and saliva samples and the recovery was 93.5%~105.8%.The results obtained with this method were accordant with those obtained by the coomassie brilliant blue(G-250) method.
The three-dimensional spectra combined with fluorescence spectroscopy under simulative physiological conditions were used to investigate the interaction between resveratrol and human serum albumin.With the presence of Tris-HCl,the endogenous fluorescence was quenched by resveratrol and the three-dimensional spectra also changed when resveratrol exsited in the system.The synchronous fluorescence intensity and the concentration of serum albumin solution have a good linear relationship.A new synchronous fluorescence method for the determination of trace proteins was developed.The spectral characterization and intensity of synchronous fluorescence were related to the value of Δλ,reaction medium and so on.Under optimized conditions,the fluorescence intensity(I) of the system was proportional to the concentration of protein in the range of 1.380~276.0 mg/L,with the detection limit of 1.037 mg/L for human serum albumin(HSA).This method was applied to the determination of proteins in human serum,urine and saliva samples and the recovery was 93.5%~105.8%.The results obtained with this method were accordant with those obtained by the coomassie brilliant blue(G-250) method.
