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2007 Volume 24 Issue 3
2007, 24(3): 241-244
Abstract:
A substrate membrane of polyphthalazinone ether sulfone ketone(PPESK) with special morphology was spun, and the asymmetric hollow-fiber membranes was formed though dry/wet spinning. The composite membrane with thin layer(≈1 μm) was successfully prepared by coating PVP and complexing silver ion. The influences of PVP concentration, mole ratio of Ag+ to C=O, operational pressure and tempe-rature, types of transition metals were systematically studied. At 200 kPa and 23℃, the propylene permeance was 16.32 GPU, and propylene/propane selectivity reached 4.79 when the concentration of PVP was 10% and mole ratio of Ag+ to C=O was 1.
A substrate membrane of polyphthalazinone ether sulfone ketone(PPESK) with special morphology was spun, and the asymmetric hollow-fiber membranes was formed though dry/wet spinning. The composite membrane with thin layer(≈1 μm) was successfully prepared by coating PVP and complexing silver ion. The influences of PVP concentration, mole ratio of Ag+ to C=O, operational pressure and tempe-rature, types of transition metals were systematically studied. At 200 kPa and 23℃, the propylene permeance was 16.32 GPU, and propylene/propane selectivity reached 4.79 when the concentration of PVP was 10% and mole ratio of Ag+ to C=O was 1.
2007, 24(3): 245-250
Abstract:
A new compound material CS-MCM-48 was prepared by coating chitosan(CS) on mesoporous molecular sieve MCM-48. When the mass ratio of CS to MCM-48 was adjusted to 1:10, the specific surface area, average pore diameter and pore volume of CS-MCM-48(1:10) reached 408 m2/g, 2.14 nm and 0.38 cm3/g, respectively. The lipase(Pseudomonas Cepacia Lipase, PSL) was immobilized on the CS-MCM-48 in a mixed solvent of phosphate buffer solution and isooctane and used for one-pot reduction and transesterification synthesis of pure enantiomers from prochiral acetophenone. The results indicate that PSL immobilized on CS-MCM-48 possessed much higher catalytic transesterification activity and enantioselectivity than on single MCM-48 or CS. The enantiomeric excess of products (S)-1-phenylethanol and (R)-1-phenylethyl acetate reached respectively 18.0% and 99% with a 1-phenylethanol conversion of 15.3% and an enantioselectivity E value of 237 in toluene at 40℃, which showed the immobilized lipase PSL/CS-MCM-48 exhibited conside-rable chiral resolution properties.
A new compound material CS-MCM-48 was prepared by coating chitosan(CS) on mesoporous molecular sieve MCM-48. When the mass ratio of CS to MCM-48 was adjusted to 1:10, the specific surface area, average pore diameter and pore volume of CS-MCM-48(1:10) reached 408 m2/g, 2.14 nm and 0.38 cm3/g, respectively. The lipase(Pseudomonas Cepacia Lipase, PSL) was immobilized on the CS-MCM-48 in a mixed solvent of phosphate buffer solution and isooctane and used for one-pot reduction and transesterification synthesis of pure enantiomers from prochiral acetophenone. The results indicate that PSL immobilized on CS-MCM-48 possessed much higher catalytic transesterification activity and enantioselectivity than on single MCM-48 or CS. The enantiomeric excess of products (S)-1-phenylethanol and (R)-1-phenylethyl acetate reached respectively 18.0% and 99% with a 1-phenylethanol conversion of 15.3% and an enantioselectivity E value of 237 in toluene at 40℃, which showed the immobilized lipase PSL/CS-MCM-48 exhibited conside-rable chiral resolution properties.
2007, 24(3): 251-255
Abstract:
Five novel compounds as lubricating additives were synthesized from the reaction of sodium piperidine-1-carbodithioate with chloroacetate. Molecular structures of the compounds were confirmed by IR, UV, 1H NMR, 13C NMR, MS and elemental analysis. They are soluble in many organic solvents(liquid paraffin, acetate, rapeseed oil) and insoluble in water. Liquid paraffin was used as a base oil in the work. The thermal stability of the novel compound was evaluated by thermogravimetric analyses(TGA) at a rate of 10℃/min under nitrogen atmosphere. The five derivatives all thermally decompose at above 195℃, and the last degradation point appears at 400℃, indicating that they may be used as the additive of conventional lubrication oil additives. The maximum non-seizure load values(PB values) of the synthetic compounds as additives in liquid paraffin was evaluated with a four-ball machine. The results show that these compounds as additives in liquid paraffin increase the load-carrying capacity. The maximum no-seizure load(866 N) of the oil sample containing 1.0% the novel additive is almost near to the ZDDP(882 N).
Five novel compounds as lubricating additives were synthesized from the reaction of sodium piperidine-1-carbodithioate with chloroacetate. Molecular structures of the compounds were confirmed by IR, UV, 1H NMR, 13C NMR, MS and elemental analysis. They are soluble in many organic solvents(liquid paraffin, acetate, rapeseed oil) and insoluble in water. Liquid paraffin was used as a base oil in the work. The thermal stability of the novel compound was evaluated by thermogravimetric analyses(TGA) at a rate of 10℃/min under nitrogen atmosphere. The five derivatives all thermally decompose at above 195℃, and the last degradation point appears at 400℃, indicating that they may be used as the additive of conventional lubrication oil additives. The maximum non-seizure load values(PB values) of the synthetic compounds as additives in liquid paraffin was evaluated with a four-ball machine. The results show that these compounds as additives in liquid paraffin increase the load-carrying capacity. The maximum no-seizure load(866 N) of the oil sample containing 1.0% the novel additive is almost near to the ZDDP(882 N).
2007, 24(3): 256-260
Abstract:
The curing reaction and thermal degradation of bisphenol A type novolac epoxy resin(bis-ANER) with 4,4'-diaminodiphenyl ether(DDE) were investigated with Fourier-transform infrared spectroscopy, differential scanning calorimetery and thermogravimetry. With extending curing time, the intensity of the IR absorbance of epoxide groups decreased, and that of the hydroxyl groups increased. In the later curing stage, the IR absorbance of the carbonyl groups appeared and its intensity increased with curing time. The apparent activation energies of the no-isothermal curing for the bis-ANER/DDE evaluated with the Kissinger and Ozawa-Flynn Wall methods were 57.6 and 61.5 kJ/mol, respectively. In addition, the thermal degradation of the bis-ANER/DDE network began with the breaking of the ether bond, and the reactions in both nitrogen and oxygen atmospheres followed the nucleation and growth mechanism in the initial degradation stage, g(α)=[-ln (1-α)]2/3. In the higher temperature stage, the thermal degradation reaction mechanisms were different in the two atmospheres, and the oxidation effect of oxygen on the thermal degradation reaction appeared.
The curing reaction and thermal degradation of bisphenol A type novolac epoxy resin(bis-ANER) with 4,4'-diaminodiphenyl ether(DDE) were investigated with Fourier-transform infrared spectroscopy, differential scanning calorimetery and thermogravimetry. With extending curing time, the intensity of the IR absorbance of epoxide groups decreased, and that of the hydroxyl groups increased. In the later curing stage, the IR absorbance of the carbonyl groups appeared and its intensity increased with curing time. The apparent activation energies of the no-isothermal curing for the bis-ANER/DDE evaluated with the Kissinger and Ozawa-Flynn Wall methods were 57.6 and 61.5 kJ/mol, respectively. In addition, the thermal degradation of the bis-ANER/DDE network began with the breaking of the ether bond, and the reactions in both nitrogen and oxygen atmospheres followed the nucleation and growth mechanism in the initial degradation stage, g(α)=[-ln (1-α)]2/3. In the higher temperature stage, the thermal degradation reaction mechanisms were different in the two atmospheres, and the oxidation effect of oxygen on the thermal degradation reaction appeared.
2007, 24(3): 261-267
Abstract:
In a Briton-Robinson(BR) buffer solution of pH 4.1~5.0, some fluoroquinolone derivatives(norfloxacin, NRF; ciprofloxacin, CPF; ofloxacin, OFL; levofloxacin, LVF) were reacted with palladium(Ⅱ) to form anion chelates, but their resonance Rayleigh scattering(RRS) was very weak. Significant enhancement of RRS intensity and new RRS spectra were observed when these anion chelates further reacted with eosin Y to form ternary complexes. These ternary complexes had similar spectral characteristics and their maximum RRS peaks were located at 368 nm. The optimum condition and the affecting factors were investigated. The linearity ranges and the detection limits for the four fluoroquinolone derivatives were 0~2.4×10-6 g/mL and 9.4×10-9 g/mL(CPF), 0~2.4×10-6 g/mL and 12.8×10-9 g/mL(NRF), 0~2.2×10-6 g/mL and 16.2×10-9 g/mL(LVF), 0~2.8×10-6 g/mL and 15.6×10-9 g/mL(OFL), respectively. The composition of the ternary ion association complex was 1:1:1 and its reaction mechanism is discussed. The method has been successfully applied to the determination of NRF in injection and in chicken serum samples and its recovery ranges from 95.0% to 101.5%. As a result, a sensitive and selective RRS method has been developed for the determination of some fluoroquinolones antibiotics.
In a Briton-Robinson(BR) buffer solution of pH 4.1~5.0, some fluoroquinolone derivatives(norfloxacin, NRF; ciprofloxacin, CPF; ofloxacin, OFL; levofloxacin, LVF) were reacted with palladium(Ⅱ) to form anion chelates, but their resonance Rayleigh scattering(RRS) was very weak. Significant enhancement of RRS intensity and new RRS spectra were observed when these anion chelates further reacted with eosin Y to form ternary complexes. These ternary complexes had similar spectral characteristics and their maximum RRS peaks were located at 368 nm. The optimum condition and the affecting factors were investigated. The linearity ranges and the detection limits for the four fluoroquinolone derivatives were 0~2.4×10-6 g/mL and 9.4×10-9 g/mL(CPF), 0~2.4×10-6 g/mL and 12.8×10-9 g/mL(NRF), 0~2.2×10-6 g/mL and 16.2×10-9 g/mL(LVF), 0~2.8×10-6 g/mL and 15.6×10-9 g/mL(OFL), respectively. The composition of the ternary ion association complex was 1:1:1 and its reaction mechanism is discussed. The method has been successfully applied to the determination of NRF in injection and in chicken serum samples and its recovery ranges from 95.0% to 101.5%. As a result, a sensitive and selective RRS method has been developed for the determination of some fluoroquinolones antibiotics.
2007, 24(3): 268-272
Abstract:
Slow scanning cyclic voltammetry was employed to study stainless steel electrode in different electrolytes, solvents and lithium-salt. The impedance diagrams of nano-SnO2 anode/electrolyte interphase at different discharge states were analyzed with alternative current impedance spectroscopy. The results suggest that nonaqueous electrolyte reacts also on the surface of a nano-SnO2 anode as in lithium rechargeable batteries during the initial charge/discharge cycles, and results in the partial irreversible capacity loss. The electrochemical reaction of nano-SnO2 anode for lithium rechargeable batteries can be deduced as follows:a passivating film forms on the surface of nano-SnO2 particles first, then Li+ ions pass through the surface film and react with nano-SnO2 to produce amorphous Li2O and to form fine grains of Li-Sn alloys in the core region underneath the passivation film.
Slow scanning cyclic voltammetry was employed to study stainless steel electrode in different electrolytes, solvents and lithium-salt. The impedance diagrams of nano-SnO2 anode/electrolyte interphase at different discharge states were analyzed with alternative current impedance spectroscopy. The results suggest that nonaqueous electrolyte reacts also on the surface of a nano-SnO2 anode as in lithium rechargeable batteries during the initial charge/discharge cycles, and results in the partial irreversible capacity loss. The electrochemical reaction of nano-SnO2 anode for lithium rechargeable batteries can be deduced as follows:a passivating film forms on the surface of nano-SnO2 particles first, then Li+ ions pass through the surface film and react with nano-SnO2 to produce amorphous Li2O and to form fine grains of Li-Sn alloys in the core region underneath the passivation film.
2007, 24(3): 273-277
Abstract:
Chlortetracycline hydrochloride can enhane the chemiluminescence of Ce(Ⅳ) and Rh6G in acidic medium. So novel molecularly imprinted polymer solid-phase extraction(MISPE) method combined with flow-injection chemiluminescence for determining chlortetracycline hydrochloride was developed. The MIP was synthesized by using tetracycline as the imprinting molecule which has a structure similar to that of chlortetracycline. A polytetrafluoroe-thylene(PTFE) tube packed with the particles of MIP was employed as an MISPE micro-column and was connected to the sampling loop of the eight-way injection valve for the preconcentration and extraction of chlortetracycline hydrochloride. The eluent was used as the carrier for extracting the adsorbed chlortetracycline hydrochloride to react with a mixture of cerium(Ⅳ) and rhodamine6G in the flow cell to produce strong CL. Intensity of CL is linearly changed with the concentration of chlortetracycline hydrochloride from 2×10-8 g/mL to 1×10-6 g/mL and the limit detection is 4×10-9 g/mL(3σ). This method has been successfully applied to the determination of chlortetracycline hydrochloride in liver of chicken sample.
Chlortetracycline hydrochloride can enhane the chemiluminescence of Ce(Ⅳ) and Rh6G in acidic medium. So novel molecularly imprinted polymer solid-phase extraction(MISPE) method combined with flow-injection chemiluminescence for determining chlortetracycline hydrochloride was developed. The MIP was synthesized by using tetracycline as the imprinting molecule which has a structure similar to that of chlortetracycline. A polytetrafluoroe-thylene(PTFE) tube packed with the particles of MIP was employed as an MISPE micro-column and was connected to the sampling loop of the eight-way injection valve for the preconcentration and extraction of chlortetracycline hydrochloride. The eluent was used as the carrier for extracting the adsorbed chlortetracycline hydrochloride to react with a mixture of cerium(Ⅳ) and rhodamine6G in the flow cell to produce strong CL. Intensity of CL is linearly changed with the concentration of chlortetracycline hydrochloride from 2×10-8 g/mL to 1×10-6 g/mL and the limit detection is 4×10-9 g/mL(3σ). This method has been successfully applied to the determination of chlortetracycline hydrochloride in liver of chicken sample.
2007, 24(3): 278-281
Abstract:
LiVPO4F was prepared with a two-step reaction method based on a carbothermal reduction(CTR) process. In the initial CTR step, V2O5, NH4H2PO4, and carbon with a high surface area reacted under an inert atmosphere to yield the trivalent vanadium phosphate, VPO4. In the second incorporation step, the CTR VPO4 reacted with LiF to yield the single phase LiVPO4F. The effect of reaction temperature on the structure and the electrochemical properties were investigated. The results show that the sample synthesized at 750℃ has a single phase LiVPO4F. XRD studies show that LiVPO4F synthesized has a triclinic structure(space group P1), isostructural with the naturally occurring mineral tavorite, LiFePO4·OH. The crystallographic parameters of the prepared LiVPO4F powders are as follows, a=0.514 9 nm, b=0.529 2 nm, c=0.744 5 nm, α=67.397°, β=67.518°, γ=82.008°, and cell volume=0.173 0 nm3. SEM image showed that the particle size was about 2 μm with homogenous distribution. Electrochemical test shows that the initial charge and discharge capacity were about 149 mA·h/g and 130 mA·h/g, respectively at a rate of 0.1C, with an average discharge voltage of 4.2 V(vs.Li/Li+), and the capacity retain 111 mA·h/g after 50 cycles.
LiVPO4F was prepared with a two-step reaction method based on a carbothermal reduction(CTR) process. In the initial CTR step, V2O5, NH4H2PO4, and carbon with a high surface area reacted under an inert atmosphere to yield the trivalent vanadium phosphate, VPO4. In the second incorporation step, the CTR VPO4 reacted with LiF to yield the single phase LiVPO4F. The effect of reaction temperature on the structure and the electrochemical properties were investigated. The results show that the sample synthesized at 750℃ has a single phase LiVPO4F. XRD studies show that LiVPO4F synthesized has a triclinic structure(space group P1), isostructural with the naturally occurring mineral tavorite, LiFePO4·OH. The crystallographic parameters of the prepared LiVPO4F powders are as follows, a=0.514 9 nm, b=0.529 2 nm, c=0.744 5 nm, α=67.397°, β=67.518°, γ=82.008°, and cell volume=0.173 0 nm3. SEM image showed that the particle size was about 2 μm with homogenous distribution. Electrochemical test shows that the initial charge and discharge capacity were about 149 mA·h/g and 130 mA·h/g, respectively at a rate of 0.1C, with an average discharge voltage of 4.2 V(vs.Li/Li+), and the capacity retain 111 mA·h/g after 50 cycles.
2007, 24(3): 282-285
Abstract:
A mixed oxalate precursor of ZnFe2O4 was prepared from Fe(NO3)3·9H2O, Zn(NO3)2·6H2O and H2C2O4·2H2O by solid-state reaction at room temperature. According to Hass low, a circulating system of the chemical reactions was designed to determine the ΔH values of reactants and resultants in the reaction. The standard formation enthalpy of Fe2(C2O4)3·5H2O(ΔHf,Fe2(C2O4)3·5H2O(s)) was calculated with the ΔH values. An isopiestic reaction calorimeter with constant surrounding temperature was used, and hydrochloric acid (3 mol/L) was employed as the solvent for calorimetric experiments. The standard formation enthalpy ΔHf,Fe2(C2O4)3·5H2O(s) is -4 082.29 kJ/mol. The enthalpy of the solid state reaction to prepare the precursor of ZnFe2O4 was calculated to be 406.21 kJ/mol, indicating that the reaction is endothermic.
A mixed oxalate precursor of ZnFe2O4 was prepared from Fe(NO3)3·9H2O, Zn(NO3)2·6H2O and H2C2O4·2H2O by solid-state reaction at room temperature. According to Hass low, a circulating system of the chemical reactions was designed to determine the ΔH values of reactants and resultants in the reaction. The standard formation enthalpy of Fe2(C2O4)3·5H2O(ΔHf,Fe2(C2O4)3·5H2O(s)) was calculated with the ΔH values. An isopiestic reaction calorimeter with constant surrounding temperature was used, and hydrochloric acid (3 mol/L) was employed as the solvent for calorimetric experiments. The standard formation enthalpy ΔHf,Fe2(C2O4)3·5H2O(s) is -4 082.29 kJ/mol. The enthalpy of the solid state reaction to prepare the precursor of ZnFe2O4 was calculated to be 406.21 kJ/mol, indicating that the reaction is endothermic.
2007, 24(3): 286-290
Abstract:
The influences of nano ZnSn(OH)6 particles in flexible polyvinyl chloride(PVC) on the flame retardancy and smoke suppression of it were studied by means of limiting oxygen index(LOI), smoke density test, thermogravimetry analysis(TGA) and SEM. The effects of nano ZnSn(OH)6 on the flame retardancy and smoke suppression are both better than those of the micron ones between 1% and 8% mass fractions of nano ZnSn(OH)6. The value of LOI increased from 27.1% to 29.5% when flexible PVC was filled with 1% nano ZnSn(OH)6. The smoke density rating decreased from 88 to 81 when 6% nano ZnSn(OH)6 was doped. The TGA indicated that the char yields of flexible PVC samples filled with nano ZnSn(OH)6 were all higher than those of the samples filled with micron ones at 400℃. The char yield of flexcible PVC filled with nano ZnSn(OH)6 was 4.3% higher than that of flexcible PVC filled with micron ones at 550℃ and was 6.4% higher than that of blank flexible PVC at the same temperature. The SEM proved that the morphology of char formed after combustion of the samples filled with the nanoparticles showed obviously bulgy state with a densified structure, which can inhibit O2 and heat and combustion gases to go into the PVC bulk. The study of some mechanical properties of the samples verified that the tensile strength and elongation at break were also improved, the best effect was obtained at 4% nano ZnSn(OH)6.
The influences of nano ZnSn(OH)6 particles in flexible polyvinyl chloride(PVC) on the flame retardancy and smoke suppression of it were studied by means of limiting oxygen index(LOI), smoke density test, thermogravimetry analysis(TGA) and SEM. The effects of nano ZnSn(OH)6 on the flame retardancy and smoke suppression are both better than those of the micron ones between 1% and 8% mass fractions of nano ZnSn(OH)6. The value of LOI increased from 27.1% to 29.5% when flexible PVC was filled with 1% nano ZnSn(OH)6. The smoke density rating decreased from 88 to 81 when 6% nano ZnSn(OH)6 was doped. The TGA indicated that the char yields of flexible PVC samples filled with nano ZnSn(OH)6 were all higher than those of the samples filled with micron ones at 400℃. The char yield of flexcible PVC filled with nano ZnSn(OH)6 was 4.3% higher than that of flexcible PVC filled with micron ones at 550℃ and was 6.4% higher than that of blank flexible PVC at the same temperature. The SEM proved that the morphology of char formed after combustion of the samples filled with the nanoparticles showed obviously bulgy state with a densified structure, which can inhibit O2 and heat and combustion gases to go into the PVC bulk. The study of some mechanical properties of the samples verified that the tensile strength and elongation at break were also improved, the best effect was obtained at 4% nano ZnSn(OH)6.
2007, 24(3): 291-295
Abstract:
The reaction between the prepolymer of Bismaleimide(BMI) and Cyanate(BCE) was studied with FTIR and DSC. The reaction mechanism of BMI/BCE was discussed. The results showed that there maybe three reactions:self-polymerization of BCE, self-polymerization of BMI, and co-reaction between BCE and BMI. The self-polymerization of BCE dominated the whole system at the first stage and the co-reaction between BCE and BMI domainted at the later stage. A kinetic analysis of BMI/BCE was carried out via differential scanning calorimetry(DSC). Non-isothermal DSC experimental data were obtained, including curing temperature 175.97℃, post-curing temperature 214.05℃ and gel temperature 139.06℃. The activation energy, frequency factor and reaction order were caculated with Kissinger, Crane methods. Their values were 39.27 kJ/mol, 499.12 s-1 and 0.83, respectively.
The reaction between the prepolymer of Bismaleimide(BMI) and Cyanate(BCE) was studied with FTIR and DSC. The reaction mechanism of BMI/BCE was discussed. The results showed that there maybe three reactions:self-polymerization of BCE, self-polymerization of BMI, and co-reaction between BCE and BMI. The self-polymerization of BCE dominated the whole system at the first stage and the co-reaction between BCE and BMI domainted at the later stage. A kinetic analysis of BMI/BCE was carried out via differential scanning calorimetry(DSC). Non-isothermal DSC experimental data were obtained, including curing temperature 175.97℃, post-curing temperature 214.05℃ and gel temperature 139.06℃. The activation energy, frequency factor and reaction order were caculated with Kissinger, Crane methods. Their values were 39.27 kJ/mol, 499.12 s-1 and 0.83, respectively.
2007, 24(3): 296-300
Abstract:
Polyvinyl alcohol(PVA) matrix resins were obtained from the suspension polymerization of vinyl acetate triallyl isocyanurate followed by alcoholysis. Three carboxylic resins with hydrophilic PVA matrix containing hydroxyl groups were prepared by the introduction of diverse carboxylic groups such as carboxylic methyl, succinic and p-phthalic acid. The conversion rates of hydroxyl groups determined by the chemical titrimetric analysis for the 3 matrix resins were 20.0%, 47.6%, 57.2%, respectively. The adsorption characteristics of L-lysine in aqueous solution on the three carboxylic and PVA resins were measured by the static adsorption isotherms. The equilibrium adsorption data were fitted to Freundlich adsorption isotherm model to evaluate the model parameters. The result shows that the adsorption isotherm data can be satis-factorily fitted with the Freundlich equation within a range of concentration 2.0~80.0 mmol/L at 298 K. At the same time, the result of dynamic adsorption of L-lysine on PVA-SuA with the initial concentration under 50.90 mmol/g shows that a pseudo-second-order equation can be used to interpret the kinetic curve and the correlation is good.
Polyvinyl alcohol(PVA) matrix resins were obtained from the suspension polymerization of vinyl acetate triallyl isocyanurate followed by alcoholysis. Three carboxylic resins with hydrophilic PVA matrix containing hydroxyl groups were prepared by the introduction of diverse carboxylic groups such as carboxylic methyl, succinic and p-phthalic acid. The conversion rates of hydroxyl groups determined by the chemical titrimetric analysis for the 3 matrix resins were 20.0%, 47.6%, 57.2%, respectively. The adsorption characteristics of L-lysine in aqueous solution on the three carboxylic and PVA resins were measured by the static adsorption isotherms. The equilibrium adsorption data were fitted to Freundlich adsorption isotherm model to evaluate the model parameters. The result shows that the adsorption isotherm data can be satis-factorily fitted with the Freundlich equation within a range of concentration 2.0~80.0 mmol/L at 298 K. At the same time, the result of dynamic adsorption of L-lysine on PVA-SuA with the initial concentration under 50.90 mmol/g shows that a pseudo-second-order equation can be used to interpret the kinetic curve and the correlation is good.
2007, 24(3): 301-305
Abstract:
By using GC/MS, the process of oxidizing reaction of atractylone is studied, and five decomposition products are obtained, which is greatly different from the references-only two decomposition products, and the mechanism of oxidizing reaction of atractylone is investigated. The hypothesized mechanism of reaction is:atractylone is readily to additively react with water and to generate the semiacetalhydroxyl at 1, 4-site. The loop of it is opened and lead to the cleavage of C-O bond because of the existence of water, the carbonyl is thus formed. The carbonyl is then oxidized to generate carboxylic group. As the carbon atom is sp2 hybridization, carboxyl can be attacked by hydroxyl from both sides of hybrid orbital, in this reaction, water is removed, and the remaining atoms are joined to form atractylenolideⅠ and iso-atractylenolideⅠ. While the proton of 7-carbon of atractylenolide Ⅰ is rather active and liable to be replaced by hydroxyl to form atractylenolide Ⅲ and atractylenolide Ⅲ is unstable and dehydrated within molecule to form atractylenolideⅡ. Moreover, atractylenolideⅢ and atractylenolideⅠ are dehydrated between two molecules to generate biatractylolide. By quantitatively analyzing the percentage of pure atractylone and atractylone in herb, the kinetic parameter is obtained, and the equations are:Rate1=k'1[x]1.84, Rate2=k'2[x]1.89, the activation energy of each is 58.05 kJ/mol and 63.17 kJ/mol respectively.
By using GC/MS, the process of oxidizing reaction of atractylone is studied, and five decomposition products are obtained, which is greatly different from the references-only two decomposition products, and the mechanism of oxidizing reaction of atractylone is investigated. The hypothesized mechanism of reaction is:atractylone is readily to additively react with water and to generate the semiacetalhydroxyl at 1, 4-site. The loop of it is opened and lead to the cleavage of C-O bond because of the existence of water, the carbonyl is thus formed. The carbonyl is then oxidized to generate carboxylic group. As the carbon atom is sp2 hybridization, carboxyl can be attacked by hydroxyl from both sides of hybrid orbital, in this reaction, water is removed, and the remaining atoms are joined to form atractylenolideⅠ and iso-atractylenolideⅠ. While the proton of 7-carbon of atractylenolide Ⅰ is rather active and liable to be replaced by hydroxyl to form atractylenolide Ⅲ and atractylenolide Ⅲ is unstable and dehydrated within molecule to form atractylenolideⅡ. Moreover, atractylenolideⅢ and atractylenolideⅠ are dehydrated between two molecules to generate biatractylolide. By quantitatively analyzing the percentage of pure atractylone and atractylone in herb, the kinetic parameter is obtained, and the equations are:Rate1=k'1[x]1.84, Rate2=k'2[x]1.89, the activation energy of each is 58.05 kJ/mol and 63.17 kJ/mol respectively.
2007, 24(3): 306-309
Abstract:
A spectrophotometric method was used to determine the critical micelle concentration of cetyltrimethyl-ammonium bromide cationic surfactant. Vis-electronic absorption spectra of a series of CTAB solutions with different concentrations were measured with EY as the probe and characterized by the overlap of the principal peak at 529~532 nm and a shoulder at 506~508 nm. A multi-peak Gaussian fitting was used to interpret the spectra and gave relative integrated absorbance(A2/A1) of the two peaks, red-shift(Δλ1, Δλ2) and half-width. A sudden change occurs at cmc in the curves of relative integrated absorbance(A2/A1), red-shift(Δλ1, Δλ2) and half-width versus the concentration of CTAB. Significantly the dependence of the cmc upon the half-width was observed and used in the determination of cmc of cationic surfactant such as CTAB.
A spectrophotometric method was used to determine the critical micelle concentration of cetyltrimethyl-ammonium bromide cationic surfactant. Vis-electronic absorption spectra of a series of CTAB solutions with different concentrations were measured with EY as the probe and characterized by the overlap of the principal peak at 529~532 nm and a shoulder at 506~508 nm. A multi-peak Gaussian fitting was used to interpret the spectra and gave relative integrated absorbance(A2/A1) of the two peaks, red-shift(Δλ1, Δλ2) and half-width. A sudden change occurs at cmc in the curves of relative integrated absorbance(A2/A1), red-shift(Δλ1, Δλ2) and half-width versus the concentration of CTAB. Significantly the dependence of the cmc upon the half-width was observed and used in the determination of cmc of cationic surfactant such as CTAB.
2007, 24(3): 310-313
Abstract:
The reaction of 4-amino-3-phenyl-5-mercapto-s-triazole(1) with β-chloro-phenyl-propanone(2) under refluxing ethanol in the presence of sodium acetate gave amino-triazolyl sulfanyl-phenylpropanone(3). The oximation of compound 3 with hydroxyamine hydrochloride yielded the corresponding oxime(4) followed by the etherification with each of chloromethy-oxadiazoles(5a~5e) and the condensation with salicylaldehyde to form oxime-ethers(6a~6e) and schiff-base oxime-ethers(7a~7e), respectively. The antibacterial activities of the compounds synthesized in vitro to Gram positive bacteria and Gram negative bacteria were tested with the standard 2-fold agar dilution method, and all the tested compounds exhibited relatively better activities against Gram positive bacteria than those against Gram negative bacteria.
The reaction of 4-amino-3-phenyl-5-mercapto-s-triazole(1) with β-chloro-phenyl-propanone(2) under refluxing ethanol in the presence of sodium acetate gave amino-triazolyl sulfanyl-phenylpropanone(3). The oximation of compound 3 with hydroxyamine hydrochloride yielded the corresponding oxime(4) followed by the etherification with each of chloromethy-oxadiazoles(5a~5e) and the condensation with salicylaldehyde to form oxime-ethers(6a~6e) and schiff-base oxime-ethers(7a~7e), respectively. The antibacterial activities of the compounds synthesized in vitro to Gram positive bacteria and Gram negative bacteria were tested with the standard 2-fold agar dilution method, and all the tested compounds exhibited relatively better activities against Gram positive bacteria than those against Gram negative bacteria.
2007, 24(3): 314-317
Abstract:
By the reaction of FeCl3 with polyvinyl alcohol fiber, the complex of PVA-Fe(Ⅲ) was synthesized. The reaction kinetics was studied, and the reaction kinetics law of PVA fiber to metal ion was established. The results show that the optimum conditions of the reaction was c(Fe(Ⅲ))=0.08 mol/L, t=60℃, time=2 h and pH=2.0. It was found that the OH oxygen in PVA bonded to Fe(Ⅲ) ion and the coordinate data of PVA fiber to Fe(Ⅲ) could be well interpreted by the Langmuir isothermal adsorption model. The saturated coordinate capacity of PVA to Fe(Ⅲ) was 171.8 mg/g(dry fiber). The results show that the reaction is consistent with the first-order kinetic model. The reaction rate constant was measured by the reaction of polyvinyl alcohol fiber with FeCl3(initial concentration 0.08 mol/L) at different temperatures and its activation energy was 144.98 kJ/mol. The reaction rate constant can be expressed as lg k=-Ea/2.303RT+20.48.
By the reaction of FeCl3 with polyvinyl alcohol fiber, the complex of PVA-Fe(Ⅲ) was synthesized. The reaction kinetics was studied, and the reaction kinetics law of PVA fiber to metal ion was established. The results show that the optimum conditions of the reaction was c(Fe(Ⅲ))=0.08 mol/L, t=60℃, time=2 h and pH=2.0. It was found that the OH oxygen in PVA bonded to Fe(Ⅲ) ion and the coordinate data of PVA fiber to Fe(Ⅲ) could be well interpreted by the Langmuir isothermal adsorption model. The saturated coordinate capacity of PVA to Fe(Ⅲ) was 171.8 mg/g(dry fiber). The results show that the reaction is consistent with the first-order kinetic model. The reaction rate constant was measured by the reaction of polyvinyl alcohol fiber with FeCl3(initial concentration 0.08 mol/L) at different temperatures and its activation energy was 144.98 kJ/mol. The reaction rate constant can be expressed as lg k=-Ea/2.303RT+20.48.
2007, 24(3): 318-322
Abstract:
A new compound,[Cu(C5H7NO2)·H2O]·H2O, was synthesized via solid state reaction of L-glutamic acid, copper acetate and non-aqueous sodium acetate, which had a mole ratio of 1:2:4. The crystal structure was characterized by means of elemental analysis, infrared spectrum, thermo-gravimetric analysis and differential thermal analysis, single crystal X-ray diffraction analysis. Thermo-gravimetric analysis and differential thermal analysis reveal that the compound contains one water molecule of crystallization and one coordinating water molecule. The analysis of crystal structure indicates that the crystal belongs to the ortho-gonal system with space group P2(1)2(1)2(1), a=0.724 4(2) nm, b=1.033 0(3) nm, c=1.107 5(3) nm, Z=4, V=0.828 8(4) nm3, Dc=1.961 g/cm3, μ=2.635 mm-1, F(000)=500, R1=0.030 7, wR2=0.069 6, GOF=1.012. The configuration of the compound is a deformed tetragonal pyramid, which is composed of the oxygen atom of C1 and C5 carboxyls, the nitrogen atom of amino group in L-glutamic acid, the oxygen atom of hydrone and copper ion. The intermolecular hydrogen bonding in the tetragonal pyramid was formed by means of carboxyl and crystalline water or coordinated water. So the three-dimensional supermo-lecular structure of the compound was formed via the hydrogen bonding and weak interaction. Optical activity analysis results show that the construction of the compound is laevorotary, and [α]D15=-38.5°, and its optical direction differed with that of ligand. It is attributed to the formation of the pentabasic ring consisting of the oxygen atom of the carboxyl and the nitrogen atom of the amino group, and then the environment of the chiral carbon atom was changed, which resulted in the change of optical direction.
A new compound,[Cu(C5H7NO2)·H2O]·H2O, was synthesized via solid state reaction of L-glutamic acid, copper acetate and non-aqueous sodium acetate, which had a mole ratio of 1:2:4. The crystal structure was characterized by means of elemental analysis, infrared spectrum, thermo-gravimetric analysis and differential thermal analysis, single crystal X-ray diffraction analysis. Thermo-gravimetric analysis and differential thermal analysis reveal that the compound contains one water molecule of crystallization and one coordinating water molecule. The analysis of crystal structure indicates that the crystal belongs to the ortho-gonal system with space group P2(1)2(1)2(1), a=0.724 4(2) nm, b=1.033 0(3) nm, c=1.107 5(3) nm, Z=4, V=0.828 8(4) nm3, Dc=1.961 g/cm3, μ=2.635 mm-1, F(000)=500, R1=0.030 7, wR2=0.069 6, GOF=1.012. The configuration of the compound is a deformed tetragonal pyramid, which is composed of the oxygen atom of C1 and C5 carboxyls, the nitrogen atom of amino group in L-glutamic acid, the oxygen atom of hydrone and copper ion. The intermolecular hydrogen bonding in the tetragonal pyramid was formed by means of carboxyl and crystalline water or coordinated water. So the three-dimensional supermo-lecular structure of the compound was formed via the hydrogen bonding and weak interaction. Optical activity analysis results show that the construction of the compound is laevorotary, and [α]D15=-38.5°, and its optical direction differed with that of ligand. It is attributed to the formation of the pentabasic ring consisting of the oxygen atom of the carboxyl and the nitrogen atom of the amino group, and then the environment of the chiral carbon atom was changed, which resulted in the change of optical direction.
2007, 24(3): 323-326
Abstract:
The radiation effect of poly(propylene carbonate)(PPC) has been studied under Co-60 and EB irradiation at room temperature. The molecular mass of PPC decreased with the increase of radiation dose. This result shows that PPC is a typical radiation degradable polymer. The degree of chain-scission Gs was estimated as Gs,γ-ray=10.81 and Gs,EB=4.9 for 1 mm PPC sheet under N2 at room temperature. Different Gs values might come from O2 effect in the radiation process. The degradation products were identified by IR spectra, the result shows that -OH group increased after radiation. With increasing absorb dose, the tensile strength and elongation at break decreased. However, as radiation sterilization dose is set in a range of 25~50 kGy, the remaining tensile strength of PPC is higher than 23 MPa, and elongation at break is longer than 4%. These results indicate that PPC can be safely sterilized by irradiation.
The radiation effect of poly(propylene carbonate)(PPC) has been studied under Co-60 and EB irradiation at room temperature. The molecular mass of PPC decreased with the increase of radiation dose. This result shows that PPC is a typical radiation degradable polymer. The degree of chain-scission Gs was estimated as Gs,γ-ray=10.81 and Gs,EB=4.9 for 1 mm PPC sheet under N2 at room temperature. Different Gs values might come from O2 effect in the radiation process. The degradation products were identified by IR spectra, the result shows that -OH group increased after radiation. With increasing absorb dose, the tensile strength and elongation at break decreased. However, as radiation sterilization dose is set in a range of 25~50 kGy, the remaining tensile strength of PPC is higher than 23 MPa, and elongation at break is longer than 4%. These results indicate that PPC can be safely sterilized by irradiation.
2007, 24(3): 327-330
Abstract:
A method for determination of Malachite green in fishes was established by high performance capillary electrophoresis using self-constructed conductivity detection system. Several parameters affecting the determination were studied, including concentration of buffer, value of pH, organic concentration, separation voltage, and sampling time. Under the following condions:uncoated fused silica capillary(45 cm×75 μm) as separation channel, HAC-NH4AC(concentration of NH4AC 12 mmol/L, pH=4.0) as running buffer, 20 kV as separation voltage, a linearity exists between peak height(y) and mass concentration of malachite green(c) in the range of 7.2~180 mg/L with regression equation y=2.02+102c, linearity coefficient is 0.996 2, determination limit is 1.8 mg/L and average recovery rate is from 90.0%~102.0%. The results show that the method is simple, quick, accurate and has high recovery.
A method for determination of Malachite green in fishes was established by high performance capillary electrophoresis using self-constructed conductivity detection system. Several parameters affecting the determination were studied, including concentration of buffer, value of pH, organic concentration, separation voltage, and sampling time. Under the following condions:uncoated fused silica capillary(45 cm×75 μm) as separation channel, HAC-NH4AC(concentration of NH4AC 12 mmol/L, pH=4.0) as running buffer, 20 kV as separation voltage, a linearity exists between peak height(y) and mass concentration of malachite green(c) in the range of 7.2~180 mg/L with regression equation y=2.02+102c, linearity coefficient is 0.996 2, determination limit is 1.8 mg/L and average recovery rate is from 90.0%~102.0%. The results show that the method is simple, quick, accurate and has high recovery.
2007, 24(3): 331-334
Abstract:
PMDA/ODA and BPDA/PPD based polyimide films prepared from polyamic acid solution(PAA method) and partly imidized polyamic acid solution(gel method) were investigated. The self-supported film with the gel method had lower solid content than that with the PAA method, and the film with lower solid content could be unistretched at higher ratio, hence make the film lower coefficient of thermal expansion(CTE)(for PMDA/ODA decreased from 35.1×10-6/℃ to 12.5×10-6/℃), higher tensile strength as well as modulus(for PMDA/ODA they were 236 MPa and 1.7 GPa, respectively; for BPDA/PPD they were 613 MPa and 9.3 GPa, respectively), but lower elongation. The CTE and elongation of the films determined in machine direction were lower than those in transversal direction, but the strength and modulus in machine direction were much higher than those in transversal direction.
PMDA/ODA and BPDA/PPD based polyimide films prepared from polyamic acid solution(PAA method) and partly imidized polyamic acid solution(gel method) were investigated. The self-supported film with the gel method had lower solid content than that with the PAA method, and the film with lower solid content could be unistretched at higher ratio, hence make the film lower coefficient of thermal expansion(CTE)(for PMDA/ODA decreased from 35.1×10-6/℃ to 12.5×10-6/℃), higher tensile strength as well as modulus(for PMDA/ODA they were 236 MPa and 1.7 GPa, respectively; for BPDA/PPD they were 613 MPa and 9.3 GPa, respectively), but lower elongation. The CTE and elongation of the films determined in machine direction were lower than those in transversal direction, but the strength and modulus in machine direction were much higher than those in transversal direction.
2007, 24(3): 335-339
Abstract:
Ultasound(US) was used to degrade nonylphenol ethoxylate(NP10EO) in water in the presence of TiO2 catalyst and H2O2. The effect of TiO2 concentration, H2O2 concentration, ultrasound power, initial concentration and pH of NP10EO on the degradation efficiency of NP10EO were investigated, and the synergistic efficiency among TiO2, H2O2 and US was discussed. The results show that the degradation efficieney of NP10EO increases with increasing ultrasound power and TiO2 concentration whithin certain ranges, and then becomes stable. The degradation efficiency of NP10EO first increases with the H2O2 concentration to reach a maximum and then decreases. When pH is less than 5, the degradation effciency is high, and the degradation effciency decreases with increasing pH. When pH is greater than 5, the degradation efficiency is low. The synergistic effect on degradating NP10EO in water by TiO2/H2O2/US was evident, and more than 98% NP10EO can be degraded in the presence of catalyst TiO2 at a concentration of 0.4 g/L, an H2O2 concentration of 0.2 g/L, an ultrasound power of 600 W, an initial concentration 80 mg/L and pH=1 of NP10EO within 120 min.
Ultasound(US) was used to degrade nonylphenol ethoxylate(NP10EO) in water in the presence of TiO2 catalyst and H2O2. The effect of TiO2 concentration, H2O2 concentration, ultrasound power, initial concentration and pH of NP10EO on the degradation efficiency of NP10EO were investigated, and the synergistic efficiency among TiO2, H2O2 and US was discussed. The results show that the degradation efficieney of NP10EO increases with increasing ultrasound power and TiO2 concentration whithin certain ranges, and then becomes stable. The degradation efficiency of NP10EO first increases with the H2O2 concentration to reach a maximum and then decreases. When pH is less than 5, the degradation effciency is high, and the degradation effciency decreases with increasing pH. When pH is greater than 5, the degradation efficiency is low. The synergistic effect on degradating NP10EO in water by TiO2/H2O2/US was evident, and more than 98% NP10EO can be degraded in the presence of catalyst TiO2 at a concentration of 0.4 g/L, an H2O2 concentration of 0.2 g/L, an ultrasound power of 600 W, an initial concentration 80 mg/L and pH=1 of NP10EO within 120 min.
2007, 24(3): 340-344
Abstract:
With azobisisobutyronitrile(AIBN) as the initiator, a novel borate ester polymer surfactant(PBE) was prepared via the direct polymerization of N-hydroxymethyl acrylamide, triethyl borate and N,N-dihydroxyethyl dodecylamine. The structure of the compound was characterized by FTIR, 1H NMR and GPC. Anti-hydrolysis ability, thermal stability(TG), emulsifying power of PBE and its borate ester monomer MBE were measured, and its surface properties at different pH values were studied by the surface tension method. The result shows by the direct polymerization synthesis process, white or light yellow powders PBE can be obtained with a yield of 77.2% after purification, and the product molecular weight Mw is about 28 400 g/mol. PBE possesses a good ability of anti-hydrolysis, and its thermolysis temperature may reach 320℃, the heat stability of which is better than that of MBE. The HLB value of PBE is in a range of 10~13, it has apparently better emulsifying power to paraffin oil, turpentine, toluene and benzine compared with MBE and commercial emulsification agent Tween-85. At 25℃, the critical micell concentration(CMC) of PBE in aqueous solution significantly decreased with pH increasing, when pH varied from 6 to 7, the CMC decrease extent was the greatest. However, the pH has little influence on the corresponding γCMC of PBE. At pH=7, 25℃, the CMC of PBE is 0.12 g/L, γCMC is 31.2 mN/m; surface activity of PBE is similar to those of regular low molecular weight surfactants, and is superior to those of certain polymeric surfactants, such as PVA and Pluronic104.
With azobisisobutyronitrile(AIBN) as the initiator, a novel borate ester polymer surfactant(PBE) was prepared via the direct polymerization of N-hydroxymethyl acrylamide, triethyl borate and N,N-dihydroxyethyl dodecylamine. The structure of the compound was characterized by FTIR, 1H NMR and GPC. Anti-hydrolysis ability, thermal stability(TG), emulsifying power of PBE and its borate ester monomer MBE were measured, and its surface properties at different pH values were studied by the surface tension method. The result shows by the direct polymerization synthesis process, white or light yellow powders PBE can be obtained with a yield of 77.2% after purification, and the product molecular weight Mw is about 28 400 g/mol. PBE possesses a good ability of anti-hydrolysis, and its thermolysis temperature may reach 320℃, the heat stability of which is better than that of MBE. The HLB value of PBE is in a range of 10~13, it has apparently better emulsifying power to paraffin oil, turpentine, toluene and benzine compared with MBE and commercial emulsification agent Tween-85. At 25℃, the critical micell concentration(CMC) of PBE in aqueous solution significantly decreased with pH increasing, when pH varied from 6 to 7, the CMC decrease extent was the greatest. However, the pH has little influence on the corresponding γCMC of PBE. At pH=7, 25℃, the CMC of PBE is 0.12 g/L, γCMC is 31.2 mN/m; surface activity of PBE is similar to those of regular low molecular weight surfactants, and is superior to those of certain polymeric surfactants, such as PVA and Pluronic104.
2007, 24(3): 345-348
Abstract:
In a weak acid buffer solution of HAC-NaAC, when cetylpyridinium bromide(CPB) is mixed with a dyestuff ethyl eosin(EE) after anionic surfactant is added, the colour of the soluotion becomes deeper, and the max absorbtion wavelength is at 516 nm. At this wavelength, the absorbence enhancement is proportional to the concentration of the anionic surfactant(AS). Based on it, a photometric method for determination of anionic surfactant in water was established. At the max absorbtion wavelength, three anionic surfactants, sodium dodecyl benzene sulfonate(SDBS), sodium lauryl sulfonate(SLS), and sodium dodecyl sulfate(SDS), in the ranges of 0~2.05×10-5 mol/L, 0~2.08×10-5 mol/L, and 0~2.04×10-5 mol/L, respectively were found to obey Beer's Law, and the apparent molar absorptivity(ε) of 2.38&×104 L/(mol·cm), 2.82&×104 L/(mol·cm) and 2.98&×104 L/(mol·cm), and the detection limit of 8.42×10-7 mol/L, 4.56×10-7 mol/L and 7.95×10-7 mol/L were obtained respectively. The proposed method has a good sensitivity and selectivity and has been applied to the determination of anionic surfactant in water samples with satisfactory results.
In a weak acid buffer solution of HAC-NaAC, when cetylpyridinium bromide(CPB) is mixed with a dyestuff ethyl eosin(EE) after anionic surfactant is added, the colour of the soluotion becomes deeper, and the max absorbtion wavelength is at 516 nm. At this wavelength, the absorbence enhancement is proportional to the concentration of the anionic surfactant(AS). Based on it, a photometric method for determination of anionic surfactant in water was established. At the max absorbtion wavelength, three anionic surfactants, sodium dodecyl benzene sulfonate(SDBS), sodium lauryl sulfonate(SLS), and sodium dodecyl sulfate(SDS), in the ranges of 0~2.05×10-5 mol/L, 0~2.08×10-5 mol/L, and 0~2.04×10-5 mol/L, respectively were found to obey Beer's Law, and the apparent molar absorptivity(ε) of 2.38&×104 L/(mol·cm), 2.82&×104 L/(mol·cm) and 2.98&×104 L/(mol·cm), and the detection limit of 8.42×10-7 mol/L, 4.56×10-7 mol/L and 7.95×10-7 mol/L were obtained respectively. The proposed method has a good sensitivity and selectivity and has been applied to the determination of anionic surfactant in water samples with satisfactory results.
2007, 24(3): 349-352
Abstract:
The thermal stability of solid aminoiminomethanesulfonic acid (AIMSO3H) was studied. The solid aminoiminomethanesulfonic acid and solid aminoiminomethanesulfonic acid hydrate can be decomposed into SO2 and urea under atmosphere condition. The decomposition increases with temperature. The hydrolysis rate of aminoiminomethanesulfonic acid in water solution was studied. It is influenced by temperature, concentration and pH. The hydrolysis rate equation of aminoiminomethanesulfonic acid is r/(mol·L-1·s-1)=k/(L0.5·mol-0.5·s-1)×c(AIMSO3H)/(mol·L-)×(c(OH-)/(mol·L-1))0.5. The activation energy of the hydrolysis reaction is 73.56 kJ/mol. Aminoiminomethanesulfonic acid is stable to some oxidants in weak acid condition.
The thermal stability of solid aminoiminomethanesulfonic acid (AIMSO3H) was studied. The solid aminoiminomethanesulfonic acid and solid aminoiminomethanesulfonic acid hydrate can be decomposed into SO2 and urea under atmosphere condition. The decomposition increases with temperature. The hydrolysis rate of aminoiminomethanesulfonic acid in water solution was studied. It is influenced by temperature, concentration and pH. The hydrolysis rate equation of aminoiminomethanesulfonic acid is r/(mol·L-1·s-1)=k/(L0.5·mol-0.5·s-1)×c(AIMSO3H)/(mol·L-)×(c(OH-)/(mol·L-1))0.5. The activation energy of the hydrolysis reaction is 73.56 kJ/mol. Aminoiminomethanesulfonic acid is stable to some oxidants in weak acid condition.
2007, 24(3): 353-356
Abstract:
Zn nanowires were fabricated by directelectro-deposition with porous aluminum oxide membrane as the templates, and ZnO nanowire arrays were prepared via the high temperature oxidation of Zn nanowires. The aperture of alumina template was altered by changing the process parameters of the preparation of alumina membranes. Therefore, the diameter of ZnO nanowires was changed, too. X-ray diffraction, transmission electron microscope were employed to study the morphology and chemical composition of ZnO nanowires. It was found that the diffraction peaks increase with the diameters of ZnO nanowires increasing. The photoluminescence property of the sample was measured with an FLS920 spectrofluorimeter, and the effects of the morphologies of ZnO nanowires on the photoluminescence were analysed by gauss curve fitting method. The results indicate that the crystallinity and the stoichiometric proportion improve gradually with the diameters of nanowires increasing from 30 nm to 60 nm. The emission peaks of ZnO nanowires with diameters of 30 nm, 40 nm, 45 nm and 55 nm in the region of ultraviolet and blue band showed a blue shift with the diameters of nanowires increasing, however, the peaks of ZnO nanowires with a diameter of 60 nm exhibited an opposite tendency. It can be deduced that there is a critical value of diameter that makes the photoluminescence property of ZnO nanowires different.
Zn nanowires were fabricated by directelectro-deposition with porous aluminum oxide membrane as the templates, and ZnO nanowire arrays were prepared via the high temperature oxidation of Zn nanowires. The aperture of alumina template was altered by changing the process parameters of the preparation of alumina membranes. Therefore, the diameter of ZnO nanowires was changed, too. X-ray diffraction, transmission electron microscope were employed to study the morphology and chemical composition of ZnO nanowires. It was found that the diffraction peaks increase with the diameters of ZnO nanowires increasing. The photoluminescence property of the sample was measured with an FLS920 spectrofluorimeter, and the effects of the morphologies of ZnO nanowires on the photoluminescence were analysed by gauss curve fitting method. The results indicate that the crystallinity and the stoichiometric proportion improve gradually with the diameters of nanowires increasing from 30 nm to 60 nm. The emission peaks of ZnO nanowires with diameters of 30 nm, 40 nm, 45 nm and 55 nm in the region of ultraviolet and blue band showed a blue shift with the diameters of nanowires increasing, however, the peaks of ZnO nanowires with a diameter of 60 nm exhibited an opposite tendency. It can be deduced that there is a critical value of diameter that makes the photoluminescence property of ZnO nanowires different.
2007, 24(3): 357-360
Abstract:
Composite modified starch(CCMS) with a high viscosity was prepared by means of crosslinking and carboxymethylation with potato starch and chloroactic acid as the major raw material. The rheological and water-loss control properties of CCMS were investigated in detail. The mechanism of water-loss control was also explored. The results show that the paste of CCMS with a dosage of 0.5%~4.0% behaved as a pseudoplastic liquid at 20℃ to 60℃, which conformed to the empirical formula of the Ostwald-De waele equation ηa=Kγn-1; CCMS was compared with MV-CMC, and it was found that the performance indexes for viscosity increase and water-loss control of CCMS matched that of MV-CMC when the loading of CCMS was only 57% and 75% that of MV-CMC in saturated salt water mud and 4% salt water mud, respectively.
Composite modified starch(CCMS) with a high viscosity was prepared by means of crosslinking and carboxymethylation with potato starch and chloroactic acid as the major raw material. The rheological and water-loss control properties of CCMS were investigated in detail. The mechanism of water-loss control was also explored. The results show that the paste of CCMS with a dosage of 0.5%~4.0% behaved as a pseudoplastic liquid at 20℃ to 60℃, which conformed to the empirical formula of the Ostwald-De waele equation ηa=Kγn-1; CCMS was compared with MV-CMC, and it was found that the performance indexes for viscosity increase and water-loss control of CCMS matched that of MV-CMC when the loading of CCMS was only 57% and 75% that of MV-CMC in saturated salt water mud and 4% salt water mud, respectively.
2007, 24(3): 361-364
Abstract:
p-tert-Butoxycarbonyloxystyrene was synthesized by Wittig reaction with changing solvent medium. The hybrid products were separated and purified by conventional liquid chromatography with neutral Al2O3 anhydrous column and n-hexane for elution, which simplifies the separation method. It was shown that the purity of the aim product was higher than 99% and its yield was 60%~70%. The intermediate product p-tert-butoxycarbonyloxybenzaldehyde could be synthesized conveniently and quantitatively. The main byproduct was triphenylphosphine oxide. The aim product, intermediate product and some byproducts were identified with FTIR and NMR.
p-tert-Butoxycarbonyloxystyrene was synthesized by Wittig reaction with changing solvent medium. The hybrid products were separated and purified by conventional liquid chromatography with neutral Al2O3 anhydrous column and n-hexane for elution, which simplifies the separation method. It was shown that the purity of the aim product was higher than 99% and its yield was 60%~70%. The intermediate product p-tert-butoxycarbonyloxybenzaldehyde could be synthesized conveniently and quantitatively. The main byproduct was triphenylphosphine oxide. The aim product, intermediate product and some byproducts were identified with FTIR and NMR.
