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2003 Volume 20 Issue 12
2003, 20(12): 1123-1128
Abstract:
The adsorption property of amino-naphthol-sulfonic acid(1,2,4-acid) onto the bi-functional hypercrosslinked polymeric adsorbent AL-8 based on the polystyrene resin is discussed from the thermodynamic and kinetic viewpoints. A well fitted Freundlich equation is obtained for the adsorption isotherm, indicating an endothermic and a favorable adsorption in the studied range. The capacity and affinity of the adsorption increase with temperature, integrating the phenomena of the ‘sorbent-motivated’ and the more predominant ‘solvent-motivated’ effects. The ΔH value is 28.272 kJ/mol, an indicative of a weakly chemical character and an easier desorption property. The negative value of ΔG indicates the spontaneous nature of the adsorption process, and the positive value of ΔS shows the increased randomness at the solid/solution interface during the adsorption process. Besides the intra-particle diffusion, other processes such as film diffusion also assume the control on the rate of adsorption simultaneously.
The adsorption property of amino-naphthol-sulfonic acid(1,2,4-acid) onto the bi-functional hypercrosslinked polymeric adsorbent AL-8 based on the polystyrene resin is discussed from the thermodynamic and kinetic viewpoints. A well fitted Freundlich equation is obtained for the adsorption isotherm, indicating an endothermic and a favorable adsorption in the studied range. The capacity and affinity of the adsorption increase with temperature, integrating the phenomena of the ‘sorbent-motivated’ and the more predominant ‘solvent-motivated’ effects. The ΔH value is 28.272 kJ/mol, an indicative of a weakly chemical character and an easier desorption property. The negative value of ΔG indicates the spontaneous nature of the adsorption process, and the positive value of ΔS shows the increased randomness at the solid/solution interface during the adsorption process. Besides the intra-particle diffusion, other processes such as film diffusion also assume the control on the rate of adsorption simultaneously.
2003, 20(12): 1129-1134
Abstract:
The adsorption of aniline, N-methylaniline and N,N-dimethylaniline on phenol formaldehyde resin(JDW-2) in aqueous solutions under static conditions has been studied. A semi-empirical rate equation adequately fits the sorption rate data of the three anilines in the initial period, that is, the adsorption is attained at about 21.5%~48.9% of equilibrium sorption. The equilibrium adsorption data for three aniline compounds in aqueous solutions are in good agreement with the Langmuir isotherm equation and Freundlich isotherm equation. The correlation coefficients are bigger than 0.99. The sorption of the three compounds in aqueous solutions is monomolecular layer adsorption with n>1.
The adsorption of aniline, N-methylaniline and N,N-dimethylaniline on phenol formaldehyde resin(JDW-2) in aqueous solutions under static conditions has been studied. A semi-empirical rate equation adequately fits the sorption rate data of the three anilines in the initial period, that is, the adsorption is attained at about 21.5%~48.9% of equilibrium sorption. The equilibrium adsorption data for three aniline compounds in aqueous solutions are in good agreement with the Langmuir isotherm equation and Freundlich isotherm equation. The correlation coefficients are bigger than 0.99. The sorption of the three compounds in aqueous solutions is monomolecular layer adsorption with n>1.
2003, 20(12): 1135-1138
Abstract:
The structures of rat liver chrotin and its walker tumoral chromatin have been studied by fluorescence lifetime, precision calorimetric determinations and energy transfer measurement. The results show that the component with ethidium bromide inserting DNA in tumoral chromatin(TC) increases by 4.86% than that in normal chromatin(NC). The formation enthalpy of the complex from ethidium bromide and DNA in TC is -15.38 kJ/mol and -13.25 kJ/mol for NC. The energy transfer efficiency between dansyl chloride and acridine orange in labeled TC is lower than that in labeled NC. The mean donor-acceptor distance is longer than that in labeled NC. These results denote that TC has a less rigid structure and higher genic activity, and can more easily form complex with ethidium bromide.
The structures of rat liver chrotin and its walker tumoral chromatin have been studied by fluorescence lifetime, precision calorimetric determinations and energy transfer measurement. The results show that the component with ethidium bromide inserting DNA in tumoral chromatin(TC) increases by 4.86% than that in normal chromatin(NC). The formation enthalpy of the complex from ethidium bromide and DNA in TC is -15.38 kJ/mol and -13.25 kJ/mol for NC. The energy transfer efficiency between dansyl chloride and acridine orange in labeled TC is lower than that in labeled NC. The mean donor-acceptor distance is longer than that in labeled NC. These results denote that TC has a less rigid structure and higher genic activity, and can more easily form complex with ethidium bromide.
2003, 20(12): 1139-1142
Abstract:
The adsorption and thermodynamic behavior of sorbic acid in aqueous solution by three kinds of macroporous polymeric resins:NDA-150, CHA-111 and Amberlite XAD-4 have been investigated by static method. The results show that isotherm adsorption curves of sorbic acid by three polymeric resins all well fit to Freundlich adsorption isotherm equation. The adsorption capacities for sorbic acid on NDA-150 are 1.4~2.4 times and 2.1~4.0 times as high as that on CHA-111 and Amberlite XAD-4 respectively, due to the differences in surface polarity and micropore structure of the resins. The negative values of the adsorption enthalpy ΔH and the absolute values<42 kJ/mol indicate the exothermic physical adsorption character. The study on the free energy of adsorption manifests that there is a rather better pore structure in NDA-150. The negative values of the adsorption entropy ΔS indicate the more restricted mobility of the sorbic acid on the resin surface than in solution.
The adsorption and thermodynamic behavior of sorbic acid in aqueous solution by three kinds of macroporous polymeric resins:NDA-150, CHA-111 and Amberlite XAD-4 have been investigated by static method. The results show that isotherm adsorption curves of sorbic acid by three polymeric resins all well fit to Freundlich adsorption isotherm equation. The adsorption capacities for sorbic acid on NDA-150 are 1.4~2.4 times and 2.1~4.0 times as high as that on CHA-111 and Amberlite XAD-4 respectively, due to the differences in surface polarity and micropore structure of the resins. The negative values of the adsorption enthalpy ΔH and the absolute values<42 kJ/mol indicate the exothermic physical adsorption character. The study on the free energy of adsorption manifests that there is a rather better pore structure in NDA-150. The negative values of the adsorption entropy ΔS indicate the more restricted mobility of the sorbic acid on the resin surface than in solution.
2003, 20(12): 1143-1147
Abstract:
The electrochemical property, chemical composition and crystal structure of electroless Co-Ni-B-Ce alloy plated in common state as well as in magnetic field were studied by means of potentiometer, plasma transmitting spectrometer, electron energy spectrometer, X-ray diffractometer and transmission electron microscope. The results showed that the static potential and polarizability of electroless Co-Ni-B alloy are remarkably improved as the plating is carried out in magnetic field in the presence of a little amount of cerium in plating bath. The cerium content in the electroless Co-Ni-B-Ce alloy increases at first with the increase of cerium in bath and decreases with maximum value at Ce=0.8 g/L in plating baths. Under the action of magnetic field and rare metal cerium, the boron content in alloy is decreased, while cobalt and nickel contents are increased. As a resolut, a amorphous Co-Ni-B alloy is transformed to microcrystalline Co-Ni-B-Ce alloy when plating in is common state, and the latter plated in magnetic field is crystallized.
The electrochemical property, chemical composition and crystal structure of electroless Co-Ni-B-Ce alloy plated in common state as well as in magnetic field were studied by means of potentiometer, plasma transmitting spectrometer, electron energy spectrometer, X-ray diffractometer and transmission electron microscope. The results showed that the static potential and polarizability of electroless Co-Ni-B alloy are remarkably improved as the plating is carried out in magnetic field in the presence of a little amount of cerium in plating bath. The cerium content in the electroless Co-Ni-B-Ce alloy increases at first with the increase of cerium in bath and decreases with maximum value at Ce=0.8 g/L in plating baths. Under the action of magnetic field and rare metal cerium, the boron content in alloy is decreased, while cobalt and nickel contents are increased. As a resolut, a amorphous Co-Ni-B alloy is transformed to microcrystalline Co-Ni-B-Ce alloy when plating in is common state, and the latter plated in magnetic field is crystallized.
2003, 20(12): 1148-1151
Abstract:
Tea-polyphenols was chosen as a precipitant to react with aluminum ion in aqueous solution for preparing aluminum tea-polyphenols precursor, the optimal pH value of the reactant solution for complete precipitation was 5.6. When the precursor was heated at 1 030℃ in an O2-rich atmosphere for 90~150 min, aluminum oxide powders with alumina content of 99.51% were prepared. The samples were characterized by DTA, TEM and XRD techniques. The resulting samples are nanomaterials consist of nearly spherical α-Al2O3 particles with diameter of 50 nm.
Tea-polyphenols was chosen as a precipitant to react with aluminum ion in aqueous solution for preparing aluminum tea-polyphenols precursor, the optimal pH value of the reactant solution for complete precipitation was 5.6. When the precursor was heated at 1 030℃ in an O2-rich atmosphere for 90~150 min, aluminum oxide powders with alumina content of 99.51% were prepared. The samples were characterized by DTA, TEM and XRD techniques. The resulting samples are nanomaterials consist of nearly spherical α-Al2O3 particles with diameter of 50 nm.
2003, 20(12): 1152-1156
Abstract:
The precursors of chloramphenicol enantiomers were resolved by capillary electrophoresis with conductance detection. The separation was performed on a fused-silica capillary of 50 μm×50 cm. A big anion formed by reaction of H3BO3 with β-CD was used as a chiral selector in a NaOH-Cit containing 9.0 mmol/L H3BO3 and 7.0 mmol/L β-CD solution(pH=3.0). Separation parameters, such as pH, concentration of running buffer and chiral selector, applied voltage were investigated. An attempt was made to elucidate the plausible mechanism of the chiral recognition. It was found that baseline separation of the enantiomers could be accomplished in 20 min under the optimum condition. Results indicated the simplicity and reliability of the enantiotropic separation for the chloramphenicol precursors.
The precursors of chloramphenicol enantiomers were resolved by capillary electrophoresis with conductance detection. The separation was performed on a fused-silica capillary of 50 μm×50 cm. A big anion formed by reaction of H3BO3 with β-CD was used as a chiral selector in a NaOH-Cit containing 9.0 mmol/L H3BO3 and 7.0 mmol/L β-CD solution(pH=3.0). Separation parameters, such as pH, concentration of running buffer and chiral selector, applied voltage were investigated. An attempt was made to elucidate the plausible mechanism of the chiral recognition. It was found that baseline separation of the enantiomers could be accomplished in 20 min under the optimum condition. Results indicated the simplicity and reliability of the enantiotropic separation for the chloramphenicol precursors.
2003, 20(12): 1157-1160
Abstract:
Oil soluble tin nanoparticles with average diameter of 40 nm have been successfully prepared by solution dispersion method. The effects of additive concentration, load applied and operating time on its antiwear and friction reduction properties as function of additive concentration in oil have been evaluated on a four-ball tester. The results show that tin nanoparticles, in the mass fraction range of 0.12%~3.00%, exhibited excellent antiwear and friction reduction properties, and could considerably improve scuffing load. The best antiwear properties were obtained at concentrations of 1.00%~2.00%. An antiwear mechanism of tin nanoparticle is proposed based on the hypothesis of transfer from "tin particle roller" into "liquid droplet roller" occuring on the friction surface.
Oil soluble tin nanoparticles with average diameter of 40 nm have been successfully prepared by solution dispersion method. The effects of additive concentration, load applied and operating time on its antiwear and friction reduction properties as function of additive concentration in oil have been evaluated on a four-ball tester. The results show that tin nanoparticles, in the mass fraction range of 0.12%~3.00%, exhibited excellent antiwear and friction reduction properties, and could considerably improve scuffing load. The best antiwear properties were obtained at concentrations of 1.00%~2.00%. An antiwear mechanism of tin nanoparticle is proposed based on the hypothesis of transfer from "tin particle roller" into "liquid droplet roller" occuring on the friction surface.
2003, 20(12): 1161-1165
Abstract:
Twelve isopentenylflavanone derivatives such as 3',5'-diisopentenyl-4'-hydroxy-2-phenyl-4H-1-benzopyran-4-one were synthesized by the reaction of isopentenylcinnamic acid with substituted phenols in the yield 69%~30%. The structures of title compounds(Ⅲa~Ⅲl) were confirmed by elemental analysis, IR, 1H NMR and MS. The physical, chemical and spectroscopic properties of these compounds were investigated. The reaction method and reaction condition had been compared and analysized. It was found that the new reaction was precede the classical. It was found from biological test that some of these compounds had good fungicidal activity. Especially inhibition rate of compound Ⅲd to Anthracnosis cucumaria and Rhizotonia Solani Kuhn. And that of compound Ⅲb, Ⅲc, Ⅲf to Piricularia oryzae Cav arrive at 100%. Most compounds showed fungicidal activity close to 90%. It provides that isopentenyl substituentes might evidently enhance fungicidal activity of this kind of the compounds.
Twelve isopentenylflavanone derivatives such as 3',5'-diisopentenyl-4'-hydroxy-2-phenyl-4H-1-benzopyran-4-one were synthesized by the reaction of isopentenylcinnamic acid with substituted phenols in the yield 69%~30%. The structures of title compounds(Ⅲa~Ⅲl) were confirmed by elemental analysis, IR, 1H NMR and MS. The physical, chemical and spectroscopic properties of these compounds were investigated. The reaction method and reaction condition had been compared and analysized. It was found that the new reaction was precede the classical. It was found from biological test that some of these compounds had good fungicidal activity. Especially inhibition rate of compound Ⅲd to Anthracnosis cucumaria and Rhizotonia Solani Kuhn. And that of compound Ⅲb, Ⅲc, Ⅲf to Piricularia oryzae Cav arrive at 100%. Most compounds showed fungicidal activity close to 90%. It provides that isopentenyl substituentes might evidently enhance fungicidal activity of this kind of the compounds.
2003, 20(12): 1166-1170
Abstract:
A double transparent window, double-walled IR reflected thin layer electrochemical cell is described. The cell is fit for both aqueous system and non-aqueous system. The results of electrochemical evaluation of K4Fe(CN)6 aqueous solution and catechol、hydroquinone in acetonitrile solution showed that the impedance effect and edging effect of the cell could be controlled to a great degree. In the spectra of in-situ FTIR spectroelectrochemical evaluation for cell in aqueous K4Fe(CN)6 solution, the negative-going C-N peak of Fe(CN)63- and the positive-going C-N peak of Fe(CN)64- were observed clearly during the oxidation process, in accordance with that reported in literatures. Meanwhile, at the low-temperature in-situ FTIR spectroelectrochemical experiment of hydroquinone in acetonitrile solution using liquid N2 as refrigerant the clear redox IR spectra with good signal-noise ratio were also obtained.
A double transparent window, double-walled IR reflected thin layer electrochemical cell is described. The cell is fit for both aqueous system and non-aqueous system. The results of electrochemical evaluation of K4Fe(CN)6 aqueous solution and catechol、hydroquinone in acetonitrile solution showed that the impedance effect and edging effect of the cell could be controlled to a great degree. In the spectra of in-situ FTIR spectroelectrochemical evaluation for cell in aqueous K4Fe(CN)6 solution, the negative-going C-N peak of Fe(CN)63- and the positive-going C-N peak of Fe(CN)64- were observed clearly during the oxidation process, in accordance with that reported in literatures. Meanwhile, at the low-temperature in-situ FTIR spectroelectrochemical experiment of hydroquinone in acetonitrile solution using liquid N2 as refrigerant the clear redox IR spectra with good signal-noise ratio were also obtained.
2003, 20(12): 1171-1175
Abstract:
The spinel lithium manganese mixed oxides(Li1+xMn2O4) were prepared from lithium nitrate, manganese acetate and citric acid by a sol-gel method and studied by powder XRD, FTIR, TG-DTA, cyclic voltammetry and constant current charging-discharging technique. The doped amount of lithium has obvious influence on the structure, initial discharge capacity and cycling performance of the mixed oxide. The charge-discharge mechanism was analyzed. The XRD results revealed the lithium manganese oxides with excessive lithium has a spinel structure. The cell constants become small and the crystal was stable when the molar ratio of lithium to manganese was 1.05:2. Two redox peaks were recorded on the cyclic voltammograms of the spinel lithium manganese oxide. The oxide has high initial discharge capacity and good reversibility. The mixed oxide Li1.05Mn2O4 has the highest capacity and cycling stability.
The spinel lithium manganese mixed oxides(Li1+xMn2O4) were prepared from lithium nitrate, manganese acetate and citric acid by a sol-gel method and studied by powder XRD, FTIR, TG-DTA, cyclic voltammetry and constant current charging-discharging technique. The doped amount of lithium has obvious influence on the structure, initial discharge capacity and cycling performance of the mixed oxide. The charge-discharge mechanism was analyzed. The XRD results revealed the lithium manganese oxides with excessive lithium has a spinel structure. The cell constants become small and the crystal was stable when the molar ratio of lithium to manganese was 1.05:2. Two redox peaks were recorded on the cyclic voltammograms of the spinel lithium manganese oxide. The oxide has high initial discharge capacity and good reversibility. The mixed oxide Li1.05Mn2O4 has the highest capacity and cycling stability.
2003, 20(12): 1176-1179
Abstract:
A fluorescent reagent, N-9-acridinyl amino acetic acid was synthesized by three methods. The yield of the second method was 78.9%. The product was characterized by IR and 1H NMR. Its fluorescence and UV spectra were studied. A maximum fluorescence intensity(F) of the sample was recorded in NH4Cl/NH3·H2O buffer system(pH=9.0). The excitation wavelength and emission wavelength were 268 nm and 460 nm respectively. The UV absorption peaks of the product were at 209 nm、253 nm and 385 nm. The fluorescent reagent has a promising use for highly selective and sensitive determination of some ions or bio-macromolecules.
A fluorescent reagent, N-9-acridinyl amino acetic acid was synthesized by three methods. The yield of the second method was 78.9%. The product was characterized by IR and 1H NMR. Its fluorescence and UV spectra were studied. A maximum fluorescence intensity(F) of the sample was recorded in NH4Cl/NH3·H2O buffer system(pH=9.0). The excitation wavelength and emission wavelength were 268 nm and 460 nm respectively. The UV absorption peaks of the product were at 209 nm、253 nm and 385 nm. The fluorescent reagent has a promising use for highly selective and sensitive determination of some ions or bio-macromolecules.
2003, 20(12): 1180-1183
Abstract:
Effects of the emulsion liquid membrane on the transport ratio of Zn2+ were studied. The membrane is composed of an amphiphilic copolymer of dodecyl methacrylate and acrylic acid, Span-80, di(2-ethylhexyl)phosphoric acid, kerosene and paraffin oil and H2SO4 aqueose solution, which is used as membrane stabilizer, surfactant, carrier, solvent and internal phase, respectively. The results showed that the transport ratio of Zn2+ was improved greatly by the steric stabilization of the amphiphilic copolymer.The optimum condition was determined as follows:ω(P(DM-AA))=3.0%, ω(Span-80)=4.0%, ω(P204)=3.0%, ω(paraffin oil)=6.0%, V(membrane phase):V(feed phase)=1:10, [H+]=1.0 mol/L, contact time 6 min, stirring rate 200~300 r/min.
Effects of the emulsion liquid membrane on the transport ratio of Zn2+ were studied. The membrane is composed of an amphiphilic copolymer of dodecyl methacrylate and acrylic acid, Span-80, di(2-ethylhexyl)phosphoric acid, kerosene and paraffin oil and H2SO4 aqueose solution, which is used as membrane stabilizer, surfactant, carrier, solvent and internal phase, respectively. The results showed that the transport ratio of Zn2+ was improved greatly by the steric stabilization of the amphiphilic copolymer.The optimum condition was determined as follows:ω(P(DM-AA))=3.0%, ω(Span-80)=4.0%, ω(P204)=3.0%, ω(paraffin oil)=6.0%, V(membrane phase):V(feed phase)=1:10, [H+]=1.0 mol/L, contact time 6 min, stirring rate 200~300 r/min.
2003, 20(12): 1184-1187
Abstract:
The silica polyurethane(SiO2/PU) nanocomposites, were prepared from cationic polyurethane ionomers as nanocapsules and tetraethoxysilane(TEOS) as precursor of SiO2 by in-situ synthesis. The nanocomposites could be well dispersed in water-based epoxy resin. The physical properties of epoxy resin electrophoresis membrane mixed with SiO2/PU nanocomposites were measured by dynamic light scattering and other methods. It was found that the physical properties such as impact strength, adhesive force and corrosion resistance of the SiO2/PU nanocomposites were considerably improved. When the mass ratio of TEOS to PU was 30:100.
The silica polyurethane(SiO2/PU) nanocomposites, were prepared from cationic polyurethane ionomers as nanocapsules and tetraethoxysilane(TEOS) as precursor of SiO2 by in-situ synthesis. The nanocomposites could be well dispersed in water-based epoxy resin. The physical properties of epoxy resin electrophoresis membrane mixed with SiO2/PU nanocomposites were measured by dynamic light scattering and other methods. It was found that the physical properties such as impact strength, adhesive force and corrosion resistance of the SiO2/PU nanocomposites were considerably improved. When the mass ratio of TEOS to PU was 30:100.
2003, 20(12): 1188-1191
Abstract:
A gel was formed by mixing MMA and rare earth (Sm, Dy, Er, and Tb) isopropoxide in N2 atmosphere. The modified PMMA materials doped with rare earth were prepared by the in-situ polymerization. The materials as characterized by FT-IR, TG, DMTA and ESEM show crosslinked structure feature without viscous flow state and no congragations were observed and most are swollen in good solvents for PMMA. The glass transition temperatures of the modified PMMA are lowered about 10℃ than that of the pure PMMA, while their decomposition temperatures are higher in 50℃ or more at the same mass loss level..
A gel was formed by mixing MMA and rare earth (Sm, Dy, Er, and Tb) isopropoxide in N2 atmosphere. The modified PMMA materials doped with rare earth were prepared by the in-situ polymerization. The materials as characterized by FT-IR, TG, DMTA and ESEM show crosslinked structure feature without viscous flow state and no congragations were observed and most are swollen in good solvents for PMMA. The glass transition temperatures of the modified PMMA are lowered about 10℃ than that of the pure PMMA, while their decomposition temperatures are higher in 50℃ or more at the same mass loss level..
2003, 20(12): 1192-1195
Abstract:
The non-isothermal crystallization of poly(ε-caprolactone)(PCL) samples with different molecular weight was studied by FT-infrared spectrometry. The non-isothermal crystallization parameters of PCL were obtained by quantitative analysis on the characteristic bands. The crystallization rate and the initiation temperature of crystallization increased with increase in the molecular weight of PCL. The non-isothermal crystallization parameters obtained by FTIR were consistent with those obtained by DSC.
The non-isothermal crystallization of poly(ε-caprolactone)(PCL) samples with different molecular weight was studied by FT-infrared spectrometry. The non-isothermal crystallization parameters of PCL were obtained by quantitative analysis on the characteristic bands. The crystallization rate and the initiation temperature of crystallization increased with increase in the molecular weight of PCL. The non-isothermal crystallization parameters obtained by FTIR were consistent with those obtained by DSC.
2003, 20(12): 1196-1199
Abstract:
The RE3+-N,N-bis(2-pyrrolidone-1-methylene)-β-alanine(PMA)-o-phenathroline(phen) ternary systems were prepared. The ternary systems were found to exhibit photochromic property. Under illumination of sunlight or mercury arc lamp in an aqueous solution their color could change from yellow to green and faded back to the original yellow color, when the illumination was shutting down. The effect of pH value of the aqueous solution on the photochromism of the system has been investigated in relation with the excitation, emission of the Eu3+-PMA-phen system and absorption spectra of the Dy3+-PMA-phen system.
The RE3+-N,N-bis(2-pyrrolidone-1-methylene)-β-alanine(PMA)-o-phenathroline(phen) ternary systems were prepared. The ternary systems were found to exhibit photochromic property. Under illumination of sunlight or mercury arc lamp in an aqueous solution their color could change from yellow to green and faded back to the original yellow color, when the illumination was shutting down. The effect of pH value of the aqueous solution on the photochromism of the system has been investigated in relation with the excitation, emission of the Eu3+-PMA-phen system and absorption spectra of the Dy3+-PMA-phen system.
2003, 20(12): 1200-1203
Abstract:
When nano-SiO2 particles were treated with silane coupling agent(KH-570), the groups of -CH=CH2 were grafted on the surface of nano-SiO2 particles successfully. By using ultrasonic dispersing method, the nano-SiO2 particles mixed with MMA and BPO were dissolved in solvents of ethyl acetate/toluene with the volume ratio of 1/1. PMMA/nano-SiO2 nanocomposites were synthesized. The samples were characterized by DSC, TGA and Vis spcetroscopy. It was noted that the silica particles acted as crosslinking points in the PMMA matrix. The thermal stability and the glass transition temperature of the nanocomposites increased with the increasing of nano-SiO2 amount. The transparences of PMMA/nano-SiO2 nanocomposites, however, decreased with the increasing of nano-SiO2 amount.
When nano-SiO2 particles were treated with silane coupling agent(KH-570), the groups of -CH=CH2 were grafted on the surface of nano-SiO2 particles successfully. By using ultrasonic dispersing method, the nano-SiO2 particles mixed with MMA and BPO were dissolved in solvents of ethyl acetate/toluene with the volume ratio of 1/1. PMMA/nano-SiO2 nanocomposites were synthesized. The samples were characterized by DSC, TGA and Vis spcetroscopy. It was noted that the silica particles acted as crosslinking points in the PMMA matrix. The thermal stability and the glass transition temperature of the nanocomposites increased with the increasing of nano-SiO2 amount. The transparences of PMMA/nano-SiO2 nanocomposites, however, decreased with the increasing of nano-SiO2 amount.
2003, 20(12): 1204-1207
Abstract:
The graft copolymerization of N-isopropylacrylamide(NIPA) onto chitosan has been investigated in water using K2S2O8 as an initiator. The polymer products shows its property of thermosensitive and has been characterized by IR, XRD and TG. The effects of reaction time, temperature, amount of initiator, monomer and solvent had been studied, and the optimum condition was:Chitosan 0.3 g, K2S2O8 10 mg, 70℃, NIPA 1.5 g, H2O 15 mL, 2 h.
The graft copolymerization of N-isopropylacrylamide(NIPA) onto chitosan has been investigated in water using K2S2O8 as an initiator. The polymer products shows its property of thermosensitive and has been characterized by IR, XRD and TG. The effects of reaction time, temperature, amount of initiator, monomer and solvent had been studied, and the optimum condition was:Chitosan 0.3 g, K2S2O8 10 mg, 70℃, NIPA 1.5 g, H2O 15 mL, 2 h.
2003, 20(12): 1208-1210
Abstract:
The bactericidal activities of two series of quaternary Gemini surfactants have been examined by the suspension quantitative germicidal tests against Escherchia, Staphylococcus aureus and Candida alibicans respectively, the dodecyltrimethylammonium bromide(C12TABr) was used for comparison. All of the quaternary Gemini surfactants showed superior bactericidal activities to C12TABr due to higher densities in both headgroup charge and alkyl chains.
The bactericidal activities of two series of quaternary Gemini surfactants have been examined by the suspension quantitative germicidal tests against Escherchia, Staphylococcus aureus and Candida alibicans respectively, the dodecyltrimethylammonium bromide(C12TABr) was used for comparison. All of the quaternary Gemini surfactants showed superior bactericidal activities to C12TABr due to higher densities in both headgroup charge and alkyl chains.
2003, 20(12): 1211-1213
Abstract:
Wittig-Horner method for the synthesis of Vitamin A derivatives is improved:3-methyl-5-(2,6,6-trimethyl-1-cyclohexen-1-yl)-1,3(or 1,4)-pentadienyl phosphonate is reacted directly with C5-aldehyde in synthesis and a double bond rearrangment step catalysted by base is curtailed.
Wittig-Horner method for the synthesis of Vitamin A derivatives is improved:3-methyl-5-(2,6,6-trimethyl-1-cyclohexen-1-yl)-1,3(or 1,4)-pentadienyl phosphonate is reacted directly with C5-aldehyde in synthesis and a double bond rearrangment step catalysted by base is curtailed.
2003, 20(12): 1214-1216
Abstract:
Adsorptive resin was used to extract syringin from Acanthopanax senticosus, and the content of syringin was assayed by HPLC. Some factors affecting the extraction efficiency such as resin type, resin amount, eluent type, eluent flow rate and amount were examined. The optimal purification condition was selected.
Adsorptive resin was used to extract syringin from Acanthopanax senticosus, and the content of syringin was assayed by HPLC. Some factors affecting the extraction efficiency such as resin type, resin amount, eluent type, eluent flow rate and amount were examined. The optimal purification condition was selected.
2003, 20(12): 1217-1219
Abstract:
Supercritical CO2 extraction was applied to the extraction of flavonoids from licorice. The optimized conditions are: CO2 pressure 30 MPa, temperature 50℃, solid to entrainer ratio 1:5(g/mL), CO2 flow rate 10 kg/h, separation pressure 5.5 MPa temperature 40℃. Results showed that the flavonoids yield obtained by supercritical CO2 extraction was 2.2 times that obtained by common solvent extraction method.
Supercritical CO2 extraction was applied to the extraction of flavonoids from licorice. The optimized conditions are: CO2 pressure 30 MPa, temperature 50℃, solid to entrainer ratio 1:5(g/mL), CO2 flow rate 10 kg/h, separation pressure 5.5 MPa temperature 40℃. Results showed that the flavonoids yield obtained by supercritical CO2 extraction was 2.2 times that obtained by common solvent extraction method.
2003, 20(12): 1220-1221
Abstract:
The oxdio-degradation of peat by nitric acid followed with extraction of humic acid(HA) and fulvic acid(FA) by sodium hydroxide has been carried out to increase the productivity of FA from peat. The additional FA could be obtained from filtrate by precitation with Al2(SO4)3solution. At optimum conditions the extracts of HA and FA from peat were 45.11% and 7.88%, respectively.
The oxdio-degradation of peat by nitric acid followed with extraction of humic acid(HA) and fulvic acid(FA) by sodium hydroxide has been carried out to increase the productivity of FA from peat. The additional FA could be obtained from filtrate by precitation with Al2(SO4)3solution. At optimum conditions the extracts of HA and FA from peat were 45.11% and 7.88%, respectively.
2003, 20(12): 1222-1224
Abstract:
The photocatalyst consisted of titanium dioxide loaded on natural zeolite was prepared by impregnation of tetrabutyl titanate acidic solution followed by calcination. The photocatalytic activity of the catalyst towards dichlorvos has been examined as function of TiO2 amount, calcination temperature of precursor, pH of sample solution and added amount of H2O2. The results indicated that the catalyst prepared by calcination at 200℃ showed the highest activity and 89% of Dichlorvos in concentration of 1.0×10-4 mol/L could be degraded over the catalyst under sunlight illumination for 6 hours.
The photocatalyst consisted of titanium dioxide loaded on natural zeolite was prepared by impregnation of tetrabutyl titanate acidic solution followed by calcination. The photocatalytic activity of the catalyst towards dichlorvos has been examined as function of TiO2 amount, calcination temperature of precursor, pH of sample solution and added amount of H2O2. The results indicated that the catalyst prepared by calcination at 200℃ showed the highest activity and 89% of Dichlorvos in concentration of 1.0×10-4 mol/L could be degraded over the catalyst under sunlight illumination for 6 hours.
