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2010 Volume 27 Issue 8
2010, 27(8): 869-874
doi: 10.3724/SP.J.1095.2010.90726
Abstract:
In recent years,significant developments in direct formic acid fuel cell(DFAFC) have been made. It was reported that the largest energy density of DFAFC with Pd as anodic catalyst is 0.25 W/cm2,which is close to that of proton exchange membrane fuel cell(PEMFC) with hydrogen as fuel and indicates the excellent development prospects of DFAFC. This review summarized the research development in DFAFC, the mechanism of the oxidation of formic acid,the underlined reason and mechanism of the increase in the performance of Pd based composite catalysts,the main problems of DFAFC and described its development prospects.
In recent years,significant developments in direct formic acid fuel cell(DFAFC) have been made. It was reported that the largest energy density of DFAFC with Pd as anodic catalyst is 0.25 W/cm2,which is close to that of proton exchange membrane fuel cell(PEMFC) with hydrogen as fuel and indicates the excellent development prospects of DFAFC. This review summarized the research development in DFAFC, the mechanism of the oxidation of formic acid,the underlined reason and mechanism of the increase in the performance of Pd based composite catalysts,the main problems of DFAFC and described its development prospects.
2010, 27(8): 875-881
doi: 10.3724/SP.J.1095.2010.90652
Abstract:
In the presence of mercaptoethanol as chain-transfer agent,hydroxyl-terminated polyacrylate(PA) with a certain molecular mass was synthesized by solution free-radical polymerization of butyl acrylate(BA) and methyl methacrylate (MMA). The PA-PU-PA hybrid emulsion was obtained by reacting PA with polyurethane(PU) prepolymer in water. FTIR and 1H NMR results of the copolymer chain structure show that when PU/PA mass ratio declined,the acrylic content in the copolymer increased and the role of hydrogen bonds between PU soft and hard segment weakened. The composite particles had homogeneous core-shell structure in TEM photograph. Waterproof and heat resistant performance of the modified latex film were improved with the decrease of PU/PA mass ratio. Water absorption of the modified film dropped from 25% to 5% and the maximum mass loss temperature was increased from 369℃ to 432℃.
In the presence of mercaptoethanol as chain-transfer agent,hydroxyl-terminated polyacrylate(PA) with a certain molecular mass was synthesized by solution free-radical polymerization of butyl acrylate(BA) and methyl methacrylate (MMA). The PA-PU-PA hybrid emulsion was obtained by reacting PA with polyurethane(PU) prepolymer in water. FTIR and 1H NMR results of the copolymer chain structure show that when PU/PA mass ratio declined,the acrylic content in the copolymer increased and the role of hydrogen bonds between PU soft and hard segment weakened. The composite particles had homogeneous core-shell structure in TEM photograph. Waterproof and heat resistant performance of the modified latex film were improved with the decrease of PU/PA mass ratio. Water absorption of the modified film dropped from 25% to 5% and the maximum mass loss temperature was increased from 369℃ to 432℃.
2010, 27(8): 882-886
doi: 10.3724/SP.J.1095.2010.90727
Abstract:
Immobilized ligand was synthesized via the Michael addition reaction between methyl acrylate (MA) and triethylenetetramine(TETA) on the surfaces of nano-silica organic/inorganic hybrid particles. The resulting immobilized ligand was utilized for the atom transfer radical polymerization(ATRP) of methyl methacrylate(MMA). Kinetic curves show the linear dependence of ln[c(M0)/c(Mt)]on time,and the molecular mass of poly (methyl methacrylate) increases linearly with monomer conversion. Compared with traditional ATRP processes,the immobilized catalyst could be easily separated and collected from final product by centrifugation. The activity of reclaimed catalyst could be retained and the catalyst can be reused for the ATRP of MMA with controllable polymerization reaction.
Immobilized ligand was synthesized via the Michael addition reaction between methyl acrylate (MA) and triethylenetetramine(TETA) on the surfaces of nano-silica organic/inorganic hybrid particles. The resulting immobilized ligand was utilized for the atom transfer radical polymerization(ATRP) of methyl methacrylate(MMA). Kinetic curves show the linear dependence of ln[c(M0)/c(Mt)]on time,and the molecular mass of poly (methyl methacrylate) increases linearly with monomer conversion. Compared with traditional ATRP processes,the immobilized catalyst could be easily separated and collected from final product by centrifugation. The activity of reclaimed catalyst could be retained and the catalyst can be reused for the ATRP of MMA with controllable polymerization reaction.
2010, 27(8): 887-892
doi: 10.3724/SP.J.1095.2010.90684
Abstract:
Poly(N,N-diallyl-N-carbobutoxymethylammonium chloride)(PDACBMAC) was prepared from N,N-diallyl-N-carbobutoxymethylammonium chloride (DACBMAC) as monomer and ammonium peroxydisulfate (APS) as initiator in water solution,and its structure was characterized by FT-IR and 1H NMR. The sterilizating property of PDACBMAC against Escherichia coli(E. coli) and its antimicrobial mechanism were also studied. The results show that the sterilizating potency of PDACBMAC against E. coli is obviously higher than that of poly (dimethyldiallylammonium chloride) (PDMDAAC) and slightly higher than that of dodecyldimethylbenzylammonium chloride(DDBAC) when the dosage is below 20 mg/L,and the bactericidal ratio is up to 99.7% when the intrinsic viscosity of PDACBMAC is 1.371 dL/g and the dosage is 30 mg/L. The bactericidal ratio is affected obviously by pH value,which increases with increasing pH in a range of 4.7~6.7,and decreases with increasing pH when pH > 6.7. The results of testing turbidity for the treated water sample show that PDACBMAC still possesses an excellent coagulation property. The results of measuring activities of the enzyme of β-D-galactosidase show that the antimicrobial mechanism of PDACBMAC is based on a sterilization action.
Poly(N,N-diallyl-N-carbobutoxymethylammonium chloride)(PDACBMAC) was prepared from N,N-diallyl-N-carbobutoxymethylammonium chloride (DACBMAC) as monomer and ammonium peroxydisulfate (APS) as initiator in water solution,and its structure was characterized by FT-IR and 1H NMR. The sterilizating property of PDACBMAC against Escherichia coli(E. coli) and its antimicrobial mechanism were also studied. The results show that the sterilizating potency of PDACBMAC against E. coli is obviously higher than that of poly (dimethyldiallylammonium chloride) (PDMDAAC) and slightly higher than that of dodecyldimethylbenzylammonium chloride(DDBAC) when the dosage is below 20 mg/L,and the bactericidal ratio is up to 99.7% when the intrinsic viscosity of PDACBMAC is 1.371 dL/g and the dosage is 30 mg/L. The bactericidal ratio is affected obviously by pH value,which increases with increasing pH in a range of 4.7~6.7,and decreases with increasing pH when pH > 6.7. The results of testing turbidity for the treated water sample show that PDACBMAC still possesses an excellent coagulation property. The results of measuring activities of the enzyme of β-D-galactosidase show that the antimicrobial mechanism of PDACBMAC is based on a sterilization action.
2010, 27(8): 893-898
doi: 10.3724/SP.J.1095.2010.90706
Abstract:
Structural modifications on 3-OH and 17-COOH were performed with ursolic acid as the starting compound. Nine compounds were synthesized and their structures were confirmed by IR,1H NMR and MS. Cell growth inhibitory effects of the derivatives against human hepato carcinoma cell HepG2 were evaluated by MTT assay. The results demonstrate that all the tested compounds exhibited certain anti-tumor activities in vitro and showed a dose-dependent manner. Derivative 9 had the best anti-cancer activity. Cell apoptosis changes were observed by Hoechst 33342/PI fluorescent stain after derivative 9 interacted with cell for 24 h. The dark blue/light red fluorescence images were taken by a laser scanning confocal microscope. Cell cycles were analyzed by flow cytometry that the cells were blocked in the S phase,and the effects were enhanced gradually with the increment of concentration.
Structural modifications on 3-OH and 17-COOH were performed with ursolic acid as the starting compound. Nine compounds were synthesized and their structures were confirmed by IR,1H NMR and MS. Cell growth inhibitory effects of the derivatives against human hepato carcinoma cell HepG2 were evaluated by MTT assay. The results demonstrate that all the tested compounds exhibited certain anti-tumor activities in vitro and showed a dose-dependent manner. Derivative 9 had the best anti-cancer activity. Cell apoptosis changes were observed by Hoechst 33342/PI fluorescent stain after derivative 9 interacted with cell for 24 h. The dark blue/light red fluorescence images were taken by a laser scanning confocal microscope. Cell cycles were analyzed by flow cytometry that the cells were blocked in the S phase,and the effects were enhanced gradually with the increment of concentration.
2010, 27(8): 899-902
doi: 10.3724/SP.J.1095.2010.90607
Abstract:
Poly (p-phenylene ethylene) s containing laterally attached push-pull unit were synthesized by Sonogashira coupling reaction in the presence of different Pd catalysts(Pd(PPh3)4 and PdCl2 (PPh3)2,PPh:P(C6H5)3). The structures and properties of the intermediate were identified by elemental analysis,IR, NMR,and so on. The polymers are soluble in common organic solvents and exhibits blue fluorescence. It has been found that the polymers prepared in the presence of different Pd catalysts have similar molecular mass and optical properties. The fact that the absorption maximum wavelength and emission maximum wavelength do not chang with the increase of the concentration of the polymers implies the electrostatic repulsion among the side chains can restrain the formation of aggregates. The optical study of the solid film of the polymers has supported the result.
Poly (p-phenylene ethylene) s containing laterally attached push-pull unit were synthesized by Sonogashira coupling reaction in the presence of different Pd catalysts(Pd(PPh3)4 and PdCl2 (PPh3)2,PPh:P(C6H5)3). The structures and properties of the intermediate were identified by elemental analysis,IR, NMR,and so on. The polymers are soluble in common organic solvents and exhibits blue fluorescence. It has been found that the polymers prepared in the presence of different Pd catalysts have similar molecular mass and optical properties. The fact that the absorption maximum wavelength and emission maximum wavelength do not chang with the increase of the concentration of the polymers implies the electrostatic repulsion among the side chains can restrain the formation of aggregates. The optical study of the solid film of the polymers has supported the result.
2010, 27(8): 903-906
doi: 10.3724/SP.J.1095.2010.90646
Abstract:
A schiff base copper complex prepared through the condensation between tris (hydroxymethyl) aminomethane and 2-pyridinecarboxaldehyde was characterized by elemental analysis,molar conductance,IR and HRMS. The interaction of the complex with culf thymus (CT-DNA) was investigated by UV spectra, viscosity measurements and DNA thermal denaturation experiments. The experimental results show that the mode of the complex bound to DNA is intercalation.
A schiff base copper complex prepared through the condensation between tris (hydroxymethyl) aminomethane and 2-pyridinecarboxaldehyde was characterized by elemental analysis,molar conductance,IR and HRMS. The interaction of the complex with culf thymus (CT-DNA) was investigated by UV spectra, viscosity measurements and DNA thermal denaturation experiments. The experimental results show that the mode of the complex bound to DNA is intercalation.
2010, 27(8): 907-910
doi: 10.3724/SP.J.1095.2010.90709
Abstract:
A lamellar mesoporous zirconia with fairly high stability was successfully synthesized using an anionic surfactant as template via a hydrothermal process and characterized by means of TG,XRD,FT-IR and N2 adsorption-desorption. The precursor of zirconia synthesized with the anionic surfactant as template and it as-product treated by NaOH solution and calcination at 500℃ both have a lamellar mesoporous structure, which implies their excellent thermal stabilities. The material owns bimodal mesoporous structure and has crystallized pore wall with a pure tetragonal phase after the decomposition of surfactant. It was also found that an alkaline treatment process plays a critical role in forming such material.
A lamellar mesoporous zirconia with fairly high stability was successfully synthesized using an anionic surfactant as template via a hydrothermal process and characterized by means of TG,XRD,FT-IR and N2 adsorption-desorption. The precursor of zirconia synthesized with the anionic surfactant as template and it as-product treated by NaOH solution and calcination at 500℃ both have a lamellar mesoporous structure, which implies their excellent thermal stabilities. The material owns bimodal mesoporous structure and has crystallized pore wall with a pure tetragonal phase after the decomposition of surfactant. It was also found that an alkaline treatment process plays a critical role in forming such material.
2010, 27(8): 911-915
doi: 10.3724/SP.J.1095.2010.90724
Abstract:
Pseudomonas stutzeri cultured in the lab were chosen to study their influences, including concentration of bacterial solution and bacterial bodies' solution,on calcium carbonate crystal growth. The kinetics and morphological variation of calcium carbonate were studied by measuring the pH and conductivity of the growth solutions. The products were characterized by XRD, SEM and FT-IR, respectively. Experimental results show that bacterial solution and bacterial bodies' solution could restrain the calcium carbonate crystallization process. Such effect could be enhanced with the increase of the concentration of bacterial solution or bacterial bodies' solution. On the basis of these results,it is fairly to speculate that the electrostatic and coordination interactions between polar groups of organic substances and Ca2+ are responsible for this morphological change. The bacterial solution could induce the formation of spherical metastable vaterite. The bacterial bodies' solution could induce the formation of hollow calcite.
Pseudomonas stutzeri cultured in the lab were chosen to study their influences, including concentration of bacterial solution and bacterial bodies' solution,on calcium carbonate crystal growth. The kinetics and morphological variation of calcium carbonate were studied by measuring the pH and conductivity of the growth solutions. The products were characterized by XRD, SEM and FT-IR, respectively. Experimental results show that bacterial solution and bacterial bodies' solution could restrain the calcium carbonate crystallization process. Such effect could be enhanced with the increase of the concentration of bacterial solution or bacterial bodies' solution. On the basis of these results,it is fairly to speculate that the electrostatic and coordination interactions between polar groups of organic substances and Ca2+ are responsible for this morphological change. The bacterial solution could induce the formation of spherical metastable vaterite. The bacterial bodies' solution could induce the formation of hollow calcite.
2010, 27(8): 916-923
doi: 10.3724/SP.J.1095.2010.90543
Abstract:
The oxidation of N,N-dimethylhydroxylamine(DMHAN) by nitrous acid in a perchloric acid and nitric acid medium as well as the effects of c (H+),c (DMHAN),ion strength and temperature on the reaction were studied. The rate equation in perchloric acid was determined as follows:-d[HNO2]/dt=k[DMHAN] [HNO2],where k=(12.8 ± 1.0) mol/(L·min) when the temperature is 18.5℃ and the ion strength is 0.73 mol/L with an activation energy about of 41.5 kJ/mol. The reaction became complicated when it was performed in nitric acid medium. The reaction between nitric acid and DMHAN occurred and nitrous acid was produced when the concentration of nitric acid was higher than 1.0 mol/L. The reaction products were analyzed and the reaction mechanism was discussed.
The oxidation of N,N-dimethylhydroxylamine(DMHAN) by nitrous acid in a perchloric acid and nitric acid medium as well as the effects of c (H+),c (DMHAN),ion strength and temperature on the reaction were studied. The rate equation in perchloric acid was determined as follows:-d[HNO2]/dt=k[DMHAN] [HNO2],where k=(12.8 ± 1.0) mol/(L·min) when the temperature is 18.5℃ and the ion strength is 0.73 mol/L with an activation energy about of 41.5 kJ/mol. The reaction became complicated when it was performed in nitric acid medium. The reaction between nitric acid and DMHAN occurred and nitrous acid was produced when the concentration of nitric acid was higher than 1.0 mol/L. The reaction products were analyzed and the reaction mechanism was discussed.
2010, 27(8): 924-930
doi: 10.3724/SP.J.1095.2010.90601
Abstract:
A series of mesoporous silica SBA-15-supported zirconium sulfate(ZS) catalysts,ZS/SBA-15, were prepared by impregnating hexagonal SBA-15 with an aqueous solution of ZS. The incorporation of ZS in the catalysts was confirmed by infrared spectroscopy (FT-IR) and X-ray energy dispersive spectrometry (EDS). X-ray diffraction(XRD) showed that ZS could be well dispersed on the support until the loading was higher than 40%. N2 adsorption-desorption and small-angle XRD were used to characterize the mesostructure of the samples. It was found that the hexagonal order and regular mesopores with unchanged pore size of SBA-15 were mostly retained after ZS incorporation; however,the intensities of XRD peaks of SBA-15 declined,and the surface area and pore volume decreased as the ZS loading increased,suggesting the partial loss of ordered mesostructure due to the impregnation of acidic ZS solution. Acid strength of the catalyst was measured via Hammett indicators. Excellent catalytic performances of these catalysts were observed in the esterifications of acetic acid with 2-ehoxyethanol and citric acid with n-butanol,respectively. The selectivities to desired esters were 100%,and the conversions of both 2-ehoxyethanol and citric acid were as high as 98% under optimal loading level and reaction conditions. The dosages of catalyst,molar ratio of alcohol to acid in reaction mixture and catalyst recycle were also investigated. The activities were decreased slightly during each recycle owing to the solubilization and loss of ZS in water,but could be mostly retained after recycle for several run times.
A series of mesoporous silica SBA-15-supported zirconium sulfate(ZS) catalysts,ZS/SBA-15, were prepared by impregnating hexagonal SBA-15 with an aqueous solution of ZS. The incorporation of ZS in the catalysts was confirmed by infrared spectroscopy (FT-IR) and X-ray energy dispersive spectrometry (EDS). X-ray diffraction(XRD) showed that ZS could be well dispersed on the support until the loading was higher than 40%. N2 adsorption-desorption and small-angle XRD were used to characterize the mesostructure of the samples. It was found that the hexagonal order and regular mesopores with unchanged pore size of SBA-15 were mostly retained after ZS incorporation; however,the intensities of XRD peaks of SBA-15 declined,and the surface area and pore volume decreased as the ZS loading increased,suggesting the partial loss of ordered mesostructure due to the impregnation of acidic ZS solution. Acid strength of the catalyst was measured via Hammett indicators. Excellent catalytic performances of these catalysts were observed in the esterifications of acetic acid with 2-ehoxyethanol and citric acid with n-butanol,respectively. The selectivities to desired esters were 100%,and the conversions of both 2-ehoxyethanol and citric acid were as high as 98% under optimal loading level and reaction conditions. The dosages of catalyst,molar ratio of alcohol to acid in reaction mixture and catalyst recycle were also investigated. The activities were decreased slightly during each recycle owing to the solubilization and loss of ZS in water,but could be mostly retained after recycle for several run times.
2010, 27(8): 931-934
doi: 10.3724/SP.J.1095.2010.90764
Abstract:
The process of persistent organic pollutants(POPs) formation was studied by using the collision chamber of tandem mass spectrometer instead of atmospheric environment. It is found that chlorobenzenes can be formed through gas phase ion-molecule reaction in the collision chamber. And the formation of chlorobenzenes in the ion source of the mass spectrometer is also observed. When benzene content is 4 × 10-3 Pa and acetyl chloride content is 4 × 10-4 Pa,the chlorobenzene content reaches 5 × 10-8 Pa,while the background of chlorobenzene is only 5 × 10-9 Pa. So it is possible that the formation of chlorobenzene by gas phase ion-molecule reactions,because chlorobenzene is formed easier in atmosphere than that in the collision chamber.
The process of persistent organic pollutants(POPs) formation was studied by using the collision chamber of tandem mass spectrometer instead of atmospheric environment. It is found that chlorobenzenes can be formed through gas phase ion-molecule reaction in the collision chamber. And the formation of chlorobenzenes in the ion source of the mass spectrometer is also observed. When benzene content is 4 × 10-3 Pa and acetyl chloride content is 4 × 10-4 Pa,the chlorobenzene content reaches 5 × 10-8 Pa,while the background of chlorobenzene is only 5 × 10-9 Pa. So it is possible that the formation of chlorobenzene by gas phase ion-molecule reactions,because chlorobenzene is formed easier in atmosphere than that in the collision chamber.
2010, 27(8): 935-938
doi: 10.3724/SP.J.1095.2010.90518
Abstract:
Light scattering(LS) technique was employed to investigate the interaction between perchlorate and cationic surfactant cetyltrimethylammonium bromide(CTAB). It was found that perchlorate could combine with CTAB in an acidic medium to form ionic associated compounds due to the electrostatic attraction,resulting in enhanced LS signals. It should be noted that anions such as Cl-,Br-,ClO3-,NO3- and PO43- can only induce weak LS signals when interacting with CTAB alone,but significant changes of LS signals can be observed once these anions coexist with perchlorate,indicating that coordinating effects exist. In order to dis-cuss the coordination mechanism,dynamic light scattering(DLS) measurements were further made with chlo-rate(Cl-) as an example.
Light scattering(LS) technique was employed to investigate the interaction between perchlorate and cationic surfactant cetyltrimethylammonium bromide(CTAB). It was found that perchlorate could combine with CTAB in an acidic medium to form ionic associated compounds due to the electrostatic attraction,resulting in enhanced LS signals. It should be noted that anions such as Cl-,Br-,ClO3-,NO3- and PO43- can only induce weak LS signals when interacting with CTAB alone,but significant changes of LS signals can be observed once these anions coexist with perchlorate,indicating that coordinating effects exist. In order to dis-cuss the coordination mechanism,dynamic light scattering(DLS) measurements were further made with chlo-rate(Cl-) as an example.
2010, 27(8): 939-943
doi: 10.3724/SP.J.1095.2010.90615
Abstract:
The first ligand of[CoCl4]2- and the second ligand of protonated N,N,N',N'-tetra-p-methyl-benzyl-ethylenediamine were used to construct a second-sphere coordination complex as the host framework. Myristicine was selectively isolated from the volatile oil of Ligustium sinense oliv by the inclusion crystalline method as the guest molecules. IR,NMR,X-ray diffraction were used to determine the structure of the inclusion complex,and the host-guest molar ratio in the complex was found to be 2:1. The myristicine was isolated from the inclusion complex via Kugelrohr vacuum distillation technique and was characterized by IR, NMR and GC. According to the result of GC,the content of myristicine in the volatile oil of Ligustium sinense oliv is 60.4%,and the purity of isolated myristicine reaches 100%.
The first ligand of[CoCl4]2- and the second ligand of protonated N,N,N',N'-tetra-p-methyl-benzyl-ethylenediamine were used to construct a second-sphere coordination complex as the host framework. Myristicine was selectively isolated from the volatile oil of Ligustium sinense oliv by the inclusion crystalline method as the guest molecules. IR,NMR,X-ray diffraction were used to determine the structure of the inclusion complex,and the host-guest molar ratio in the complex was found to be 2:1. The myristicine was isolated from the inclusion complex via Kugelrohr vacuum distillation technique and was characterized by IR, NMR and GC. According to the result of GC,the content of myristicine in the volatile oil of Ligustium sinense oliv is 60.4%,and the purity of isolated myristicine reaches 100%.
2010, 27(8): 944-949
doi: 10.3724/SP.J.1095.2010.90755
Abstract:
Modified multi-walled carbon nanotubes(MWCNTs) were chosen as adsorbents for the adsorption of rare earths. Nitric acid (HNO3),sodium hypochlorite (NaClO),hydrogen peroxide (H2O2),and potassium permanganate(KMnO4) were used for the modification of MWCNTs. The concentrations of rare earths were determined with UV-Vis spectrometry. The adsorption capacities of rare earths on MWCNTs treated with different modification methods were compared with each other. The experimental results indicate that MWCNTs modified with NaClO has the highest adsorption capacity of rare earths. As representitives,the adsorptions of samarium(Sm),gadolinium(Gd),and ytterbium(Yb) on MWCNTs modified with NaClO were investigated in detail. Effects of various parameters such as the rare earth concentration,pH value,ion strength,amount of MWCNTs,and experimental temperature were investigated. The adsorption of Sm,Gd and Yb onto MWCNTs modified with NaClO increased with pH value in a range of 2~7. However,the adsorption capacity of the three rare earths decreased with increasing solution ion strength and MWCNTs mass. The adsorption reactions of all the three rare earths on MWCNTs modified with NaClO were exothermic processes. The thermodynamic functions,△H,were calculated to be-6.44 kJ/mol,-5.63 kJ/mol,-8.31 kJ/mol for Sm, Gd, and Yb, respectively. Furthermore, the adsorption data were fitted with Langmuir and Freundlich isotherm models,indicating that both the models can fit the adsorption of Sm,Gd, and Yb well.
Modified multi-walled carbon nanotubes(MWCNTs) were chosen as adsorbents for the adsorption of rare earths. Nitric acid (HNO3),sodium hypochlorite (NaClO),hydrogen peroxide (H2O2),and potassium permanganate(KMnO4) were used for the modification of MWCNTs. The concentrations of rare earths were determined with UV-Vis spectrometry. The adsorption capacities of rare earths on MWCNTs treated with different modification methods were compared with each other. The experimental results indicate that MWCNTs modified with NaClO has the highest adsorption capacity of rare earths. As representitives,the adsorptions of samarium(Sm),gadolinium(Gd),and ytterbium(Yb) on MWCNTs modified with NaClO were investigated in detail. Effects of various parameters such as the rare earth concentration,pH value,ion strength,amount of MWCNTs,and experimental temperature were investigated. The adsorption of Sm,Gd and Yb onto MWCNTs modified with NaClO increased with pH value in a range of 2~7. However,the adsorption capacity of the three rare earths decreased with increasing solution ion strength and MWCNTs mass. The adsorption reactions of all the three rare earths on MWCNTs modified with NaClO were exothermic processes. The thermodynamic functions,△H,were calculated to be-6.44 kJ/mol,-5.63 kJ/mol,-8.31 kJ/mol for Sm, Gd, and Yb, respectively. Furthermore, the adsorption data were fitted with Langmuir and Freundlich isotherm models,indicating that both the models can fit the adsorption of Sm,Gd, and Yb well.
2010, 27(8): 950-954
doi: 10.3724/SP.J.1095.2010.90737
Abstract:
Salicylaldehyde-1,2-phenylenediamine(SPS) was synthesized by the reaction of salicylaldehyde with phenylenediamine. A copper(Ⅱ) ionic selective electrode with a sensitive membrane consisted of carbon paste and neutral SPS carrier was fabricated with liquid paraffin as the binder. The Cu(Ⅱ)-selective electrode was deployed to determine the concentration of SCN- anion and exhibited a Nernstian response to SCN- ions over a range of 1.0 × 10-6~1.0 × 10-2 mol/L,with a regression equation of E(mV)=-51.19 lg cSCN--853.75(r=0.9997) and a detection limit of 4.0 × 10-7 mol/L. The response time of the electrode is less than 30 s. The electrode also shows a high selectivity,good stability and durability. The electrode has been successfully applied in determing the concentrations of SCN- in waste water samples.
Salicylaldehyde-1,2-phenylenediamine(SPS) was synthesized by the reaction of salicylaldehyde with phenylenediamine. A copper(Ⅱ) ionic selective electrode with a sensitive membrane consisted of carbon paste and neutral SPS carrier was fabricated with liquid paraffin as the binder. The Cu(Ⅱ)-selective electrode was deployed to determine the concentration of SCN- anion and exhibited a Nernstian response to SCN- ions over a range of 1.0 × 10-6~1.0 × 10-2 mol/L,with a regression equation of E(mV)=-51.19 lg cSCN--853.75(r=0.9997) and a detection limit of 4.0 × 10-7 mol/L. The response time of the electrode is less than 30 s. The electrode also shows a high selectivity,good stability and durability. The electrode has been successfully applied in determing the concentrations of SCN- in waste water samples.
2010, 27(8): 955-959
doi: 10.3724/SP.J.1095.2010.90739
Abstract:
The anodic behaviors of Pb-0.07% Ca-1.2% Sn-0.05% Al-0.1% Ag-(0,0.01%,0.15%, 0.5%) mixed rare-earth alloys in sulfuric acid solution were studied by means of electrochemical impedance spectroscopy(EIS),A. C. voltammetry,cyclic voltammetry and corrosion mass loss tests,respectively. The experimental results show that the mixed rare-earth in the Pb Ca-Sn-Al-Ag alloy can improve the corrosion resistance. Moreover,the oxygen overpotentials of the electrodes with mixed rare earth are higher than those of their counterparts. The results show that the addition of rare-earth can inhibit the growth of the anodic Pb(Ⅱ) oxides and can also improve the corrosion resistance. It was shown that rare earth element can compensate for the effect of premature capacity loss for the Pb-Ca-Sn-Al-Ag content. The La-Ce mixed rare earth with a content of 0.5% exhibited better comprehensive performances in all aspects.
The anodic behaviors of Pb-0.07% Ca-1.2% Sn-0.05% Al-0.1% Ag-(0,0.01%,0.15%, 0.5%) mixed rare-earth alloys in sulfuric acid solution were studied by means of electrochemical impedance spectroscopy(EIS),A. C. voltammetry,cyclic voltammetry and corrosion mass loss tests,respectively. The experimental results show that the mixed rare-earth in the Pb Ca-Sn-Al-Ag alloy can improve the corrosion resistance. Moreover,the oxygen overpotentials of the electrodes with mixed rare earth are higher than those of their counterparts. The results show that the addition of rare-earth can inhibit the growth of the anodic Pb(Ⅱ) oxides and can also improve the corrosion resistance. It was shown that rare earth element can compensate for the effect of premature capacity loss for the Pb-Ca-Sn-Al-Ag content. The La-Ce mixed rare earth with a content of 0.5% exhibited better comprehensive performances in all aspects.
2010, 27(8): 960-964
doi: 10.3724/SP.J.1095.2010.90622
Abstract:
A highly sensitive hydrogen sulfide gas sensor was developed by immobilization of thionine dye doped polyvinyl alcohol film onto the surface of a K+-exchanged glass optical waveguide via a spin-coated method. The sensing film presents a color change from purple to colorless when exposed to H2S gas,causing a decrease in the evanescent-wave absorption of the film,and an increase of the output light intensity of the sensor(signal). The sensor performance was tested for the detection of H2 S gas by controlled flow injection. The experimental result shows that the sensor has a good linear response(r=0.99667) to H2S gas in a range of 56 mg/m3 to 0.14 mg/m3. The detection limit for H2S is 0.11 mg/m3(S/N=3). The RSD of output light intensity is 4.0% and response time (t90) < 2 s. This sensor shows high sensitivity,fast response,good reversibility and repeatability.
A highly sensitive hydrogen sulfide gas sensor was developed by immobilization of thionine dye doped polyvinyl alcohol film onto the surface of a K+-exchanged glass optical waveguide via a spin-coated method. The sensing film presents a color change from purple to colorless when exposed to H2S gas,causing a decrease in the evanescent-wave absorption of the film,and an increase of the output light intensity of the sensor(signal). The sensor performance was tested for the detection of H2 S gas by controlled flow injection. The experimental result shows that the sensor has a good linear response(r=0.99667) to H2S gas in a range of 56 mg/m3 to 0.14 mg/m3. The detection limit for H2S is 0.11 mg/m3(S/N=3). The RSD of output light intensity is 4.0% and response time (t90) < 2 s. This sensor shows high sensitivity,fast response,good reversibility and repeatability.
2010, 27(8): 965-969
doi: 10.3724/SP.J.1095.2010.90721
Abstract:
Thin films consisted of iron phosphate nanopaticles were prepared by spin-coating mixed solutions of iron nitrate,methanol and phosphate acid. The effects of coater speed and drying temperature on film thickness and refractive index were studied. It was found that when the thin films were dried at 150℃ or higher,the thickness(130 nm) and refractive index(1.7) of the thin films remained nearly unchanged. A composite optical waveguide sensing unit for ammonia vapor was fabricated by spin coating iron phosphate precursor on a single-mode potassium ion exchanged glass followed by spin coating a thin film of a pH indicator dye(bromothymol bule,BTB) onto the composite film. The experimental results show that the sensing unit has a ammonia vapor detection concentration limit of 0.35 mg/m3. It also has unique features such as fast response(10 s),short recovery time(90 s) and good reversibility and reusability.
Thin films consisted of iron phosphate nanopaticles were prepared by spin-coating mixed solutions of iron nitrate,methanol and phosphate acid. The effects of coater speed and drying temperature on film thickness and refractive index were studied. It was found that when the thin films were dried at 150℃ or higher,the thickness(130 nm) and refractive index(1.7) of the thin films remained nearly unchanged. A composite optical waveguide sensing unit for ammonia vapor was fabricated by spin coating iron phosphate precursor on a single-mode potassium ion exchanged glass followed by spin coating a thin film of a pH indicator dye(bromothymol bule,BTB) onto the composite film. The experimental results show that the sensing unit has a ammonia vapor detection concentration limit of 0.35 mg/m3. It also has unique features such as fast response(10 s),short recovery time(90 s) and good reversibility and reusability.
2010, 27(8): 970-977
doi: 10.3724/SP.J.1095.2010.90772
Abstract:
The self-assembling,hybridization and orientation of SH-ssDNA on the surface of thin-film nano-gold electrodes were characterized systematically by means of the electrochemical impedance technique. The effects of assembling time,concentration and the length of SH-ssDNA on its self-assembling were investigated. The Rct and surface coverage reached the highest values when assembling time was 15 h. The influences of the concentration and length of SH-ssDNA and its hybridization method with complementary DNA on the hybridization reaction were also studied. The result shows the change of Rct decreases with the increase of the SH-ssDNA concentration. The Rct was increased by 16% when the concentration of SH-ssDNA was 5 μmol/L. The data simulation and analysis of impedance spectroscopy indicated that a unique self-assembled monolayer of SH-ssDNA was formed with an upright orientation on the nano-Au electrode surface. The result shows the hybridization efficiency is closely associated with the coverage of SH-ssDNA.
The self-assembling,hybridization and orientation of SH-ssDNA on the surface of thin-film nano-gold electrodes were characterized systematically by means of the electrochemical impedance technique. The effects of assembling time,concentration and the length of SH-ssDNA on its self-assembling were investigated. The Rct and surface coverage reached the highest values when assembling time was 15 h. The influences of the concentration and length of SH-ssDNA and its hybridization method with complementary DNA on the hybridization reaction were also studied. The result shows the change of Rct decreases with the increase of the SH-ssDNA concentration. The Rct was increased by 16% when the concentration of SH-ssDNA was 5 μmol/L. The data simulation and analysis of impedance spectroscopy indicated that a unique self-assembled monolayer of SH-ssDNA was formed with an upright orientation on the nano-Au electrode surface. The result shows the hybridization efficiency is closely associated with the coverage of SH-ssDNA.
2010, 27(8): 978-982
doi: 10.3724/SP.J.1095.2010.90635
Abstract:
A glassy carbon electrode modified with hydrophobicity 1-n-butyl-3-methylimidazolium hexafluoro-phosphate([BMIM]PF6/GCE) was fabricated. In a 0.2 mol/L phosphate buffer solution(pH 4.0~8.0), cyclic voltammetry and differential pulse stripping voltammetry were used to investigate the electrochemical behavior of luteolin at the modified electrode and a new method for detection of luteolin was established. As a result,an improved response of luteolin at the modified electrode was observed with peak potential shift negatively and increase of peak current. An electrocatalytic quasi-reversible redox process of controlled by absorption was obtained for luteolin on the surface of the modified electrode in a potential range of-0.2~0.7 V at pH=7.0. The charge transfer coefficient(α) and adsorbed amount(Γ) were calculated to be 0.5 and 4.6 × 10-10mol/cm2,respectively. The anodic current increased linearly with luteolin concentration in a range of 1.0 × 10-10~1.6 × 10-8 mol/L with a detection limit of 3.2 × 10-11 mol/L,and the recovery is between 98.7% and 102.0%. The method is simple,quick,accurate and reliable. It may provide a novel way for flavonoid determination in wild chrysanthemum flower.
A glassy carbon electrode modified with hydrophobicity 1-n-butyl-3-methylimidazolium hexafluoro-phosphate([BMIM]PF6/GCE) was fabricated. In a 0.2 mol/L phosphate buffer solution(pH 4.0~8.0), cyclic voltammetry and differential pulse stripping voltammetry were used to investigate the electrochemical behavior of luteolin at the modified electrode and a new method for detection of luteolin was established. As a result,an improved response of luteolin at the modified electrode was observed with peak potential shift negatively and increase of peak current. An electrocatalytic quasi-reversible redox process of controlled by absorption was obtained for luteolin on the surface of the modified electrode in a potential range of-0.2~0.7 V at pH=7.0. The charge transfer coefficient(α) and adsorbed amount(Γ) were calculated to be 0.5 and 4.6 × 10-10mol/cm2,respectively. The anodic current increased linearly with luteolin concentration in a range of 1.0 × 10-10~1.6 × 10-8 mol/L with a detection limit of 3.2 × 10-11 mol/L,and the recovery is between 98.7% and 102.0%. The method is simple,quick,accurate and reliable. It may provide a novel way for flavonoid determination in wild chrysanthemum flower.
2010, 27(8): 983-986
doi: 10.3724/SP.J.1095.2010.90788
Abstract:
The alumina superfine powder was preparated by chemical precipitation with AlCl3 and ammonia as raw material. Results show that the pH value of the precipitation process influences the crystallinity of productboehmite greatly. The precursor was dried by the spray drying technology,and the powder was calcined at different temperatures in a tubular furnace. Al2O3-superfine powder was tested by means of XRD,BET,and SEM,and so on. It shows that the higher pH value in the precipitation process is in favor of the raising of the product's crystallinity. The order of phase change during calcination process is AlOOH→Amorphous-Al2O3 + γ-Al2O3→θ-Al2O3 →α-Al2O3. The powder obtained by spray drying has morphology of disc-shape or round bowl-shape with uniformity. The range of the particle size distribution is narrow,and the diameter of the powder is between 4 and 10 μm. The surface area of the powder is about 391 m2/g,and it can still reach 185 m2/g after calcining at 1200℃ for 2 h.
The alumina superfine powder was preparated by chemical precipitation with AlCl3 and ammonia as raw material. Results show that the pH value of the precipitation process influences the crystallinity of productboehmite greatly. The precursor was dried by the spray drying technology,and the powder was calcined at different temperatures in a tubular furnace. Al2O3-superfine powder was tested by means of XRD,BET,and SEM,and so on. It shows that the higher pH value in the precipitation process is in favor of the raising of the product's crystallinity. The order of phase change during calcination process is AlOOH→Amorphous-Al2O3 + γ-Al2O3→θ-Al2O3 →α-Al2O3. The powder obtained by spray drying has morphology of disc-shape or round bowl-shape with uniformity. The range of the particle size distribution is narrow,and the diameter of the powder is between 4 and 10 μm. The surface area of the powder is about 391 m2/g,and it can still reach 185 m2/g after calcining at 1200℃ for 2 h.
2010, 27(8): 987-989
doi: 10.3724/SP.J.1095.2010.90675
Abstract:
Ion beam bombardment was used to bombard the carbon nanotubes. Scanning electron microscopy photographs indicate that ion beam bombardment can eliminate the impurities conveniently. On the other hand,Raman spectra analysis results show that ion beam bombardment do not cause obvious damages on carbon nanotubes. Urea added to carbon nanotubes as an impurity disappears after being irradiating, indicating that the main mechanism of the impurities removal by ion beam is sputtering effect.
Ion beam bombardment was used to bombard the carbon nanotubes. Scanning electron microscopy photographs indicate that ion beam bombardment can eliminate the impurities conveniently. On the other hand,Raman spectra analysis results show that ion beam bombardment do not cause obvious damages on carbon nanotubes. Urea added to carbon nanotubes as an impurity disappears after being irradiating, indicating that the main mechanism of the impurities removal by ion beam is sputtering effect.
2010, 27(8): 990-992
doi: 10.3724/SP.J.1095.2010.90738
Abstract:
The polyoxometalates α-Na10 (PW9V3(H2O)3O37)·16H2O,α-Na10 (PW11V(H2O)O37)·16H2O and [H3O]3 [NH4]18[Mo57V6O183(NO)6(H2O)48]·56H2O (abbreviated as α-PW9V3,α-PW11V and Mo57V6,respectively) were prepared using a reported method. Their antibacterial activities against common bacteria,Escherichia coli,Bacillus subtilis,yeast and Aspergillus niger,were studied by a disk diffusion method. They all showed fairly strong antibacterial activities with α-PW11V being the highest among them.
The polyoxometalates α-Na10 (PW9V3(H2O)3O37)·16H2O,α-Na10 (PW11V(H2O)O37)·16H2O and [H3O]3 [NH4]18[Mo57V6O183(NO)6(H2O)48]·56H2O (abbreviated as α-PW9V3,α-PW11V and Mo57V6,respectively) were prepared using a reported method. Their antibacterial activities against common bacteria,Escherichia coli,Bacillus subtilis,yeast and Aspergillus niger,were studied by a disk diffusion method. They all showed fairly strong antibacterial activities with α-PW11V being the highest among them.
