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2019 Volume 36 Issue 11
2019, 36(11): 1221-1236
doi: 10.11944/j.issn.1000-0518.2019.11.190146
Abstract:
The pollution issues of water and air in China currently become severe. Many pollutants that endanger people's health are urgently needed to be treated. As a kind of emerging porous material, the metal-organic framework has many applications in the treatment processes of pollutants. This paper introduces the structural information of chromium terephthalate metal organic framework material (MIL-101) and its functionally modified materials. The main synthesis methods of this material are summarized as well. The research progress of the application of this material in the environmental pollutant removal is analyzed, including the adsorption treatment of heavy metal ions, pesticides, antibiotics, organic dyes and iodide ions, etc. It also has the potential of monitoring pollutants and risk warning. This paper also points out some problems which are still pending.
The pollution issues of water and air in China currently become severe. Many pollutants that endanger people's health are urgently needed to be treated. As a kind of emerging porous material, the metal-organic framework has many applications in the treatment processes of pollutants. This paper introduces the structural information of chromium terephthalate metal organic framework material (MIL-101) and its functionally modified materials. The main synthesis methods of this material are summarized as well. The research progress of the application of this material in the environmental pollutant removal is analyzed, including the adsorption treatment of heavy metal ions, pesticides, antibiotics, organic dyes and iodide ions, etc. It also has the potential of monitoring pollutants and risk warning. This paper also points out some problems which are still pending.
2019, 36(11): 1237-1247
doi: 10.11944/j.issn.1000-0518.2019.11.190115
Abstract:
Four commercial low density polyethylene(LDPE) resins with different melt flow rates were selected and their chain microstructures and the rheological properties were studied by high-temperature gel permeation chromatography(HT-GPC), 13carbon nuclear magnetic resonance spectroscopy(13C NMR), differential scanning calorimetry(DSC) and rheometer. The above resins are divided into two groups, D-1 and Q-1, D-3 and Y-1. Two resins in the same group have similar relative molecular mass. The results of 13C NMR spectroscopy show that the four LDPE resins not only contain short chain branches(SCB), but also have long chain branches(LCB), and the content of SCB is much higher than that of LCB, while the butyl branch in SCB is the highest one. The thermal fractionation(successive self-nucleation/annealing, SSA) results show that every resin contains different crystallizable methylene sequence lengths, i.e., the distribution of SCB in the intramolecular chain exhibits heterogeneity. The effects of molecular mass and its distribution, methylene sequence length and its distribution, branching content and crystallinity on melting behavior, rheological behavior and mechanical properties of the films were investigated. It is found that the low relative molecular mass end in Q-1 and LCB content in Y-1 influence their melt flow rate, the average methylene sequence length determines the melt temperature peaks, and the crystallinity influences the mechanical property of films. Based on the above results, the relationship between structure and property is established.
Four commercial low density polyethylene(LDPE) resins with different melt flow rates were selected and their chain microstructures and the rheological properties were studied by high-temperature gel permeation chromatography(HT-GPC), 13carbon nuclear magnetic resonance spectroscopy(13C NMR), differential scanning calorimetry(DSC) and rheometer. The above resins are divided into two groups, D-1 and Q-1, D-3 and Y-1. Two resins in the same group have similar relative molecular mass. The results of 13C NMR spectroscopy show that the four LDPE resins not only contain short chain branches(SCB), but also have long chain branches(LCB), and the content of SCB is much higher than that of LCB, while the butyl branch in SCB is the highest one. The thermal fractionation(successive self-nucleation/annealing, SSA) results show that every resin contains different crystallizable methylene sequence lengths, i.e., the distribution of SCB in the intramolecular chain exhibits heterogeneity. The effects of molecular mass and its distribution, methylene sequence length and its distribution, branching content and crystallinity on melting behavior, rheological behavior and mechanical properties of the films were investigated. It is found that the low relative molecular mass end in Q-1 and LCB content in Y-1 influence their melt flow rate, the average methylene sequence length determines the melt temperature peaks, and the crystallinity influences the mechanical property of films. Based on the above results, the relationship between structure and property is established.
2019, 36(11): 1248-1256
doi: 10.11944/j.issn.1000-0518.2019.11.190210
Abstract:
CO2 based plastics (PPC) is a high molecular mass copolymer of carbon dioxide and propylene oxide. PPC is quite sensitive to ultraviolet (UV) irradiation and its molecular mass decreases quickly with UV-irradiation accompanied by significant loss of mechanical strength. To improve the UV irradiation resistance of PPC is of key importance for its application as agricultural mulching film, which is always under UV irradiation during the whole coverage. In this work, an epoxide with UV absorber function, i.e., 2-hydroxy-4(2, 3-epoxypropoxy)benzophenone (HEB), was designed and prepared. By means of terpolymerization of CO2, propylene oxide and HEB, terpolymer PPCH with UV absorber side chain was successfully synthesized, where the chemical structure as well as the HEB content was determined by 1H NMR spectroscopy. Under the premise of ensuring PPCH molecular mass not less than 5.0×104, the maximum molar fraction of HEB incorporated into the PPCH terpolymer was 0.32%, and such PPCH showed a tensile strength of 30.97 MPa, a glass transition temperature (Tg) of 26.7℃, and the temperature at 5% mass loss of thermal decomposition (Td-5%) of 216.9℃. When PPC was exposed under UV irradiation for 240 h, its number-average molecular mass decreased by 67.8%, accompanied by 10.1% loss of tensile strength and 40.1% loss of elongation at break. As a comparison, the number-average molecular mass of PPCH with 0.06% molar fraction HEB showed only 6.2% decrease correspondingly. It showed 1.7% loss of tensile strength and 13.3% decrease of elongation at break, indicating that PPCH had improved UV-irradiation resistance performance due to the existence of UV absorbable functional group like HEB. PPCH and PPC blended with similar 2, 4-dihydroxyl benzophenone (BP) content were compared for hot water (50℃) extraction test. No BP was extracted in PPCH providing stable UV absorption performance, while the PPC/BP blend showed sharp drop in UV absorption upon hot water extraction. Therefore, terpolymerization of CO2, propylene oxide with UV absorbable monomer is an effective way to improve the UV irradiation resistance performance of CO2 copolymer.
CO2 based plastics (PPC) is a high molecular mass copolymer of carbon dioxide and propylene oxide. PPC is quite sensitive to ultraviolet (UV) irradiation and its molecular mass decreases quickly with UV-irradiation accompanied by significant loss of mechanical strength. To improve the UV irradiation resistance of PPC is of key importance for its application as agricultural mulching film, which is always under UV irradiation during the whole coverage. In this work, an epoxide with UV absorber function, i.e., 2-hydroxy-4(2, 3-epoxypropoxy)benzophenone (HEB), was designed and prepared. By means of terpolymerization of CO2, propylene oxide and HEB, terpolymer PPCH with UV absorber side chain was successfully synthesized, where the chemical structure as well as the HEB content was determined by 1H NMR spectroscopy. Under the premise of ensuring PPCH molecular mass not less than 5.0×104, the maximum molar fraction of HEB incorporated into the PPCH terpolymer was 0.32%, and such PPCH showed a tensile strength of 30.97 MPa, a glass transition temperature (Tg) of 26.7℃, and the temperature at 5% mass loss of thermal decomposition (Td-5%) of 216.9℃. When PPC was exposed under UV irradiation for 240 h, its number-average molecular mass decreased by 67.8%, accompanied by 10.1% loss of tensile strength and 40.1% loss of elongation at break. As a comparison, the number-average molecular mass of PPCH with 0.06% molar fraction HEB showed only 6.2% decrease correspondingly. It showed 1.7% loss of tensile strength and 13.3% decrease of elongation at break, indicating that PPCH had improved UV-irradiation resistance performance due to the existence of UV absorbable functional group like HEB. PPCH and PPC blended with similar 2, 4-dihydroxyl benzophenone (BP) content were compared for hot water (50℃) extraction test. No BP was extracted in PPCH providing stable UV absorption performance, while the PPC/BP blend showed sharp drop in UV absorption upon hot water extraction. Therefore, terpolymerization of CO2, propylene oxide with UV absorbable monomer is an effective way to improve the UV irradiation resistance performance of CO2 copolymer.
2019, 36(11): 1257-1265
doi: 10.11944/j.issn.1000-0518.2019.11.190139
Abstract:
A series of phenolic derivatives was synthesized and characterized by Fourier transform infrared spectrometer(FTIR), nuclear magnetic resonance spectroscopy(NMR) and electrospray ionisation mass spectrometry(ESI-MS). Their whitening activity was also tested. The results showed that the tyrosinase inhibitory activities HB-1(0.229±0.026), HB-3a(0.829±0.135), HB-3b(0.446±0.047), HMB-3a(1.747±0.215), HMB-3b(1.307±0.058) and HPE-4b(2.501±0.261) were significantly better than those of the positive control, α-arbutin (3.60±0.029). The antioxidant activities of these compounds were tested to whitening potentials. The results showed that the antioxidant activities of HB-3b and HMB-3a were comparable to the positive control substance quercetin and lycopene. Therefore, such compounds can be developed and utilized as whitening agents and antioxidants.>
A series of phenolic derivatives was synthesized and characterized by Fourier transform infrared spectrometer(FTIR), nuclear magnetic resonance spectroscopy(NMR) and electrospray ionisation mass spectrometry(ESI-MS). Their whitening activity was also tested. The results showed that the tyrosinase inhibitory activities HB-1(0.229±0.026), HB-3a(0.829±0.135), HB-3b(0.446±0.047), HMB-3a(1.747±0.215), HMB-3b(1.307±0.058) and HPE-4b(2.501±0.261) were significantly better than those of the positive control, α-arbutin (3.60±0.029). The antioxidant activities of these compounds were tested to whitening potentials. The results showed that the antioxidant activities of HB-3b and HMB-3a were comparable to the positive control substance quercetin and lycopene. Therefore, such compounds can be developed and utilized as whitening agents and antioxidants.>
2019, 36(11): 1266-1274
doi: 10.11944/j.issn.1000-0518.2019.11.190078
Abstract:
A new and efficient method for the synthesis of potentially biologically active cyano-containing benzofuran-2-one derivatives has been developed. In the presence of low-cost CuI and zinc powder, the three-component reactions of para-quinone methides with 1, 1-azobis(cyclohexanecarbonitrile) and H2O proceed smoothly through radical cascades, including 1, 6-conjugate addition/aromatization, inert C(aryl)-C(t-butyl) bond cleavage and downstream cyano-insertion/cyclization/hydrolysis, which leads to a series of cyano-containing benzofuran-2-ones. This method offers a simple and efficient way for the synthesis of cyano-containing benzofuranone derivatives, as well as a new idea for the high-value application of para-quinone methides.
A new and efficient method for the synthesis of potentially biologically active cyano-containing benzofuran-2-one derivatives has been developed. In the presence of low-cost CuI and zinc powder, the three-component reactions of para-quinone methides with 1, 1-azobis(cyclohexanecarbonitrile) and H2O proceed smoothly through radical cascades, including 1, 6-conjugate addition/aromatization, inert C(aryl)-C(t-butyl) bond cleavage and downstream cyano-insertion/cyclization/hydrolysis, which leads to a series of cyano-containing benzofuran-2-ones. This method offers a simple and efficient way for the synthesis of cyano-containing benzofuranone derivatives, as well as a new idea for the high-value application of para-quinone methides.
2019, 36(11): 1275-1285
doi: 10.11944/j.issn.1000-0518.2019.11.190046
Abstract:
Bismuth tungstate/graphitic carbon nitride (Bi2WO6/g-C3N4) composite photocatalyst modified by Bi2WO6 quantum dots and nanosheets was prepared through ultrasonic-hydrothermal method using sodium oleate as auxiliary reagent. The compositions, structures and light absorption properties of Bi2WO6/g-C3N4 were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), Brunauer-Emmett-Teller (BET) and other techniques. The mechanism of synthetic reaction was proposed. Photocatalytic reduction of aqueous rhodamine B (RhB) was employed to assess the visible light photocatalytic activity of Bi2WO6/g-C3N4. Electrochemical impedance spectroscopy (EIS) and photocurrent characteriations demonstated that Bi2WO6/g-C3N4 with the heterogeneous interface separated the photo-generated electron-hole paris effectively. Hence, a rapid RhB degradation by Bi2WO6/g-C3N4-30(the number 30 represents the mass fraction(%) of g-C3N4) under visible light irradiation was achieved at 95.8% in 120 min. The results confirmed that the photogenerated holes were main active specie in the photodegradation process. Moreover, the relationship of heterogenrous interface and photocatalytic performance was investigated, and involved photocatalytic mechanism was revealed.
Bismuth tungstate/graphitic carbon nitride (Bi2WO6/g-C3N4) composite photocatalyst modified by Bi2WO6 quantum dots and nanosheets was prepared through ultrasonic-hydrothermal method using sodium oleate as auxiliary reagent. The compositions, structures and light absorption properties of Bi2WO6/g-C3N4 were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), Brunauer-Emmett-Teller (BET) and other techniques. The mechanism of synthetic reaction was proposed. Photocatalytic reduction of aqueous rhodamine B (RhB) was employed to assess the visible light photocatalytic activity of Bi2WO6/g-C3N4. Electrochemical impedance spectroscopy (EIS) and photocurrent characteriations demonstated that Bi2WO6/g-C3N4 with the heterogeneous interface separated the photo-generated electron-hole paris effectively. Hence, a rapid RhB degradation by Bi2WO6/g-C3N4-30(the number 30 represents the mass fraction(%) of g-C3N4) under visible light irradiation was achieved at 95.8% in 120 min. The results confirmed that the photogenerated holes were main active specie in the photodegradation process. Moreover, the relationship of heterogenrous interface and photocatalytic performance was investigated, and involved photocatalytic mechanism was revealed.
2019, 36(11): 1286-1293
doi: 10.11944/j.issn.1000-0518.2019.11.190073
Abstract:
The selective aerobic oxidation of alcohols to carbonyl compounds was achieved by introduction of MgAl hydrotalcite into the metallotetraphenylporphyrins(MTPPs, M=Co, Fe, Mn, Ni) catalytic oxidation system. The results indicated that CoTPP exhibited the highest catalytic activity in the oxidation of benzyl alcohol to benzaldehyde through molecular oxygen/isobutyraldehyde(IBA) system, and MgAl hydrotalcite additive could effectively improve the catalytic selectivity of aldehyde. Under the optimized conditions(benzyl alcohol 1 mmol, acetonitrile 2 mL, CoTPP 5 mg, MgAl hydrotalcite 18 mg, IBA 5 mmol, reaction temperature 60℃, oxygen atmosphere, reaction time 2 h), the conversion of benzyl alcohol and the selectivity of benzaldehyde reached 94% and 92%, respectively. The catalytic system also exhibited good catalytic performance in the oxidation of other benzylic alcohols.
The selective aerobic oxidation of alcohols to carbonyl compounds was achieved by introduction of MgAl hydrotalcite into the metallotetraphenylporphyrins(MTPPs, M=Co, Fe, Mn, Ni) catalytic oxidation system. The results indicated that CoTPP exhibited the highest catalytic activity in the oxidation of benzyl alcohol to benzaldehyde through molecular oxygen/isobutyraldehyde(IBA) system, and MgAl hydrotalcite additive could effectively improve the catalytic selectivity of aldehyde. Under the optimized conditions(benzyl alcohol 1 mmol, acetonitrile 2 mL, CoTPP 5 mg, MgAl hydrotalcite 18 mg, IBA 5 mmol, reaction temperature 60℃, oxygen atmosphere, reaction time 2 h), the conversion of benzyl alcohol and the selectivity of benzaldehyde reached 94% and 92%, respectively. The catalytic system also exhibited good catalytic performance in the oxidation of other benzylic alcohols.
2019, 36(11): 1294-1300
doi: 10.11944/j.issn.1000-0518.2019.11.190081
Abstract:
The orderly mesoporous KF/Al-Ce-SBA-15(KF/ACS) solid bases were successfully prepared with cetyltrimethylammonium bromide(CATB)-poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) triblock copolymer (P123) as the dual-template and KF as the modifier in two steps. The structure and property of the obtained catalysts were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and CO2-temperature programmed desorption (TPD). The results illustrated that the KF/ACS catalysts possess both an ordered mesostructure and superbasicity when the introduced Al/Ce atomic ratio is 0.12 and the loading amounts(mass fraction) of KF is 10%. The catalytic activity of the prepared materials was evaluated in the ring-opening reaction of propylene oxide (PO) with methanol. It shows excellent catalytic performance exhibiting 92.0% yield of propylene glycol monomethyl ether (PM) and 96.1% selectivity to 1-methoxy-2-propanol (PPM) and the by-products of dipropylene glycol methyl ether was effectively inhibited.
The orderly mesoporous KF/Al-Ce-SBA-15(KF/ACS) solid bases were successfully prepared with cetyltrimethylammonium bromide(CATB)-poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) triblock copolymer (P123) as the dual-template and KF as the modifier in two steps. The structure and property of the obtained catalysts were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and CO2-temperature programmed desorption (TPD). The results illustrated that the KF/ACS catalysts possess both an ordered mesostructure and superbasicity when the introduced Al/Ce atomic ratio is 0.12 and the loading amounts(mass fraction) of KF is 10%. The catalytic activity of the prepared materials was evaluated in the ring-opening reaction of propylene oxide (PO) with methanol. It shows excellent catalytic performance exhibiting 92.0% yield of propylene glycol monomethyl ether (PM) and 96.1% selectivity to 1-methoxy-2-propanol (PPM) and the by-products of dipropylene glycol methyl ether was effectively inhibited.
2019, 36(11): 1301-1307
doi: 10.11944/j.issn.1000-0518.2019.11.190041
Abstract:
In order to study the effect of light on the oxidation stability of biodiesel, the jatropha biodiesel was treated with light in different wavelengths at 20℃ for 48 hours. The treated samples were then analyzed for oxidative stability. The results showed that light promoted the oxidation of biodiesel. The short-wavelength light represented by violet light had the strongest promoting effect on the oxidation of jatropha oil biodiesel. The induction period decreased from 5.12 h to 2.65 h in 48%; the red light with longer wavelength has the weakest promoting effect on the oxidation of biodiesel, and the induction period is reduced to 4.61 h, which is reduced in 10%. The acid value titration, composition analysis and UV characterization of light-treated biodiesel with different wavelengths showed that the acid value of biodiesel increased from 0.2577 mg/g to 0.3438 mg/g as the wavelength of light decreased. The relative content of methyl linoleate in the carbon-carbon double bond decreases; the absorption peak of the conjugated double bond increases. This shows that the shorter the wavelength of light, the stronger the promotion toward biodiesel oxidation.
In order to study the effect of light on the oxidation stability of biodiesel, the jatropha biodiesel was treated with light in different wavelengths at 20℃ for 48 hours. The treated samples were then analyzed for oxidative stability. The results showed that light promoted the oxidation of biodiesel. The short-wavelength light represented by violet light had the strongest promoting effect on the oxidation of jatropha oil biodiesel. The induction period decreased from 5.12 h to 2.65 h in 48%; the red light with longer wavelength has the weakest promoting effect on the oxidation of biodiesel, and the induction period is reduced to 4.61 h, which is reduced in 10%. The acid value titration, composition analysis and UV characterization of light-treated biodiesel with different wavelengths showed that the acid value of biodiesel increased from 0.2577 mg/g to 0.3438 mg/g as the wavelength of light decreased. The relative content of methyl linoleate in the carbon-carbon double bond decreases; the absorption peak of the conjugated double bond increases. This shows that the shorter the wavelength of light, the stronger the promotion toward biodiesel oxidation.
2019, 36(11): 1308-1316
doi: 10.11944/j.issn.1000-0518.2019.11.190089
Abstract:
In order to solve the problem that polyaspartic acid (PASP) has poor scale inhibition effect at high Ca2+ concentration and poor effect of dispersing iron oxide, tyrosine (Tyr) was grafted to the side chain of PASP by ring-opening modification of the intermediate polysuccinimide (PSI). An environmentally friendly scale inhibitor of tyrosine-polyaspartic acid copolymer (Tyr-PASP) was synthesized and possessed a plurality of functional groups such as carboxyl group, amino group, amide group and phenolic hydroxyl group. The static scale inhibition experiment proved that Tyr-PASP possessed a better scale inhibition ability than PASP. When the molar ratio of n(Tyr):n(PSI)=1:1, Tyr-PASP showed the best scale inhibition effect against CaCO3, and the inhibition efficiency reached up to 100% with a mass concentration of 4 mg/L. At 5 mg/L, the inhibition efficiency against CaSO4 also achieved 100%. After the addition of Tyr-PASP, the crystal form of scale changed from stable calcite and aragonite to unstable vaterite, and the morphology became loose. Molecular dynamics simulations show that the binding between Tyr/PASP and calcite is exothermic and the binding energy is much higher than that of conventional adsorption energy. Electrostatic forces play a major role in the binding between Tyr-PASP and calcite. In addition, the dispersion effect of Tyr-PASP on iron oxide is also significantly improved.
In order to solve the problem that polyaspartic acid (PASP) has poor scale inhibition effect at high Ca2+ concentration and poor effect of dispersing iron oxide, tyrosine (Tyr) was grafted to the side chain of PASP by ring-opening modification of the intermediate polysuccinimide (PSI). An environmentally friendly scale inhibitor of tyrosine-polyaspartic acid copolymer (Tyr-PASP) was synthesized and possessed a plurality of functional groups such as carboxyl group, amino group, amide group and phenolic hydroxyl group. The static scale inhibition experiment proved that Tyr-PASP possessed a better scale inhibition ability than PASP. When the molar ratio of n(Tyr):n(PSI)=1:1, Tyr-PASP showed the best scale inhibition effect against CaCO3, and the inhibition efficiency reached up to 100% with a mass concentration of 4 mg/L. At 5 mg/L, the inhibition efficiency against CaSO4 also achieved 100%. After the addition of Tyr-PASP, the crystal form of scale changed from stable calcite and aragonite to unstable vaterite, and the morphology became loose. Molecular dynamics simulations show that the binding between Tyr/PASP and calcite is exothermic and the binding energy is much higher than that of conventional adsorption energy. Electrostatic forces play a major role in the binding between Tyr-PASP and calcite. In addition, the dispersion effect of Tyr-PASP on iron oxide is also significantly improved.
2019, 36(11): 1317-1322
doi: 10.11944/j.issn.1000-0518.2019.11.190065
Abstract:
The active component of active carbon-supported Pd of the anode catalyst in direct formic acid fuel cell(DFAFC) is easy to aggregate and has electrocorrosive effect on the carbon carrier, resulting in low catalytic activity and stability. In this paper, regulating the carbon catalyst carrier effectively improved the catalytic activity and stability for formic acid electrooxidation. The polypyrrole(PPy) doped carbon was synthesized by low temperature chemical oxidation and activated carbon was added during the polymerization process. Pd catalyst supported on the carbon composites was prepared. The surface morphology of the pyropolypyrrole doped catalyst was characterized. It is found that the Pd nanoparticles could be stabilized at 2.25 nm. The surface nitrogen element of the catalyst exists in the form of pyrrole nitrogen. The carbon-based pyrolytic polypyrrole supported Pd has excellent performance for the formic acid electrocatalytic oxidation. Compared with the Pd/C catalyst, the specific activity per Pd unit mass is increased by 2.5 times.
The active component of active carbon-supported Pd of the anode catalyst in direct formic acid fuel cell(DFAFC) is easy to aggregate and has electrocorrosive effect on the carbon carrier, resulting in low catalytic activity and stability. In this paper, regulating the carbon catalyst carrier effectively improved the catalytic activity and stability for formic acid electrooxidation. The polypyrrole(PPy) doped carbon was synthesized by low temperature chemical oxidation and activated carbon was added during the polymerization process. Pd catalyst supported on the carbon composites was prepared. The surface morphology of the pyropolypyrrole doped catalyst was characterized. It is found that the Pd nanoparticles could be stabilized at 2.25 nm. The surface nitrogen element of the catalyst exists in the form of pyrrole nitrogen. The carbon-based pyrolytic polypyrrole supported Pd has excellent performance for the formic acid electrocatalytic oxidation. Compared with the Pd/C catalyst, the specific activity per Pd unit mass is increased by 2.5 times.
2019, 36(11): 1323-1332
doi: 10.11944/j.issn.1000-0518.2019.11.190102
Abstract:
Porous biomass carbon with high specific surface area(2167 m2/g) was prepared from corn stalk. By optimizing the experimental conditions, porous biomass carbon material with the best performance can be obtained with specific capacitance of 390 F/g at a current density of 1 A/g. More importantly, liquid-phase symmetric supercapacitors were assembled with the optimal porous biomass carbon as the electrode material and 3 mol/L KOH solution as the electrolyte. The present symmetrical supercapacitors have an energy density of 7 Wh/kg at the power density of 818 W/kg, and 91.1% capacitance retention after 10000 cycles. Meanwhile, after charged, two such supercapacitors in series can easily illuminate 15 LED lights and drive the small fans to work normally. These results indicate that porous biomass carbon from corn stalks has great practical significance as an advanced electrode material for supercapacitors.
Porous biomass carbon with high specific surface area(2167 m2/g) was prepared from corn stalk. By optimizing the experimental conditions, porous biomass carbon material with the best performance can be obtained with specific capacitance of 390 F/g at a current density of 1 A/g. More importantly, liquid-phase symmetric supercapacitors were assembled with the optimal porous biomass carbon as the electrode material and 3 mol/L KOH solution as the electrolyte. The present symmetrical supercapacitors have an energy density of 7 Wh/kg at the power density of 818 W/kg, and 91.1% capacitance retention after 10000 cycles. Meanwhile, after charged, two such supercapacitors in series can easily illuminate 15 LED lights and drive the small fans to work normally. These results indicate that porous biomass carbon from corn stalks has great practical significance as an advanced electrode material for supercapacitors.
2019, 36(11): 1333-1342
doi: 10.11944/j.issn.1000-0518.2019.11.190127
Abstract:
Novel molecularly imprinted polymer (MIP) microspheres were prepared by the precipitation polymerization method using 2-isopentyl cyclopentanone as the dummy template. The surface chemical groups were characterized by Fourier transform infrared spectroscopy (FTIR) and the particle size distribution was characterized by scanning electronic microscope (SEM). Adsorption dynamics, isotherm adsorption behavior and application capacity for this MIP in solid phase extraction of rose oxide were explored. The results indicated that MIPs could reach adsorption equilibrium within 25 min, showing a rapid adsorption dynamics, and the first order model was better to describe its adsorption dynamics behavior. Additionally, the Freundlich isotherm model was more suitable to describe the isotherm adsorption behavior and a maximum binding site number (149.3 μmol/g) was obtained by fitting the isotherm data to the Langmuir model. A mean adsorption potential energy of 166.7 kJ/mol indicated a chemical adsorption process for MIPs. The selectivity factor for MIPs toward rose oxide relative to geraniol and citronellol was 3.710 and 5.636, respectively. Especially, this MIP possessed higher competitive adsorption capacity toward rose oxide in the mixture, with an adsorption capacity of 18.03 mg/g. Under the optimized solid phase extraction conditions, i.e., washing by using 1 mL acetonitrile, 1 mL acetonitrile-water mixture(volume ratio 9.5:0.5) and 2 mL acetonitrile-methanol-water mixture (volume ratio 8:1:2) and eluting by using 3 mL methanol-acetic acid mixture(volume ratio 9:1), rose oxide can be separated and enriched from crude rose extract by using molecularly imprinted polymeric solid phase extraction, with a recovery of 96.23%.
Novel molecularly imprinted polymer (MIP) microspheres were prepared by the precipitation polymerization method using 2-isopentyl cyclopentanone as the dummy template. The surface chemical groups were characterized by Fourier transform infrared spectroscopy (FTIR) and the particle size distribution was characterized by scanning electronic microscope (SEM). Adsorption dynamics, isotherm adsorption behavior and application capacity for this MIP in solid phase extraction of rose oxide were explored. The results indicated that MIPs could reach adsorption equilibrium within 25 min, showing a rapid adsorption dynamics, and the first order model was better to describe its adsorption dynamics behavior. Additionally, the Freundlich isotherm model was more suitable to describe the isotherm adsorption behavior and a maximum binding site number (149.3 μmol/g) was obtained by fitting the isotherm data to the Langmuir model. A mean adsorption potential energy of 166.7 kJ/mol indicated a chemical adsorption process for MIPs. The selectivity factor for MIPs toward rose oxide relative to geraniol and citronellol was 3.710 and 5.636, respectively. Especially, this MIP possessed higher competitive adsorption capacity toward rose oxide in the mixture, with an adsorption capacity of 18.03 mg/g. Under the optimized solid phase extraction conditions, i.e., washing by using 1 mL acetonitrile, 1 mL acetonitrile-water mixture(volume ratio 9.5:0.5) and 2 mL acetonitrile-methanol-water mixture (volume ratio 8:1:2) and eluting by using 3 mL methanol-acetic acid mixture(volume ratio 9:1), rose oxide can be separated and enriched from crude rose extract by using molecularly imprinted polymeric solid phase extraction, with a recovery of 96.23%.
