Biodiesel is an attractive alternative to fossil fuels due to the energy and environmental concerns. In this paper, seven different multi –SO_(3)H functionalized ILs based on the low-cost less-substituted amines, whi...Biodiesel is an attractive alternative to fossil fuels due to the energy and environmental concerns. In this paper, seven different multi –SO_(3)H functionalized ILs based on the low-cost less-substituted amines, which contained massive sites for functionalization of sulfonic acid groups and further treatment of sulfonate-based anions, were prepared as catalysts with high acidity and desirable catalytic activity for the synthesis of biodiesel from the esterification of oleic acid with methanol. The physicochemical properties of these acidic ILs were characterized by a variety of analytical techniques such as FT-IR, EA, TGA, and the Br?nsted acidity was well determined by UV–vis. Among the ILs prepared, [EDA-PS][P-TSA] showed the highest catalytic activity for esterification due to its high acidity and appropriate miscibility with reactants, with an ultrahigh97.58% conversion of oleic acid under the optimum conditions(i.e. reaction time, 1.8 h;catalyst amount, 3 wt%;alcohol/acid molar ratio, 13:1,temperature 70℃) acquired from the Box–Behnken response surface methodology. With the novel strategy of multi –SO_(3) H modification on ILs,our catalyst had an approaching or even superior oleic acid conversion rate compared to other reported catalysts with considerably lower catalyst dosage and shorter reaction time. More importantly, it also exhibited high generality for converting various FFA feedstocks into biodiesel with considerable conversion within 93.59–94.33% under a rather lower catalyst dosage, which showed the valuable potential for converting low-cost oils into biodiesel from an economic and environmental perspective.展开更多
of main observation and conclusion The AL-P25 composites(AL=alizarin,P25=nano titanium dioxide)with oxygen vacancies were synthesized by a simple hydrothermal method and applied for the photoreduction of Cr(VI)under v...of main observation and conclusion The AL-P25 composites(AL=alizarin,P25=nano titanium dioxide)with oxygen vacancies were synthesized by a simple hydrothermal method and applied for the photoreduction of Cr(VI)under visible light.The AL-P25 composites were characterized by scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy analysis,Fourier transform infrared spectrometer,thermo-gravimetric analysis,UV-vis diffuse reflectance spectroscopy,photoluminescence spectroscopy and electron paramagnetic resonance spectroscopy.The results suggested that the AL-P25 composites were successfully prepared,and alizarin was linked to P25 via Ti—O—C bonds.AL-P25 composites represented excellent photoreduction efficiency on Cr(VI)under visible light,which was 99.4%after 60 min of illumination.Finally,a photocatalytic mechanism of AL-P25 composites was proposed that ligand-metal charge transfer(LMCT)process between alizarin and P25 effectively enhances separation efficiency of photogenerated electrons and holes.展开更多
Here,nitrogen-doped carbon quantum dots(N-CQDs)were successfully synthesized by the solvothermal method using graphite as the carbon source and N,N-dimethylformamide as the nitrogen source.We characterized the structu...Here,nitrogen-doped carbon quantum dots(N-CQDs)were successfully synthesized by the solvothermal method using graphite as the carbon source and N,N-dimethylformamide as the nitrogen source.We characterized the structure and chemical constitution of N-CQDs using X-ray diffraction,Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy.We investigated the pump-and temperature-dependent photoluminescence(PL)properties and the dynamic exciton recombination processes of N-CQDs,using both steady-state and time-resolved PL techniques.The spectral results show that the PL emission peak located at 518 nm at room temperature,mainly originates from the n-π∗transition on the surface of N-CQDs.The pump fluence and PL integral intensity were analyzed to demonstrate the existence of single-photon excitation under the 405 nm laser excitation.As the temperature increases,the non-radiative transition gradually increases,which decreases the PL intensity,the full width at half maxima first narrows and then widens and the PL lifetime gradually decreases.Furthermore,we combined the N-CQDs with chip to prepare light-emitting diode(LED).The resulting chromaticity coordinate was obtained to be(0.29,0.40).This study offers a comprehensive understanding of the luminescence mechanism in N-doped CQDs and introduces a novel approach for the quickly fabrication of full-color display LEDs.展开更多
The urban cemetery is the material carrier of citizens’view of life and death,and it also evolves with time as a special part of the urban form.Since the reform of the housing system in the 1990s,China has entered a ...The urban cemetery is the material carrier of citizens’view of life and death,and it also evolves with time as a special part of the urban form.Since the reform of the housing system in the 1990s,China has entered a period of rapid urbanization,and the urban cemeteries has entered a cycle of shock and accelerated transformation.The cemeteries originally located on the urban fringe were gradually surrounded by new built-up areas as the city sprawled,and then most of them inevitably migrated outward under the pressure of urban population explosion and land shortage.Taking Nanjing as an example,this paper presents the morphological evolution of Nanjing’s urban cemetery since the early 20th century,discusses the relationship between the evolution of the cemetery and the urban fringe belt,and analyzes the reasons for its evolution.The different types of morphological evolution of Nanjing cemetery are further summarized,revealing the general law and its Chinese particularity.The article concludes with a discussion of the value and significance of morphological research on urban cemeteries in China.展开更多
基金supporting by National Natural Science Foundation of China(Grant No.21878054)Project on the Integration of Industry and Education of Fujian Province(Project No.2018Y4008)。
文摘Biodiesel is an attractive alternative to fossil fuels due to the energy and environmental concerns. In this paper, seven different multi –SO_(3)H functionalized ILs based on the low-cost less-substituted amines, which contained massive sites for functionalization of sulfonic acid groups and further treatment of sulfonate-based anions, were prepared as catalysts with high acidity and desirable catalytic activity for the synthesis of biodiesel from the esterification of oleic acid with methanol. The physicochemical properties of these acidic ILs were characterized by a variety of analytical techniques such as FT-IR, EA, TGA, and the Br?nsted acidity was well determined by UV–vis. Among the ILs prepared, [EDA-PS][P-TSA] showed the highest catalytic activity for esterification due to its high acidity and appropriate miscibility with reactants, with an ultrahigh97.58% conversion of oleic acid under the optimum conditions(i.e. reaction time, 1.8 h;catalyst amount, 3 wt%;alcohol/acid molar ratio, 13:1,temperature 70℃) acquired from the Box–Behnken response surface methodology. With the novel strategy of multi –SO_(3) H modification on ILs,our catalyst had an approaching or even superior oleic acid conversion rate compared to other reported catalysts with considerably lower catalyst dosage and shorter reaction time. More importantly, it also exhibited high generality for converting various FFA feedstocks into biodiesel with considerable conversion within 93.59–94.33% under a rather lower catalyst dosage, which showed the valuable potential for converting low-cost oils into biodiesel from an economic and environmental perspective.
基金This work was supported by the National High Technology Research and Development Program of China(863 Program)(No.2012AA063504)the National Natural Science Foundation of China(Nos.U1407116,21511130020,21276193,201405008)the Tianjin Municipal Natural Science Foundation(No.13JCZDJC35600).
文摘of main observation and conclusion The AL-P25 composites(AL=alizarin,P25=nano titanium dioxide)with oxygen vacancies were synthesized by a simple hydrothermal method and applied for the photoreduction of Cr(VI)under visible light.The AL-P25 composites were characterized by scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy analysis,Fourier transform infrared spectrometer,thermo-gravimetric analysis,UV-vis diffuse reflectance spectroscopy,photoluminescence spectroscopy and electron paramagnetic resonance spectroscopy.The results suggested that the AL-P25 composites were successfully prepared,and alizarin was linked to P25 via Ti—O—C bonds.AL-P25 composites represented excellent photoreduction efficiency on Cr(VI)under visible light,which was 99.4%after 60 min of illumination.Finally,a photocatalytic mechanism of AL-P25 composites was proposed that ligand-metal charge transfer(LMCT)process between alizarin and P25 effectively enhances separation efficiency of photogenerated electrons and holes.
基金This paper is grateful for the Natural Science Foundation of Heilongjiang Province(LH2020F041)Fundamental Research Funds in Heilongjiang Provincial Universities[145209148].
文摘Here,nitrogen-doped carbon quantum dots(N-CQDs)were successfully synthesized by the solvothermal method using graphite as the carbon source and N,N-dimethylformamide as the nitrogen source.We characterized the structure and chemical constitution of N-CQDs using X-ray diffraction,Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy.We investigated the pump-and temperature-dependent photoluminescence(PL)properties and the dynamic exciton recombination processes of N-CQDs,using both steady-state and time-resolved PL techniques.The spectral results show that the PL emission peak located at 518 nm at room temperature,mainly originates from the n-π∗transition on the surface of N-CQDs.The pump fluence and PL integral intensity were analyzed to demonstrate the existence of single-photon excitation under the 405 nm laser excitation.As the temperature increases,the non-radiative transition gradually increases,which decreases the PL intensity,the full width at half maxima first narrows and then widens and the PL lifetime gradually decreases.Furthermore,we combined the N-CQDs with chip to prepare light-emitting diode(LED).The resulting chromaticity coordinate was obtained to be(0.29,0.40).This study offers a comprehensive understanding of the luminescence mechanism in N-doped CQDs and introduces a novel approach for the quickly fabrication of full-color display LEDs.
文摘The urban cemetery is the material carrier of citizens’view of life and death,and it also evolves with time as a special part of the urban form.Since the reform of the housing system in the 1990s,China has entered a period of rapid urbanization,and the urban cemeteries has entered a cycle of shock and accelerated transformation.The cemeteries originally located on the urban fringe were gradually surrounded by new built-up areas as the city sprawled,and then most of them inevitably migrated outward under the pressure of urban population explosion and land shortage.Taking Nanjing as an example,this paper presents the morphological evolution of Nanjing’s urban cemetery since the early 20th century,discusses the relationship between the evolution of the cemetery and the urban fringe belt,and analyzes the reasons for its evolution.The different types of morphological evolution of Nanjing cemetery are further summarized,revealing the general law and its Chinese particularity.The article concludes with a discussion of the value and significance of morphological research on urban cemeteries in China.
