Constructing nanocomposites that combine the advantages of composite materials,nanomaterials,and interfaces has been regarded as an important strategy to improve the photocatalytic activity of TiO2.In this study,2D‐2...Constructing nanocomposites that combine the advantages of composite materials,nanomaterials,and interfaces has been regarded as an important strategy to improve the photocatalytic activity of TiO2.In this study,2D‐2D TiO2 nanosheet/layered WS2(TNS/WS2)heterojunctions were prepared via a hydrothermal method.The structure and morphology of the photocatalysts were systematically characterized.Layered WS2(~4 layers)was wrapped on the surface of TiO2 nanosheets with a plate‐to‐plate stacked structure and connected with each other by W=O bonds.The as‐prepared TNS/WS2 heterojunctions showed higher photocatalytic activity for the degradation of RhB under visible‐light irradiation,than pristine TiO2 nanosheets and layered WS2.The improvement of photocatalytic activity was primarily attributed to enhanced charge separation efficiency,which originated from the perfect 2D‐2D nanointerfaces and intimate interfacial contacts between TiO2 nanosheets and layered WS2.Based on experimental results,a double‐transfer photocatalytic mechanism for the TNS/WS2 heterojunctions was proposed and discussed.This work provides new insights for synthesizing highly efficient and environmentally stable photocatalysts by engineering the surface heterojunctions.展开更多
Zeolite P was synthesized through hydrothermal method based on a kind of Class C fly ash(FA). X-ray diffraction(XRD), scanning electron microscopy(SEM), and Brunauer–Emmett–Teller(BET) were used to analyze and chara...Zeolite P was synthesized through hydrothermal method based on a kind of Class C fly ash(FA). X-ray diffraction(XRD), scanning electron microscopy(SEM), and Brunauer–Emmett–Teller(BET) were used to analyze and characterize the synthetic sample. The kinetics and thermodynamics of copper and nickel ions removed by the zeolite samples were experimentally explored in detail. The results of kinetic treatment showed the second-order exchange second-order saturation model(SESSM) can well describe the removal process of copper ions, while the first-order empirical kinetic model(FEKM) is the best kinetic model for nickel ions. Langmuir and Freundlich isotherms were used to fit the equilibrium concentration of Cu(Ⅱ) or Ni(Ⅱ) under certain conditions. Whether for copper or nickel ion, the Langmuir model is in good agreement with the experimental equilibrium concentration.The apparent theoretical removal capacities for Cu(Ⅱ) and Ni(Ⅱ) can reach to 138.1 mg·g^(-1) and 77.0 mg·g^(-1),respectively.展开更多
Novelthree-dimensionalstring and ball-like titanium dioxide/reduced graphene oxide, TiO_2/rGO(STG) composites were prepared using a one-step hydrolysis process followed by a low-temperature hydrothermaltreatment. The ...Novelthree-dimensionalstring and ball-like titanium dioxide/reduced graphene oxide, TiO_2/rGO(STG) composites were prepared using a one-step hydrolysis process followed by a low-temperature hydrothermaltreatment. The STG composites exhibited excellent photo-catalytic degradation performance for methylene blue owing to a good synergistic effect between TiO_2 and rGO. The STG composites with 1.0 wt% of rGO loading exhibited the highest removalrate of 86.0% for methylene blue and its reaction rate constant(5.27 × 10^(-3) min^(-1)) was much higher than those of pure string and ball-like TiO_2(ST). In addition, the STG composites also showed an outstanding capability for the photo-catalysis degradation of other cationic dyes. In addition, a possible photo-catalytic degradation mechanism for the STG composite was postulated, in which~?O_2^- and~·OH were the main oxidizing groups. This work of fers new insights into a better design and preparation of novelcomposite materials for the removalof organic dyes.展开更多
In this study, a new mass model involving superheat, initial temperature, liquid height, evaporator diameter, and flashing time is established to describe the flash evaporation process of water film. Of 469 sets of fl...In this study, a new mass model involving superheat, initial temperature, liquid height, evaporator diameter, and flashing time is established to describe the flash evaporation process of water film. Of 469 sets of flash experimental data from three previous researches, 305 sets were applied to optimize parameters, and the other 164 sets were used to verify the practicability of the model. The results showed that the mean relative error between the literature data and the model values was less than 16.3%, and the model statistics proved that the model was well-posed. Then, the kinetic model was obtained using the time derivative of the new mass model. Computational fluid dynamics simulation of water film flash evaporation was studied based on a user-defined function program of the new evaporation kinetic model. The new kinetic model shows more consistency with the experimental phenomena in terms of evaporated mass and temperature compared with the evaporation–condensation model in Fluent software and Gopalakrishna's model. This new kinetic model can be extended to describe the flash process of water solution under other conditions.展开更多
Inorganic arsenicals, including arsenite （As III） and arsenate （AsV）, are well-known human carcinogens. Recently, studies have indicated that arsenic triglutathione （As（GS）3） is unstable in an aqueous solution...Inorganic arsenicals, including arsenite （As III） and arsenate （AsV）, are well-known human carcinogens. Recently, studies have indicated that arsenic triglutathione （As（GS）3） is unstable in an aqueous solution. The present study was designed to evaluate the degradation mechanism of As（GS）3 in an aqueous solution using high-performance liquid chromatography-electrospray ionisation mass spectrometry （HPLC-ESI-MS）. Based on the fragments obtained from MS2 and MSa, we identified two new compounds： one was an isomer of glutathione （GSH）, and the other was a product from the cleavage of the glutamyl of oxidised glutathione （GSSG）. The isomerization of GSH resulted in the loss of its function such as detoxification of many reactive metabolites. The formation of the two new compounds affected the ratio of GSH/ GSSG, and thus may affect the antioxidant and detoxifica- tion of GSH/GSSG in mammalian cells.展开更多
This note describes a kind of ionic sieve with high selectivity to remove trace lead in water, in which stannic molybdopyrophosphate is used to be the substrate. The mechanism of selective separation on the surface of...This note describes a kind of ionic sieve with high selectivity to remove trace lead in water, in which stannic molybdopyrophosphate is used to be the substrate. The mechanism of selective separation on the surface of ionic sieve of removal of lead was explored by analyzing fourier transformation infrared spectra (FTIR), X-ray photoelectron spectrometry (XPS) and the results of selective adsorptivity experiment. The investigation suggests that in the process of synthesizing ionic sieve the olation reactions occur in solid phase by thermodynamic recrystallization and the adsorption units with special selectivity to lead are formed by chemical modification. After the ion exchange for Pb2+, the oaltion reactions not only keep the microstructures of adsorption units from collapse, but also provide lead cavties with special selectivity to lead ion that are capable of having special binding 'memory effect' to Pb2+ by SnO32- and P2O74- groups on the surface of this ionic sieve. Meanwhile, the selective展开更多
We reported a facile and green hydrothermal strategy to tailor the carbon dots layer(CDL)and oxygen vacancies(Vo)modified on Ti0_(2),by using ascorbic acid as CDL precursor and Vo regulator.The amorphous CDL was unifo...We reported a facile and green hydrothermal strategy to tailor the carbon dots layer(CDL)and oxygen vacancies(Vo)modified on Ti0_(2),by using ascorbic acid as CDL precursor and Vo regulator.The amorphous CDL was uniformly coated on the surface of the as prepared CDL@TiO_(2-x) composites by Ti-O-C bond.With the increase of carbon content,the amorphous CDL gradually became thicker,while the Vo concentration first increased and then decreased.1.5 CDL@TiO_(2-x) possessed the highest Vo concentration.With the decoration of CDL and Vo,the photoreduction properties of CDL@TiO_(2-x) composites were significantly improved.Under simulated solar light and visible light,the reaction rates of 1.5 CDL@TiO_(2-x) were 9.6 times and 216 times higher than that of pure Ti0_(2)/respectively.Interestingly,the results discovered that CDL and Vo influenced the properties of CDL@TiO_(2-x) composites in different ways.The primary function of CDL was to improve the utilization of solar light,and the enhancement of the charge transfer ability was decided by Vo and CDL together.Our work provides a new strategy for the modification of Ti0_(2) and sheds new light on the respective role of CDL and Vo when they coexist in the catalyst.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
基金supported by the National High Technology Research and Development Program of China(863 Program,2012AA063504)the National Natural Science Foundation of China(U1407116,21511130020,21276193)the Tianjin Municipal Natural Science Foundation(13JCZDJC35600)~~
文摘Constructing nanocomposites that combine the advantages of composite materials,nanomaterials,and interfaces has been regarded as an important strategy to improve the photocatalytic activity of TiO2.In this study,2D‐2D TiO2 nanosheet/layered WS2(TNS/WS2)heterojunctions were prepared via a hydrothermal method.The structure and morphology of the photocatalysts were systematically characterized.Layered WS2(~4 layers)was wrapped on the surface of TiO2 nanosheets with a plate‐to‐plate stacked structure and connected with each other by W=O bonds.The as‐prepared TNS/WS2 heterojunctions showed higher photocatalytic activity for the degradation of RhB under visible‐light irradiation,than pristine TiO2 nanosheets and layered WS2.The improvement of photocatalytic activity was primarily attributed to enhanced charge separation efficiency,which originated from the perfect 2D‐2D nanointerfaces and intimate interfacial contacts between TiO2 nanosheets and layered WS2.Based on experimental results,a double‐transfer photocatalytic mechanism for the TNS/WS2 heterojunctions was proposed and discussed.This work provides new insights for synthesizing highly efficient and environmentally stable photocatalysts by engineering the surface heterojunctions.
基金Supported by the National Natural Science Foundation of China(51478308)the Scientific Research Special Fund of Marine Public Welfare Industry(201405008)the Natural Science Foundation of Tianjin(14JCYBJC23300)
文摘Zeolite P was synthesized through hydrothermal method based on a kind of Class C fly ash(FA). X-ray diffraction(XRD), scanning electron microscopy(SEM), and Brunauer–Emmett–Teller(BET) were used to analyze and characterize the synthetic sample. The kinetics and thermodynamics of copper and nickel ions removed by the zeolite samples were experimentally explored in detail. The results of kinetic treatment showed the second-order exchange second-order saturation model(SESSM) can well describe the removal process of copper ions, while the first-order empirical kinetic model(FEKM) is the best kinetic model for nickel ions. Langmuir and Freundlich isotherms were used to fit the equilibrium concentration of Cu(Ⅱ) or Ni(Ⅱ) under certain conditions. Whether for copper or nickel ion, the Langmuir model is in good agreement with the experimental equilibrium concentration.The apparent theoretical removal capacities for Cu(Ⅱ) and Ni(Ⅱ) can reach to 138.1 mg·g^(-1) and 77.0 mg·g^(-1),respectively.
基金supported by the National High Technology Research and Development Program of China ("863" Program, No. 2012AA063504)the National Natural Science Foundation of China (Nos. 21276193, 215111300020, 201405008, and U1407116)the Natural Science Foundation of Tianjin, China (No. 13JCZDJC35600)
文摘Novelthree-dimensionalstring and ball-like titanium dioxide/reduced graphene oxide, TiO_2/rGO(STG) composites were prepared using a one-step hydrolysis process followed by a low-temperature hydrothermaltreatment. The STG composites exhibited excellent photo-catalytic degradation performance for methylene blue owing to a good synergistic effect between TiO_2 and rGO. The STG composites with 1.0 wt% of rGO loading exhibited the highest removalrate of 86.0% for methylene blue and its reaction rate constant(5.27 × 10^(-3) min^(-1)) was much higher than those of pure string and ball-like TiO_2(ST). In addition, the STG composites also showed an outstanding capability for the photo-catalysis degradation of other cationic dyes. In addition, a possible photo-catalytic degradation mechanism for the STG composite was postulated, in which~?O_2^- and~·OH were the main oxidizing groups. This work of fers new insights into a better design and preparation of novelcomposite materials for the removalof organic dyes.
基金supported by the Scientific Research Special Fund of Marine Public Welfare Industry(No.20140508)National Natural Science Foundation of China(No.51478308)Natural Science Foundation of Tianjin(No.14JCYBJC23300)
文摘In this study, a new mass model involving superheat, initial temperature, liquid height, evaporator diameter, and flashing time is established to describe the flash evaporation process of water film. Of 469 sets of flash experimental data from three previous researches, 305 sets were applied to optimize parameters, and the other 164 sets were used to verify the practicability of the model. The results showed that the mean relative error between the literature data and the model values was less than 16.3%, and the model statistics proved that the model was well-posed. Then, the kinetic model was obtained using the time derivative of the new mass model. Computational fluid dynamics simulation of water film flash evaporation was studied based on a user-defined function program of the new evaporation kinetic model. The new kinetic model shows more consistency with the experimental phenomena in terms of evaporated mass and temperature compared with the evaporation–condensation model in Fluent software and Gopalakrishna's model. This new kinetic model can be extended to describe the flash process of water solution under other conditions.
文摘Inorganic arsenicals, including arsenite （As III） and arsenate （AsV）, are well-known human carcinogens. Recently, studies have indicated that arsenic triglutathione （As（GS）3） is unstable in an aqueous solution. The present study was designed to evaluate the degradation mechanism of As（GS）3 in an aqueous solution using high-performance liquid chromatography-electrospray ionisation mass spectrometry （HPLC-ESI-MS）. Based on the fragments obtained from MS2 and MSa, we identified two new compounds： one was an isomer of glutathione （GSH）, and the other was a product from the cleavage of the glutamyl of oxidised glutathione （GSSG）. The isomerization of GSH resulted in the loss of its function such as detoxification of many reactive metabolites. The formation of the two new compounds affected the ratio of GSH/ GSSG, and thus may affect the antioxidant and detoxifica- tion of GSH/GSSG in mammalian cells.
基金This work was supported by the National Advanced Materials Committee of China (Grant No. 863-715-004-220)the National Natural Science Foundation of China (Grant No. 29971022).
文摘This note describes a kind of ionic sieve with high selectivity to remove trace lead in water, in which stannic molybdopyrophosphate is used to be the substrate. The mechanism of selective separation on the surface of ionic sieve of removal of lead was explored by analyzing fourier transformation infrared spectra (FTIR), X-ray photoelectron spectrometry (XPS) and the results of selective adsorptivity experiment. The investigation suggests that in the process of synthesizing ionic sieve the olation reactions occur in solid phase by thermodynamic recrystallization and the adsorption units with special selectivity to lead are formed by chemical modification. After the ion exchange for Pb2+, the oaltion reactions not only keep the microstructures of adsorption units from collapse, but also provide lead cavties with special selectivity to lead ion that are capable of having special binding 'memory effect' to Pb2+ by SnO32- and P2O74- groups on the surface of this ionic sieve. Meanwhile, the selective
基金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).
文摘We reported a facile and green hydrothermal strategy to tailor the carbon dots layer(CDL)and oxygen vacancies(Vo)modified on Ti0_(2),by using ascorbic acid as CDL precursor and Vo regulator.The amorphous CDL was uniformly coated on the surface of the as prepared CDL@TiO_(2-x) composites by Ti-O-C bond.With the increase of carbon content,the amorphous CDL gradually became thicker,while the Vo concentration first increased and then decreased.1.5 CDL@TiO_(2-x) possessed the highest Vo concentration.With the decoration of CDL and Vo,the photoreduction properties of CDL@TiO_(2-x) composites were significantly improved.Under simulated solar light and visible light,the reaction rates of 1.5 CDL@TiO_(2-x) were 9.6 times and 216 times higher than that of pure Ti0_(2)/respectively.Interestingly,the results discovered that CDL and Vo influenced the properties of CDL@TiO_(2-x) composites in different ways.The primary function of CDL was to improve the utilization of solar light,and the enhancement of the charge transfer ability was decided by Vo and CDL together.Our work provides a new strategy for the modification of Ti0_(2) and sheds new light on the respective role of CDL and Vo when they coexist in the catalyst.
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.
