High temperature heat-treatment of wood, which is value-added green product, is one of the altematives to chemical treatment. It has better dimensional stability, thermal insulating properties and biological resistanc...High temperature heat-treatment of wood, which is value-added green product, is one of the altematives to chemical treatment. It has better dimensional stability, thermal insulating properties and biological resistance compared to kiln dried wood. It also has dark brown color which is very important for decorative purposes. Unfortunately, this color changes during weathering. Developing a transparent and non-toxic coating for the protection of heat-treated wood against discoloration without changing its natural appearance is the main objective of this study. For this purpose, waterborne acrylic polyurethane base was chosen because of its durability against weathering and non-toxic nature. Natural antioxidants which are extracted from barks and CeO2 nano particles （alone or together with lignin stabilizer） were used as additives to develop different coatings. The protective characteristics of these coatings were compared with highly pigmented and toxic industrial coating under accelerated weathering conditions. The results showed that acrylic polyurethane coatings protected wood better compared to commercially available coating tested in this study. The chemical modifications during accelerated weathering of coated and heat-treated wood surfaces were monitored by X-ray photoelectron spectroscopy analysis. The morphological changes took place during weathering were studied by fluorescence microscope analysis.展开更多
In this study,aquatic toxic effect of atrazine,and nano-CeO2,the accumulation,reproduction and adsorp-tion of atrazine onto nano-CeO2 and the facilitated transport of atrazine into D.magna by nano-CeO2 were exam-ined....In this study,aquatic toxic effect of atrazine,and nano-CeO2,the accumulation,reproduction and adsorp-tion of atrazine onto nano-CeO2 and the facilitated transport of atrazine into D.magna by nano-CeO2 were exam-ined.The results showed that atrazine concentrations of 3.0,4.0,and 10.0 mg/L exhibited 43%,56%,68% mortali-ties,respectively,which indicated the mortality was 56% while the concentration of nano-CeO2 was 4.0 mg/L.D.magna accumulated considerably more atrazine when exposed to atrazine-contaminated water in the presence of nano-CeO2.At the same time,atrazine and nano-CeO2 yielded a significant reduction of the reproduction rate at all concentrations tested.What is more,the co-exposure of nano-CeO2 and atrazine was observed to significantly de-crease the reproduction rate of D.magna,and atrazine adsorbed on nano-CeO2 quickly.Therefore,attention should be paid to their associations with other contaminants for the risk assessment of nano-CeO2 and it is worthy of notice that the sorption of atrazine on nano-CeO2 would enhance the toxicity of atrazine to D.magna.展开更多
Thermally stable Zr4+, Al3+, and Si4+ cations were incorporated into the lattice of CeO2 nano‐rods (i.e., CeO2‐NR) in order to improve the specific surface area. The undoped and Zr4+, Al3+, and Si4+ doped nano‐rods...Thermally stable Zr4+, Al3+, and Si4+ cations were incorporated into the lattice of CeO2 nano‐rods (i.e., CeO2‐NR) in order to improve the specific surface area. The undoped and Zr4+, Al3+, and Si4+ doped nano‐rods were used as supports to prepare MnOx/CeO2‐NR, MnOx/CZ‐NR, MnOx/CA‐NR, and MnOx/CS‐NR catalysts, respectively. The prepared supports and catalysts were comprehensively characterized by transmission electron microscopy (TEM), high‐resolution TEM, X‐ray diffraction, Raman and N2‐physisorption analyses, hydrogen temperature‐programmed reduction, ammonia temperature‐programmed desorption, in situ diffuse reflectance infrared Fourier‐transform spectroscopic analysis of the NH3 adsorption, and X‐ray photoelectron spectroscopy. Moreover, the catalytic performance and H2O+SO2 tolerance of these samples were evaluated through NH3‐selective catalytic reduction (NH3‐SCR) in the absence or presence of H2O and SO2. The obtained results show that the MnOx/CS‐NR catalyst exhibits the highest NOx conversion and the lowest N2O concentration, which result from the largest number of oxygen vacancies and acid sites, the highest Mn4+ content, and the lowest redox ability. The MnOx/CS‐NR catalyst also presents excellent resistance to H2O and SO2. All of these phenomena suggest that Si4+ is the optimal dopant for the MnOx/CeO2‐NR catalyst.展开更多
Pr-CeO2 Nano-crystalline red pigments were prepared by low-temperature combustion with a later hydrothermal treatment using Ce（NO3）3·6H2O and Pr6O11 as raw materials. The phase composition, coloring mechanism a...Pr-CeO2 Nano-crystalline red pigments were prepared by low-temperature combustion with a later hydrothermal treatment using Ce（NO3）3·6H2O and Pr6O11 as raw materials. The phase composition, coloring mechanism and morphology of pigments were analyzed by XRD, SEM, EDS and XPS. Results showed that Pr-CeO2 solid solution with a fluorite structure was obtained by the diffusion of Pr^＋3 into CeO2 crystal lattice during the synthesis process. XPS analysis indicated that Pr^＋3 substitutes Ce^＋4 in CeO2 and is compensated by oxygen vacancies. Compared with low-temperature combustion synthesis, the Pr-CeO2 pigments prepared with a subsequent hydrothermal treatment have an average grain size of about 16.70 nm, and the crystallinity and red tonality are improved.展开更多
文摘High temperature heat-treatment of wood, which is value-added green product, is one of the altematives to chemical treatment. It has better dimensional stability, thermal insulating properties and biological resistance compared to kiln dried wood. It also has dark brown color which is very important for decorative purposes. Unfortunately, this color changes during weathering. Developing a transparent and non-toxic coating for the protection of heat-treated wood against discoloration without changing its natural appearance is the main objective of this study. For this purpose, waterborne acrylic polyurethane base was chosen because of its durability against weathering and non-toxic nature. Natural antioxidants which are extracted from barks and CeO2 nano particles （alone or together with lignin stabilizer） were used as additives to develop different coatings. The protective characteristics of these coatings were compared with highly pigmented and toxic industrial coating under accelerated weathering conditions. The results showed that acrylic polyurethane coatings protected wood better compared to commercially available coating tested in this study. The chemical modifications during accelerated weathering of coated and heat-treated wood surfaces were monitored by X-ray photoelectron spectroscopy analysis. The morphological changes took place during weathering were studied by fluorescence microscope analysis.
基金supported by Chongqing Key Laboratory of Micro/Nano Materials Engineering and Technology (No. KFJJ1106)Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection (No.JLCBE11004)Jiangsu Marine Resources Development Research Institute (No. JSIMR10E04)
文摘In this study,aquatic toxic effect of atrazine,and nano-CeO2,the accumulation,reproduction and adsorp-tion of atrazine onto nano-CeO2 and the facilitated transport of atrazine into D.magna by nano-CeO2 were exam-ined.The results showed that atrazine concentrations of 3.0,4.0,and 10.0 mg/L exhibited 43%,56%,68% mortali-ties,respectively,which indicated the mortality was 56% while the concentration of nano-CeO2 was 4.0 mg/L.D.magna accumulated considerably more atrazine when exposed to atrazine-contaminated water in the presence of nano-CeO2.At the same time,atrazine and nano-CeO2 yielded a significant reduction of the reproduction rate at all concentrations tested.What is more,the co-exposure of nano-CeO2 and atrazine was observed to significantly de-crease the reproduction rate of D.magna,and atrazine adsorbed on nano-CeO2 quickly.Therefore,attention should be paid to their associations with other contaminants for the risk assessment of nano-CeO2 and it is worthy of notice that the sorption of atrazine on nano-CeO2 would enhance the toxicity of atrazine to D.magna.
基金supported by National Natural Science Foundation of China (21876168, 21507130)Youth Innovation Promotion Association of CAS (2019376)the Chongqing Science & Technology Commission (cstc2016jcyjA0070, cstckjcxljrc13)~~
文摘Thermally stable Zr4+, Al3+, and Si4+ cations were incorporated into the lattice of CeO2 nano‐rods (i.e., CeO2‐NR) in order to improve the specific surface area. The undoped and Zr4+, Al3+, and Si4+ doped nano‐rods were used as supports to prepare MnOx/CeO2‐NR, MnOx/CZ‐NR, MnOx/CA‐NR, and MnOx/CS‐NR catalysts, respectively. The prepared supports and catalysts were comprehensively characterized by transmission electron microscopy (TEM), high‐resolution TEM, X‐ray diffraction, Raman and N2‐physisorption analyses, hydrogen temperature‐programmed reduction, ammonia temperature‐programmed desorption, in situ diffuse reflectance infrared Fourier‐transform spectroscopic analysis of the NH3 adsorption, and X‐ray photoelectron spectroscopy. Moreover, the catalytic performance and H2O+SO2 tolerance of these samples were evaluated through NH3‐selective catalytic reduction (NH3‐SCR) in the absence or presence of H2O and SO2. The obtained results show that the MnOx/CS‐NR catalyst exhibits the highest NOx conversion and the lowest N2O concentration, which result from the largest number of oxygen vacancies and acid sites, the highest Mn4+ content, and the lowest redox ability. The MnOx/CS‐NR catalyst also presents excellent resistance to H2O and SO2. All of these phenomena suggest that Si4+ is the optimal dopant for the MnOx/CeO2‐NR catalyst.
基金This work was supported by the Scientific Research Foundation of Shaanxi University of Science and Technology (No. SUST-B06)
文摘Pr-CeO2 Nano-crystalline red pigments were prepared by low-temperature combustion with a later hydrothermal treatment using Ce（NO3）3·6H2O and Pr6O11 as raw materials. The phase composition, coloring mechanism and morphology of pigments were analyzed by XRD, SEM, EDS and XPS. Results showed that Pr-CeO2 solid solution with a fluorite structure was obtained by the diffusion of Pr^＋3 into CeO2 crystal lattice during the synthesis process. XPS analysis indicated that Pr^＋3 substitutes Ce^＋4 in CeO2 and is compensated by oxygen vacancies. Compared with low-temperature combustion synthesis, the Pr-CeO2 pigments prepared with a subsequent hydrothermal treatment have an average grain size of about 16.70 nm, and the crystallinity and red tonality are improved.
