The V2O5-WO3-MoO3/TiO2 honeycomb catalyst was prepared with industrial grade chemicals. The structural and physico-chemical properties were analyzed with X-ray diffraction (XRD), scanning electron micrograph (SEM) and...The V2O5-WO3-MoO3/TiO2 honeycomb catalyst was prepared with industrial grade chemicals. The structural and physico-chemical properties were analyzed with X-ray diffraction (XRD), scanning electron micrograph (SEM) and mercury porosimetry. The NOx conversion and durability were investigated on a pilot plant test set under the actual operational conditions of a coal fired boiler. The catalyst monolith had good formability with mass percentage of V:W:Mo:TiO2 :fiber glass= 1:4.5:4.5:72:18. Vanadium, tungsten and molybdenum species were highly dispersed on anatase TiO2 without causing the transformation of anatase TiO2 to rutile by calcining under a current of air at 450℃ for 4.5 h, but there were some degrees of crystal distortion. The catalyst particle sizes were almost uniform with close pile-up and the pore structure was regular with complete macro-pore formation and large specific surface area. The NOx conversion was sensitive to temperature but nearly insensitive to NH3 . The catalyst showed strong adaptability to NOx concentration with activity above 80% in the range of 615-1640 mg·m-3 . Within the range of 720-8640 h continuous operation, the NOx conversion dropped at a rate of about 1% reduction per 600 h.展开更多
Diluted magnetic oxides have evolved into a popular branch of materials science during the last decade. In the first few years,people attributed the ferromagnetism to the magnetic dopants. However,the observation of f...Diluted magnetic oxides have evolved into a popular branch of materials science during the last decade. In the first few years,people attributed the ferromagnetism to the magnetic dopants. However,the observation of ferromagnetism in undoped HfO_2 thin films made it more controversial and promoted extensive research on the ferromagnetism in various undoped oxides. Both of the experimental works and theoretical studies have shown that intrinsic defects in oxide nanomaterials play a crucial role in the origin of such an unexpected ferromagnetism,in spite of some contradicting views which kind of defects is predominant. In the past several years,we have conducted systematic and thorough research on the room temperature ferromagnetism in undoped ZrO_2 thin films,and clarify some physics behind it. We firstly prepared undoped ZrO_2 thin films by different ways,such as Pulsed electron beam deposition,magnetron sputtering,and electron beam evaporation,and successfully obtained ZrO_2 thin films with different crystalline structure,in particular a pure high-temperature stabilized one,by adjusting some preparation parameters during the deposition process or post-annealing treatment. A phase-dependent ferromagnetism was then confirmed to exist in such ZrO_2 thin films. Further,we conducted exhaustive defect analysis and characterization by X-ray photoelectron spectroscopy,photoluminescence spectra,and electron paramagnetic resonance,respectively,and found the oxygen vacancy,specifically the single ionized oxygen vacancy( V_O^+),has a remarkable influence on the enhancement of ferromagnetism. Herein,we will review the work in detail on the phase-dependent and oxygen vacancy-enhanced room temperature ferromagnetism in undoped ZrO_2 thin films.展开更多
This work has been undertaken to study the influences of pH value on the characteristics and activity of photocatalyst by deposition- precipitation method during its preparation process. A series of Pt-modified TiO2 w...This work has been undertaken to study the influences of pH value on the characteristics and activity of photocatalyst by deposition- precipitation method during its preparation process. A series of Pt-modified TiO2 were prepared by deposition-precipitation method at different pH values as well as wet impregnation method, and characterized by XRD, XPS, TEM, UV-Vis and photoluminescence （PL）. It was found that the catalysts had the highest photocatalytic activity for NO conversion when pH value was kept at around 7. And the sample prepared by deposition-precipitation method showed higher activity than that by impregnation method. This was mainly due to their high value in highly-dispersed platinum oxides （PtOx） content on the surface of the catalysts. The results from UV-Vis absorption showed that highest absorbance was obtained for Pt/TiO2 prepared at pH values of around 7. And PL spectra results indicated that the recombination rate of photogenerated electrons and holes of the samples prepared by deposition-precipitation method was lower than that prepared by impregnation method. And in the zeta potential study, the pH values for the isoelectric point of the preparing slurry of 0.05 wt.%Pt/TiO2 and 0.5 wt.%Pt/TiO2 were determined to be 6.5-8.5, which further confirmed the enrichment of PtOx dopants for the catalysts repapered when pH value was around 7.展开更多
Aim of the present study was to synthesize titanium dioxide nanoparticles （YiO2 NPs） from marine actinobacteria and to develop an eco-friendly azo-dye degradation method. A total of five actinobacterial isolates wer...Aim of the present study was to synthesize titanium dioxide nanoparticles （YiO2 NPs） from marine actinobacteria and to develop an eco-friendly azo-dye degradation method. A total of five actinobacterial isolates were isolated from Chennai marine sediments, Tamilnadu, India and analyzed for the synthesis of TiO2 NPs using titanium hydroxide. Among these, the isolate PSV 3 showed positive results for the synthesis of TiO2 NPs, which was confirmed by UV analysis. Further characterization of the synthesized TiO2 NPs was done using XRD, AFM and FI＇-IR analysis. Actinobacterial crude extract and synthesized TiO2 NPs was found efficient in degrading azo dye such as Acid Red 79 （AR-79） and Acid Red 80 （AR-80）. Degradation percentage was found to be 81% for AR-79, 83% for AR-80 using actinobacterial crude extract and 84% for AR-79, 85% for AR-80 using TiO2 NPs. Immobilized actinobacterial ceils showed 88% for AR-79 and 81% for AR- 80, dye degrading capacity. Degraded components were characterized by FT-IR and GC-MS analysis. The phytotoxicity test with 500 μg/mL of untreated dye showed remarkable phenotypic as well as cellular damage to Tagetes erecta plant. Comparatively no such damage was observed on plants by degraded dye components. In biotoxicity assay, treated dyes showed less toxic effect as compared to the untreated dyes.展开更多
Heavy hydrocarbons （HHCs） in soils impacted by crude oil spills are generally recalcitrant to biodegrada- tion due to their low bioavailability and complex chemical structure. In this study, soils were pretreated wi...Heavy hydrocarbons （HHCs） in soils impacted by crude oil spills are generally recalcitrant to biodegrada- tion due to their low bioavailability and complex chemical structure. In this study, soils were pretreated with varying concentrations of ultraviolet radiation A （UVA） or ultraviolet radiation C （UVC） activated titanium dioxide （TiO2） （1%-5%） under varying moisture conditions （0%- 300% water holding capacity （WHC）） to enhance biodegradation of HCCs and shorten remediation time- frames. We demonstrate that pretreatment of impacted soils with UVC-activated TiO2 in soil slurries could enhance bioremediation of HHCs. Total petroleum hydrocarbon （TPH） removal after 24 h exposure to UVC （254 nm and 4.8 mW/cm2） was （19.15：1.6）% in slurries with 300% WHC and 5 wt-% TiO2. TPH removal was non-selective in the C15-C36 range and increased with moisture content and TiO2 concentration. In a 10-d bioremediation test, TPH removal in treated soil increased to （26.05：0.9）%, compared to （15.45：0.8）% for controls without photo- catalytic pre-treatment. Enhanced biodegradation was also confirmed by respirometry. This suggests that addition of UVC-activated TiO2 to soil slurries can transform recalcitrant hydrocarbons into more bioavailable and biodegradable byproducts and increase the rate of subsequent biodegradation. However, similar results were not observed for soils pretreated with UVA activated TiO2. This suggests that activation of TiO2 by sunlight and direct addition of TiO2 to unsaturated soils within landfarming setting may not be a feasible approach. Nevertheless, less than 1% of UVA （7.5 mW/cm2） or UVC （1.4 mW/cm2） penetrated beyond 0.3 cm soil depth, indicating that limited light penetration through soil would hinder the ability of TiO2 to enhance soil bioremediation under land farming conditions.展开更多
基金Supported by the Science and Technology Development Planning of Shandong Province(2011GSF11716)China Scholarship Council for Researching in University of Birmingham
文摘The V2O5-WO3-MoO3/TiO2 honeycomb catalyst was prepared with industrial grade chemicals. The structural and physico-chemical properties were analyzed with X-ray diffraction (XRD), scanning electron micrograph (SEM) and mercury porosimetry. The NOx conversion and durability were investigated on a pilot plant test set under the actual operational conditions of a coal fired boiler. The catalyst monolith had good formability with mass percentage of V:W:Mo:TiO2 :fiber glass= 1:4.5:4.5:72:18. Vanadium, tungsten and molybdenum species were highly dispersed on anatase TiO2 without causing the transformation of anatase TiO2 to rutile by calcining under a current of air at 450℃ for 4.5 h, but there were some degrees of crystal distortion. The catalyst particle sizes were almost uniform with close pile-up and the pore structure was regular with complete macro-pore formation and large specific surface area. The NOx conversion was sensitive to temperature but nearly insensitive to NH3 . The catalyst showed strong adaptability to NOx concentration with activity above 80% in the range of 615-1640 mg·m-3 . Within the range of 720-8640 h continuous operation, the NOx conversion dropped at a rate of about 1% reduction per 600 h.
基金Sponsored by the National Natural Science Foundation of China(Grant No.50931002,51072094 and 51372135)the Ministry of Education of the People’s Republic of China(Grant No.113007A)the Tsinghua University Initiative Scientific Research Program
文摘Diluted magnetic oxides have evolved into a popular branch of materials science during the last decade. In the first few years,people attributed the ferromagnetism to the magnetic dopants. However,the observation of ferromagnetism in undoped HfO_2 thin films made it more controversial and promoted extensive research on the ferromagnetism in various undoped oxides. Both of the experimental works and theoretical studies have shown that intrinsic defects in oxide nanomaterials play a crucial role in the origin of such an unexpected ferromagnetism,in spite of some contradicting views which kind of defects is predominant. In the past several years,we have conducted systematic and thorough research on the room temperature ferromagnetism in undoped ZrO_2 thin films,and clarify some physics behind it. We firstly prepared undoped ZrO_2 thin films by different ways,such as Pulsed electron beam deposition,magnetron sputtering,and electron beam evaporation,and successfully obtained ZrO_2 thin films with different crystalline structure,in particular a pure high-temperature stabilized one,by adjusting some preparation parameters during the deposition process or post-annealing treatment. A phase-dependent ferromagnetism was then confirmed to exist in such ZrO_2 thin films. Further,we conducted exhaustive defect analysis and characterization by X-ray photoelectron spectroscopy,photoluminescence spectra,and electron paramagnetic resonance,respectively,and found the oxygen vacancy,specifically the single ionized oxygen vacancy( V_O^+),has a remarkable influence on the enhancement of ferromagnetism. Herein,we will review the work in detail on the phase-dependent and oxygen vacancy-enhanced room temperature ferromagnetism in undoped ZrO_2 thin films.
基金supported by the National Natural Science Foundation of China (No. 50908201)
文摘This work has been undertaken to study the influences of pH value on the characteristics and activity of photocatalyst by deposition- precipitation method during its preparation process. A series of Pt-modified TiO2 were prepared by deposition-precipitation method at different pH values as well as wet impregnation method, and characterized by XRD, XPS, TEM, UV-Vis and photoluminescence （PL）. It was found that the catalysts had the highest photocatalytic activity for NO conversion when pH value was kept at around 7. And the sample prepared by deposition-precipitation method showed higher activity than that by impregnation method. This was mainly due to their high value in highly-dispersed platinum oxides （PtOx） content on the surface of the catalysts. The results from UV-Vis absorption showed that highest absorbance was obtained for Pt/TiO2 prepared at pH values of around 7. And PL spectra results indicated that the recombination rate of photogenerated electrons and holes of the samples prepared by deposition-precipitation method was lower than that prepared by impregnation method. And in the zeta potential study, the pH values for the isoelectric point of the preparing slurry of 0.05 wt.%Pt/TiO2 and 0.5 wt.%Pt/TiO2 were determined to be 6.5-8.5, which further confirmed the enrichment of PtOx dopants for the catalysts repapered when pH value was around 7.
基金VIT University,Vellore,and TamilnaduIndia for supporting this study
文摘Aim of the present study was to synthesize titanium dioxide nanoparticles （YiO2 NPs） from marine actinobacteria and to develop an eco-friendly azo-dye degradation method. A total of five actinobacterial isolates were isolated from Chennai marine sediments, Tamilnadu, India and analyzed for the synthesis of TiO2 NPs using titanium hydroxide. Among these, the isolate PSV 3 showed positive results for the synthesis of TiO2 NPs, which was confirmed by UV analysis. Further characterization of the synthesized TiO2 NPs was done using XRD, AFM and FI＇-IR analysis. Actinobacterial crude extract and synthesized TiO2 NPs was found efficient in degrading azo dye such as Acid Red 79 （AR-79） and Acid Red 80 （AR-80）. Degradation percentage was found to be 81% for AR-79, 83% for AR-80 using actinobacterial crude extract and 84% for AR-79, 85% for AR-80 using TiO2 NPs. Immobilized actinobacterial ceils showed 88% for AR-79 and 81% for AR- 80, dye degrading capacity. Degraded components were characterized by FT-IR and GC-MS analysis. The phytotoxicity test with 500 μg/mL of untreated dye showed remarkable phenotypic as well as cellular damage to Tagetes erecta plant. Comparatively no such damage was observed on plants by degraded dye components. In biotoxicity assay, treated dyes showed less toxic effect as compared to the untreated dyes.
文摘Heavy hydrocarbons （HHCs） in soils impacted by crude oil spills are generally recalcitrant to biodegrada- tion due to their low bioavailability and complex chemical structure. In this study, soils were pretreated with varying concentrations of ultraviolet radiation A （UVA） or ultraviolet radiation C （UVC） activated titanium dioxide （TiO2） （1%-5%） under varying moisture conditions （0%- 300% water holding capacity （WHC）） to enhance biodegradation of HCCs and shorten remediation time- frames. We demonstrate that pretreatment of impacted soils with UVC-activated TiO2 in soil slurries could enhance bioremediation of HHCs. Total petroleum hydrocarbon （TPH） removal after 24 h exposure to UVC （254 nm and 4.8 mW/cm2） was （19.15：1.6）% in slurries with 300% WHC and 5 wt-% TiO2. TPH removal was non-selective in the C15-C36 range and increased with moisture content and TiO2 concentration. In a 10-d bioremediation test, TPH removal in treated soil increased to （26.05：0.9）%, compared to （15.45：0.8）% for controls without photo- catalytic pre-treatment. Enhanced biodegradation was also confirmed by respirometry. This suggests that addition of UVC-activated TiO2 to soil slurries can transform recalcitrant hydrocarbons into more bioavailable and biodegradable byproducts and increase the rate of subsequent biodegradation. However, similar results were not observed for soils pretreated with UVA activated TiO2. This suggests that activation of TiO2 by sunlight and direct addition of TiO2 to unsaturated soils within landfarming setting may not be a feasible approach. Nevertheless, less than 1% of UVA （7.5 mW/cm2） or UVC （1.4 mW/cm2） penetrated beyond 0.3 cm soil depth, indicating that limited light penetration through soil would hinder the ability of TiO2 to enhance soil bioremediation under land farming conditions.
