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太阳光TiO2薄层光催化降解有机磷农药的研究 总被引:22,自引:5,他引:22
研究了在太阳光的照射下,TiO2薄层光催化降解有机磷农药的可行性。结果表明,0.65×10-4mol·L-1的久效磷、甲拌磷农药光照他可完全降解至PO43-;加入微量的H2O2或通入空气可大大提高光解率;有机磷农药初始浓度增加,其光解率下降;光照120h后TiO2薄层的光催化活性没有减弱,可以连续使用。初步探讨了有机磷农药光催化降解的机理,认为·OH和O22-是最主要的氧化剂。 相似文献
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纳米Fe2O3/Fe3O4光催化法处理造纸废水的研究 总被引:2,自引:0,他引:2
以纳米Fe_2O_3/Fe_3O_4为催化剂,用光催化氧化法处理造纸废水。研究结果表明:该催化剂能有效、快速地降低废水中的COD_(Cr),催化剂用量、H_2O_2用量、pH值、反应时间等各因素对处理效果的影响大小依次为:光照时间>H_2O_2用量>催化剂用量>溶液pH值;室温下最佳反应条件为:催化剂用量0.5g·L~(-1)、30%的H_2O_2用量为5‰(V/V)、pH=3.0,300W高压汞灯光照4h,废水的COD_(Cr)值从800 mg·L~(-1)降到48mg·L~(-1),去除率达到94%。实验进一步考察了太阳光照射下催化剂对废水的降解效果,表明太阳光光照下催化剂对废水也有较好的处理效果。Fe_3O_4的存在使催化剂具有一定磁性,可利用磁分离法将催化剂从体系中分离。 相似文献
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掺铋纳米TiO_2制备及可见光催化降解有机污染物 总被引:1,自引:0,他引:1
采用在酸性条件下超声沉淀的方法低温制备了Bi掺杂TiO_2纳米粉体,采用X射线光电子能谱(XPS)、X射线衍射(XRD)和透射电镜(TEM)对催化剂进行了初步表征,发现其禁带宽度变窄,主要为锐钛矿(82.7%)和金红石(17.3%)混晶,纳米尺寸为25.8nm。以酸性桃红(SRB)和无色小分子2,4-二氯苯酚(2,4-dichlorophenol,2,4-DCP)作为探针反应,在可见光照射下(λ420nm)测定了SRB降解过程中总有机碳(1OC)的变化,发现SRB的TOC去除率为61.6%。跟踪测定光催化反应体系中氧化物种,表明光催化涉及羟基自由基(·OH)过程,所制备的催化剂在可见光下具有较高的催化氧化活性。 相似文献
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《International Journal of Hydrogen Energy》2019,44(29):14624-14634
Photocatalytic hydrogen production is a promising approach of sustainable economy, because a use of sunlight and water to produce a fuel will solve a problem of fossil fuels depletion. Metal sulfides are well known photocatalysts in water splitting process, but in absence of sacrificial electron donor they undergo a photocorrosion. In this paper we studied a possible strategy to protect the sulfide photocatalysts and to improve its photostability by a deposition of small amount of ruthenium oxide at surface of sulfides. Nanocrystalline zinc sulfide and copper sulfide were prepared in a hydrothermal way and have been functionalized by RuO2. As prepared photocatalysts showed good activity towards hydrogen formation. Modification of sulfides with ruthenium oxide had a few positive effects: it expanded a light absorption range by photocatalysts, enhanced the photocatalytic activity towards H2 formation, improved a photostability in comparison with neat ZnS and CuS as well as protected from the electronic and structural changes within semiconductors due to irradiation. 相似文献
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《International Journal of Hydrogen Energy》2022,47(39):17214-17223
The photocatalytic evolution of H2 over La2O3 decorated TiO2 catalyst was examined under solar light. It was observed that during the course of the reaction, the transformation of La2O3/TiO2 into La2O3–TiO2–La2O2CO3 occurred and these species effectively suppressed electron-hole pair recombination by forming electron trapping centres on the surface, resulting in an increased visible light absorption and improved H2 yield. The 2 wt%La2O3/TiO2 nanocomposite demonstrated better H2 yield (~8.76 mmol (gcat)?1) than the bare TiO2 (~1.1 mmol (gcat)?1). The catalyst was stable even after several consecutive recycles with no substantial loss of hydrogen production rate. The H2 rates were correlated with the physicochemical characteristics of the catalysts examined by BET–SA, H2-TPR, XRD, UV-DRS, Raman spectroscopy, FTIR, HRTEM, EPR and PL spectroscopy. 相似文献
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《International Journal of Hydrogen Energy》2023,48(79):30909-30929
Moderate or Intense Low-oxygen Dilution (MILD) combustion of a syngas fuel under air-fuel, oxygen-enhanced, and oxy-fuel condition are numerically studied with using counterflow diffusion flame. Fuel composition, temperature of oxidant (Tox), and oxygen mole fraction (XO2) are selected as the main parameters. Fake species (FCO2) with the same CO2 physical properties is used for separation the physical and chemical effects of replacing CO2 with N2. According to the results, under the high preheating temperatures, the chemical effect of changing the oxidant composition from N2 to CO2 is the main reason of the changes in flame structure, ignition delay time (IDT) and heat release rate (HRR) while physical differences play a more prominent role in the low preheating temperature MILD combustion. In all XO2, the physical and chemical effects of replacing CO2 with N2 have almost the same role on the maximum flame temperature. The results of IDT expressed that chemical discrepancies of CO2 and N2 play a key role on IDT enhancement by increasing CO2 in the oxidant composition. The sensitivity analysis of CH2O for variations of Tox and XO2 shows that reactions R54, R56, R58, and R101 are the main responsible of lower HRR and higher IDT by moving from air-syngas to oxy-fuel MILD combustion. 相似文献
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Xiaoxiao Chen Mengyao Liu Lijuan Zhang Yunshan Zhou Enming Ping Chunyan Ding 《International Journal of Hydrogen Energy》2021,46(24):13029-13037
ZIF-67@NH2–SiO2 composites were prepared by loading the metal-organic frameworks ZIF-67 on amino modified SiO2 gel particles (NH2–SiO2, 80–100 mesh) through layer-by-layer self-assembly method. Systematic investigation on the effects of ZIF-67 loading amounts on NH2–SiO2 packed stainless steel chromatographic column (specification 1.0 m×2.0 mm I.D.), the flow rate of He as carrier gas and the injection amount of mixed gas (H2/D2) on the hydrogen isotope H2/D2 separation performance at liquid nitrogen temperature, unraveled the optimal conditions for H2/D2 isotope separation. The results showed that the optimal stationary phase materials under the optimized conditions can effectively separate H2 and D2 with separation resolution R = 1.52 and the separation time t = 10.15 min. The superior performance of the ZIF-67 is tentatively thought to be due to kinetic quantum sieving (pore size 3.3 Å) effect and chemical affinity sieving effect of Co ion in ZIF-67. 相似文献
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《Energy》1999,24(1):21-30
The photocatalytic reduction of CO2 was investigated using TiO2 powders in supercritical fluid CO2. These were irradiated in a stainless steel vessel at 9.0 MPa and 35°C. After reducing the CO2 pressure to the ordinary state, pure water was added to the vessel while avoiding air contamination. No gaseous reduction products were observed. Formic acid was obtained only in aqueous solution. The optimal irradiation time for the production of formic acid was 5 h. Addition of acidic solutions rather than pure water was preferable for formic acid formation. Formic acid seems to be produced through the protonation of reaction intermediates on TiO2 powders in solutions. The CO2-reduction system described here may be of practical value for efficient CO2-conversion and fixation, storage of solar energy, and production of raw materials for the photochemical industry. 相似文献
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Honghua Li Cuixia Li Lijun Han Chunshan Li Suojiang Zhang 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2016,38(3):420-426
Carbon dioxide was photocatalytically reduced to produce methanol and ethanol in the presence of CuO-loaded titania powders suspended in water containing Na2SO3 as the hole scavenger. The photocatalysts were synthesized by an impregnation method using P25 (Degussa) as support. At the optimum amount of copper oxide loading (3 wt%), the methanol and ethanol yields were 12.5 and 27.1 μmol/g-catal., respectively, following 6 h of UV illumination. The redistribution of photogenerated charge carriers in CuO/TiO2 facilitates electron trapping and prohibits the recombination of electrons and holes, which significantly increases photoefficiency. The addition of Na2SO3 promotes the formation of ethanol. 相似文献
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Numerical analysis on flame structure in a counterflow diffusion flame has been conducted for understanding the effects of CO2 addition to fuel, systematically varying initial concentration of CO2 and axial velocity gradient. The effects of CO2 addition to fuel side in a counterflow diffusion flame are globally divided into two categories: diluent effects due to the relative reduction in the concentrations of the reactive species, and direct chemical effects caused by the breakdown of CO2 through the reactions of third‐body collision and thermal dissociation. The deflection of CO2 mole fraction profile with mixture fraction clarifies that the converted CO quantity from CO2 is not negligible at low axial velocity gradients. It is also known that the addition of CO2 does not alter the basic skeleton of the H2–O2 reaction mechanism, but contributes to the formation and destruction of hydrocarbon products such as HCO. At high axial velocity gradients the CO converted reaction is suppressed and then CO2 plays the role of a diluent at these conditions. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献