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321.
Si掺杂TiO2纳米管阵列制备、表征及其光催化氧化降解室内典型VOCs 总被引:1,自引:1,他引:0
以Na2SiF6/HF为电解液,采用阳极氧化法一步制备了Si掺杂的TiO2纳米管阵列光催化剂,通过SEM、XRD、DRS和EDX等表征手段对制备的催化剂进行了表征,并以甲苯为降解目标物,考察了Si掺杂的TiO2纳米管阵列光催化剂的活性以及各种反应参数对活性的影响.结果表明,TiO2纳米管阵列以锐钛矿和金红石2种晶形存在,Si高分散于TiO2纳米管的管壁上.Si的掺杂提高了TiO2对紫外光的吸收,其禁带宽度与TiO2相比发生了蓝移.Si掺杂的TiO2纳米管阵列具有较大比表面积.当以电解液中Na2SiF6浓度为0.03 mol·L-1,在400℃焙烧1 h制备的Si掺杂的TiO2纳米管阵列为光催化剂时,甲苯的降解率最高,降解率达到60%,与纯TiO2纳米管阵列相比,催化活性提了1倍. 相似文献
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目的将石墨膜置于9×10^5~9×10^7 rad(Si)总剂量下获得辐射改性石墨膜材料,探讨空间粒子辐射作用下石墨膜拉伸强度的演变规律。方法采用SEM、XRD、煅烧分析及XPS等手段分析石墨膜的结构及成分。结果石墨膜为有序堆积的层状结构,层间距为0.3355 nm,碳的质量分数高达99.75%,挥发分的质量分数为0.04%,灰分的质量分数为0.21%,XPS只检测到C1s及O1s峰。石墨膜的平均热膨胀系数为负值,且其峰值仅为-1.33×10^-6/℃,具备出色的结构稳定性。空间粒子辐射环境模拟试验表明,随着辐射剂量的升高,石墨膜的拉伸强度逐渐衰减,在更高剂量辐射下,石墨膜的拉伸强度趋向稳定。通过Raman光谱仪对辐射石墨膜结构的分析,揭示了力学性能的演变机理。结论辐射石墨膜的拉伸强度与其缺陷含量有很大的相关性,未经过辐射的原始石墨膜的缺陷含量最低,其拉伸强度最大,随着石墨膜的缺陷含量逐渐增多,其拉伸强度逐渐降低。 相似文献
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A new method for the preparation of rubber sheet strewn with titanium dioxide particles (TiO2-strewn sheet) is presented. This simple and low cost method is based on the use of TiO2 powder (Degussa P25) being strewn onto the sheet made from rubber latex (60% HA) through a steel sieve. The characteristic of the TiO2-strewn sheet was studied by using scanning electron microscopy/energy dispersive X-ray spectrometer (SEM/EDS) and X-ray diffractometer (XRD) techniques. The photocatalytic activity of TiO2-strewn rubber sheet was evaluated using Indigo Carmine (IC) dye as a model for organic dye pollutant in water. The results showed that the TiO2-strewn sheet could degrade IC dye solution under UV light irradiation. The effects of pH, initial concentration, and the intensity of UV light on the photodegradation were also investigated. Kinetics of the photocatalytic degradation was of the first-order reaction. The used TiO2-strewn sheet can be recovered and reused. The recycling uses did not require any cleaning between successive uses and no decline in the photodegradation efficiency was observed compared with freshly prepared TiO2-strewn sheet. 相似文献
324.
Photocatalytic degradation of perfluorooctanoic acid with β-Ga2O3 in anoxic aqueous solution 总被引:1,自引:0,他引:1
Perfluorooctanoic acid (PFOA) is a new-found hazardous persistent organic pollutant, and it is resistant to decomposition by hydroxyl radical (HO·) due to its stable chemical structure and the high electronegativity of fluorine. Photocatalytic reduction of PFOA with β-Ga2O3 in anoxic aqueous solution was investigated for the first time, and the results showed that the photoinduced electron (ecb-) coming from the β-Ga2O3 conduction band was the major degradation substance for PFOA, and shorter-chain perfluorinated carboxylic acids (PFCAs, CnF2n+1COOH, 1 ≤ n ≤ 6) were the dominant products. Furthermore, the concentration of F- was measured by the IC technique and defluorination efficiency was calculated. After 3 hr, the photocatalytic degradation efficiency was 98.8% and defluorination efficiency was 31.6% in the presence of thiosulfate and bubbling N2. The degradation reaction followed first-order kinetics (k = 0.0239 min-1, t1/2 = 0.48 hr). PFCAs (CnF2n+1COOH, 1 ≤ n ≤ 7) were detected and measured by LC-MS and LC-MS/MS methods. It was deduced that the probable photocatalytic degradation mechanism involves ecb- attacking the carboxyl of CnF2n+1COOH, resulting in decarboxylation and the generation of CnF2n+1·. The produced CnF2n+1· reacted with H2O, forming CnF2n+1OH, then CnF2n+1OH underwent HF loss and hydrolysis to form CnF2n+1COOH. 相似文献
325.
Photocatalytic degradation of phenanthrene on soil surfaces in the presence of nanometer anatase TiO2 under UV-light 总被引:1,自引:1,他引:0
The effect of nanometer anatase TiO2 was investigated on the photocatalytic degradation of phenanthrene on soil surfaces under a variety of conditions. After being spiked with phenanthrene, soil samples loaded with different amounts of TiO2 (0 wt.%, 1 wt.%, 2 wt.%, 3 wt.%, and 4 wt.%) were exposed to UV-light irradiation for 25 hr. The results indicated that the photocatalytic degradation of phenanthrene followed the pseudo first-order kinetics. TiO2 significantly accelerated the degradation of phenanthrene with the half-life reduced from 45.90 to 31.36 hr for TiO2 loading of 0 wt.% and 4 wt.%, respectively. In addition, the effects of H2O2, light intensity and humic acid on the degradation of phenanthrene were investigated. The degradation of phenanthrene increased with the concentration of H2O2, light intensity and the concentration of humic acids. It has been demonstrated that the photocatalytic method in the presence of nanometer anatase TiO2 was a very promising technology for the treatments of soil polluted with organic substances in the future. 相似文献
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Ming GE Changsheng GUO Xingwang ZHU Lili MA Wei HU Yuqiu WANG Zhenan HAN 《Frontiers of Environmental Science & Engineering》2009,3(3):271
ZnO/TiO2 composites were synthesized by using the solvothermal method and ultrasonic precipitation followed by heat treatment in order to investigate their photocatalytic degradation of methyl orange (MO) in aqueous suspension under UV irradiation. The composition and surface structure of the catalyst were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and transmission electron microscopy (TEM). The degradation efficiencies of MO at various pH values were obtained. The highest degradation efficiencies were obtained before 30min and after 60min at pH 11.0 and pH 2.0, respectively. A sample analysis was conducted using liquid chromatography coupled with electrospray ionization ion-trap mass spectrometry. Six intermediates were found during the photocatalytic degradation process of quinonoid MO. The degradation pathway of quinonoid MO was also proposed. 相似文献
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