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81.
采用溶胶-凝胶法制备了纯TiO2、TiO2-SiO2、V5+/TiO2-SiO2光催化剂,并分别负载于玻璃纤维布上,利用X射线衍射(XRD)和比表面及孔隙度(BET)分析技术对样品进行了表征。以甲醛的降解率来评价复合光催化剂的光催化活性。结果表明:玻璃纤维布预处理方式、TiO2与SiO2的复合配比、V的掺杂量、煅烧温度对纳米TiO2的光催化活性有影响。V5+/TiO2-SiO2复合光催化剂比表面积为143.74 m2/g,晶粒粒径为16.9 nm。 相似文献
82.
使用溶剂热法成功地制备了由BiOBr、还原氧化石墨烯(RGO)和硅藻土组成的三元复合光催化剂,应用XRD、SEM、XPS 、UV–Vis、BET和ESR等方法对催化剂进行了表征,并研究了其在可见下光催化降解甲醛气体的性能和催化机理。结果表明,硅藻土和BiOBr的质量比为1.5时,所制得的复合光催化剂对甲醛气体的光催化降解效率最高,3 h可达89.6%,其应用的最适宜空气相对湿度为45%。经过4个循环的重复使用后,复合光催化剂的催化性能衰减很小。复合光催化剂降解甲醛气体的主要活性物种为羟基自由基和光生空穴,其高催化性能主要得益于硅藻土吸附富集了低浓度甲醛气体以及RGO增加了光生载流子的分离效率。本研究结果可为开发可见下光催化降解甲醛气体工艺开发提供参考。 相似文献
83.
为了探明海水体系中多相光催化降解污染物的机制和路径,研究了在可见光激发下不同介孔TiO2光催化降解纯水和模拟海水中四环素(TC)的过程,明确了不同盐离子对光催化降解过程的影响.结合自由基捕获实验,电子自旋共振(ESR)光谱和中间产物分析研究了光降解污染物的主要活性物种和模拟海水中TC降解途径.结果表明,模拟海水中TC光催化过程会受到显著抑制,手性介孔TiO2催化剂对TC光降解反应速率相比其在纯水体系降低了70%左右,而非手性TiO2光催化剂在海水体系中几乎不能降解TC.模拟海水中阴离子对光降解过程影响较小,但Mg2+和Ca2+存在会显著抑制光催化过程.无论在纯水还是模拟海水中,可见光激发后催化剂产生的活性物种都是空穴为主,因此模拟海水中降解路径与纯水体系中相同.盐离子不会抑制活性物种的产生,但Mg2+和Ca2+会富集在TC分子中电负性强的原子周边,阻碍空穴等对TC分子中电负性强原子的攻击,从而抑制了光催化降解效率. 相似文献
84.
1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (or p,p′-DDT) is one of the most persistent pesticides. It is resistant to breakdown in nature and cause the water contamination problem. In this work, a major objective was to demonstrate the application of N-doped TiO2 in degradation and mineralization of the p,p′-DDT under UV and visible light in aqueous solution. The N-doped TiO2 nanopowders were prepared by a simple modified sol–gel procedure using diethanolamine (DEA) as a nitrogen source. The catalyst characteristics were investigated using XRD, SEM, TEM, and XPS. The adsorption and photocatalytic oxidation of p,p′-DDT using the synthesized N-doped TiO2 under UV and visible light were conducted in a batch photocatalytic experiment. The kinetics and p,p′-DDT degradation performance of the N-doped TiO2 were evaluated. Results show that the N-doped TiO2 can degrade p,p′-DDT effectively under both UV and visible lights. The rate constant of the p,p′-DDT degradation under UV light was only 0.0121 min?1, whereas the rate constant of the p,p′-DDT degradation under visible light was 0.1282 min?1. Under visible light, the 100% degradation of p,p′-DDT were obtained from N-doped TiO2 catalyst. The reaction rate of p,p′-DDT degradation using N-doped TiO2 under visible light was sixfold higher than that under UV light. According to Langmuir-Hinshelwood model, the adsorption equilibrium constant (K) for the N-doped TiO2 under visible light was 0.03078 L mg?1, and the apparent reaction rate constant (k) was 1.3941 mg L?1-min. Major intermediates detected during the p,p′-DDT degradation were p,p′-DDE, o,p′-DDE, p,p′-DDD and p,p′-DDD. Results from this work can be applied further for the breakdown of p,p′-DDT molecule in the real contaminated water using this technology. 相似文献
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AbstractA novel method of synthesis of tin dioxide quantum dots employing Camellia sinensis shoots as reducing agent and stabilizer is presented. The quantum dots were characterized by UV spectroscopy, X-Ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and transmission electron microscopy. The crystalline tin dioxide quantum dots with an average size of 4.3?nm were of flake like morphology capped by phenolic compounds of Camellia sinensis. The quantum dots were employed for the photocatalytic degradation of thiamethoxam resulting in 57% degradation within 45 mins. 相似文献
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Jinglian ZHAO Liang ZHAO Xinping WANG 《Frontiers of Environmental Science & Engineering in China》2008,2(4):415-420
The photocatalytic performance of ZnO/ZnS hybrid nanocomposite was largely higher than that of the mere ZnO or ZnS nanoparticles,
but the complicated procedure and misdistribution of final products limited its large-scale productions. The exploration of
a novel synthesis route of ZnO/ZnS hybrid photocatalysts with high catalytic performance is becoming a crucial step for the
large-scale application of ZnO/ZnS hybrid photocatalytic technique. Preparation and characterization of nanosized ZnO/ZnS
hybrid photocatalysts were studied in this paper. The photocatalysts were obtained via microwave-hydrothermal crystallization
with the help of sodium citrate. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy
(TEM), particle size distribution (PSD), and Fourier transformed infrared spectroscopy (FT-IR). The results indicated that
so-synthesized ZnO/ZnS samples consisted of the high pure cubic (sphalerite) ZnS and hexagonal ZnO nanocrystallines with a
narrow particle size distribution. The possible formation mechanisms of ZnO/ZnS nanocrystallines were mainly attributed to
the superficially protective effect of citrate. The photocatalytic experiments demonstrated that the ZnO/ZnS photocatalysts
exhibited a higher catalytic activity for the degradation of acid fuchsine than other monocomponents. 相似文献