共查询到20条相似文献,搜索用时 31 毫秒
1.
Yu Liu Hongbing Yu Zhenning Lv Sihui Zhan Jiangyao Yang Xinhong Peng Yixuan Ren Xiaoyan Wu 《环境科学学报(英文版)》2012,24(10):1867-1875
Cerium-doped SiO2/TiO2 nanostructured fibers were fabricated by electrospinning technology. The prepared fibers were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Using the fibers as catalysts, photocatalytic degradation of Methylene Blue (MB) aqueous solution was carried out under simulated sunlight. The 0.2% Ce doping proved to be the optimal concentration for the doping of TiO2/SiO2, compared to other Ce-doped molar concentrations. The 0.2% Ce-doped SiO2/TiO2 fibers exhibited higher photocatalytic activity than industrial Degussa P25 and the samples doped with only Ce or SiO2. The reasons for improving the photocatalytic activity were also discussed. Several operational parameters were studied, which showed that the photocatalytic efficiency of MB was influenced by parameters such as the initial dye concentration, the initial pH, inorganic anions, and so on. In addition, the influences of an electron acceptor and a radical scavenger suggested that OH was the dominant photooxidant during the photocatalytic process. The reuse evaluation of the fibers indicated that their photocatalytic activity had good stability. 相似文献
2.
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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It is important to develop efficient and economic techniques for removing volatile organic compounds (VOCs) in indoor air. Heterogeneous TiO2-based semiconductors are a promising technology for achieving this goal. Anatase/brookite/rutile tricrystalline TiO2 with mesoporous structure was synthesized by a low-temperature hydrothermal route in the presence of HNO3. The obtained samples were characterized by X-ray diffraction and N2 adsorption–desorption isotherm. The photocatalytic activity was evaluated by photocatalytic decomposition of toluene in air under UV light illumination. The results show that tricrystalline TiO2 exhibited higher photocatalytic activity and durability toward gaseous toluene than bicrystalline TiO2, due to the synergistic effects of high surface area, uniform mesoporous structure and junctions among mixed phases. The tricrystalline TiO2 prepared at RHNO3 = 0.8, containing 80.7% anatase, 15.6% brookite and 3.7% rutile, exhibited the highest photocatalytic activity, about 3.85-fold higher than that of P25. The high activity did not significantly degrade even after five reuse cycles. In conclusion, it is expected that our study regarding gas-phase degradation of toluene over tricrystalline TiO2 will enrich the chemistry of the TiO2-based materials as photocatalysts for environmental remediation and stimulate further research interest on this intriguing topic. 相似文献
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ZnBiYO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiYO4 were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV–Vis diffuse reflectance. ZnBiYO4 crystallized with a tetragonal spinel structure with space group I41/A. The lattice parameters for ZnBiYO4 were a = b = 11.176479 Å and c = 10.014323 Å. The band gap of ZnBiYO4 was estimated to be 1.58 eV. The photocatalytic activity of ZnBiYO4 was assessed by photodegradation of methyl orange under visible light irradiation. The results showed that ZnBiYO4 had higher catalytic activity compared with N-doped TiO2 under the same experimental conditions using visible light irradiation. The photocatalytic degradation of methyl orange with ZnBiYO4 or N-doped TiO2 as catalyst followed first-order reaction kinetics, and the first-order rate constant was 0.01575 and 0.00416 min− 1 for ZnBiYO4 and N-doped TiO2, respectively. After visible light irradiation for 220 min with ZnBiYO4 as catalyst, complete removal and mineralization of methyl orange were observed. The reduction of total organic carbon, formation of inorganic products, SO42 − and NO3−, and evolution of CO2 revealed the continuous mineralization of methyl orange during the photocatalytic process. The intermediate products were identified using liquid chromatography–mass spectrometry. The ZnBiYO4/(visible light) photocatalysis system was found to be suitable for textile industry wastewater treatment and could be used to solve other environmental chemical pollution problems. 相似文献
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利用静电纺丝技术原位制备了准一维结构CaIn_2O_4-In_2O_3纳米带.采用XRD、SEM、TEM、EDS、UV-vis DRS、N_2吸附-脱附曲线等对合成的光催化剂进行表征,并以对苯二甲酸(TA)为分子探针物质,结合荧光技术探讨了光催化反应过程中·OH自由基的变化.以亚甲基蓝(MB)为降解目标物,考察了CaIn_2O_4-In_2O_3纳米带的光催化活性,并研究了溶液pH及MB初始浓度对其光催化活性的影响.研究结果表明,宽度约为(663±75) nm的CaIn_2O_4-In_2O_3纳米带由直径约为80 nm的纳米颗粒组成,且纳米颗粒之间有一定的孔隙.模拟太阳光辐照120 min,MB的降解率为76%,且降解过程服从一级动力学模型.CaIn_2O_4-In_2O_3纳米带在酸性环境中显正电性,且光催化反应体系中·OH自由基的生成量随反应时间线性增加.CaIn_2O_4与In_2O_3的耦合使得合成的光催化剂在模拟太阳光下具有良好的光催化活性. 相似文献
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Highly active mesoporous TiO_2 of about 6 nm crystal size and 280.7 m~2/g specific surface areas has been successfully synthesized via controlled hydrolysis of titanium butoxide at acidic medium. It was characterized by means of XRD(X-ray diffraction), SEM(scanning electron microscopy), TEM(transmission electron microscopy), FT-IR(Fourier transform infrared spectroscopy), TGA(thermogravimetric analysis), DSC(differential scanning calorimetry) and BET(Brunauer–Emmett–Teller) surface area. The degradation of dichlorophenol-indophenol(DCPIP) under ultraviolet(UV) light was studied to evaluate the photocatalytic activity of samples. The effects of different parameters and kinetics were investigated. Accordingly, a complete degradation of DCPIP dye was achieved by applying the optimal operational conditions of 1 g/L of catalyst, 10 mg/L of DCPIP, pH of 3 and the temperature at 25 ± 3°C after 3 min under UV irradiation. Meanwhile, the Langmuir–Hinshelwood kinetic model described the variations in pure photocatalytic branch in consistent with a first order power law model.The results proved that the prepared TiO_2 nanoparticle has a photocatalytic activity significantly better than Degussa P-25. 相似文献
8.
Ashok Kumar Chakraborty Md Emran Hossain Md Masudur Rhaman K M A Sobahan 《环境科学学报(英文版)》2014,26(2):458-465
A nanoheterojunction composite photocatalyst Bi2O3/TiO2working under visible-light(λ 420 nm) was prepared by combining two semiconductors Bi2O3 and TiO2 varying the Bi2O3/TiO2molar ratio. Maleic acid was employed as an organic binder to unite Bi2O3 and TiO2 nanoparticles. The SEM, TEM, XRD and diffuse reflectance spectra were utilized to characterize the prepared Bi2O3/TiO2nanoheterojunction. The nanocomposite exhibited unusual high photocatalytic activity in decomposing 2-propanol in gas phase and phenol in aqueous phase and, evolution of CO2 under visible light irradiation while the end members exhibited low photocatalytic activity. The composite was optimized to 5 mol% Bi2O3/TiO2. The remarkable high photocatalytic efficiency originates from the unique relative energy band position of Bi2O3 and TiO2 as well as the absorption of visible light by Bi2O3. 相似文献
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利用高压静电纺丝技术,制得含羧基的导电聚合物纤维(聚偏氟乙烯/苯乙烯-马来酸酐共聚物/纳米石墨).水热条件下在纤维表面原位合成了纳米级的TiO2,再通过水热法在TiO2表面制备了微米级的球形CuO颗粒,得到CuO-TiO2/导电聚合物纤维复合材料.运用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、紫外-可见吸收光谱仪(UV-Vis)和热失重分析(TGA)对复合材料的结构与性能进行表征,并利用氙灯模拟太阳光进行光催化降解次甲基蓝实验.结果发现,CuO-TiO2/导电聚合物纤维复合材料的降解效率高于CuO-TiO2/非导电聚合物纤维、CuO-TiO2粉体和Degussa P25,光催化降解3.5h时,次甲基蓝的残留率为4.7%. 相似文献
10.
TiO2-石墨烯(Gn)复合材料光催化降解O3研究 总被引:1,自引:2,他引:1
通过改性Hummer法及溶胶凝胶法,制备出TiO2-石墨烯光催化复合材料.经吸附-光催化活性实验选出光催化活性最高的含C量为1.5%(质量分数)的TiO2-石墨烯复合材料,并在自行设计的模拟大型客机环境的气相光催化反应器中,进行O3光催化降解实验研究.结果表明,TiO2-石墨烯复合光催化材料在较短时间内对O3有较高的降解效率,且其光催化活性显著优于纯TiO2材料.初始O3浓度为(0.150~0.200)×10-6时,复合光催化剂受紫外光激发60 min的光催化降解率为66.12%,初始O3浓度为(0.950~1.000)×10-6时,其光催化降解率约为77%,较低浓度时((0.100~0.150)×10-6),O3去除率也能达到45.45%.此外,通过探讨光催化材料的重复使用性能,表明复合光催化剂重复使用4次以内,其对O3的光催化降解率保持基本稳定. 相似文献
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TiO_2 nanotube(Ti NT) electrodes anodized in fluorinated organic solutions were successfully prepared on Ti sheets. Field-emission scanning electron microscopy(FE-SEM) and X-ray diffraction(XRD) were performed to characterize the TiNT electrodes. The linear voltammetry results under irradiation showed that the TiNT electrode annealed at 450°C presented the highest photoelectrochemical activity. By combining photocatalytic with electrochemical process, a significantly synergetic effect on ammonia degradation was observed with Na_2SO_4 as supporting electrolyte at pH 10.7. Furthermore, the photoelectrocatalytic efficiency on the ammonia degradation was greatly enhanced in presence of chloride ions without the limitation of pH. The degradation rate was improved by 14.8 times reaching 4.98 × 10~(-2) min~(-1) at pH 10.7 and a faster degradation rate of 6.34 × 10~(-2) min~(-1)was obtained at pH 3.01. The in situ photoelectrocatalytic generated active chlorine was proposed to be responsible for the improved efficiency. On the other hand, an enhanced degradation of ammonia using TiNT electrode fabricated in fluorinated organic solution was also confirmed compared to TiNT electrode anodized in fluorinated water solution and TiO_2 film electrode fabricated by sol–gel method. Finally, the effect of chloride concentration was also discussed. 相似文献
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The immobilization of pre-dispersed TiO2 colloids onto the external surface of the clay mineral montmorillonite (Mt) was accomplished and regulated via a self-assembly method employing the cationic surfactant cetyltrimethylammonium bromide (CTAB). The role of CTAB in the synthesis process was investigated by preparing a series of TiO2-CTAB-Mt composites (TCM) with various CTAB doses. The results indicated that a uniform and continuous TiO2 film was deposited on the external surface of montmorillonite in the composite synthesized with 0.1 wt.% of CTAB, and the TCM nano-composites showed much higher values for specific surface area, average pore size and pore volume than the raw montmorillonite clay. Then, the formed TCM materials were applied in photocatalytic degradation of 2,4-dichlorophenol (2,4-DCP) in aqueous solution. The degradation efficiency reached as high as 94.7%. Based on the degradation intermediates benezoquinone, fumaric acid and oxalic acid identified by LC–MS analysis, a mechanism for the photocatalytic oxidation of 2,4-DCP on TiO2/Mt nano-composites is proposed. 相似文献
13.
采用溶胶凝胶法制备了BiOCl/TiO2复合催化剂,透射电镜(TEM)照片显示,两种半导体分布均匀、相互连接,形成的异质结可以为电子传导提供有效通道.经过氯化处理的复合材料具备更强的光催化能力,在紫外光条件下对苯的降解率达到90%,是原BiOCl/TiO2的2倍、纯TiO2的10倍.本文利用X射线光电子能谱、红外光谱和电子顺磁共振,对表面氯化的机理进行研究.结果表明,氯元素以Ti—Cl的方式吸附在催化剂表面,在光照条件下光生空穴夺取一个电子,使其生成氯自由基,进而配合超氧、羟基,构成一种新型的三自由基光催化体系,使催化降解能力大幅提升.最后,利用实验方法得到了光生氯自由基的直接证据,并构建了该体系的光催化反应机理. 相似文献
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设计并制备了新型WC/TiO2纳米复合界面光催化剂应用于酚类污染物的光催化降解反应中.采用X射线衍射(XRD)和扫描电子显微镜(SEM)技术分析了WC/TiO2纳米复合界面光催化剂的晶型和表面形貌.结果显示锐钛矿型TiO2纳米颗粒均匀地分散在WC纳米球表面并很好地构筑了WC/TiO2界面.研究了不同WC负载比例的WC/TiO2光催化剂在模拟太阳光照射下降解苯酚的光催化性能.结果表明:WC/TiO2复合界面的形成可以有效地提高TiO2光催化降解性能;其中,3%WC/TiO2(质量分数)光催化降解苯酚的活性最高.利用紫外-可见光谱(UV-Vis)和高效液相色谱-质谱联用技术(HPLC-MS)分析了WC/TiO2纳米复合界面光催化剂降解苯酚的中间产物,提出了苯酚在WC/TiO2界面上可能的降解机理. 相似文献
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SiO2纳米颗粒内嵌强化介孔TiO2单晶光催化降解盐酸四环素 总被引:1,自引:0,他引:1
吸附性能和光生载流子的分离效率是决定光催化降解抗生素的主要因素.为提高介孔TiO_2单晶(MSCs)的吸附性能和光生载流子的分离效率,在MSCs内部构建SiO_2纳米颗粒吸附结构.同时,利用表面光电压谱、氮气等温吸附-脱附、X射线衍射等研究其结构特性.最后,以盐酸四环素为抗生素代表,通过控制SiO_2纳米颗粒比表面积,考察SiO_2对复合材料吸附及光催化性能的影响.结果表明,SiO_2纳米颗粒与TiO_2单晶复合显著提高了材料的吸附性能,表面保护蚀刻进一步提升了材料的比表面积.实验条件下,高比表面积SiO_2-TiO_2单晶复合材料(KSiO_2@TiO_2)对盐酸四环素的平衡吸附量、降解效率、降解速率常数和矿化率分别达到了0.96 mg·g-1、90.2%、0.0079 min-1、54.4%,分别是MSCs的4.4、1.5、2.6和3.1倍.副产物分析表明,SiO_2复合介孔单晶材料更易将盐酸四环素降解为小分子物质. 相似文献
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We describe here a one-step method for the synthesis of Au/TiO2 nanosphere materials, which were formed by layered deposition of multiple anatase TiO2 nanosheets. The Au nanoparticles were stabilized by structural defects in each TiO2 nanosheet, including crystal steps and edges, thereby fixing the Au–TiO2 perimeter interface. Reactant transfer occurred along the gaps between these TiO2 nanosheet layers and in contact with catalytically active sites at the Au–TiO2 interface. The doped Au induced the formation of oxygen vacancies in the Au–TiO2 interface. Such vacancies are essential for generating active oxygen species (*O−) on the TiO2 surface and Ti3 + ions in bulk TiO2. These ions can then form Ti3 +–O−–Ti4 + species, which are known to enhance the catalytic activity of formaldehyde (HCHO) oxidation. These studies on structural and oxygen vacancy defects in Au/TiO2 samples provide a theoretical foundation for the catalytic mechanism of HCHO oxidation on oxide-supported Au materials. 相似文献
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A novel visible light-active photocatalyst formulation(NdT/OP) was obtained by supporting N-doped TiO_2(NdT) particles on up-conversion luminescent organic phosphors(OP). The photocatalytic activity of such catalysts was evaluated for the mineralization process of spiramycin in aqueous solution. The effect of NdT loading in the range 15–60 wt.% on bulk and surface characteristics of NdT/OP catalysts was investigated by several chemicophysical characterization techniques. The photocatalytic performance of NdT/OP catalysts in the removal of spyramicin from aqueous solution was assessed through photocatalytic tests under visible light irradiation. Total organic carbon(TOC) of aqueous solution,and CO and CO_2 gas concentrations evolved during the photodegradation were analyzed. A dramatic enhancement of photocatalytic activity of the photostructured visible active NdT/OP catalysts,compared to NdT catalyst,was observed. Only CO_2 was detected in gas-phase during visible light irradiation,proving that the photocatalytic process is effective in the mineralization of spiramycin,reaching very high values of TOC removal. The photocatalyst NdT/OP at 30 wt.% of NdT loading showed the highest photocatalytic activity(58%of TOC removed after 180 min irradiation against only 31% removal after 300 min of irradiation of NdT). We attribute this enhanced activity to the high effectiveness in the utilization of visible light through improved light harvesting and exploiting. OP particles act as "photoactive support",able to be excited by the external visible light irradiation,and reissue luminescence of wavelength suitable to promote NdT photomineralization activity. 相似文献
18.
Jiemei Yu Zongming Liu Haitao Zhang Taizhong Huang Jitian Han Yihe Zhang Daohuang Chong 《环境科学学报(英文版)》2015
Three types of TiO2 nanostructures were synthesized via a facile hydrolysis method at 195 °C. Effects of the preparation method and doping with N and F on the crystal structure and photocatalytic performance of TiO2 were investigated. The nanomaterials were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller porosimetry, ultraviolet–visible diffuse reflectance spectroscopy and fluorescent emission spectra. Their photo-catalytic activity was examined by the photodegradation of methylene blue in aqueous solution under both ultra-violet and visible light irradiation. The results show that nitrogen and fluorine co-doped anatase TiO2 had the characteristics of a smaller crystalline size, broader light absorption spectrum and lower charge recombination than pure TiO2. Most importantly, more efficient photocatalytic activity under both ultra-violet and visible light was observed. The obtained N–F-TiO2 nanomaterial shows considerable potential for water treatment under sunlight irradiation. 相似文献
19.
The photocatalytic degradation of methylene blue(MB) over Fe-doped CaTiO3 under UV-visible light was investigated. The as-prepared samples were characterized using X-ray diffraction(XRD), scanning electron microscope(SEM) equipped with an energy dispersive spectrometer(EDS) system, Fourier transform infrared spectra(FT-IR), and UV-visible diffuse reflectance spectroscopy(DRS). The results show that the doping with Fe significantly promoted the light absorption ability of CaTiO3 in the visible light region. The Fe-doped CaTiO3 exhibited higher photocatalytic activity than CaTiO3 for the degradation of MB.However, the photocatalytic activity of the Fe-doped CaTiO3 was greatly influenced by the calcination temperature during the preparation process. The Fe-doped CaTiO3 prepared at500°C exhibited the best photocatalytic activity, with degradation of almost 100% MB(10 ppm)under UV-visible light for 180 min. 相似文献
20.
To utilize visible light more effectively in photocatalytic reactions, a fly ash cenosphere (FAC)-supported CeO2-BiV04 (CeO2-BiVO4/FAC) composite photocatalyst was prepared by modified metalorganic decomposition and impregnation methods. The physical and photophysical properties of the composite have been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and UV-Visible diffuse reflectance spectra. The XRD patterns exhibited characteristic diffraction peaks of both BiVO4 and Ce02 crystalline phases. The XPS results showed that Ce was present as both Ce4+ and Ce3+ oxidation states in Ce02 and dispersed on the surface of BiV04 to constitute a p-n heterojunction composite. The absorption threshold of the CeO2-BiVO4/FAC composite shifted to a longer wavelength in the UV-Vis absorption spectrum compared to the pure Ce02 and pure BiV04. The composites exhibited enhanced photocatalytic activity for Methylene Blue (MB) degradation under visible light irradiation. It was found that the 7.5 wt.% CeO2-BiVO4/FAC composite showed the highest photocatalytic activity for MB dye wastewater treatment. 相似文献