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1.
A lost of culturability of bacteria Escherichia coli K12 was observed after exposition to a solar simulator (UV–vis) in a laboratory batch photoreactor. The bacterial inactivation reactions have been carried out using titanium dioxide (TiO2) P25 Degussa and FeCl3 as catalysts. At the starting of the treatment, the suspensions were at their “natural” pH. An increase in the efficiency in the water disinfection was obtained when some advanced oxidation processes such as UV–vis/TiO2, UV–vis/TiO2/H2O2, UV–vis/Fe3+/H2O2, UV–vis/H2O2 were applied. The presence of H2O2 accelerates the rate of disinfection via TiO2. The addition of Fe3+ (0.3 mg/l) to photocatalytic system decreases the time required for total disinfection (<1 CFU/ml), for TiO2 concentrations ranging between 0.05 and 0.5 g/l. At TiO2 concentrations higher than 0.5 g/l the addition of Fe3+ does not significantly increase the disinfection rate. The systems: Fenton (H2O2/Fe3+/dark), H2O2/dark, H2O2/TiO2/dark showed low disinfection rate. The effective disinfection time (EDT24) was reached after 60 and 30 min of illumination for the Fe3+ and TiO2 photoassisted systems, respectively. EDT24 was not reached for the system in the absence of catalyst (UV–vis). The effect on the bacterial inactivation of different mixture of chemical substance added to natural water was studied. 相似文献
2.
The effect of TiO2 on the grain growth of the ZnO–Bi2O3–CoO–MnO ceramic system prepared by chemical coprecipitation, was studied between 1150 and 1300 °C in air. Bi2O3 melts during firing, and then TiO2 dissolves into Bi2O3-rich liquid. TiO2 initially reacts with Bi2O3 to form Bi4Ti3O12. Above ≈1050 °C, Bi4Ti3O12 reacts with ZnO to form Zn2TiO4 spinel phase. The kinetic study of grain growth carried out using the expression Gn–Gon=Ko·t·exp(−Q/RT) gave grain exponent (n) value as 6 and the apparent activation energy (Q) as 226.46 kJ/mol. 1.00 mol% TiO2 addition increased the grain growth exponent value from 6 to 7 and apparent activation energy with 1.00 mol% TiO2 addition was found to be 197.10 kJ/mol. The ZnO grain size gradually increases with increasing TiO2 content. Addition of TiO2 may increase the reactivity of the Bi2O3-rich liquid towards the ZnO grain, thus affecting the ZnO grain growth. 相似文献
3.
The coupled photocatalyst WO3/TiO2 is prepared by ball milling by doping WO3 into TiO2 and using H2O solution as disperser. The coupled photocatalyst WO3/TiO2 is characterized by UV–VIS diffuse reflection spectrum, X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and Transmission electron microscopy (TEM). The results show that the optimum percentage of WO3 doped is 3% and that the photocatalytic activity of the coupled WO3/TiO2 photocatalyst is much higher than that of TiO2 and WO3–TiO2 with no ball milling. Compared with TiO2, the photoexcited wavelength range of the WO3/TiO2 photocatalyst red-shifts about 50 nm, and the light absorption intensity is also improved. The crystal phase of TiO2 is not changed and new crystal phases are not found during the process of ball milling. WO3 and TiO2 coupled highly, forming the WO3/TiO2 photocatalyst. The increased photocatalytic activity of the coupled photocatalyst may be attributed to the enhance charge separation efficiency and the extend wavelength range of photoexcitation. 相似文献
4.
Beata Tryba Antoni W. Morawski Michio Inagaki Masahiro Toyoda 《Applied catalysis. B, Environmental》2006,63(3-4):215-221
H2O2 used in the photo-Fenton reaction with iron catalyst can accelerate the oxidation of Fe2+ to Fe3+ under UV irradiation and in the dark (in the so called dark Fenton process). It was proved that conversion of phenol under UV irradiation in the presence of H2O2 predominantly produces highly hydrophilic products and catechol, which can accelerate the rate of phenol decomposition. However, while H2O2 under UV irradiation could decompose phenol to highly hydrophilic products and dihydroxybenzenes in a very short time, complete mineralization proceeded rather slowly. When H2O2 is used for phenol decomposition in the presence of TiO2 and Fe–TiO2, decrease of OH radicals formed on the surface of TiO2 and Fe–TiO2 has been observed and photodecomposition of phenol is slowed down. In case of phenol decomposition under UV irradiation on Fe–C–TiO2 photocatalyst in the presence of H2O2, marked acceleration of the decomposition rate is observed due to the photo-Fenton reactions: Fe2+ is likely oxidized to Fe3+, which is then efficiently recycled to Fe2+ by the intermediate products formed during phenol decomposition, such as hydroquinone (HQ) and catechol. 相似文献
5.
以Bi(NO3)3·5H2O、Co(CH3COO)2·4H2O为原料,采用化学沉淀-水热法制备了Co3O4-Bi2O2CO3异质结构复合半导体光催化剂,并通过X射线衍射仪(XRD)、扫描电镜(SEM)、X射线光电子能谱(XPS)、紫外可见漫反射光谱(DRS)、荧光光谱(PL)等手段对所合成的复合型催化剂进行了理化性能表征。研究结果表明:引入Co3O4没有改变Bi2O2CO3物相结构,但促进了Bi2O2CO3 对可见光的吸收能力,提高了Bi2O2CO3表面吸附氧物种的数量,抑制了光生载流子复合。复合光催化剂对罗丹明B(RhB)的光催化脱色实验显示引入Co3O4能够明显提高Bi2O2CO3催化剂的光催化脱色能力。尤其是Co3O4引入量为0.6%的Co3O4-Bi2O2CO3样品对罗丹明B染料的光催化脱色率可达到97%(模拟日光照射30min)。本文为复合型光催化剂制备提供了简单易行的技术路线,制备的新型半导体复合光催化剂Co3O4-Bi2O2CO3在环境净化方面表现出了较好的应用前景。 相似文献
6.
Baozhu Tian Jinlong Zhang Tianzhong Tong Feng Chen 《Applied catalysis. B, Environmental》2008,79(4):394-401
Gold loaded on TiO2 (Au/TiO2) catalysts were prepared using Au(I)–thiosulfate complex (Au(S2O3)23−) as the gold precursor for the first time. The samples were characterized by UV–vis diffuse reflectance spectra, X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic absorption flame emission spectroscopy (AAS), and X-ray photoelectron spectroscopy (XPS) methods. Using Au(S2O3)23− as gold precursor, ultra-fine gold nanoparticles with a highly disperse state can be successfully formed on the surface of TiO2. The diameter of Au nanoparticles increases from 1.8 to 3.0 nm with increasing the nominal Au loading from 1% to 8%. The photocatalytic activity of Au/TiO2 catalysts was evaluated from the analysis of the photodegradation of methyl orange (MO). With the similar Au loading, the catalysts prepared with Au(S2O3)23− precursor exhibit higher photocatalytic activity for methyl orange degradation when compared with the Au/TiO2 catalysts prepared with the methods of deposition–precipitation (DP) and impregnation (IMP). The preparation method has decisive influences on the morphology, size and number of Au nanoparticles loaded on the surface of TiO2 and further affects the photocatalytic activity of the obtained catalysts. 相似文献
7.
Jiefang Zhu Zhigang Deng Feng Chen Jinlong Zhang Haijun Chen Masakazu Anpo Jiazhen Huang Lizhong Zhang 《Applied catalysis. B, Environmental》2006,62(3-4):329-335
Cr3+-doped anatase titanium dioxide photocatalysts were prepared by the combination of sol–gel process with hydrothermal treatment. The samples were characterized by UV–vis diffuse reflectance spectroscopy, X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) specific surface area (SBET), transmission electron microscopy (TEM), atomic absorption flame emission spectroscopy (AAS), electron paramagnetic resonance (EPR) spectroscopy and X-ray photoelectron spectroscopy (XPS). It was confirmed that Cr substitutes Ti4+ in TiO2 lattice in trivalent ionic state, and the concentrations of dopants Cr3+ decrease from the exterior to the interior of doped TiO2. The photocatalytic activity of Cr-TiO2 was investigated for the photocatalytic degradation of XRG aqueous solution both under UV and visible light irradiation. Due to the excitation of 3d electron of Cr3+ to the conduction band of TiO2, Cr-TiO2 shows a good ability for absorbing the visible light to degrade XRG. Doping of chromium ions effectively improves the photocatalytic activity under both UV light irradiation and visible light irradiation with an optimal doping concentration of 0.15% and 0.2%, respectively. The special distribution of dopants Cr3+ seems having a good effect on enhancing the photocatalytic activity of Cr-TiO2. 相似文献
8.
Wenyue Su Jianxiong Chen Ling Wu Xinchen Wang Xuxu Wang Xianzhi Fu 《Applied catalysis. B, Environmental》2008,77(3-4):264-271
Nanocrystalline TiO2 incorporated with praseodymium(III) nitrate has been prepared by an ultrasound method in a sol–gel process. The prepared sample is characterized by X-ray diffraction (XRD), nitrogen adsorption (BET surface area), UV–vis diffuse reflectance spectroscopy (UV–Vis DRS) and X-ray photoelectron spectroscopy (XPS). The prepared material consists of TiO2 nanocrystalline with 5 nm size incorporated with highly dispersed Pr(NO3)3. Visible light absorptions at 444, 469, 482 and 590 nm are observed in the prepared sample. These bands are attributed to the 4f transitions 3H4 → 3P2, 3H4 → 3P1, 3H4 → 3P0 and 3H4 → 1D2 of praseodymium(III) ions, respectively. This sample Pr(NO3)3-TiO2, as a novel visible light photocatalyst, shows high activity and stability in the decomposing rhodamine-B (RhB) and 4-chlorophenol (4-CP) under visible light irradiation. Results examined by electron spin resonance spectroscopy (ESR) reveal that the irradiation (>420 nm) of the photocatalyst dispersed in RhB aqueous solution induces the generation of highly active hydroxyl radicals (OH), leading to the cleavage of the whole conjugated chromophore structure of RhB. A mechanism based on local excitation of praseodymium(III) nitrate chromophore and interfacial charge transfer from the chromophore to TiO2 is proposed to explain the formation of active hydroxyl radicals in the photocatalytic system under visible light irradiation. 相似文献
9.
Shihong Xu Wenfeng Shangguan Jian Yuan Mingxia Chen Jianwei Shi 《Applied catalysis. B, Environmental》2007,71(3-4):177-184
A magnetically separable nitrogen-doped photocatalyst TiO2−xNx/SiO2/NiFe2O4 (TSN) with a typical ferromagnetic hysteresis was prepared by a simple process: the magnetic SiO2/NiFe2O4 (SN) dispersion prepared by a liquid catalytic phase transformation method and the visible-light-active photocatalyst TiO2−xNx were mixed, sonificated, dried, and calcined at 400 °C. The prepared photocatalyst is photoactive under visible light irradiation and easy to be separated from a slurry-type photoreactor under the application of an external magnetic field, being one of promising photocatalysts for wastewater treatment. Transmission electron microscope (TEM) and X-ray diffractometer (XRD) were used to characterize the structure of the TSN photocatalyst. The results indicate that the magnetic SiO2/NiFe2O4 (SN) nanoparticles adhere to the surface of TiO2−xNx congeries. The magnetic photocatalyst TSN shows high catalytic activity for the degradation of methyl orange in water under UV and visible light irradiation (λ > 400 nm). SiO2 coating round the surface of NiFe2O4 nanoparticles prevents effectively the injection of charges from TiO2 particles to NiFe2O4, which gives rise to the increase in photocatalytic activity. Moreover, the recycled TSN exhibits a good repeatability of the photocatalytic activity. 相似文献
10.
Wenjie Ren Zhihui Ai Falong Jia Lizhi Zhang Xiaoxing Fan Zhigang Zou 《Applied catalysis. B, Environmental》2007,69(3-4):138-144
A visible-light-active TiO2 photocatalyst was prepared through carbon doping by using glucose as carbon source. Different from the previous carbon-doped TiO2 prepared at high temperature, our preparation was performed by a hydrothermal method at temperature as low as 160 °C. The resulting photocatalyst was characterized by XRD, XPS, TEM, nitrogen adsorption, and UV–vis diffuse reflectance spectroscopy. The characterizations found that the photocatalyst possessed a homogeneous pore diameter about 8 nm and a high surface area of 126 m2/g. Comparing to undoped TiO2, the carbon-doped TiO2 showed obvious absorption in the 400–450 nm range with a red shift in the band gap transition. It was found that the resulting carbon-doped TiO2 exhibits significantly higher photocatalytic activity than the undoped counterpart and Degussa P25 on the degradation of rhodamine B (RhB) in water under visible light irradiation (λ > 420 nm). This method can be easily scaled up for industrial production of visible-light driven photocatalyst for pollutants removal because of its convenience and energy-saving. 相似文献
11.
为提高TiO2的可见光光电催化活性,本文用Bi2MoO6和碳量子点(CQDs)对TiO2纳米管阵列(TNA)进行了改性。以CQDs、Bi(NO3)3·5H2O和Na2MoO4为原料,通过简单的溶剂热法,在TNA中沉积了CQDs和Bi2MoO6,成功制备了新型Bi2MoO6@CQDs/TNA。扫描电镜(SEM)和元素mapping分析结果表明,CQDs和Bi2MoO6成功涂覆在TNA管壁上。通过在可见光下降解甲基橙(MO)溶液,评价了所制备的光催化剂的光电催化性能。结果显示,经3 h的光电催化降解,Bi2MoO6@CQDs/TNA对MO的去除率比Bi2MoO6/TNA高32%。CQDs优异的上转换光致发光(UCPL)性能促进了TiO2在可见光下被激发产生光生载流子,同时Bi2MoO6与TiO2的耦合抑制了光生载流子的复合,从而提高了Bi2MoO6@CQDs/TNA的光电催化活性。 相似文献
12.
Weixin ZHANG Jie XING Zeheng YANG Mei KONG Hongxu YAO 《Frontiers of Chemical Science and Engineering》2013,7(2):192
The TiO2 hollow nanospheres with diameters of about 230 nm were prepared by a simple and controllable route based on hydrolysis of Ti(OBu)4 on the surfaces of the Cu2O solid nanospheres followed by inward etching of the Cu2O nanospheres. The as-prepared samples were characterized by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The further post-heat treatment led to the high crystallization of the TiO2 hollow nanospheres. The photocatalytic performances of these samples were evaluated for the photodegradation of rhodamine B (RhB) under UV-light irradiation. The as-prepared TiO2 hollow nanospheres showed higher photocatalytic activity than the CuO and the CuO/TiO2 hollow nanospheres. Effects of temperature and time for post-heat treatment of TiO2 as well as initial RhB concentrations on the RhB photodegradation have also been studied. The results show that the TiO2 hollow nanospheres have the good reusability as photocatalysts and are promising in waste water treatment. 相似文献
13.
采用水热和沉淀两步合成法制备AgBr/Zn3(OH)2V2O7·2H2O催化剂,研究其在可见光下降解亚甲基蓝溶液的性能,并考察催化剂用量、亚甲基蓝溶液初始浓度、pH值以及盐浓度对光催化性能的影响,评价AgBr/Zn3(OH)2V2O7·2H2O催化剂的重复使用性能。结果表明,在前驱液pH为10、120 ℃水热10 h、Ag与Br物质的量比为0.20条件下制备的复合催化剂在可见光下反应120 min后,1.0 g·L-1的催化剂对10 mg·L-1的亚甲基蓝溶液脱色率达到85.2%。NaCl对亚甲基蓝的降解起抑制作用,Na2SO4对亚甲基蓝的降解起促进作用。催化剂重复使用4次后,光照120 min后的亚甲基蓝溶液脱色率可达66.4%。催化剂对不同初始浓度亚甲基蓝溶液的光催化降解符合一级动力学模型。 相似文献
14.
Enhanced high-potential and elevated-temperature cycling stability of LiMn2O4 cathode by TiO2 modification for Li-ion battery 总被引:1,自引:0,他引:1
The surface of spinel LiMn2O4 was modified with TiO2 by a simple sol–gel method to improve its electrochemical performance at elevated temperatures and higher working potentials. Compared with pristine LiMn2O4, surface-modification improved the cycling stability of the material. The capacity retention of TiO2-modified LiMn2O4 was more than 85% after 60 cycles at high potential cycles between 3.0 and 4.8 V at room temperature and near to 90% after 30 cycles at elevated temperature of 55 °C at 1C charge–discharge rate. SEM studies shows that the surface morphology of TiO2-modified LiMn2O4 was different from that of pristine LiMn2O4. Powder X-ray diffraction indicated that spinel was the only detected phase in TiO2-modified LiMn2O4. Introduction of Ti into LiMn2O4 changed the electronic structures of the particle surface. Therefore a surface solid compound of LiTixMn2−xO4 may be formed on LiMn2O4. The improved electrochemical performance of surface-modified LiMn2O4 was attributed to the improved stability of crystalline structure and the higher Li+ conductivity. 相似文献
15.
C. Euvananont C. Junin K. Inpor P. Limthongkul C. Thanachayanont 《Ceramics International》2008,34(4):1067-1071
TiO2 films deposited by various coating techniques were investigated for self-cleaning applications. The optical coating layers of TiO2 films prepared from a sol–gel precursor were deposited on glass substrates using spin coating, dip coating and screen printing techniques. Effects of film deposition techniques on crystal structure, microstructure, thickness, photocatalytic activity, hydrophilicity and optical properties of the films were investigated using XRD, AFM, SEM, surface profilometer, UV–vis spectrophotometer and contact angle measurement. Dip coating the TiO2 optical film two and three times resulted in superhydrophilic surfaces. Increasing number of dipping times was found to increase the photocatalytic activity. 相似文献
16.
Effect of additives, In2O3, SnO2, CoO, CuO and Ag, on the catalytic performance of Ga2O3–Al2O3 prepared by sol–gel method for the selective reduction of NO with propene in the presence of oxygen was studied. As for the reaction in the absence of H2O, CoO, CuO and Ag showed good additive effect. When H2O was added to the reaction gas, the activity of CoO-, CuO- and Ag-doped Ga2O3–Al2O3 was depressed considerably, while an intensifying effect of H2O was observed for In2O3- and SnO2-doped Ga2O3–Al2O3. Of several metal oxide additives, In2O3-doped Ga2O3–Al2O3 showed the highest activity for NO reduction by propene in the presence of H2O. Kinetic studies on NO reduction over In2O3–Ga2O3–Al2O3 revealed that the rate-determining step in the absence of H2O is the reaction of NO2 formed on Ga2O3–Al2O3 with C3H6-derived species, whereas that in the presence of H2O is the formation of C3H6-derived species. We presumed the reason for the promotional effect of H2O as follows: the rate for the formation of C3H6-derived species in the presence of H2O is sufficiently fast compared with that for the reaction of NO2 with C3H6-derived species in the absence of H2O. Although the retarding effect of SO2 on the activity was observed for all of the catalysts, SnO2–Ga2O3–Al2O3 showed still relatively high activity in the lower temperature region. 相似文献
17.
采用溶胶-凝胶法制备系列BixTi1-xO_2光催化剂以及N和Bi共掺杂Ti O_2光催化剂,采用XRD、UV-Vis、N2-物理吸附和TEM等对催化剂进行微观结构表征,以普通节能灯为光源,考察催化剂光催化氧化室内甲醛的性能。结果表明,在Bi掺杂的Ti O_2光催化剂体系中,Bi0.15Ti0.85O_2光催化剂催化降解甲醛效果最佳,400℃焙烧2.5 h,节能灯光照48 h,可将(1.05±0.05)mg·m-3甲醛降解至0.08 mg·m-3,甲醛转化率92.8%,达到室内空气质量标准。当N与Bi共掺杂时,节能灯光照24 h,Bi0.15Ti0.85O_2-N(0.2)光催化剂表现出最佳的光催化氧化降解甲醛性能,即可将甲醛由(1.05±0.05)mg·m-3降解至0.082 mg·m-3,甲醛转化率达92.0%,较Bi0.15Ti0.85O_2催化剂光催化效率提高50%。 相似文献
18.
Galina N. Kryukova Galina A. Zenkovets Alexei A. Shutilov Michael Wilde Kerstin Günther Dieter Fassler Klaus Richter 《Applied catalysis. B, Environmental》2007,71(3-4):169-176
TiO2 (anatase) with different microstructure was synthesized by thermal hydrolysis of the titanyl sulfate and studied by X-ray powder diffraction, high resolution transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The effect of titanium dioxide structure, regular or distorted, on the photocatalytic degradation of Acid Orange 7 Dye (AO7) in water upon ultraviolet light was studied. It was found that synthesized TiO2 possesses a relatively high reactivity when illuminated but also show different adsorption in the dark. The relationship between these behaviors depends on the real structure of the catalysts. Catalysts with a perfect structural ordering formed after heating at temperature higher than 500 °C show better photocatalytic performance. Small amount of Pt added into the TiO2 structure was found to improve further the catalyst reactivity. Pt-modified titania catalysts oxidize AO7 more efficiently than P-25 Degussa TiO2. Doping effect of Pt on the structural and photocatalytic properties of the samples is discussed. 相似文献
19.
Ag-based catalysts supported on various metal oxides, Al2O3, TiO2, and TiO2–Al2O3, were prepared by the sol–gel method. The effect of SO2 on catalytic activity was investigated for NO reduction with propene under lean burn condition. The results showed the catalytic activities were greatly enhanced on Ag/TiO2–Al2O3 in comparison to Ag/Al2O3 and Ag/TiO2, especially in the low temperature region. Application of different characterization techniques revealed that the activity enhancement was correlated with the properties of the support material. Silver was highly dispersed over the amorphous system of TiO2–Al2O3. NO3− rather than NO2− or NOx reacted with the carboxylate species to form CN or NCO. NO2 was the predominant desorption species in the temperature programmed desorption (TPD) of NO on Ag/TiO2–Al2O3. More amount of formate (HCOO−) and CN were generated on the Ag/TiO2–Al2O3 catalyst than the Ag/Al2O3 catalyst, due to an increased number of Lewis acid sites. Sulfate species, resulted from SO2 oxidation, played dual roles on catalytic activity. On aged samples, the slow decomposition of accumulated sulfate species on catalyst surface led to poor NO conversion due to the blockage of these species on active sites. On the other hand, catalytic activity was greatly enhanced in the low temperature region because of the enhanced intensity of Lewis acid site caused by the adsorbed sulfate species. The rate of sulfate accumulation on the Ag/TiO2–Al2O3 system was relatively slow. As a consequence, the system showed superior capability for selective adsorption of NO and SO2 toleration to the Ag/Al2O3 catalyst. 相似文献
20.
Emmanuel Lecrenay Kinya Sakanishi Tomoshige Nagamatsu Isao Mochida Teruo Suzuka 《Applied catalysis. B, Environmental》1998,18(3-4):325-330
Catalytic activities of Al2O3–TiO2 supporting CoMo and NiMo sulfides (CoMoS and NiMoS) catalysts were examined in the transalkylation of isopropylbenzene and hydrogenation of naphthalene as well as the hydrodesulfurization (HDS) of model sulfur compounds, conventional gas oil (GO), and light cycle oil (LCO). Al2O3–TiO2 supporting catalysts exhibited higher activities for these reactions except for the HDS of the gas oil than a reference Al2O3 supporting catalyst, indicating the correlation of these activities. Generally, more content of TiO2 promoted the activities. Inferior activity of the catalyst for HDS of the gas oil is ascribed to its inferior activity for HDS of dibenzothiophene (DBT) in gas oil as well as in model solvent decane, while the refractory 4,6-dimethyldibenzothiophene (4,6-DMDBT) in gas oil as well as in decane was more desulfurized on the catalyst. Characteristic features of Al2O3–TiO2 catalyst are discussed based on the paper results. 相似文献