Characterisation of titania nanotubes supported gold particles for MTBE photocatalytic degradation

Au/TNT catalysts were prepared with different gold loadings by deposition – precipitation. The catalysts were characterised by techniques including XRD, HRTEM, AAS and N₂ adsorption analysis. Experimental results show that the value of surface areas and pore volumes increase with increasing Au amounts. The surface area and pore volume of catalyst with high gold loading (3.1?wt-%) are 325?m²?g^?1 and 1.34?cm^3?g^?1. The photocatalytic performance for degradation of MTBE markedly depends on gold concentration. The activity drop is attributed to the size growth and agglomeration of the gold nanoparticles. Photoactivity improvement is related to the number of nucleation centres and fine particles size. It can be concluded that there is a 10% improvement in efficiency for deposition of gold in the highest concentration compared to pure titanium nanotubes during the first 20?min of the reaction. So the photocatalytic degradation of MTBE occurs in a shorter time.     

掺杂过渡金属离子的纳米TiO_2光催化降解制革废水

以石英砂为载体,液相沉积水解法制备的纳米TiO2膜为光催化剂,通过掺杂过渡金属离子对膜进行改性。在高压紫外灯光、低压紫外灯光和自然光照射条件下,分别对制革废水进行处理。以CODCr为评价指标,分析了不同光照条件对TiO2膜光催化性能的影响。结果表明,在高压紫外灯光照15 min后,Hg/TiO2膜光降解率最高,CODCr去除率为50.23%。通过探讨各种掺杂离子对膜的改性规律发现,改性效果与过渡金属离子电荷和半径的比值有关。对于同周期的元素,第二过渡周期的掺杂效果好于第一、第三过渡周期,但掺杂规律不像第一、第三过渡周期那样明显,随原子半径的减小而增大。对于同一族的元素,离子的掺杂作用基本上随着原子半径的增大而增大。     

Construction of quantum-scale catalytic regions on anatase TiO2 nanoparticles by loading TiO2 quantum dots for the photocatalytic degradation of VOCs

We constructed quantum-scale catalytic regions on the surfaces of TiO₂ nanoparticles by loading TiO₂ quantum dots (QDs) with a two-step method. The removal rate and mineralization efficiency of toluene were measured and then used in evaluating the oxidation performance of the prepared samples. A home-built atmospheric surface photovoltage spectrometer and X-ray photoelectron spectrometer were used in analyzing band alignment across the interface between TiO₂ QD and TiO₂ particle and the transfer of charge carriers at the surface. Results showed that an upward band bending formed from the TiO₂ particle to the TiO₂ QD and promoted the accumulation of holes at the QD side. Moreover, the QD and surrounding substrate TiO₂ formed a quantum-scale catalytic region, improving the reaction probability of electron-hole pairs and corresponding intermediates. The mineralization efficiency of toluene in QD-loaded TiO₂ reached 95.8%. The synthetic method is green and simple, showing potential in scale production and industrial application.     

Photocatalytic degradation of methyl tert-butyl ether (MTBE) by Fe-TiO2 nanoparticles

Nowadays, since the underground waters are known as the main source for supplying the drinking water, their pollution to the organic contaminants such as methyl tert-butyl ether (MTBE) is a very significant issue. Therefore, in this study, photocatalytic degradation of MTBE was investigated in the aqueous soloution of Fe-TiO₂ nanoparticale under UV irradiation (wavelenght 254 nm) in a batch reactor. The Fe-TiO₂ mixed oxides were prepared by sol–gel impregnation method. The samples were characterized by X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM) and BET specfic surface area. Then, the effect of various operational parameters namely pH, catalyst loading, molar ratio of [H₂O₂]₀/[MTBE]₀ and UV light intensity on degradation of aqueous MTBE were evaluated in a batch reactor. The optimal condition to achieve the best degradation for the initial concentration of 75 ppm MTBE was found at pH 7, catalyst concentration 2 g/L, molar ratio of [H₂O₂]₀/[MTBE]₀ 4, and UV irradiation 24 W. Total degradation of MTBE with initial concentration of 75 ppm was reached in optimal condition after 70 min. In addition, investigations were also carried out to determine the appropriate kinetics of MTBE degradation using UV/Fe-TiO₂/H₂O₂ process in optimal condition.     

金属离子掺杂TiO2的制备及光催化降解水溶性甲醛的研究

采用溶胶-凝胶法制备了掺杂有Cu2+、Ni2+、Pb2+、Zn2+、Fe3+的TiO2光催化剂,考察了其对水中甲醛的光催化降解效果,并用XRD对催化剂进行表征。对影响TiO2光催化效率的因素:掺杂金属离子的种类、掺杂浓度、反应体系中添加微量游离Fe2+等进行探讨,实验结果表明,Pb2+离子掺杂对TiO2光催化降解甲醛有明显的促进作用,在紫外灯照射下,当TiO2光催化剂用量为5 g/L,掺Pb2+离子物质的量分数为0.5%,向反应体系添加低浓度Fe2+(1.5 mg/L)时,反应20 h后,对甲醛的降解率可提高至99.23%。     

掺杂铁TiO_2纳米微粒的制备及光催化性能

以钛酸四丁酯为前驱体,采用溶胶-凝胶法制备了Fe3+掺杂改性纳米TiO2光催化剂,通过纯TiO2和掺铁TiO2分别做光催化剂时甲基橙溶液在紫外光下的光催化降解试验发现,掺杂铁离子可以有效提高TiO2的光催化活性,结果表明:选用Fe3+掺杂量为0.05%,煅烧温度在500℃下得到的Fe3+-TiO2催化剂,在甲基橙溶液pH值为3,催化剂投加量为1 g/L时,其光催化活性达到最佳效果。     

掺杂铁TiO2纳米微粒的制备及光催化性能

以钛酸四丁酯为前驱体,采用溶胶-凝胶法制备了Fe^3＋掺杂改性纳米TiO2光催化剂,通过纯TiO2和掺铁TiO2分别做光催化剂时甲基橙溶液在紫外光下的光催化降解试验发现,掺杂铁离子可以有效提高TiO2的光催化活性．结果表明：选用Fe^3＋掺杂量为0．05％,煅烧温度在500℃下得到的Fe^3＋-TiO2催化剂,在甲基橙溶液pH值为3,催化剂投加量为1g／L时,其光催化活性达到最佳效果。     

Fe~(3+)、Eu~(3+)共掺纳米TiO_2光催化降解N-(2-苯并咪唑基)-氨基甲酸甲酯

采用溶胶-凝胶-微波法制备Fe3+、Eu3+共掺杂纳米TiO2(Fe/Eu-TiO2),并通过紫外-可见吸收光谱(UV-Vis)、荧光光谱(FS)、X射线衍射(XRD)、扫描电镜(SEM)、比表面积测定(BET)等手段对其进行表征。结果表明:在500℃氮气保护下退火制得的Fe/Eu-TiO2为锐钛矿相纳米颗粒,平均粒径为20—50 nm;对可见光的响应范围为370—770 nm。光催化降解N-(2-苯并咪唑基)-氨基甲酸甲酯(多菌灵)的实验表明,Fe3+、Eu3+共掺杂对TiO2光催化表现出协同增效作用,在可见光下能产生更多的羟基自由基,对多菌灵降解速率常数kapp为0.046 66 min-1,大于分别单掺Fe3+和Eu3+的TiO2纳米粒子。     

Enhancement of photocatalytic activity of TiO2 by adsorbed aluminium(III)

The photocatalytic activity of TiO₂ (Degussa P-25) in the mineralization of maleic acid in aqueous solution at pH = 3 is greatly enhanced by the previous adsorption of aluminium(III) on the catalyst surface. The nature of the intermediates detected during maleic acid degradation is also affected by the presence of Al(III). The observed differences can be related to an oxygen reactivity enhancement. The effect of aluminium(III) in the maleic acid adsorption over the TiO₂ surface has also been investigated by using the ATR–FT-IR technique. The UV–vis diffuse reflectance spectra of the catalyst shows a red shift due to aluminium adsorption. At neutral pH, the positive effect of adsorbed Al(III) is not observed.     

阳光下TiO2/GAC光催化处理洗涤剂废水的研究

利用太阳光作光源，采用固定在颗粒活性炭中的TiO2(TiO2／GAC)作光催化剂，利用其将活性炭极好的吸附性与TiO2优良的光催化性能结合于一体的特性，设计了对以洗衣粉配置的洗涤剂模拟废水的两种处理方案：同时光照-吸附法和吸附饱和-光照水洗再生法，并在实验基础上对两种方案的一些性能进行了讨论。     

TiO2光催化降解气态污染物的影响因素研究进展

TiO2光催化技术作为处理气态污染物的一种手段,具有高效、稳定、无二次污染等优点。光催化反应效率的高低受到TiO2自身性质、光催化反应工艺条件等因素的影响。本文分别从TiO2晶型、晶粒尺寸、TiO2的存在形态、TiO2的负载、掺杂改性、贵金属沉积等与TiO2材料性质相关的因素以及废气初始浓度与流速、废气中的含氧量、湿度、光源和光照强度、反应温度等光催化反应的工艺条件两方面,概述了目前关于TiO2光催化净化废气影响因素的研究进展,介绍了TiO2在气相光催化过程中的失活与再生,并从可见光催化剂的制备应用、多组分污染物气相光催化降解机理及影响因素等方面对未来TiO2光催化研究方向提出建议。     

Copper reduced defective TiO2 nanoparticles with enhanced visible light photocatalytic activity

Defective TiO₂ attracted increasing attention due to its high photocatalytic activities. Herein, we report a facile and efficient method to fabricate gray defective TiO₂ by vacuum annealing raw TiO₂ materials with copper powders. The treated TiO₂ nanoparticles exhibit significantly enhanced visible‐light‐photocatalytic performance with photo‐degradation rate increased to 400% as that of pristine commercial P25 under visible light. The performance enhancements can be attributed to the disordered structure, optimized optical and electronic properties of defective TiO₂. In addition, this facile Cu reduction method provides an effective way to generate defective sites in other metal oxides for various potential applications.     

Ce掺杂TiO_2纳米粒子的制备及其光催化活性研究

以钛酸四丁酯为原料,采用溶胶-凝胶法制备了纯的和掺杂铈的TiO2纳米粒子,并利用XRD和UV-VIS对其进行表征,且在紫外光下,以甲基橙的光催化降解为模型反应,考察了TiO2纳米粒子的光催化活性和不同Ce掺杂量对光催化活性的影响。结果表明,Ce的掺杂抑制了锐钛矿晶粒的生长,并使TiO2纳米粒子的光谱响应范围拓展到可见光区,掺杂Ce的摩尔分数为0.05%时,TiO2纳米粒子具有最佳的光催化活性。     

Yb/TiO2光催化降解染料废水的研究

采用胶-溶凝胶法制备纳米掺镱TiO2光催化剂Yb/TiO2.在紫外灯下照射,对罗丹明B模拟染料废水进行光催化降解研究,优化了光催化的反应条件.结果表明:当掺镱量n(Yb)/n(TiO2)为1.0％,催化剂用量为2g·L-1,溶液pH值为4,光照时间为3h,染料废水的起始浓度为10mg·L-1时,染料废水的降解率可达95.32％.     

Construction of metallic nanocrystalline TaB2 coupled with TiO2 for enhanced photocatalytic degradation

The search for new low-cost co-catalysts that can replace precious metals is highly desirable and challenging. Transition metal diboride can be ideal candidates due to their excellent electrical conductivity and suitable work function. In this work, a novel TaB₂@TiO₂ heterostructure has been successfully constructed by a facile sol-gel method. The results show that TaB₂ has a suitable work function and B–O bonds are formed at the interface of the TaB₂@TiO₂ heterojunction, which makes it easier for the photogenerated electrons of TiO₂ to migrate to the surface of TaB₂ and promotes the effective separation of photogenerated carriers. In addition, the metallic nanocrystalline TaB₂ also significantly increases the specific surface area of the heterojunction. The above two points lead to more hydroxyl radicals and superoxide radicals production, thus substantially improving the photocatalytic degradation performance. Therefore, the 3 wt% TaB₂ (TT3) catalyst degraded rhodamine B (RhB, 20 mg/L) with an efficiency of 100% under 90 min irradiation, which is much higher than pristine TiO₂～92% and commercial TiO₂ (P25)～64%. Furthermore, its photocatalytic rate is about 1.73 times and 3.77 times of pristine TiO₂ and commercial TiO₂ (P25), respectively. This finding can provide new insights for the replacement of photocatalytic noble metal co-catalysts.     

Comparative study of MTBE photocatalytic degradation with TiO2 and Cu-TiO2

The iron species in layered clays are active for catalytically oxidizing synthetic dyes with H₂O₂ under visible irradiation (λ > 420 nm). Three layered clays, Montmorillonite, Laponite, and Nontronite, in which the iron species exist in different chemical environment, were used to investigate the role of the iron species in the clays. It was found that the reactivity of the iron species greatly depends on their chemical environments. The exchangeable interlayer iron ions in the clay exhibit much better ability to catalyze the mineralization of malachite green (MG) than the structural iron at the centers of octahedrons that are sandwiched by two layers of SiO₄ tetrahedrons. The interactions among the foreign ligands, such as phosphate and EDTA, and the two types of iron species are dissimilar, causing the different effects of the ligands on the degradation kinetics. The EPR results show explicitly that the reaction over the two iron species proceeds through different pathways. This explains the differences in the degradation kinetics for the photodegradation of MG by H₂O₂ over different clays. These iron-containing clay minerals are chemically and mechanically stable, we do not observe any noticeable loss of activity and damage of the clay structure after 14 recycles.     

亲油性纳米TiO2的合成及其光催化氧化催化裂化汽油脱硫的研究

以非离子表面活性剂span-40为改性剂在乙醇中对合成的纳米TiO2进行了表面改性,利用傅里叶红外光谱进行了表征,并研究了其在水/油两相系统中光催化氧化催化裂化汽油脱硫情况.结果表明,纳米TiO2表面有span-40存在,并能稳定悬浮存在于油相中;在水/油体积比为11、亲油性纳米TiO2加入量为1g/L的条件下,以500 W高压汞灯为光源照射2 h后,催化裂化(FCC)汽油的脱硫率为92.8%;光催化氧化FCC汽油脱硫为一级动力学反应,反应速率常数为1.3289 h-1,半衰期为0.52h.     

Fullerene modification CdSe/TiO2 and modification of photocatalytic activity under visible light

CdSe, CdSe-TiO₂, and CdSe-C₆₀/TiO₂ composites were prepared using sol–gel method, and their photocatalytic activity was evaluated by measuring the degradation of rhodamine B solutions under visible light. The surface area, surface structure, crystal phase, and elemental identification of these composites were characterized by nitrogen adsorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and UV-visible (vis) absorption spectrophotometry. XRD showed that the CdSe-C₆₀/TiO₂ composite contained a typical single and clear anatase phase. SEM of the CdSe-C₆₀/TiO₂ composites revealed a homogenous composition in the particles. EDX revealed the presence of C and Ti with strong Cd and Se peaks in the CdSe-C₆₀/TiO₂ composite. The degradation of dye was determined by UV–vis spectrophotometry. An increase in photocatalytic activity was observed and attributed to an increase in the photoabsorption effect by fullerene and the cooperative effect of the CdSe. The repeatability of photocatalytic activity was also tested in order to investigate the stability of C₆₀ and CdS-C₆₀/TiO₂ composites.     

超重力场中纳米TiO2粒子表面包覆Al2O3膜及其表征

基于异相表面成核和撞击流-旋转填料床反应器的微观混合原理,以纳米水合氧化钛(TiO2·nH2O)粒子为固相基体,六水氯化铝溶液为包覆相,采用液相包覆-界面反应的方法在纳米TiO2前体颗粒表面包覆了纳米Al2O3膜,并对超重力场中纳米粒子表面包覆过程进行了初步分析。通过IR、TEM、Zeta电位分析和XRD分析,证实了纳米TiO2前体颗粒表面包覆了一层厚约5nm的致密海绵状膜。IR和XRD谱图表明,在Al2O3纳米膜层和纳米TiO2颗粒之间的界面上形成了Ti—O—Al键,包覆膜层的晶体结构以γ-Al2O3为主的混合晶型。