多种光源下氮掺杂TiO_2光催化降解染料废水的研究

以尿素为氮源,采用溶胶-凝胶法制备了氮掺杂纳米TiO2粉末,以甲基橙溶液为模拟染料废水,分别在可见光、模拟太阳光和紫外光条件下,研究了氮掺杂纳米TiO2光催化降解染料废水的性能。结果表明:氮掺杂可以提高TiO2的可见光催化活性;氮含量和煅烧温度对氮掺杂TiO2光催化活性影响较大,n(N)∶n(Ti)为10%且经500℃煅烧的氮掺杂TiO2在可见光和模拟太阳光下均具有最佳的光催化活性;然而在紫外光下,氮掺杂TiO2的光催化活性低于未掺杂的TiO2样品。     

自燃烧法合成氮、铁共掺杂TiO2及其可见光光催化活性

以硫酸钛、硝酸铁、尿素为原料,采用自燃烧法制备了氮、铁共掺杂的纳米TiO2粉体.XRD结果显示氮、铁共掺杂的纳米TiO2主要为锐钛矿相.当氮、铁共掺杂时,二氧化钛光谱吸收红移至可见区.XPS结果表明:铁进入TiO2的晶格中形成浅势,氮则取代氧原子形成了N-Ti键,它们的形成降低了二氧化钛的带隙,从而提高了可见光区的光催化能力.当氮、铁对钛的物质的量比分别为0.5%和0.6%时,其在可见光下降解亚甲基蓝的降解率分别是单掺杂和纯TiO2的1.4和3倍.     

CdS修饰TiO_2纳米带制备及光催化降解有毒有机污染物

以硫酸钛为原料,在210℃低温下,水热制备Ti O2纳米带.通过沉淀法用CdS修饰Ti O2纳米带表面,制得Ti O2@CdS复合光催化剂,采用XRD、TEM和反射紫外对其结构及光化学特性进行初步表征.以可见光(λ≥450 nm)光催化降解罗丹明B(Rhodamine B,RhB)、水杨酸(Salicylic Acid,SA)及2,4-二氯苯酚(2,4-Dichlorophenol,2,4-DCP)为探针反应,研究反应温度、介质和负载CdS对Ti O2@CdS结构性能的影响.结果表明,所制备的Ti O2纳米带分散性好.复合粉末由锐钛矿相Ti O2和立方相CdS组成.常温25℃中性介质中用CdS修饰的Ti O2的活性,在可见光照射下,为单纯Ti O2纳米带的29倍.同时,Ti O2也促进了CdS可见光光催化活性的提高.通过跟踪降解体系紫外-可见光谱(UV-vis)、红外光谱(FTIR)和总有机碳(TOC)测定,结果发现Ti O2@CdS/vis体系在pH7.0时,对SA的降解率较Ti O2纳米带有显著地提高,反应15 h和21 h后,RhB和2,4-DCP的矿化率分别可达到47.8%和30.8%.     

氮掺杂TiO2光催化降解气相有机物(苯/乙烯)及其作用机理

采用氨水浸渍法制备氮掺杂Ti O2,在掺氮前,对沉淀法制备的无定形Ti O2粉末进行不同温度的煅烧,考察样品的前处理温度对掺氮效果的影响。实验证明,氮掺杂对Ti O2的晶相组成、晶粒尺寸和比表面积影响很小,所制备的掺氮样品具有可见光吸收,其中又以120TN样品的可见光吸收最显著。可见光光催化反应实验结果表明,掺氮样品(120TN)对乙烯的转化率为14.6%,矿化率92.0%;对苯的转化率43.0%,矿化率32.3%。紫外光光催化实验结果表明该样品基本上维持了Ti O2的紫外光光催化活性。模拟太阳光催化实验表明,该样品比Ti O2的光催化活性有大幅提高。SPX测试表明,氮是掺杂在Ti O2的氧空位或该位置的间隙处。综合分析表明Ti O2掺杂氮的结构形式应为O-Ti-N结构。并探讨了氨水浸渍法中N氮掺杂Ti O2催化剂的形成过程。     

可见光响应的铁掺杂二氧化钛的制备及其光催化性能研究

以硝酸铁、硫酸氧钛为出发原料,通过直接化学法合成了锐钛矿型的Fe掺杂的Ti O2纳米光催化剂;通过X射线衍射仪、傅里叶红外光谱仪、紫外-可见-近红外分光光度计、热差热重分析仪对样品的结构以及性能进行了表征。结果表明:Fe掺杂的纳米Ti O2光催化剂的紫外吸收光谱和纯Ti O2相比,吸收带边发生红移,光响应范围拓展到在可见光区域;Fe的掺杂可以提高Ti O2的光催化性能,其中1%的Fe-Ti O2对亚甲基蓝的光催化活性最高。在模拟可见光条件下,Fe-Ti O2表现出了较优的光催化性能,光照10 min后,降解率高达83.9%。     

Ag-N共掺杂TiO_2/膨润土光催化降解染料废水

采用溶胶-凝胶法制备了银氮共掺杂光催化剂Ag-N-Ti O2/膨润土,通过XRD和FTIR对其结构进行了表征,优化了该催化剂降解耐酸枣红染料废水的反应条件。结果表明,催化剂中有锐钛矿型Ti O2生成,部分Ti O2进入了膨润土层间,增大了其晶面层间距,并通过Ti—O—Si键实现了膨润土对Ti O2的固载;掺杂的Ag、N可能进入了Ti O2晶格,拓宽了其光谱响应范围,并提高了其光催化活性。当催化剂用量为2 g/L,溶液p H为3,光照时间为120 min,紫外光或可见光照射下,该催化剂对50 mg/L的耐酸枣红的降解率分别达到93.0%和89.3%,并在可见光下对其它3种50 mg/L的染料废水的降解率也达到了90%以上。     

Ag-N共掺杂TiO_2/膨润土光催化降解染料废水

采用溶胶-凝胶法制备了银氮共掺杂光催化剂Ag-N-Ti O2/膨润土,通过XRD和FTIR对其结构进行了表征,优化了该催化剂降解耐酸枣红染料废水的反应条件。结果表明,催化剂中有锐钛矿型Ti O2生成,部分Ti O2进入了膨润土层间,增大了其晶面层间距,并通过Ti—O—Si键实现了膨润土对Ti O2的固载;掺杂的Ag、N可能进入了Ti O2晶格,拓宽了其光谱响应范围,并提高了其光催化活性。当催化剂用量为2 g/L,溶液p H为3,光照时间为120 min,紫外光或可见光照射下,该催化剂对50 mg/L的耐酸枣红的降解率分别达到93.0%和89.3%,并在可见光下对其它3种50 mg/L的染料废水的降解率也达到了90%以上。     

尿素为氮源制备氮掺杂二氧化钛光催化剂

以Ti(SO4)2为前驱物,尿素为沉淀剂和掺杂剂,采用水热法结合固相反应法制得了锐钛矿相掺氮纳米TiO2纳米粉体。采用XRD对制备的掺氮氧化钛结构进行了表征,以亚甲基蓝为模拟污染物,考察了不同煅烧温度制备的光催化剂在可见光照射下的光催化性能。结果表明,煅烧温度高于160℃时氮可掺进TiO2晶体中,且温度越高,掺氮量越高;煅烧温度为200℃时,氮掺杂TiO2粉体可见光催化活性最强,在波长不低于400nm的可见光作用下,对亚甲基蓝的4h降解率达62.5%。     

负载型掺氮TiO_2光催化剂的制备及可见光催化活性研究

采用减压蒸馏凝胶-煅烧法制备得到纯态Ti O2、Ti O2/甲壳素、掺氮Ti O2、负载型掺氮Ti O2/甲壳素4种光催化剂,对比研究了在钠灯(中心波长589 nm)照射下对甲基橙的催化降解活性,发现纯态Ti O2、Ti O2/甲壳素、掺氮Ti O2几乎没有催化活性,负载型掺氮Ti O2/甲壳素具有较好的可见光催化活性。研究了煅烧温度、煅烧时间、体系p H值对负载型掺氮Ti O2/甲壳素催化活性的影响。结果表明,负载型掺氮Ti O2/甲壳素在煅烧温度400℃、煅烧时间2 h、初始p H值3时催化活性最佳,甲基橙的残留率为2%。     

负载型掺氮TiO_2光催化剂的制备及可见光催化活性研究

采用减压蒸馏凝胶-煅烧法制备得到纯态Ti O2、Ti O2/甲壳素、掺氮Ti O2、负载型掺氮Ti O2/甲壳素4种光催化剂,对比研究了在钠灯(中心波长589 nm)照射下对甲基橙的催化降解活性,发现纯态Ti O2、Ti O2/甲壳素、掺氮Ti O2几乎没有催化活性,负载型掺氮Ti O2/甲壳素具有较好的可见光催化活性。研究了煅烧温度、煅烧时间、体系p H值对负载型掺氮Ti O2/甲壳素催化活性的影响。结果表明,负载型掺氮Ti O2/甲壳素在煅烧温度400℃、煅烧时间2 h、初始p H值3时催化活性最佳,甲基橙的残留率为2%。     

可见光响应的Fe^3＋修饰纳米TiO2光催化降解氮氧化物研究

为了在光催化转化氮氧化物的反应中利用可见光,以Fe（NO3）·9H2O作为Fe^3＋源,采用浸渍的方法,制备了Fe^3＋修饰的纳米TiO2。经XRD分析表明,搀杂和煅烧过程没有改变TiO2的晶型。由XRD和XPS图谱可知,Fe^3＋在TiO2表面形成Ti—O—Fe键。催化剂的UV-Vis漫反射光谱显示,Fe^3＋修饰TiO2催化剂的吸收光谱发生了一定程度的红移,在可见光区有一定的吸收。Fe^3＋修饰TiO2催化在蓝光照射下对NOx有一定的转化而且在模拟自然光下NOx的转化效率也有所提高。合适的Fe^3＋修饰量对修饰过程非常重要,Fe^3＋/Ti^4＋摩尔比为0.2%并在600℃下煅烧1.0 h的催化剂在可见光下转化NOx的活性最高。     

Modeling Optical Changes in Perovskite Capacitor Materials Due to dc-Field Degradation

The depth sensitivity of spectroscopic ellipsometry (SE) to the presence of oxygen vacancies (V_O^••), in perovskite titanates, was examined over the wavelength range from 250 to 750 nm. To determine the effect of oxygen vacancy concentration, reference optical properties of barium titanate (BaTiO₃) and Fe-doped SrTiO₃ were determined for oxidized and reduced samples. These reference data were used to model the sensitivity of SE to changes due to degradation. Using these models, it was found that SE could detect reduced layers of 4 Å for BaTiO₃ and an 8 Å layer for Fe-doped SrTiO₃. From the models, concentration gradients were resolvable by SE with an average diffusion depth (√ Dt ) of 10 Å for BaTiO₃ and 50 Å for Fe-doped SrTiO₃. These models also predict that SE should be able to discern different degradation mechanisms through the way the optical properties change during degradation.     

纳米光催化剂降解室内微量苯类挥发性有机化合物

社会的迅速发展给人类带来物质文明的同时,也使得环境污染变得日益严重,特别是在近年来由人类活动产生的气态污染物严重威胁到环境和人体健康。习近平总书记曾说过,绿水青山就是金山银山。但是,气态污染物相继排放到大气中,促使人们有必要开发出合适的技术来净化空气。苯类挥发性有机化合物(苯类VOCs)是室内空气中常见的气态污染物之一,应该经过物理吸附并转化成无危害的化合物等。光催化氧化技术(PCO)可以在光照作用下,利用光子的能量使光催化剂表面产生高活性物质来有效降解苯类VOCs,并且不会产生二次污染。目前,已有许多不同结构和物理化学性能的光催化体系被应用于降解苯类VOCs,本文首先对光催化降解苯类VOCs的基本原理、影响光催化反应的因素和提高降解效率的方法进行了系统分析,综述了各类纳米催化剂的设计理念以及其在光催化降解苯类VOCs过程中的性能,并对未来纳米催化剂的设计进行了展望。     

Photocatalytic Degradation of Organic Dyes by a High Efficient TiO2-Based Catalysts Under Solar Light Irradiation

In this work, the Er³⁺:YAlO₃/Fe-doped TiO₂ composite, a high efficient TiO₂-based photocatalyst, was synthesized by ultrasonic dispersion and liquid boil methods. Among which, the Er³⁺:YAlO₃ is a kind of upconversion luminescence agent, which was prepared by nitrate-citric acid method. It can emit ultraviolet light under visible light excitation. The Er³⁺:YAlO₃/Fe-doped TiO₂ composite was characterized by X-ray diffraction and UV–vis spectral techniques. The degradation of Acid Red B dye was used to evaluate the photocatalytic activity of the Er³⁺:YAlO₃/Fe-doped TiO₂ composite under solar light irradiation. It was found that the photocatalytic activity of Er³⁺:YAlO₃/Fe-doped TiO₂ composite was much higher than that for the similar system with only Fe-doped TiO₂. And the influencing factors, such as Er³⁺:YAlO₃ content, irradiation time, initial concentration of Acid Red B, addition amount of Er³⁺:YAlO₃/Fe-doped TiO₂ and NaCl, on the photocatalytic degradation were also investigated. The Er³⁺:YAlO₃ as upconversion luminescence agent can elevate the photocatalytic activity of Fe-doped TiO₂ powder. Moreover, the Fe²⁺ ion can restrain the recombination of photogenerated electrons and holes. Thus, this Er³⁺:YAlO₃/Fe-doped TiO₂ composite is a useful material for the detoxification of wastewater because it can efficiently utilize solar light by converting visible light into ultraviolet light.     

有机颜料敏化TiO_2光催化降解二甲酚橙

以工业有机颜料C.I.颜料黄154(PY)为敏化剂,采用溶剂热法制备了PY/TiO2复合光催化剂。利用扫描电镜(SEM)、X射线衍射(XRD)、紫外-可见漫反射光谱(UV-Vis DRS)及热重-差热扫描量热(TG-DSC)对材料进行了表征。以氙灯为光源考察了PY/TiO2在降解二甲酚橙过程中的可见光催化性能。结果表明,与PY复合后,催化剂的光谱响应范围由387.5 nm拓展到540 nm的可见光区,光照110 min后二甲酚橙降解率达到96.9%。     

含钛高炉渣催化剂光催化降解亚甲基蓝

实验制备了含钛高炉渣光催化剂,负载于玻璃表面,通过对水溶液中染料亚甲基蓝的降解实验,研究了含钛高炉渣的光催化效果,评价了含钛高炉渣光催化剂与热处理温度、溶液的pH值、不同光源、空气流量的影响关系. 结果表明,经处理的含钛高炉渣催化剂具有光催化性,经600oC处理的催化剂的光催化性最好,适当的pH值与空气通入量、提高紫外光强度及缩短光源的波长均有助于染料的降解.     

Alumina Particle Degradation during Solid Particle Impact on Glass

Particle degradation limits the reuse of powders in industrial powder-blast processes. In this paper the degradation behavior of Al₂O₃ powder is studied during erosion of glass substrates. Three techniques were used on original and multiply used powders: particle size measurements, single particle crushing tests, and microstrain analysis by X-ray diffraction. Combination of the three techniques shows that the degradation is dominated by flaws present in the original particles. Fracture at repeated use decreases the particle size, but by removing flaws also increases the degradation resistance of the particles.     

One-pot synthesis of bifunctionalized TiO<Subscript>2</Subscript> mesoporous photocatalyst with visible light response

A series of Fe-doped SH/TiO₂ mesoporous photocatalysts have been firstly prepared by one-pot method using P123 as structure-directing agent. This bifunctionalized mesoporous TiO₂ possesses perfect anatase crystal structure and high surface area. The surface area of Fe-doped SH/TiO₂ mesoporous material is 4 times higher than that of P25. Based on the EPR results, it was found that trivalent Fe ions exist at low spin state and substitutes a part of Ti⁴⁺ ions into TiO₂ lattice. Fe-dropping in TiO₂ extends the adsorption band side of the resulting material to about 600 nm. Much high photocatalytic activity in the degradation of phenanthrene was obtained on the bifunctionalized mesoporous TiO₂ under visible light irradiation (λ > 420 nm), which is 6 times higher than that of pristine mesoporous TiO₂. The enhancement in the photocatalytic activity of bifunctionalized TiO₂ is ascribed to the extended absorption to visible light and strong interaction between SH-groups and PHE molecules.     

N修饰纳米TiO_2可见光催化降解氮氧化物

为了充分利用可见光催化转化氮氧化物,采用碳酸铵作为N源,用浸渍的方法制备了掺N的纳米TiO2。XRD分析结果表明,修饰和煅烧过程没有改变TiO2的晶型;由X光电子能谱(XPS)可得,N在TiO2晶格中形成N—Ti—O键;催化剂的UV-Vis漫反射光谱显示,N修饰TiO2催化剂的吸收光谱发生了一定程度的红移,在可见光区有一定的吸收。N修饰TiO2催化在蓝光照射下对NO2有一定的转化。合适的N修饰量和煅烧温度对修饰过程非常重要,m[(NH4)2CO3]/m(TiO2)为0.20的混合物在600℃下煅烧1.0 h的催化剂在可见光下转化NO2的活性最高。     

掺杂Fe~(3+)纳米TiO_2膜光催化降解VOCs

利用玻璃弹簧负载TiO_2膜光催化降解VOCs,以室内空气污染物甲醛、丙酮和甲苯为目标污染物,采用自制反应器,分析了初始浓度、空气湿度和气体流量对甲苯降解效果的影响,考察了三种物质混合的降解效果,对比了在相同条件下单一甲苯和VOCs中甲苯的降解效果。结果表明,气体流速5 L·min~(-1)时,甲苯的降解效率为74.6%,空气湿度为30%时,甲苯降解率为81.6%,初始浓度为0.173 mg·L~(-1)时,甲苯降解率为94%,在这三种情况下,甲苯降解效果较好;对VOCs中甲苯和单一甲苯的降解效果进行对比,发现混合气体中甲苯的降解率在反应205 min后高于单一甲苯。