过氧化氢分解动力学法考察钛白粉颜料的紫外屏蔽性能

基于过氧化氢的光分解反应,探索了一种新的分析工业金红石型钛白粉颜料紫外屏蔽性能的方法。 在主波长为365 nm的紫外光源下,钛白粉颜料水悬浮体系中,通过氧气生成动力学可以有效地反映不同钛白粉紫外屏蔽性能差异。 该方法具有简单快捷、重现性好等优点。     

β-环糊精强化紫外光降解2,2-双（4-羟基-3-甲基苯）丙烷

用稳态荧光光谱法研究了2,2-双(4-羟基-3-甲基苯)丙烷(双酚C)与β-环糊精形成1∶1稳定的包结物,其生成常数为4.94×103 L/mol;研究了β-环糊精存在下双酚C的紫外光(λmax=254 nm)降解行为,结果表明,β-环糊精可促进水溶液中双酚C的紫外光降解,光降解反应符合假一级反应动力学规律. 10 mg/L双酚C经60 min紫外光照射,β-环糊精可使双酚C 的紫外光降解效率从36%提高至86%,在pH值2～8范围内,pH值对双酚C的光降解没有明显的影响;当pH＞8时,双酚C的光降解反应明显加快,随着β-CD浓度的增加双酚C的光降解反应速率也逐渐增加,当β-CD的浓度超过8.0×10-5 mol/L时,双酚C的光降解反应速率不再明显增加. β-环糊精对双酚C的包结作用引起双酚C分子键能的削弱,导致双酚C光降解作用的增强.     

溶胶-凝胶-水热法制备Ce-Si/TiO2及其可见光催化性能

以钛酸四正丁酯、正硅酸乙酯、六水硝酸铈为原料, 在140 ℃下通过溶胶-凝胶-水热法水解制备Ce-Si/TiO2. 所得样品用X射线衍射、氮吸附、透射电镜、紫外漫反射、傅里叶变换红外光谱、X射线光电子能谱等测试手段分析, 结果显示400-600 ℃条件下焙烧所有样品均为锐钛矿, 样品具有较大的比表面积, Si和Ce均被引入到TiO2中. 在可见光照射下, 以脱色降解罗丹明B为探针反应, 研究其可见光催化性能, 结果表明, 与未掺杂和单一组分掺杂的二氧化钛相比较, 共掺杂的二氧化钛具有更高的催化性能, 当Ce/Ti和Si/Ti的物质的量比分别为0.010和0.10时,可见光催化性能最好.     

溶胶-凝胶-水热法制备Ce-Si/TiO2及其可见光催化性能

以钛酸四正丁酯、正硅酸乙酯、六水硝酸铈为原料,在140℃下通过溶胶-凝胶-水热法水解制备Ce-Si/TiO2.所得样品用X射线衍射、氮吸附、透射电镜、紫外漫反射、傅里叶变换红外光谱、X射线光电子能谱等测试手段分析,结果显示400-600℃条件下焙烧所有样品均为锐钛矿,样品具有较大的比表而积,Si和Ce均被引入到TiO2中.在可见光照射下,以脱色降解罗丹明B为探针反应,研究其可见光催化性能,结果表明,与末掺杂和单一组分掺杂的二氧化钛相比较,共掺杂的二氧化钛具有更高的催化性能,当Ce/Ti和Si/Ti的物质的量比分别为0.010和0.10时,可见光催化性能最好.     

氧化锌包覆超细二氧化钛的制备及其紫外屏蔽性能

采用分步-均一沉淀法,以尿素为沉淀剂制备粒径为40nm的锐钛矿型二氧化钛超细粒子,并在其表面包覆晶体粒径为10.2nm的氧化锌,研究了不同含量的氧化锌对包覆效果及紫外吸收性能的影响.结果表明,合成的氧化锌包覆超细锐钛矿型TiO₂的紫外吸收性能明显高于锐钛矿型超细二氧化钛、金红石型二氧化钛及市售氧化锌.     

一种荧光增强的反应型硫化氢荧光探针

基于二硝基苯醚的硫解反应识别机制,设计合成了羟基芘甲醛为荧光基团的探针分子8-(2,4-二硝基苯酚基)芘甲醛(PCNP),研究了PCNP缓冲溶液分散体系对H_2S的响应.未与H_2S作用时,分子内光致电子转移过程导致探针分子PCNP几乎不发光,当体系中存在H_2S时,PCNP发生硫解反应,光致电子转移过程被阻断,羟基芘甲醛发出橙色荧光.PCNP分子对H_2S响应迅速、灵敏,0.1 mmol·L~(-1)硫化氢存在下10 min内荧光强度响应达到最大值,荧光增强达260倍,反应速率常数为0.20 min~(-1),探针分子对H_2S检测限为0.10μmol·L~(-1),并且具有良好选择性.     

5-苯甲酰基-2,4-二羟基苯甲醛的合成、晶体结构及紫外吸收性能研究

以2,4-二羟基二苯甲酮为原料,经过醚化、Vilsmeier-Haack反应和脱甲基化三步反应制备5-苯甲酰基-2,4-二羟基苯甲醛,反应总收率达到74.1%。通过~1H NMR、~(13)C NMR、IR、MS和X-ray单晶衍射对目标产物进行结构表征,晶体结构显示两个苯环并不共平面,分子内和分子间的氢键连接分子形成三维网状结构。考查该化合物的紫外吸收性能,在293 nm和324 nm有很好的紫外吸收,兼具长波紫外线UVA和中波紫外线UVB的吸收性能。     

制备均一形貌的长二氧化钛纳米管

在温和的水热条件下,用碱溶液处理不同粒径的锐钛矿相和金红石相二氧化钛 纳米粉体,得到了不同形貌的二氧化钛纳米管,并用TEM,XRD,FT-Raman和BET等 对其进行了表征。金红石相的超细纳米晶有利于形成均一形貌的纳米管,用粒径仅 为7.2 nm的金红石相纳米粉体为前驱体得到了长度为500 nm的长二氧化钛纳米管。 用纳米晶反应活性对晶粒尺寸的依赖性及晶相稳定性解释了长纳米管的形成机理。     

金红石相二氧化钛纳米晶的光催化活性

以苯酚光催化氧化和铬酸根光催化还原反庆为模型反应,研究不同粒径的金红石相二氧化钛纳米晶的光催化性活性。用XRD,TEM和BET等表明超细金红石相二氧化钛的粒径为7～8nm,UV-vis谱表明其吸收带边界蓝移11nm。在上述反应中,具有量子尺寸效应的金红石相二氧化钛(7nm)均表现出很高的催化活性,催化活性随粒径增大而迅速下降。7.2nm金红石相二氧化钛的光催化活性与6.8nm的锐钛矿相二氧化钛相当。     

4-氯酚稀水溶液的脉冲辐解研究

利用脉冲电子束进行了多种条件下4－氯酚稀水溶液的脉冲辐解研究,对其瞬态光谱中的主要吸收峰作了归属,并初步考察了这些瞬态物种的生长、衰减等行为,研究表明,·OH基与4－氯酚在碱性条件下反应生成氯代酚氧基,速率常数为4.14×10^9L/(mol·s),在酸性条件下要经过OH-adducts;H原子与4-氯酚反应生成H-adducts的速率常为2.0×10^9L/(mol·s),产物可通过双分子二级反应逐步脱氯;eaq^-可直接从4-氯酚分子夺氯,反应速率常数为1.82×10^9/L(mol·s)。     

Photocatalytic degradation and kinetics of Orange G using nano-sized Sn(IV)/TiO2/AC photocatalyst

Sn(IV) doped and nano-sized TiO₂ immobilized on active carbon (AC) (Sn(IV)/TiO₂/AC) were prepared by the sol–gel and dip-calcination method. An azo dye, Orange G (OG), was used as a model compound to study its photocatalytic activity in a fluidized bed photoreactor. The addition of Sn(IV) on TiO₂ could greatly improve the activity of TiO₂, and the optimal amount of tin was 2.5 at.%. The effects of calcination temperature, pH value, the initial hydrogen peroxide concentration ([H₂O₂]₀), the catalyst amount ([TiO₂]), the initial OG concentration ([dye]₀) and co-existing negative ions on the photocatalytic activity of Sn(IV)/TiO₂/AC were studied. The optimal conditions were as follows: pH 2.00, [H₂O₂]₀ = 1.5mL/L, [dye]₀ = 50 mg/L, [TiO₂] = 12.5 g/L, when the 300 W high pressure mercury light was used as the light source. Under these conditions, the degradation efficiency of OG reached 99.1% after 60 min reaction. The kinetics of the OG degradation was also analyzed. The results showed that the kinetics of this reaction fit the Langmiur–Hinshelwood kinetics model well and the absorption of OG on the Sn(IV)/TiO₂/AC surface was the controlling step in the whole degradation process. In addition, the catalyst, liquid and gas were separated effectively, and the integrative process of reaction and separation was achieved during the experiment.     

MoS_2负载量对MoS_2/TiO_2光催化降解苯酚效率的影响及其作用机理研究

通过水解法制备TiO_2纳米颗粒,与经过超声处理后的MoS_2片层纳米材料复合制备MoS_2/TiO_2纳米催化剂,考察不同MoS_2负载量对其光催化降解苯酚效率及路径的影响。XRD、SEM、EDS、FT-IR和UV-vis DRS等表征结果表明,复合催化剂主要由锐钛矿型TiO_2和MoS_2组成;剥离后的MoS_2呈现薄片层状结构,均匀地分散在TiO_2纳米颗粒当中。光催化降解苯酚性能测试结果显示,对于MoS_2/TiO_2催化剂,MoS_2负载量的提高有利于光催化降解苯酚效率的提高;当MoS_2负载量为27%时,复合M o S2/TiO_2纳米颗粒的光催化性能最佳,反应80 min后可将苯酚完全降解。通过对苯酚降解过程中生成中间产物跟踪发现,MoS_2负载量的提高有利于促进中间产物苯醌、对苯二酚以及邻苯二酚的生成,进而提升了MoS_2/TiO_2复合材料的光催化性能。     

Enhanced Visible-light Photocatalytic Activity of g-C3N4/Nitrogen-doped Graphene Quantum Dots/TiO2 Ternary Heterojunctions for Ciprofloxacin Degradation with Narrow Band Gap and High Charge Carrier Mobility

Limited visible-light absorption and high recombination rate of photogenerated charges are two main drawbacks in g-C₃N₄-based photocatalysts. To solve these problems, g-C₃N₄/nitrogen-doped graphene quantum dots (NGQDs)/TiO₂ ternary heterojunctions were facilely prepared via a one-step calcining method. The morphology, structure, optical and electrochemical properties of g-C₃N₄/NGQDs/TiO₂ were characterized and explored. The optimal g-C₃N₄/NGQDs/TiO₂ composite exhibits enhanced photocatalytic degradation performance of ciprofloxacin (CIP) compared with the as-prepared g-C₃N₄, TiO₂(P25) and g-C₃N₄/TiO₂ heterojunction under visible light irradiation. The apparent rate constant of the composite is around 6.43, 4.03 and 2.30 times higher than those of g-C₃N₄, TiO₂ and g-C₃N₄/TiO₂, respectively. The enhanced photocatalytic efficiency should be mainly attributed to the improvement of light absorption and charge separation and transfer efficiency, originating from the narrow band gap and high charge carrier mobility. The active species trapping experiments results showed that the h⁺ and ^·O₂^- were the main active species in the degradation process. A possible photocatalytic reaction mechanism of the g-C₃N₄/NGQDs/TiO₂ composite for the enhanced degradation of CIP under visible light irradiation was also proposed.     

The photocatalytic activity of TiO2 foam and surface modified binary oxide titania nanoparticles

Surface modified titania dioxide composite nanoparticles prepared by hydrogen reduction reaction and a mesoporous TiO₂ foam made from a surface modifier and a long chain organic surfactant were characterized by diffractive, spectroscopic and microscopic techniques and studied for their catalytic activity towards the decomposition of an industrial water pollutant, methyl orange. The surface deposition of ruthenium and silicon particles improved the photocatalytic activity of the composite particles resulting in a faster decomposition of the methyl orange compared to commercial TiO₂ alone. Modification of TiO₂ with RuO₂ only offered a marginal benefit over TiO₂ while the incorporation of RuO₂ and SiO₂ into TiO₂ resulted in a marked increase in the rate constant and catalytic activity. These results are consistent with the enhanced surface properties of the composite materials resulting from the modification of TiO₂ with RuO₂ and SiO_2. This surface enhancement effects appear synergetic to the charge separation process and hence the photocatalytic results are explained on the basis of a mechanism involving efficient charge transfer across the interfaces of the composites involving photogenerated electron–hole pairs. Results obtained in this study show that the percentage degradation after 1 h of illumination was 47.15% for TiO₂ foam, 75.5 and 106.4%, respectively, for TiO₂/RuO₂ (SiO₂ 5%, w/w) and TiO₂/RuO₂(SiO₂ 10%, w/w) and 34.15% for commercial TiO₂.     

Photocatalytic degradation of toluene in the gas phase: comparative study of some TiO2 supports

The Langmuir–Hinshelwood (L–H) kinetic model has been used to describe the degradation of the toluene on three TiO₂-based photocatalysts supports. The determination of the L–H rate constant (k) showed that the UV illumination parameter seems to be more important than the quantity of TiO₂ per unit area. The constant k is the greatest for the less density TiO₂ photocatalyst. The comparison between the Langmuir adsorption constant (K) in the dark and under UV irradiation shows that the adsorption constant for the high kinetic catalyst increases while it decreases for the other two.     

TiO2-SA纳米光催化材料接枝动力学、结构及性能

采用后处理表面改性法在纳米TiO₂表面接枝水杨酸(SA)(TiO₂-SA), 分别考察了超声搅拌、溶剂、物料比、pH值及温度等因素对接枝过程及光催化材料性能的影响, 并研究了接枝反应动力学. 通过傅里叶变换红外(FT-IR)光谱、X射线光电子能谱(XPS)、X射线衍射(XRD)等对TiO₂-SA纳米光催化材料进行了结构表征, 并提出了结构模型. 通过接触角测定、同步热分析(热重-差示扫描量热法(TG-DSC))、紫外-可见漫反射光谱(UV-VisDRS)、扫描电子显微镜(SEM)对光催化材料进行了性能表征. 结果表明, 水杨酸改性纳米TiO₂可以提高疏水性及分散性, 减缓在溶剂中的沉降速度, 并能稳定吸附在油-水界面, 实现了光谱响应范围向可见光的拓展. 在紫外光照射下, TiO₂-SA表现出优异的光催化降解硝基苯性能.     

TiO2光电化学电池催化氧化甲基红

以钛基TiO₂薄膜为光阳极，研究了光电化学电池中阳极光催化降解偶氮染料甲基红的动力学. 结果表明，短接光电化学电池分隔了光催化过程的阴、阳极反应，有利于抑制光生载流子的复合，提高光催化氧化速率. 相同实验条件下短路光电流越大，则甲基红降解速率越高. 在基底和TiO₂薄膜之间夹层SnO₂得到组装电极Ti/SnO₂/TiO₂，进一步提高了光生载流子的分离效率；同时采用电化学阻抗谱（EIS）评价了电极的光催化性能.     

Dispersion properties of TiO2 nano-powder synthesized by homogeneous precipitation process at low temperatures

The dispersion stability of rutile TiO₂ powder with a unique nano-structure synthesized by homogeneous precipitation process at low temperatures (HPPLT) has been investigated with adding the various electrolytes in both pure aqueous and organic media. Zeta potential measurements have shown that the addition of electrolytes such as CsCl, CaCl₂, FeCl₃, and ZrCl₄ to aqueous and pure organic dispersion media leads to generally a charge reversal from negative to positive on the surface of TiO₂ particle. The electrostatic repulsive force acting on between TiO₂ particles dispersed in pure organic media was found to be significantly greater than that in aqueous media, which is closely related to the physical properties of the organic solvents, such as viscosities and dielectric constant. The surface potentials of TiO₂ particles have been greatly modified by the particulate properties, pH, dispersion medium, and valence of the ionic species, which governs the colloidal behavior of TiO₂ particles virtually.     

一维TiO2锐钛矿/金红石异相结的制备及光催化降解甲醛性能

TiO₂异相结主要通过高温方法制备,所制备材料的形貌和组成较难控制,尤其是在较低温度下一步制备一维TiO₂异相结仍具有一定的挑战性。采用简单、方便的一步水热法,在较低温度下(180℃)制备了一维纳米TiO₂异相结材料。X射线衍射(XRD)和高分辨透射电镜(HRTEM)分析表明,制备的材料以一维金红石相TiO₂纳米棒(长度：(400±50) nm,直径：(60±5) nm)为基本结构,粒径分布均匀的锐钛矿相TiO₂纳米粒子(直径：(9.5±0.5) nm)高密度、单分散地负载在纳米棒上。通过控制水热反应时间成功调控了异相结中锐钛矿相TiO₂的含量(20%～50%),进而实现了其光催化降解HCHO性能的调控。实验结果表明,当锐钛矿相TiO₂的含量为33%时(TiO₂-24,水热时间24 h制备的样品),异相结光催化剂表现出最佳的HCHO降解性能：在低光强LED灯(波长为365 nm,光强为12.26 mW·cm