纳米TiO2光催化剂的改性研究

纳米TiO2作为光催化剂,由于其化学性质稳定、无毒、成本低和抗光腐蚀等优点在环境净化领域中有着广泛应用,而针对其光生电子-空穴复合率高,对可见光吸收率差,光催化效率不高等问题,科研人员致力于TiO2光催化剂的改性研究。综述了纳米TiO2光催化剂改性的研究进展,介绍了改性的不同方法,其中包括贵金属沉积、复合半导体、金属离子掺杂、非金属掺杂、共掺杂、表面光敏化等,并提出了TiO2光催化剂改性技术期待解决的问题和今后的研究方向。     

纳米TiO2光催化剂可见光响应的改性研究

综述纳米TiO2光催化剂对可见光响应的改性研究,介绍复合半导体、染料光敏化及非金属掺杂改性的方法,可以将只能由UV光激发的TiO2光催化反应红移到可见光区域进行。文中最后提出了金属与非金属复合掺杂改性TiO2是今后的一个重要研究方向,并存在巨大的研究空间。     

复合磁性纳米材料可见光催化降解染料废水性能研究

采用水热法,沉淀法和光致还原联合的方法制备Ag/AgCl/Fe_3O_4磁性纳米复合光催化材料,以扫描电子显微镜(SEM)、X-射线衍射(XRD)、紫外-可见光吸收光谱(UV-vis)等手段对催化剂的晶型结构、元素组成、形貌和光吸收特性等性能进行表征和分析。并且选择亚甲基蓝(MB)作为降解对象考察了Ag/AgCl/Fe_3O_4的可见光催化活性。实验结果表明:与纯AgCl和Fe_3O_4相比,Ag/AgCl/Fe_3O_4表现出优异的可见光光催化性能,主要是由于Ag纳米颗粒的表面等离子共振效应,提高可见光吸收性能的同时,可有效抑制光生电子空穴对的复合,从而提高其光催化活性。当催化剂经5次循环使用后,MB的降解率从100%逐渐降到90%。催化剂的活性略微降低,Ag/AgCl/Fe_3O_4具有较好的循环使用稳定性。     

纳米TiO2光催化剂的改性研究

纳米TiO2作为光催化剂,由于其化学性质稳定、无毒、成本低和抗光腐蚀等优点在环境净化领域中有着广泛应用,而针对其光生电子-空穴复合率高,对可见光吸收率差,光催化效率不高等问题,科研人员致力于TiO2光催化剂的改性研究.综述了纳米TiO2光催化剂改性的研究进展,介绍了改性的不同方法,其中包括贵金属沉积、复合半导体、金属离...     

Vis/LaFeO3/PDS复合高级氧化体系降解亚甲基蓝的机制

采用超声辅助溶胶-凝胶法制备对可见光(Vis)有良好响应性的LaFeO₃晶体,将其与过二硫酸盐(PDS)结合,构建Vis/LaFeO₃/PDS复合高级氧化体系,用以降解亚甲基蓝(MB)。结果表明:在PDS浓度为0.5 mmol/L、LaFeO₃投加量为0.5 g/L时,Vis/LaFeO₃/PDS体系30 min对质量浓度为30 mg/L的MB的去除率可达92.4%;复合体系对pH值有较强的适应性,Vis、LaFeO₃、PDS三者复合,通过提高光生电子-空穴对的分离效率,促进Fe(Ⅱ)/Fe(Ⅲ)的氧化还原循环和氧空位向活性氧自由基的转化,提高了空穴(h⁺)、SO^-₄·、单线态氧(¹O₂)等活性物质的产生效率和氧化活性能力的发挥。Vis/LaFeO₃/PDS体系是光催化和过硫酸盐高级氧化技术的高效结合,其协同效应在废水中难降解有机物的治理方面具有较好的应用前景。     

金属有机骨架材料Cu_3(BTC)_2的制备及其光催化性能研究

以三水硝酸铜为铜源,通过调控水热温度合成出高结晶度的金属有机骨架Cu3(BTC)2材料。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和热重(TG)手段对所制备的样品进行表征,同时以甲基橙和罗丹明B作为目标降解物研究Cu3(BTC)2材料的光催化性能。光催化降解结果显示:Cu3(BTC)2材料对罗丹明B有较好的降解效率,水热温度对Cu3(BTC)2材料的结构及光催化效率影响较大,水热温度为140℃制备的Cu3(BTC)2样品具有较高的光催化效率。这主要是由于高的结晶度可以产生更多的光生电子空穴对和提供更多的反应活性位,这将在处理环境污染物方面有着巨大的潜在的应用前景。     

P25对TiO_2镀膜光催化活性的影响

通过向钛酸四正丁酯溶胶中添加纳米级TiO2粉末（P25）,来提高煅烧TiO2镀层的光催化活性。用不锈钢丝网作为煅烧TiO2镀层载体,以甲基橙降解效果来衡量TiO2镀层的光催化活性。实验结果表明,当溶胶中P25添加量为1g／L、镀膜次数为4次时,镀层光催化活性达到最大,150min内甲基橙降解率达到69．8％。     

W-S-TiO2/SBA-15复合材料的表征及其可见光降解性能

利用介孔分子筛SBA-15的良好负载性和孔道均匀性,以钛酸四丁酯、硫代硫酸钠、钨酸钠分别作为钛、硫、钨源,水热合成了W-S-TiO2/SBA-15材料。对材料进行XRD、BET、SEM、XPS、UV-Vis分析。结果显示TiO2的负载并没有破坏SBA-15的介孔结构,UV-Vis分析发现掺杂W、S后,合成材料对光的响应拓展到可见光区,XPS分析证实了硫以阳离子S6+进入TiO2晶格,而W以同晶取代方式占据晶格中Ti的位置。光催化实验考察了材料5h内对20mg/L亚甲基蓝的去除效果,结果显示可见光下W-S-TiO2/SBA-15光催化效率分别是未掺杂样品和市售DegussaP25光催化剂的3.7和7.2倍,具备良好的可见光催化能力。     

水热法合成的LaVO4/WO3复合纳米片的可见光光催化还原工业废水中Cr（VI）效果分析

针对工业废水中Cr(Ⅵ)毒性大,迁移性强的问题,采用水热法制备了不同复合比例的LaVO_4/WO_3复合纳米片光催化剂,通过XRD、SEM、XPS和DRS测试手段进行了表征。结果表明:LaVO_4能进入WO_3晶格之中,使其产生晶格缺陷;晶格缺陷可作为活性位点,促进光生载流子的分离,提高WO_3的光催化活性。可见光下光催化还原工业废水中Cr(Ⅵ)测试表明:LaVO_4/WO_3复合纳米片的光催化还原效率比WO_3更高,当LaVO_4以质量比为3%负载WO_3时,复合纳米片光催化还原性最高,可达92%,是纯WO_3还原效率的8.3倍。分析结果表明,LaVO_4能使WO_3的氧空位得到扩散,提高界面光生电子的迁移速率,促进光生电子还原Cr(Ⅵ),提高复合纳米片的光催化还原性能。本研究为重金属工业废水,特别是难降解重金属污染物高效治理技术的研发提供了理论参考。     

水热法制备Bi3O4Cl及其光催化降解罗丹明B的研究

以硝酸铋为铋源,通过一锅法水热制备新型铋基光催化剂Bi3O4Cl采用X射线衍射（XRD）、扫描电子显微镜（SEM）和紫外可见漫反射（uV—VisDRS）手段对所制备的样品进行表征,同时以罗丹明B为目标降解物研究Bi3O4Cl的光催化性能。光催化降解结果表明：水热温度对光催化效率影响较大,水热温度为90℃制备的Bi3O4Cl样品具有较高的光催化效率,这主要是由于其具有较小的禁带宽度和对目标分子较好的吸附能力引起的。本实验提供了一种新型光催化剂Bi3O4Cl的制备方法,有助于促进光催化技术在环境污染控制领域的应用与发展。     

Preparation and characterization of Fe_2O_3/Bi_2WO_6 composite and photocatalytic degradation mechanism of microcystin-LR

The long-standing popularity of semiconductor photocatalysis,due to its great potential in a variety of applications,has resulted in the creation of numerous semiconductor photocatalysts,and it stimulated the development of various characterization methods.In this study,Fe_2O_3/Bi_2WO_6 composite with a flower-like microsphere and hierarchical structure was synthesized with the facile hydrothermal-impregnation method without any surfactants.X-ray diffraction(XRD),scanning electron microscopy(SEM),ultraviolet-visible(UV-Vis) diffuse reflectance spectroscopy,and photoluminescence spectroscopy were used to characterize the structures of the samples.The specific surface area was estimated with the Brunauer-Emmett-Teller(BET) method,and pore size distribution was determined using the Barrett-Joyner-Halenda(BJH)method.The synthesized Fe_2O_3/Bi_2WO_6 composite had an average diameter of approximately 4 nm,with smaller specific surface area and larger pore diameter than those of pristine Bi_2WO_6.The results of XRD and SEM analyses confirmed that the composite was composed of Fe_2O_3 and Bi_2WO_6.The absorption edge of Bi_2WO_6 was at a wavelength of 460 nm.By contrast,the absorption edge of Fe_2O_3/Bi_2WO_6 to visible light was redshifted to 520 nm,with narrower bandgap width and stronger visible light response.It was also found that the main active substances in the degradation of microcystin-LR(MC-LR) were hydroxyl radicals(·OH) and electron holes(h~+).Consequently,the results further showed that the heterojunction between Fe_2O_3 and Bi_2WO_6 can improve the charge transfer rate and effectively separate the photoinduced electrons and holes.Compared with Bi_2WO_6,Fe_2O_3/Bi_2WO_6 had no significant difference in the adsorption capacity of MC-LR and had more efficient photocatalytic degradation activity of MC-LR.The degradation rates of MC-LR by Fe_2O_3/Bi_2WO_6 and Bi_2WO_6 reached 80% and 56%,respectively.The degradation efficiency of MC-LR was affected by the initial pH value,initial Fe_2O_3/Bi_2WO_6 concentration,and initial MC-LR concentration.     

FeS矿活化H2O2降解水中对氯苯胺的实验研究

以对氯苯胺(PCA)为目标污染物,研究了常温下Fe S矿活化H2O2非均相类Fenton体系对难降解有机物的去除效果。分析了初始p H值、催化剂和H2O2投加量等重要因素对PCA降解率的影响。当PCA浓度为0.2×10-3mol/L,溶液初始p H值为3.0,H2O2投加量为3.2×10-3mol/L,Fe S矿用量为0.4 g/L,反应20 min时,PCA去除率可达100%,且反应进行到40 min后,已达到完全脱氯效果。在此基础上,通过对Cl-、SO42-、Fe3+等中间产物离子和总有机碳(TOC)变化规律的测定,探讨了有机物降解机理。研究结果表明:Fe S矿对催化H2O2氧化具有很强的催化活性,能提高H2O2的利用效率,相比于单一含铁矿物具有更好的催化性能,并且催化剂易于沉淀分离,回收利用。     

生物炭/铁酸锰对Zn^2+和Cu^2+的吸附性能试验

为探求吸附效果好、回收方便的吸附剂以解决重金属污染废水的处理难题,以玉米秸秆和铁酸锰为原料,通过溶胶-凝胶法以蛋清为络合剂经热解制备了一种生物炭/铁酸锰(BC/FM)复合材料,在对该复合材料扫描电子显微镜(SEM)和磁滞回线分析的基础上,进行了去除废水中Zn^2+、Cu^2+的吸附试验。结果表明,铁酸锰可有效地负载到生物炭上,形成官能团丰富、磁性良好的复合材料;BC/FM对Zn^2+、Cu^2+的吸附最佳pH值分别为5和6,并均在90 min达到吸附平衡,准二级模型能更好地描述BC/FM对Zn^2+、Cu^2+吸附过程;Langmuir模型拟合曲线和Freundlich模型拟合曲线分别适用于描述BC/FM对Zn^2+、Cu^2+的等温吸附过程,且均为自发吸热反应;BC/FM对Zn^2+、Cu^2+吸附机制主要为络合反应。     

Degradation of phenol by TiO2-based heterogeneousphotocatalysts in presence of sunlight

This paper reports the results of a study on the titanium dioxide Anjatox^®, which shows very interesting photocatalytic activity. Produced for commercial purposes as a white pigment, its features make it very interesting in the field of heterogeneous photocatalysis. The results obtained with this photocatalyst are compared with the behavior of the well-studied and widely used TiO₂ Degussa P-25^® under identical conditions. The degradation experiments showed that the photocatalytic efficiency of Anjatox^® is comparatively close to that of Degussa P-25^®. Both Anjatox^® and Degussa P-25^® show optimum degradation efficiency at a certain loading rate. The particle crystallite size and the BET surface area of the Anjatox^® TiO₂ are also compared with Degussa P-25^®. Moreover the XRD study showed that TiO₂ Anjatox^® was more crystalline than the TiO₂ Degussa P-25. The particle size histogram of TiO₂ Anjatox^® was found to be comparatively uniform like TiO₂ Degussa P-25^®. The use of TiO₂ Anjatox^® in heterogeneous photocatalysis is more desirable when high photocatalyst loading is required because of its low cost. The cost of Anjatox TiO₂ was INR.110.00/Kg and the cost of Degussa P-25 was INR 1000/Kg (Jan 2006).     

磁性Fe_3O_4/碳纳米管复合材料光催化处理刚果红染料废水

采用共沉淀法制备了一种磁性Fe3O4/CNTs(碳纳米管复合物),采用XRD、SEM、VSM等对Fe3O4/CNTs复合材料的晶相、颗粒大小和磁性能进行了表征。以刚果红染料废水处理为例,研究了不同处理工艺、催化剂投加量、溶液p H、催化剂重复使用等因素对Fe3O4/CNTs材料光催化脱色刚果红染料废水效果的影响。结果表明,当刚果红染料起始质量浓度为10 mg/L,用量为0.2 g/L,3%的H2O20.2 m L,光照50 min后,Fe3O4/CNTs对刚果红溶液的脱色率达到97.0%。催化剂重复使用第4次,对刚果红染料的脱色率仍可达87%以上。此外,Fe3O4纳米粒子的存在使Fe3O4/CNTs材料具有较强的磁性,且可通过外加磁场将其从处理后的水体中快速分离回收。     

二氧化钛—氧化石墨烯复合物去除水中有机污染物的性能研究

采用水热法制备了二氧化钛—氧化石墨烯复合物(TiO_2-GO)。X射线衍射花样表明:TiO_2具有锐钛矿结构,透射电子显微镜显示TiO_2纳米粒子均匀分散在GO片层上。在去除水中有机污染物方面:与GO相比,TiO_2纳米粒子的存在可抑制GO的团聚,保证了TiO_2-GO对污染物的强吸附性;与单一TiO_2纳米粒子相比,GO的引入增强了TiO_2-GO对可见光的吸收,提高了TiO_2-GO复合物对污染物的吸附,并且GO与TiO_2之间的相互作用使TiO_2-GO表现出与TiO_2纳米粒子不同的光降解机制。     

深部互层咸水层二氧化碳分布特征探究

通过构造砂页岩互层结构,并根据渗透率对砂岩层岩性进行分类,建立了多岩相非均质模型,利用多组分多相流数值模拟软件TOUGH2/ECO2N探究二氧化碳注入深部互层咸水层后的分布特征,结果显示二氧化碳聚集在低渗透性的页岩层底部,呈分层结构,砂岩层中优先在渗透率较高的岩相中运移并呈分散分布;超临界二氧化碳不断溶于地层水,含饱和二氧化碳的咸水密度增加并缓慢下沉,无明显分层现象。     

Preparation of 2D square-like Bi2S3-BiOCl heterostructures with enhanced visible light-driven photocatalytic performance for dye pollutant degradation

A series of Bi₂S₃-BiOCl composites with two-dimensional (2D) square-like structures were prepared via a two-step anion exchange route. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and diffuse reflectance spectra (DRS) were used to investigate the properties of the as-prepared Bi₂S₃-BiOCl heterostructures. The coupling of BiOCl and Bi₂S₃ induced enhanced photoabsorption efficiency and bandgap narrowing. A reactive brilliant red X-3B dye was used as a contaminant to test the photocatalytic activity of the obtained Bi₂S₃-BiOCl samples under visible light irradiation. The sample Bi₂S₃-BiOCl with a mass ratio of 8:4 exhibited the highest photodegradation efficiency, which was six times higher than that of pure BiOCl. In addition, a mechanism for the enhancement of photocatalytic activity is proposed.     

Photodegradation of reactive blue 19 dye using magnetic nanophotocatalyst α-Fe_2O_3/WO_3:A comparison study of α-Fe_2O_3/WO_3 and WO_3/NaOH

The photocatalytic degradation of reactive blue 19(RB19) dye was investigated in a slurry system using ultraviolet(UV) and light-emitting diode(LED) lamps as light sources and using magnetic tungsten trioxide nanophotocatalysts(α-Fe_2O_3/WO_3 and WO_3/NaOH) as photocatalysts.The effects of different parameters including irradiation time,initial concentration of RB19,nanophotocatalyst dosage,and pH were examined.The magnetic nanophotocatalysts were also characterized with different methods including scanning electron microscopy(SEM),energydispersive X-ray spectroscopy(EDS),transmission electron microscopy(TEM),X-ray diffraction(XRD),photoluminescence(PL),differential reflectance spectroscopy(DRS),Fourier transform infrared spectroscopy(FTIR),and vibrating sample magnetometry(VSM).The XRD and FTIR analyses confirmed the presence of tungsten trioxide on the iron oxide nanoparticles.The VSM analysis confirmed the magnetic ability of the new synthesized nanophotocatalyst Ω-Fe_2O_3/WO_3 with 39.6 emu/g of saturation magnetization.The reactor performance showed considerable improvement in the α-Fe_2O_3-modified nanophotocatalyst.The impact of visible light was specifically investigated,and it was compared with UV-C light under the same experimental conditions.The reusability of the magnetic nanophotocatalyst α-Fe_2O_3/WO_3 was tested during six cycles,and the magnetic materials showed an excellent removal efficiency after six cycles,with just a 7% decline.