纳米TiO_2膜制备与光催化降解CHCl_3

采用溶胶法制备纳米TiO2 薄膜 ,其晶体为锐钛矿型。若加入PEG 2 0 0 0可使薄膜呈多孔状 ,并影响薄膜的透光率。纳米TiO2 薄膜对CHCl3 的光降解有很好的催化性能 ,而多孔状纳米TiO2 薄膜的催化性能更优 ,光催化条件下的CHCl3 分解率接近 90 %。     

纳米TiO2薄膜光催化降解苯酚的试验研究

采用交流磁控溅射法分别在载玻片、抛光单晶硅片（ITO玻璃）和铝片上制备出纳米TiO2薄膜,研究了薄膜厚度、退火温度及衬底对薄膜光催化降解苯酚性能的影响.结果表明：薄膜经500℃退火处理后TiO2由非晶态转变为锐钛矿结构,光催化降解性能得以提高;薄膜厚度在200nm以内时,随着厚度的增加则薄膜的光催化性能提高.比较了以玻璃、ITO玻璃和铝片为衬底制备的TiO2薄膜光催化降解苯酚的效果,结果表明,以铝片为衬底的降解效果最好,其在紫外光照射5 h后对苯酚的降解率达51%;ITO衬底次之;玻璃衬底的效果最差,不及铝片衬底的一半.     

纳米TiO2对水中对羟基苯甲酸吸附及光催化降解

以BDH粉末TiO2为光催化剂,研究了水体中对羟基苯甲酸在纳米TiO2颗粒上的吸附行为,并研究了对羟基苯甲酸的二氧化钛光催化降解效果。结果表明：TiO2对羟基苯甲酸的吸附作用明显依赖于水溶液的pH,对羟基苯甲酸的光催化降解效果与其在催化剂表面的吸附行为密切相关,提高吸附速率,对羟基苯甲酸的去除率也随之提高。     

TiO2固定膜光催化降解甲胺磷农药废水

采用自制的TiO2固定膜浅池反应器对经生化处理后的甲胺磷农药废水进行了降解试验。经处理后废水中的COD降为59．3mol/L、有机磷被全部降解为无机磷,达到《污水综合排放标准》（GB8978－1996）中的一级排放标准。     

纳米TiO2光催化降解室内空气污染物的实验研究

本文介绍了纳米TiO2降解室内空气污染物的原理,理论分析纳米TiO2颗粒大小对其光催化氧化能力的影响程度。实验证实了纳米TiO2能有效地分解室内空气污染物。得出了空气流速、污染物浓度、紫外光强度与光催化氧化效果之间的变化关系。最后指出了纳米TiO2光催化技术发展应该注意的问题。     

光学纤维载TiO2膜光催化氧化降解苯酚

采用光学纤维载TiO2膜光催化氧化新型反应器研究了外加不同氧化剂（H2O2、O3或通入空气）时对苯酚的降解效果，试验结果表明，在外加氧时对苯酚的降解效果最好；随着苯酚起始浓度的减小，苯酚的降解率增大，1mg/L苯酚溶液经80min反应后的降解率为97．8％，此时苯酚浓度降至检测限以下。     

TiO2-活性炭组合光催化降解苯酚废水

论证了TiO2－活性炭组合光催化降解苯酚废水的可行性。试验结果表明，同单纯TiO2悬浮体系相比，组合体系对苯酚的去除率显著提高，降解时间亦随之减少。活性炭的加入显著增强了TiO2光降解苯酚的能力。     

纳米TiO2改性多功能建筑涂料的制备与性能研究

利用高速分散技术制备纳米TiO2改性多功能建筑涂料,通过对涂膜的疏水性能、耐碱（水）性能、机械性能、耐光稳定性能和对气态氨和甲醛的光催化降解等的研究表明,该涂料具有较高的光催化活性、疏水性、耐候性及良好的使用性能,在不破坏涂膜的前提下对低浓度气态污染物氨和甲醛具有较高的降解率,且降解为无害的小分子物质.     

掺Fe^3＋纳米TiO2薄膜的制备及光催化性能研究

采用溶胶凝胶法制备纳米TiO2薄膜过程中加入Fe^3＋，可以提高二氧化钛的光催化活性，Fe^3＋的最佳掺杂浓度在0．10％左右。     

纳米TiO2-AC负载膜光催化降解偶氮染料

以钛酸四丁酯和活性炭为主要原料，采用溶胶-凝胶-浸渍法制备纳米TiO2-AC负载膜催化剂，并借助流化床反应器分别对两种典型的偶氮类染料橙黄C、活性艳红X-3B模拟废水进行了UV光降解、暗态吸附及光催化降解研究，探讨了pH值、外加氧化剂对光催化去除率的影响，同时对催化剂进行回收再生利用试验。结果表明：纳米TiO2-AC负载膜具有很好的光催化活性、吸附特性及可再生性，两种染料1h的光催化降解率最高分别可达99．71％和97．12％。反应过程中固、液、气三相能够有效分离，实现了反应与分离的一体化。     

SnO2纳米粒子的制备与降解甲醛效果研究

采用了一种新颖而有效的方法制备SnO2纳米粒子：利用氩弧焊电弧形成的高温将反应台上的锡蒸发,在装置的另一端通过高压直流电场收集锡粒子,制得纳米级锡粒子,然后在空气气氛下将纳米锡粒子在800℃～90℃范围内进行热处理,最终得到SnO2纳米粒子。制得的SnO2纳米粒子粒径在50nm左右,且杂质较少。将制得的SnO2纳米粒子...     

SiO_2/TiO_2复合膜光催化降解胶片废水的研究

以煤矸石烧结滤料为载体,以SiO2/TiO2复合膜为催化剂,在自制的紫外光光催化反应器中,以去除胶片废水的色度为研究目标,考察了废水色度、pH、曝气/光照对SiO2/TiO2复合膜光催化活性的影响.结果表明,当废水的初始吸光度为0.554、光催化降解的时间为2 h时.SiO2/TiO2复合膜光催化降解胶片废水的脱色率可达到99.4%;脱色率与光照时间呈线性相关(R2=0.994 2),且可用Langmuir-Hinshelwood一级动力学模型进行拟合,表观速率常数为0.027 5min-1;SiO2/TiO2复合膜光催化降解胶片废水的处理费用约为1.2元/m3,较接触氧化工艺的处理成本低,有一定的工程应用价值.     

Photocatalytic transformation and mineralization of 2,4,6-trinitrotoluene (TNT) in TiO2 slurries

An analysis of the photodegradation of TNT in a TiO₂ slurry reactor is presented. The rates and extent of TNT transformation and mineralization are compared for photocatalytic and direct photolytic reactions under conditions of varying light energies and in the presence and absence of oxygen. Certain initial organic transformation products are identified for both photocatalytic and photolytic reactions. Nitrate, nitrite, and ammonium ions are analyzed and the possibility of semiconductor sensitization by colored compounds is considered. TNT was transformed rapidly under each set of photochemical conditions but destruction was faster and more complete with TiO₂ photocatalysis. Transformation by-products were destroyed readily under oxygenated photocatalytic conditions and were observed to be more refractory under direct photolytic conditions. Mass balances performed on carbon and nitrogen revealed that when the TiO₂ photocatalyst was utilized in the presence of oxygen and near u.v. radiation (λ > 340 nm) approx. 90% of the TNT was mineralized and 35% of the total nitrogen was recovered as ammonium ion after 120 min. Among the large number of organic transformation products produced photocatalytically, trinitrobenzoic acid, trinitrobenzene and trinitrophenol have been identified as oxidative intermediate species and dinitroaniline as a reduction product. The photocatalytic transformation of TNT appears to involve both oxidative and reductive steps and sensitization by colored compounds plays no detectable role in degradation.     

Bi2MoO6/AgBr的制备及其光催化活性增强机制

采用水热法合成了Z型异质结Bi₂MoO₆/Ag Br光催化剂,利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、比表面积测试仪(BET)、稳态/瞬态荧光光谱仪等对其微观形貌、物相组成以及光电性能等特性进行表征;通过对目标污染物罗丹明B(Rh B)的降解分析该催化剂的活性和降解机理。结果表明,该催化剂由立方相的Bi₂Mo O₆纳米片堆叠而成的纳米微球和负载在其表面的Ag Br纳米花簇构成,异质结的形成使得比表面积增加了7.2 m²/g,光生电子对寿命延长。Bi₂Mo O₆与Ag Br复合后光催化活性明显提高,当Ag Br复合量为10%时效果最佳,光催化反应速率常数是Bi₂Mo O₆的1.6倍。当Rh B浓度为0.5×10^-5mol/L、Bi₂Mo O₆/Ag Br投加量为250 mg/L、p H值=7时,反应20 min后对Rh B的降解率可达到95.9%,且Bi₂Mo O₆/Ag Br经过5次循环实验后仍具有较高的光催化活性。自由基捕获实验结果表明,Bi₂MoO₆的主要活性基为·O₂^-,Bi₂Mo O₆/Ag Br的主要活性基团为·O₂^-和h⁺。根据以上实验结果,提出了一种由Ag⁰粒子为通道的Z型电荷转移机理。     

Degradation of the antibiotic oxolinic acid by photocatalysis with TiO2 in suspension

In the work presented here, a photocatalytic system using titanium Degussa P-25 in suspension was used to evaluate the degradation of 20 mg L⁻¹ of antibiotic oxolinic acid (OA). The effects of catalyst load (0.2-1.5 g L⁻¹) and pH (7.5-11) were evaluated and optimized using the surface response methodology and the Pareto diagram. In the range of variables studied, low pH values and 1.0 g L⁻¹ of TiO₂ favoured the efficiency of the process. Under optimal conditions the evolution of the substrate, chemical oxygen demand, dissolved organic carbon, toxicity and antimicrobial activity on Escherichia coli cultures were evaluated. The results indicate that, under optimal conditions, after 30 min, the TiO₂ photocatalytic system is able to eliminate both the substrate and the antimicrobial activity, and to reduce the toxicity of the solution by 60%. However, at the same time, ∼53% of both initial DOC and COD remain in solution. Thus, the photocatalytical system is able to transform the target compound into more oxidized by-products without antimicrobial activity and with a low toxicity. The study of OA by-products using liquid chromatography coupled with mass spectrometry, as well as the evaluation of OA degradation in acetonitrile media as solvent or in the presence of isopropanol and iodide suggest that the reaction is initiated by the photo-Kolbe reaction. Adsorption isotherm experiments in the dark indicated that under pH 7.5, adsorption corresponded to the Langmuir adsorption model, indicating the dependence of the reaction on an initial adsorption step.     

Photocatalytic inactivation of E. coli in surface water using immobilised nanoparticle TiO2 films

Photocatalysis is a promising method for the disinfection of potable water in developing countries where solar irradiation can be employed, thus reducing the cost of treatment. In addition to microbial contamination, water normally contains suspended solids, dissolved inorganic ions and organic compounds (mainly humic substances) which may affect the efficacy of solar photocatalysis. In this work the photocatalytic and photolytic inactivation rates of Escherichia coli using immobilised nanoparticle TiO₂ films were found to be significantly lower in surface water samples in comparison to distilled water. The presence of nitrate and sulphate anions spiked into distilled water resulted in a decrease in the rate of photocatalytic disinfection. The presence of humic acid, at the concentration found in the surface water, was found to have a more pronounced affect, significantly decreasing the rate of disinfection. Adjusting the initial pH of the water did not markedly affect the photocatalytic disinfection rate, within the narrow range studied.     

g-C3N4光催化混凝土对NO降解性能研究

研究了不同制备工艺及掺量的石墨相氮化碳(g-C₃N₄)对混凝土的力学性能及对NO气体光催化降解性能的影响及变化规律。通过TEM、SEM、XRD分别对材料的物相及微观结构进行了表征,利用微机控制全自动压力试验机和氮氧化物分析仪分别研究了掺g-C₃N₄后混凝土的抗压强度及对NO的降解性能。结果表明,四种不同种类的g-C₃N₄掺入后混凝土都具有对NO的降解作用,其中,少层g-C₃N₄的降解率最高,且在紫外线等照射24 h后其仍能保持较高的降解率;g-C₃N₄掺量不超过0.8%时混凝土的抗压强度不会有太大影响,在此范围内尽可能提高g-C₃N₄的掺量来提高其对NO的降解作用。     

Bacterial responses to Cu-doped TiO2 nanoparticles

The toxicity of Cu-doped TiO₂ nanoparticles (NPs, 20 nm), synthesized by a flame aerosol reactor, to Mycobacterium smegmatis and Shewanella oneidensis MR-1, is the primary focus of this study. Both doped and non-doped TiO₂ NPs (20 nm) tended to agglomerate in the medium solution, and therefore did not penetrate into the cell and damage cellular structures. TiO₂ particles (< 100 mg/L) did not apparently interfere with the growth of the two species in aqueous cultures. Cu-doped TiO₂ NPs (20 mg/L) significantly reduced the M. smegmatis growth rate by three fold, but did not affect S. oneidensis MR-1 growth. The toxicity of Cu-doped TiO₂ NPs was driven by the release of Cu²⁺ from the parent NPs. Compared to equivalent amounts of Cu²⁺, Cu-doped TiO₂ NPs exhibited higher levels of toxicity to M. smegmatis (P-value < 0.1). Addition of EDTA in the culture appeared to significantly decrease the anti-mycobacterium activity of Cu-doped TiO₂ NPs. S. oneidensis MR-1 produced a large amount of extracellular polymeric substances (EPS) under NP stress, especially extracellular protein. Therefore, S. oneidensis MR-1 was able to tolerate a much higher concentration of Cu²⁺ or Cu-doped TiO₂ NPs. S. oneidensis MR-1 also adsorbed NPs on cell surface and enzymatically reduced ionic copper in culture medium with a remediating rate of 61 µg/(liter?OD₆₀₀? hour) during its early exponential growth phase. Since the metal reducing Shewanella species can efficiently “clean” metal-oxide NPs, the activities of such environmentally relevant bacteria may be an important consideration for evaluating the ecological risk of metal-oxide NPs.