TiO_2光催化氧化改性技术研究进展

综合光催化氧化改性技术研究资料,简述了TiO2光催化氧化反应机理,对提高光催化效果的方法进行了总结,并提出了TiO2光催化氧化改性技术今后的研究方向。     

TiO2掺杂及固定化技术降解造纸废水研究进展

纳米TiO2采用掺杂过渡金属离子和固定化技术,能有效提高其光催化活性和反应效率,在处理废水有机污染物等方面具有广阔的应用前景.文章介绍了纳米TiO2的光催化氧化降解机理、掺杂不同过渡金属离子对TiO2光催化性能的影响和在不同基质上光催化活性的比较以及在制浆造纸废水处理等方面的研究进展.     

纳米TiO2掺杂过渡金属在造纸废水处理中的应用

纳米TiO2掺杂过渡金属离子,能有效提高其光催化活性和反应效率,在处理造纸工业废水等方面具有广阔的应用前景.综述了纳米TiO2的光催化氧化降解机理,纳米TiO2掺杂过渡金属离子的制备方法,掺杂不同金属离子对TiO2光催化性能的影响以及在降解造纸工业废水等多种有机废水的应用.     

纳米TiO2的改性及在造纸废水处理中的应用

光催化氧化技术作为一种新型的污染控制治理手段日益受到重视.综述了纳米TiO2光催化氧化机理、改性方法及其在造纸废水处理中的应用研究进展.     

TiO2在处理染料废水中的应用

主要对光催化剂氧化机理，光催化降解影响因素，TiO2光催化剂改性和其实际应用中固定化方面进行了综合评述。     

TiO2光催化降解印染废水的工艺研究

用悬浮法光催化氧化实际印染废水，并与不加催化剂的光降解处理废水的结果进行比较，结果表明：采用TiO2为催化剂可以显著加快光催化氧化过程。探讨了处理时间、处理温度、TiO2催化剂用量等因素对废水的去除和脱色的影响。实验结果表明，光催化处理该染料废水的最佳工艺条件为：处理时间6h，温度30℃，TiO2用量为1mg／mL。     

纳米TiO2光催化处理脱墨制浆废水

纳米TiO2光催化氧化处理废水技术因其具有高效、无二次污染等特点正成为研究和应用的重点。本论文对采用纳米TiO2光催化氧化技术深度处理造纸脱墨制浆废水进行了研究。研究结果发现：在光照强度、液流速度、液层厚度中，影响处理效果的最重要因素是光照强度，其次是液层厚度，而液液速度影响不显著。光照强度高，液层薄，有一定的液流速度，有利于光催化瓜原进行。最佳反应条件为光照强度75W，液层厚度15mm，液流速度10L／h，在此条件下CODCr去除率可以达到60．4％。     

溶液pH值对活性紫5染料光催化氧化降解的影响

活性染料废水具有色度高、可生化降解性差、有机物浓度高等特点,属于难处理工业废水.光催化氧化技术是高级氧化法在废水处理中的重要方法之一,氧化能力强和非选择性氧化是其主要特点,但各种工艺条件会影响光催化氧化的效果.本论文使用光催化法对活性紫5染料溶液进行氧化降解,所用催化剂为TiO2,重点讨论了溶液pH值对活性紫5染料降解率的影响,经过相关实验及讨论得知:光催化剂TiO2本身对活性紫5染料的吸附性能有限,经过30 min的吸附后,TiO2对活性紫5染料的吸附率最高只达到了 9.98％;在不同pH值条件下,TiO2都能够很好的光催化降解活性紫5染料,在pH值为2.95的条件下,经过120 min的反应后,活性紫5染料的脱色率最高可达到96.8％,且COD的去除率也高达79.3％,取得了很好的处理效果.     

用纳米技术处理造纸工业废水的研究进展

纳米技术的出现及其应用在水处理中的研究，可望使造纸废水处理技术获得较大的突破。以纳米TiO2光催化氧化技术、纳滤膜技术和纳米絮凝技术为重点、介绍了纳米技术应用于造纸废水处理的研究新进展。     

TiO_2在处理染料废水中的应用

主要对光催化剂氧化机理,光催化降解影响因素,TiO2光催化剂改性和其实际应用中固定化方面进行了综合评述。     

Effects of pH and catalyst concentration on photocatalytic oxidation of aqueous ammonia and nitrite in titanium dioxide suspensions

Batch experiments were conducted to study the effects of titanium dioxide (TiO2) concentration and pH on the initial rates of photocatalytic oxidation of aqueous ammonium/ ammonia (NH4+/NH3) and nitrite (NO2-) in UV-illuminated TiO2 suspensions. While no simple kinetic model could fit the data at lower TiO2 concentrations, at TiO2 concentrations > or = 1 g/L, the experimental data were consistent with a model assuming consecutive first-order transformation of NH4+/NH3 to NO2- and NO2- to nitrate (NO3-). For TiO2 concentrations > or = 1 g/L, the rate constants for NO2 photocatalytic oxidation to NO3 were far more dependent on TiO2 concentration than were those for NH4+/NH3 oxidation to NO2-, suggesting that, without sufficient TiO2, complete oxidation of NH4+/NH3 to NO3- will not occur. Initial NH4+/NH3 photocatalytic oxidation rates were proportional to the initial concentrations of neutral NH3 and not total NH3(i.e., [NH4+] + [NH3]). Thus, the pH-dependent equilibrium between NH4+ and NH3, and not the pH-dependent electrostatic attraction between NH4+ and the TiO2 surface, is responsible for the increase in rates of NH4+/NH3 photocatalytic oxidation with increasing pH. Electrostatic adsorption, however, can partly explain the pH dependence of the initial rates of NO2- photocatalytic oxidation. Initial rates of NO2- photocatalytic oxidation were 1 order of magnitude higher for NO2- versus NH4+/NH3, indicating thatthe rate of NH4+/NH3 photocatalytic oxidation to NO3- was limited by NH4+/NH3 oxidation to NO2- under our experimental conditions.     

Selective photocatalytic oxidation of NH3 to N2 on platinized TiO2 in water

Selective photocatalytic oxidation of NH3 to N2 is proposed as a new treatment method for controlling the levels of ammonia in water. The photocatalytic oxidation of ammonia on naked and metallized TiO2 in water saturated with air, nitrogen, or NO2 gas was investigated. While the slow photocatalytic oxidation of NH3 to NO2-/NO3- is the only pathway for decomposition of NH3 on naked TiO2 and Au/TiO2, a new pathway, that of selective oxidation of ammonia to dinitrogen, opens up on Pt/TiO2. The formation of dinitrogen from the oxidation of 15NH3 was confirmed by mass spectrometric detection of 15N2. The photocatalytic conversion of NH3 to N2 greatly increases when the Pt/TiO2 suspension is saturated with NO2 gas, whereas NO2 itself shows little reactivity with naked TiO2 and Au/TiO2. Over 80% of the total nitrogen available in ammonia (0.1 mM) is converted into N2 within 40 min illumination of the N2O-saturated Pt/TiO2 suspension. The ability of N2O to accept the conduction band electrons of Pt/TiO2 was verified by photoelectrochemical measurements. NO2 reductively decomposes to generate OH radicals on Pt/TiO2; the rate of ammonia degradation in the NO2-saturated Pt/TiO2 suspension significantly decreases in the presence of excess tert-butyl alcohol, an OH radical scavenger. The presence of Pt deposits on the TiO2 particles changes the photocatalytic pathway of ammonia conversion by both enhancing OH radical production from NO2 and stabilizing intermediate NHx (x=0, 1, 2) species to facilitate their recombination into N2.     

吸附式纳米TiO2电极光电催化氧化罗丹明B研究

利用多孔金属基材料吸附式负载纳米TiO2作为光电阳极,与纳米TiO2胶体本身形成的多相光催化体系复合,进行光电催化与多相光催化复合氧化降解罗丹明B(一种人工合成有机染料)。使用分光光度计测定罗丹明B溶液的吸光度表征罗丹明B的降解率,证实吸附式纳米TiO2光电极催化氧化的光电协同作用。研究了偏电压、电解质、曝气速度、供氧方式等因素对光电催化氧化过程的影响。结果表明,光电催化延缓了光生电子和空穴的复合,提高了光催化效率,验证了光电协同作用;在偏电压为0.8V、无水硫酸钠电解质为0.5g/L、H2O2为2mL/L供氧的条件下,光电催化氧化降解罗丹明B的效果最好,紫外灯照射15min,罗丹明B的降解率达到97.4%。     

多相光催化氧化技术在造纸废水处理中的应用

多相光催化氧化是近年来日益受重视的污染治理新技术，本就多相当催化氧化技术的基本原理和特点，作了一般的阐述，并介绍了其在造纸废水处理方面的研究进展，存在的问题及发展前景。     

纳米Fe2O3靶向鸡肉腐败菌光催化抑菌效能 特性研究

目的探索可见光下纳米Fe2O3对鸡肉腐败菌的光催化抑菌效能特性及机制。方法以Escherichia coli及鸡肉腐败菌Pseudomonas fluorescens和Macrococcus caseolyticus为受试菌株,可见光照为激发条件,研究纳米Fe2O3对细菌菌落数量和菌体脂质氧化程度的影响。结果纳米Fe2O3在可见光下能够有效抑制E.coli、P.fluorescens和M.caseolyticus生长繁殖,1.2 mmol/L的H2O2能够增强Fe2O3的光催化抑菌活性;当Fe2O3质量浓度为0.4 g/L时,对P.fluorescens和M.caseolyticus的抑菌作用效果最强;在光催化过程中,P.fluorescens和M.caseolyticu的脂质氧化值随着反应时间延长呈先升高后降低的趋势,在120 min分别达到最大值1.31nmol/mg(细胞干重)和2.14 nmol/mg(细胞干重)。结论可见光条件下,M.caseolyticus对光催化反应比P.fluorescens更加敏感,纳米Fe2O3先引起细菌体内脂质氧化,进而导致菌体细胞破裂而死亡。     

絮凝-纳米二氧化钛光催化氧化法处理造纸废水

通过絮凝-纳米TiO2光催化氧化法对造纸废水进行了处理,并对其处理工艺进行了研究。讨论了在常温下,混凝过程中硫酸铝的投加量和废水pH值以及纳米光催化氧化过程中纳米TiO2投加量、H2O2投加量和光照时间等因素对造纸废水的COD去除率的影响,结果表明,造纸废水的COD去除率达到95%以上,色度去除率达到98%以上,pH值6.82,造纸废水的各项指标达到了排放标准。     

Integrated system for the treatment of oxides of nitrogen from flue gases

A novel and effective system was developed for the complete treatment of NOx from flue gases. The system consisted of photocatalytic or ozone oxidation of NOx, followed by scrubbing and biological denitrification. Maximum photocatalytic oxidation of NOx was achieved while using powdered TiO2 at a catalytic loading rate of 10 g/h, relative humidity of 50%, and a space time of 10 s. The used catalyst was regenerated and reused. A total of 72% of oxidized NO was recovered as HNO3/HNO2 in the regeneration process. Stoichiometrically, 10% excess ozone was able to affect 100% oxidation of NO to NO2. Presence of SO2 adversely influenced the oxidation of NO by ozone. The scrubbing of NO was effective with distilled water. Heterotrophic denitrifiers were able to denitrify the leachate with an efficiency of 90%, using sewage (COD 450 mg/L) as electron donor. The new integrated treatment system seems to be a promising alternative for complete treatment of NOx from flue gases.     

Enhanced degradation in nanocomposites of TiO2 and biodegradable polymer

Nanocomposites of titamium dioxide (TiO2) particles and biodegradable poly (butylene succinate) (PBS) were fabricated by melt-blending using a high-shear extruder. TiO2 particles were highly dispersed in the PBS matrix by high-shear processing, and the addition of TiO2 particles into PBS did not decrease its mechanical strength. The photocatalytic decomposition and biodegradable properties of the nanocomposites were evaluated by UV irradiation or enzymatic degradation methods in vitro. It was found that both the esterase enzyme and UV irradiation decomposed the nanocomposites. Photocatalytic decomposition of PBS clearly depended on the size and dispersibility of TiO2 particles in PBS polymer. Higher dispersibility and smaller size of TiO2 particles were effective on the photocatalytic oxidation of PBS. In addition, decomposition rate under a simultaneous UV irradiation treatment and immersion in an enzyme solution was higher than those under UV irradiation or immersion in an enzyme solution. These results indicate that the nanocomposites can easily be decomposed not only by an enzyme in soil or compost, but also by photocatalytic oxidation of TiO2 under sunlight.     

Plasma surface modified TiO2 nanoparticles: improved photocatalytic oxidation of gaseous m-xylene

Titanium dioxide (TiO(2)) is a preferred catalyst for photocatalytic oxidation of many air pollutants. In an effort to enhance its photocatalytic activity, TiO(2) was modified by pulsed plasma treatment. In this work, TiO(2) nanoparticles, coated on a glass plate, were treated with a plasma discharge of hexafluoropropylene oxide (HFPO) gas. By appropriate adjustment of discharge conditions, it was discovered that the TiO(2) particles can be either directly fluorinated (Ti-F) or coated with thin perfluorocarbon films (C-F). Specifically, under relatively high power input, the plasma deposition process favored direct surface fluorination. The extent of Ti-F formation increased with increasing power input. In contrast, at lower average power inputs, perfluorocarbon films are deposited on the surface of the TiO(2) particles. The plasma surface modified TiO(2) nanoparticles were subsequently employed as catalysts in the photocatalytic oxidation of m-xylene in air, as carried out inside a batch reactor with closed loop constant gas circulation. Both types of modified TiO(2) were significantly more catalytically active than that of the unmodified particles. For example, the rate constant of m-xylene degradation was increased from 0.012 min(-1) with untreated TiO(2) to 0.074 min(-1) with fluorinated TiO(2). Although it is not possible to provide unequivocal reasons for this increased photocatalytic activity, it is noted that the plasma surface treatment converted the TiO(2) from hydrophilic to highly hydrophobic, which would provide more facile catalyst adsorption of the xylene from the flowing air. Also, based on literature reports, the use of fluorinated TiO(2) reduces electron-hole recombination rates, thus increasing the photocatalytic activity.     

Modeling of an annular photocatalytic reactor for water purification: oxidation of pesticides

Photocatalytic oxidation (PCO) over titanium dioxide (TiO2) is a "green" sustainable process for the treatment and purification of water and wastewater. However, the application of PCO for wastewater treatment on an industrial scale is currently hindered by a lack of simple mathematical models that can be readily applied to reactor design. Current models are either too simplistic or too rigorous to be useful in photocatalytic reactor design, scale-up, and optimization. In this paper a simple mathematical model is presented for slurry, annular, photocatalytic reactors that still retains the essential elements of a rigorous approach while providing simple solutions. The model extends the applicability of the thin-film model of photocatalytic reactors previously presented to include the case of geometrically thick photoreactors (i.e., those reactors in which the thickness of the annular zone is significant as compared to the outer radius of the reactor). The model uses a novel six-flux absorption-scattering model to represent the radiation field in the reaction space, which assumes that scattered photons follow the route of the six directions of the Cartesian coordinates. The model was successfully validated with experimental results from the photocatalytic oxidation of the pesticide isoproturon in an experimental reactor. The mathematical model presented may be used as a tool for the design, scale-up, and optimization of annular photocatalytic reactors for water treatment and purification.