Effect of dye-metal complexation on photocatalytic decomposition of the dyes on TiO2 under visible irradiation

The photocatalytic degradation of dyes (Acid Chrome Blue K (ACBK) and Alizarin Red (AR)) with strong complexation ability was investigated in the presence of metal ions under visible light irradiation.It was found that, at low dye-metal ratio, the photodegradation of ACBK was markedly inhibited by the addition of high oxidative potential Cu2+.However, at high dye-metal ratio, the presence of Cu2+ enhanced the photodegradation of ACBK.The negtive effect of Cu2+ on the photodegradation of AR was observed for all dye-metal ratios.The relative chemical inert Zn2+ tended to enhance the photodegradation of both anionic dyes.The mechanism underlying the different effect of Cu2+ is discussed from the different roles of surface-adsorbed and dye-coordinated Cu2+ in the photodegradation of dyes.     

Reaction site and mechanism in the UV or visible light induced TiO2 photodegradation of Orange G

For TiO2 heterogeneous reaction, the reaction site and the detailed mechanism are interesting and controversy topics. In this paper, effects of surface fluorination of TiO2 on the photocatalytic degradation of an azo dye, Orange G（OG） under UV or visible light irradiation were investigated, and the possible reaction site and mechanism were elucidated. The adsorption of OG on TiO2 was nearly inhibited by fluoride but its UV light induced photodegradation rate was greatly increased by a factor of about 2.7, which was due to the more generated free hydroxyl radicals. It supported the views that fluoride could desorb the oxidant species from surface and that the reaction sites could move to the bulk solution. In TiO2/Vis system, the observed inhibition effects of fluorination could be interpreted by the competitive adsorption, which provided additional evidences that the visible light sensitized photodegradation of dye pollutants on the catalyst surface.     

Microwave photocatalytic degradation of Rhodamine B using TiO2 supported on activated carbon： Mechanism implication

The photocatalytic degradation of Rhodamine B (RhB) was carried out using TiO2 supported on activated carbon (TiO2-AC) under microwave irradiation. Composite catalyst TiO2-AC was prepared and characterized using X-ray di raction (XRD), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET). In the process of microwave-enhanced photocatalysis (MPC), RhB (30 mg/L) was almost completely decoloured in 10 min, and the mineralization e ciency was 96.0% in 20 min. The reaction rate constant of RhB in MPC using TiO2-AC by pseudo first-order reaction kinetics was 4.16 times of that using Degussa P25. Additionally, according to gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS) identification, the major intermediates of RhB in MPC included two kinds of N-de-ethylation intermediates (N,N-diethyl-N’-ethyl-rhodamine (DER)), oxalic acid, malonic acid, succinic acid, and phthalic acid, maleic acid, 3-nitrobenzoic acid, and so on. The degradation of RhB in MPC was mainly attributed to the destruction of the conjugated structure, and then the intermediates transformed to acid molecules which were mineralized to water and carbon dioxide.     

负载型TiO2固定相光催化氧化法降解水中呋码唑酮

以高压汞灯为光源、负载在海砂上的ＴｉＯ２为催化剂，采用敞口固定床型光催化反应器对水中难降解的呋码唑酮（ＦＴＤ）进行了固定相光催化氧化实验。结果表明，反应速率可用ＬａｎｇｍｕｉｒＨｉｎｓｈｅｌｗｏｏｄ方程描述，与光分解相比，光催化氧化的突出优点是矿化程度高，相同光辐射条件下反应１００ｍｉｎ，０．１０ｍｍｏｌ／Ｌ的ＦＴＤ水溶液经光催化氧化后ＴＯＣ的去除率为８９．１％，而经光分解后ＴＯＣ的去除率仅为２８．８％；在反应体系中投加少量臭氧或过氧化氢可以显著提高ＦＴＤ的氧化效率，说明光催化氧化可以兼容Ｏ３／ＵＶ、Ｈ２Ｏ２／ＵＶ等光激发氧化工艺。制得的负载型ＴｉＯ２具有较高的机械强度和化学稳定性，可重复利用。探讨了充氧、ＦＴＤ浓度及ｐＨ值等对光催化氧化过程的影响。     

普伐他汀的光催化降解性能及机理研究

通过水热法合成Bi₂WO₆,并利用XPS,XRD,BET,UV-Vis和SEM等方法对样品进行了表征;通过光催化性能实验考察了Bi₂WO₆投加量,溶液pH值对普伐他汀（PR）降解效果的影响;通过自由基捕获实验及中间产物的鉴定探明了Bi₂WO₆光催化降解PR过程的主要活性自由基,中间产物及降解机理,并采用发光细菌急性毒性试验评估了PR降解前后的毒性.结果表明,所制备的Bi₂WO₆是由大量纳米片组成的正交晶系花瓣状微球,各元素物质的量比为Bi：W：O=2.5：1：6.7,比表面积为26.67m²/g,带隙能为2.74eV;光催化性能结果表明,对于10mg/L PR,当溶液pH=6.5,Bi₂WO₆投加量为0.4g/L时降解效果最佳,降解率可达80.6%,矿化度为40.2%;自由基捕获实验结果表明降解过程中h⁺起主要的氧化作用,·OH和·O₂^-的氧化起辅助作用.基于活性自由基和中间产物的鉴别结果提出了Bi₂WO₆光催化降解PR的机理,即以h⁺为主,·OH和·O₂^-为辅联合攻击PR分子中C－C键,C＝C双键,酯键等化学键,进而将其分解为易降解小分子有机物.另外,毒性测试结果表明PR经光催化降解后的小分子产物与PR原液相比毒性并没有增强.     

氯离子对模拟太阳光活化过一硫酸氢钾氧化卡马西平的影响规律

研究了氯离子存在条件下模拟太阳光活化过一硫酸盐(PMS)催化氧化模型污染物卡马西平(CBZ)的效果及机理.结果表明,无氯离子存在时,光活化PMS在30 min内只能转化25％左右的CBZ;随着氯离子浓度的增加,PMS/氯离子光催化体系对CBZ的氧化速率也迅速增加.通过电子顺磁共振(EPR)测试、活性种捕获实验等方式确定...     

纳米TiO2对气相中甲醛光催化降解的研究

采用溶胶-凝胶法制备了掺杂金属离子的纳米TiO₂光催化剂,运用透射电镜和X射线衍射手段对催化剂的结构进行了表征,并将制备的光催化剂负载于不锈钢丝网、玻璃弹簧和泡沫镍板3种不同载体上,以室内空气典型污染物甲醛气体为模型反应物,研究了3种不同改性纳米TiO₂光催化剂对甲醛气体的光催化作用,3种光催化反应器的催化效率以及环境因素对光催化效率的影响,同时考察了催化剂的失活特征.结果表明:该负载型纳米TiO₂光催化剂具有较高的光催化活性,其中掺镧1.5%(质量分数)的TiO₂对甲醛的降解率最高,60 min达到91.5%,大于掺铁和掺银;泡沫镍板作为负载载体的光催化效率大于玻璃弹簧和不锈钢丝网;循环风量和不同波长紫外光对该光催化反应影响不大,反应中催化剂存在失活现象,但在清洁后能够恢复.      

光催化氧化与生物氧化组合技术对染料化合物降解研究

将多相光催化氧化法与生物氧化法相结合，探讨两种组合技术对染料化合物的降解。实验选用100ppm的甲基橙和典型实验溶液，适当配以一定浓度范围的生活污水，以保证生物菌种的生存条件。实验结果证明先生物氧化、后光催化氧化是一种比较好的组合方式，24h生物氧化，溶液COD去除达69．68％，色度去除达22．39％，随后光催化氧化1h，COD去除达84．65％，色度去除达91．31％。由此说明，这种组合方式可以体现出两种反应的互补性，尤其对生化处理后的残留色度有明显的改善。     

Photocatalytic degradation of dye effluent by titanium dioxide pillar pellets in aqueous solution

Photocatalytic oxidation (PCO) process is an effective way to deal with organic pollutants in wastewater which could be difficult to be degraded by conventional biological treatment methods. Normally the TiO2 powder in nanometre size range was directly used as photocatalyst for dye degradation in wastewater. However the titanium dioxide powder was arduous to be recovered from the solution after treatment. In this application, a new form of TiO2(i. e. pillar pellets ranging from 2.5 to 5.3 mm long and with a diameter of 3.7 mm) was used and investigated for photocatalytic degradation of textile dye effluent. A test system was built with a flat plate reactor(FPR) and UV light source(blacklight and solar simulator as light source respectively) for investigating the effectiveness of the new form of TiO2. It was found that the photocatalytic process under this configuration could efficiently remove colours from textile dyeing effluent. Comparing with the TiO2 powder, the pellet was very easy to recovered from the treated solution and can be reused in multiple times without the significant change on the photocatalytic property. The results also showed that to achieve the same photocatalytic performance, the FPR area by pellets was about 91% smaller than required by TiO2 powder. At least TiO2 pellet could be used as an alternative form of photocatalyst in applications for textile effluent treatment process, also other wastewater treatment processes.     

TiO2薄膜光催化剂的制备及其活性

用活化反应蒸发技术制备了不同附载条件的TiO2薄膜光催化剂，膜厚度在0．5μm－1.2μm之间，经400℃退火后用XRD测定其晶型结构，发现无定型TiO2已部分转变为锐钛矿型。薄膜光催化剂连续使用两次活性会下降，用HCl冲洗活性即可恢复。考察了不同波长的电光源和不同辐射强度的太阳光下两种催化剂薄膜的活性比较，结果发现短波长电光源下（254nm）膜厚度以0．5μm最佳，而强烈辐射的太阳光下膜厚度以1.2μm最佳。     

TiO_2光催化降解活性艳兰KN-R的研究

以纳米TiO2为光催化剂,以活性艳兰KN-R为模拟染料废水,研究了溶液pH值、TiO2投加量、H2O2用量及染料初始浓度对染料脱色率的影响。结果表明,活性艳兰KN-R的脱色率随溶液pH值的升高及染料初始浓度的降低而增大;TiO2和H2O2的投加量均存在一个最佳值,在本实验条件下,它们分别为0.5g/L和2.0×10-2mol/L,低于或超过该值都会导致染料脱色率的下降。在适宜的操作条件下,活性艳兰KN-R的脱色率可达98%以上,化学需氧量(COD)的去除率在70%以上。     

Enhanced photocatalytic activity of fish scale loaded TiO2 composites under solar light irradiation

Fish scale (FS) loaded TiO₂ composites were investigated as photocatalysts in degradation of Methyl Orange under solar light irradiation. Composites were prepared through sol-gel method by varying mass ratio of TiO₂/FS at 90:10, 70:30 and 50:50, respectively. The catalysts prepared in this study were characterized by using XRD, SEM, FT-IR and nitrogen sorption. The effects of solar irradiation, mass ratio of TiO₂/FS composites, irradiation time and catalyst loadings were studied. Synergistic effect was found in TiO₂/FS of 90:10 composite which performed higher photocatalytic degradation than synthesized TiO₂ under solar light irradiation. However, further increasing fish scale content in the composites reduced the photocatalytic activity drastically. Under solar light irradiation, all the catalysts in this study exhibited photocatalytic activity, except TiO₂/FS of 50:50 composite that only acted as a weak biosorbent without performing any photocatalytic property. Photocatalytic degradation increased with increasing catalyst loading and irradiation time but decreased with increased of initial dye concentration.     

光催化降解有机磷农药的研究

研究以ＴｉＯ２粉末作为光催化剂,光降解３种不同结构的有机磷农药的可行性。结果表明,有机磷农药结构不同其光降解率不同;浓度１．０×１０－４ｍｏｌ／Ｌ的４种有机磷农药,３７５Ｗ中压汞灯照射４０ｍｉｎ有机磷将完全转变为无机磷,并检测出人效磷农药催化降解的部分中间产物。研究光催化剂ＴｉＯ２的用量、空气流量、外加Ｆｅ３＋浓度对光催化降解的影响,并初步探讨了机理。     

二氧化钛悬浆体系太阳光催化降解甲基橙研究

利用太阳光作为光源，采用二氧化钛悬浆体系，考察了甲基橙溶液光催化降解反应中影响反应速度的相关因素．实验结果表明，太阳光强度、二氧化钛的投加量、反应器的Ａ／Ｖ值、溶液的初始浓度是影响反应速率的重要因素．在平均照度为９２６００ｌｘ的晴天，初始浓度为２０ｍｇ／Ｌ的甲基橙溶液，初始ｐＨ为３８８，反应器Ａ／Ｖ值为３６ｍ－１时，光照２ｈ后色度去除率达９０％以上，４ｈ后ＴＯＣ去除率接近７０％．实验结果证明了非聚焦开放式反应器构型和二氧化钛悬浆体系能很好地利用太阳能、有效地完成对甲基橙的脱色和有机碳的去除．各因素与甲基橙脱色速率的关系将作为进一步设计反应器的重要参数．     

负载型纳米TiO2光催化降解水中微量三氯乙烯

利用负载型纳米TiO_2作为光催化剂,对水中微量三氯乙烯进行紫外光催化降解处理。研究表明,三氯乙烯光催化降解过程符合表现一级反应动力学规律。不同的三氯乙烯初始浓度、光照强度和催化剂用量,对三氯乙烯的光催化降解具有不同的效果。在一定初始浓度范围内,随着初始浓度的增大,三氯乙烯光催化降解的反应速率常数逐渐减小;光强与反应速率常数呈正比例相关,显示出有一个最佳值;催化剂的用量与反应速率常数并非呈直线相关。此外,还讨论了三氯乙烯光催化降解的机理。     

有机物结构对光催化氧化降解影响的初步研究

研究了以TiO2 半导体为催化剂 ,有机物分子结构如芳烃取代度、环效应和卤代度对光催化氧化降解的影响。结果表明 ,对芳烃类衍生物 ,单取代基较双取代基降解容易 ,能形成贯穿共轭体系的难降解。环效应、卤代度对光催化降解有较大影响。芳烃、环烷烃、烷烃逐次减弱 ,卤代度越高 ,降解越困难 ,全卤代时基本不降解     

负载型纳米TiO2/AC对偶氮染料的光催化降解研究

以钛酸四丁酯和粒状活性炭(AC)为主要原料,采用溶胶-凝胶-浸渍法制备出负载型纳米TiO2/AC催化剂.在流化床反应器中分别对2种典型的偶氮类染料橙黄G、活性艳红X-3B模拟废水进行了光催化降解研究,探讨了pH值、外加氧化剂对光催化降解率的影响,并对催化剂进行了回收再生利用试验.结果表明,TiO2/AC催化剂具有良好的光催化活性、吸附特性及可再生性,60 min后对2种染料反应的光催化降解率分别可达到99.71%和97 12%,反应180 min后的TOC去除率分别达到81.54%和81.99%;反应后TiO2/AC催化剂回收率大于95%,经焙烧再生后对橙黄G反应60 min的光催化降解率仍高达95.93%.     

平板构型太阳光催化反应系统中甲基橙降解脱色研究

利用太阳光作为光源，采用自制的非聚焦开放式平板构型光催化反应装置和二氧化钛悬浆体系，以甲基橙溶液光催化脱色为依据，考虑了不同催化剂投加量、溶液初始浓度、ＵＶ辐射强度及体系流量等因素条件下，反应系统的运行情况．实验结果表明，自制的平板式太阳光反应系统能够很好的利用太阳光，在较广泛的运行条件下均能达到较高的去污效果．本实验的最佳运行条件为：平均ＵＶ光照强度２６９３Ｗ／ｍ２的晴天，ＴｉＯ２催化剂投加量１ｇ／Ｌ，系统循环流量１６００Ｌ／ｈ，初始浓度为２０ｍｇ／Ｌ的甲基橙溶液１５Ｌ，光照１ｈ色度去除率达８３６％以上，光照２ｈ达９７９％．     

CTAC改性膨润土吸附去除水体中高氯酸盐的离子交换性能研究

选用阳离子表面活性剂十六烷基三甲基氯化铵(CTAC)改性膨润土以提高膨润土对ClO4-的吸附能力.试验结果表明,CTAC改性能显著提高膨润土对ClO4-的吸附能力,在0.1～l mmol·L-1的C1O4-溶液中,6h内能迅速达到吸附平衡.有机膨润土对ClO4-的吸附最符合Langmuir等温吸附模型,其吸附容量可达0.48 mmol·g-1.pH值在4～10范围内变化对ClO-的吸附几乎没有影响.高的分配系数(Kd＞1.5×103cm3·g-1)表明有机膨润土对ClO4-有很高的选择性,各阴离子的分配系数从小到大的顺序为HPO42-＜ SO42-＜ NO3-＜ ClO4-,这与阴离子的自由水合能大小相一致.1 mol·L-1 HCl溶液对吸附剂的再生效率在96％左右,可直接使用,不用再改性.     

不同煅烧温度制备TiO_2及光解2-氯苯甲酸

为了考察煅烧温度对TiO2结构和光催化活性的影响,以酞酸丁酯作为前驱体,利用溶胶-凝胶法在不同煅烧温度下制备TiO2,并用亚甲基蓝测试其光催化活性。TG热重分析表明,450~700℃时TiO2有晶型变化,XRD表征说明,TiO2晶型受煅烧温度影响显著,其中450~600℃煅烧制备的TiO2为锐钛矿型,650℃煅烧时TiO2出现金红石晶型;亚甲基蓝光解实验结果表明,煅烧温度显著影响TiO2的光催化活性,其中,450~600℃煅烧TiO2对亚甲基蓝光解效果较好,光降解2.5h后降解率高达95%~97%;550℃煅烧制备的锐钛矿型TiO2对2-氯苯甲酸有一定光解催化效果,紫外光解4h后降解率高达80%左右,光解过程符合零级动力学模式。