纳米TiO2光催化降解偶氮染料的研究

以刚果红为目标物,采用纳米TiO2为光催化剂.探讨了光降解偶氮染料的实验条件.结果表明,催化剂用量、溶液初始pH值、H2O2用量等因素对光催化降解效率具有显著影响,光催化降解刚果红的反应为一级动力学反应.     

纳米TiO2光催化降解酸性嫩黄动力学

采用纳米TiO2光催化降解酸性嫩黄.当进水浓度为20mg/L时,通过降解效率的比较得出反应的最佳条件为TiO2的投加量600mg/L,pH值为原水3.56,宜选择紫外光作为光源.实验还发现,酸性嫩黄的光催化降解动力学符合Langmiur-Hinshelwood动力学模型,并求得反应速率常数k=0.36mg/L·min,表观吸附平衡常数K=0.0169 L/mg.     

掺杂Yb的TiO2光催化剂的制备和性能

采用溶胶-凝胶法制备了Yb掺杂TiO2纳米光催化剂,并通过XRD和BET等手段进行了表征.以对苯二甲酸作为探针分子,结合化学荧光技术研究了光催化剂表面羟基自由基的生成;并以苯酚为光催化降解反应模型化合物,考察了光催化剂的活性.测定了苯酚在TiO2和Yb掺杂TiO2光催化剂上的吸附常数.结果表明：Yb掺杂使TiO2的粒径减小,比表面积增大,同时导致羟基自由基的生成速率增大.Yb掺杂有利于反应底物在催化剂表面的吸附,Yb的最佳掺入量为Yb/Ti摩尔比=0.8%.     

纳米二氧化钛光催化降解染料酸性红B的实验研究

利用溶胶-凝胶法自制TiO2光催化剂,采用悬浮体系,研究偶氮染料酸性红B的光催化降解过程,考察了活化温度、活化时间、溶液初始pH值、催化剂投加量、染料浓度等因素对光催化降解效率的影响。实验表明:自制的二氧化钛具有良好的光催化性。当催化剂用量为1.0g/L、pH值为3、酸性红B染料初始浓度20mg/L时,120分钟降解率可达85%,180分钟基本降解完全。     

纳米二氧化钛光催化降解染料废水动力学研究

以纳米二氧化钛为光催化剂,研究了光催化降解染料废水溶液的动力学规律及溶液的pH值、TiO2投加量和染料起始浓度对光催化降解活染料废水动力学的影响。结果表明,该反应符合Langmuir-Hinshelwood(L-H)动力学模型,且光催化过程符合一级反应动力学方程,一级反应动力学常数(K')随溶液pH值及染料起始浓度的降低而增大;TiO2的最佳投加量为2.0 g/L,低于或超过该值都会导致降解速率的下降。     

纳米TiO_2光催化降解DMF

研究了纳米TiO2(P25)光催化降解DMF水溶液,考察了初始浓度、溶液pH值、空气、H2O2、O3对DMF降解率的影响。结果表明:在低浓度范围内,光催化降解DMF遵循L-H方程,表观反应速率常数k=33.3mg/(L.m in),吸附速率常数K=1.84×10-4L/mg,并通过静态吸附实验验证了P25表面对DMF的弱吸附特性,进而得出吸附过程是DMF光催化降解的控制步骤。pH值对DMF降解率影响较大,当pH值由11.0降为4.0时,DMF降解率由51.5%升高到71.0%。空气和H2O2的加入能够加速DMF的光催化降解,O3体系可以显著增强P25对DMF光催化降解效应,其降解率和降解效率分别是空气体系的1.5和2倍左右。     

Nd2O3／TiO2光催化剂的光生羟基自由基和光活性

以硝酸钕和钛酸四正丁酯作为前驱体,采用溶胶-凝胶法制备了Nd2O3/TiO2纳米光催化剂,并通过XRD和BET等手段进行了表征.以对苯二甲酸作为探针分子,结合化学荧光技术研究了光催化剂表面羟基自由基的生成;并以甲基橙为光催化降解反应模型化合物,考察了光催化剂的活性.测定了甲基橙在TiO2和Nd2O3/TiO2(1.0%)光催化剂上的吸附常数.结果表明:Nd2O3掺杂使TiO2的粒径减小,比表面积增大;羟基自由基的生成速率越大,催化剂的催化活性越高.Nd2O3掺杂有利于反应底物在催化剂表面的吸附,Nd2O3的最佳掺入量为Nd/Ti(摩尔比)=1.0%.     

TiO2/SiO2/Fe3O4的光催化性能及动力学

采用溶胶－凝胶法在表面包覆了SiO2的磁基体Fe3O4上负载TiO2,制备了复合光催化剂TiO2/SiO2/Fe3O4。用AFM和XRD等对其进行了表征,并对其光催化降解溴氨酸的pH值、催化剂加入量、初始溶液浓度等条件进行了探讨。结果表明,当pH＝4.0、催化剂用量为2.0 g/L、初始溶液浓度为30 mg/L、光照时间为30 min时,溴氨酸脱色率可达96.2％,COD去除率为85.1％;动力学研究表明：在实验浓度范围内,溴氨酸的光催化降解反应符合一级动力学规律,反应速率常数（k）与初始溶液浓度（c0）的关系为lnk =－0.171lnc0－2.360;经过4次循环使用后,复合光催化剂仍能保持较高的光催化活性和较高的回收率。     

纳米TiO2光催化氧化愈创木酚的降解机理

以木质素的模型物愈创木酚(G-M)为研究对象,采用自制的纳米TiO2作光催化剂,在一定的降解条件下对G-M光催化降解的动力学和机理进行了研究.实验表明G-M的光催化降解过程包括吸附和降解两部分,通过对G-M在TiO2表面吸附性能的测定,得到其吸附平衡常数,在此基础上运用L-H方程对G-M光催化降解的动力学方程进行讨论,得到降解反应动力学方程1/r=1.744/C 0.103 4.采用有机物特征功能团的显色法,对G-M光催化降解反应过程的中间产物进行了分析,推断在G-M降解反应过程中出现了开环、脱羧,最终完全分解矿化生成二氧化碳和水.     

二氧化钛光催化氧化水中天然有机物富里酸

以p-25型纳米TiO2为催化剂对富里酸(fulvic acid,FA)进行了光催化氧化的试验研究。考察了光催化剂投加量,FA的初始浓度,pH值等因素对FA光催化去除效果的影响。结果表明:投加纳米TiO2作光催化剂后可使得FA的去除率由单使用紫外光照射的35%提高至92%~100%。本试验条件下,FA的光催化降解遵循一级反应动力学规律,光催化降解速率常数K值随着FA初始浓度的增大而减小,且分别在TiO2投加量为0.3 g/L和pH=7时有最大值,对处理后的水样进行三维荧光分析发现FA在光催化过程中没有转化成新的荧光物质。     

Enhanced adsorption of two azo dyes produced by carbon modification of TiO2

The process of removal of two azo dyes (Reactive Red 198 and Direct Green 99) from water was investigated. The adsorption of azo dyes onto surfaces of pristine TiO₂, P25 and carbon-modified TiO₂ (at 120 °C for 24 h) was presented. The Freundlich model of adsorption isotherm was found for pristine TiO₂ and TiO₂-P25. Modification of TiO₂ by carbon lead to the change from the Freundlich model to the Langmuir model of adsorption isotherm. For the TiO₂-C photocatalyst the adsorption capacity was determined, which was almost two times higher for Direct Green 99 than Reactive Red 198 dyes. As a result we observed the increase of photocatalytic activity of carbon-modified TiO₂ photocatalyst.     

Intrinsic photocatalytic oxidation of the dye adsorbed on TiO2 photocatalysts by diffuse reflectance infrared Fourier transform spectroscopy

Photocatalytic oxidation of aqueous pollutants by semiconductor photocatalysts was found efficient. The overall process by which the heterogeneous photocatalysis proceeds includes: the sequence of the adsorption of reactants, surface reaction and the desorption of final products. As a result, factors such as, the presence of oxygen concentration, pH values of the aqueous solution, pore properties for photocatalyst particles all determine the rate of photodegradation. This study is to concentrate on the photocatalytic mechanisms of the intrinsic reaction occurred on the photocatalysts and the adsorbed dye in air atmosphere. Additionally, the photocatalytic activities of adsorbed dyes prepared under different pH values were also examined and the solid-state results were compared with the aqueous systems at the same pH conditions. Dark adsorption experiments at different pH conditions showed that the saturation amount of dyes adsorbed on the catalysts differs significantly. However, the solid-state photodegradation rates of adsorbed dyes on TiO₂ at various pH values only showed slightly different, which is opposite to the results obtained from the aqueous systems. This evidence reveals that the external and internal mass transport processes are rate-controlling steps that restricted the photodegradation reaction of aqueous dyes at different pH conditions. Furthermore, this investigation supports a proposed direct photocatalytic mechanism for aqueous systems that the photocatalytic oxidation always begins with the adsorption process and the adsorbed dye will then be attacked by the excited hole–electron pairs and hydroxyl radicals from TiO₂ surface to produce final products.     

Ce4+的掺杂和染料结构对TiO2光催化性能的影响

采用浸渍法制备了掺杂Ce^4 的TiO2粉体光催化剂,考察了Ce^4 的含量对TiO2光催化性能的影响,并且研究了它对直接耐晒蓝和4,2-(吡啶偶氮)-间笨二酚钠两种染料的降解效果。结果表明,以TiO2干凝胶为母体,浸渍Ce^4 所制备的粉体光催化剂Ce^4 /TiO2降解效果分别比纯TiO2高45％和23％其对偶氮基团的分解效果明显高于对吡啶环和间苯二酚基的分解。X射线衍射分析表明,该法制备的TiO2粉体中锐钛矿相占90％以上,没有铈的氧化物形式,平均晶粒粒径为1nm;红外吸收光谱分析表明,Ce^4 ／TiO2和TiO2红外吸收光谱图相似,说明掺杂Ce^4 并没有极大地改变TiO2的化学结构。     

Removal of reactive dyes from wastewater using Fe(III) coagulant

The coagulation-flocculation process was employed for the treatment of reactive dye wastewaters, with ferric chloride hexahydrate employed as the coagulant. The process was found to be very effective with a more than 99.5% colour removal. Typical representatives of monochlorotriazine reactive dyes, with azo and anthraquinone chromophores, were CI Reactive Red 45 and CI Reactive Green 8, which were chosen as the model dyes. In order to determine the optimum pH range and coagulant concentration, a series of jar tests was done. Further experiments were conducted using a square flocculation tank with turbine impeller applying rapid and slow mix operations. The optimisation of initial rapid mixing, which has an important role in the overall coagulation process efficiency, was carried out. The optimum combination of velocity gradient and time of rapid mix was suggested for reactive dye wastewater treatment. Sedimentation curves for both model dyes were also obtained.     

钙镁离子对二氧化钛光催化氧化水中腐殖酸的影响

考察了间歇反应器中钙离子存在下腐殖酸分子在TiO2颗粒表面的吸附行为,进而以125 W (Emax=365 nm) 汞灯为中心光源,考察了钙镁离子对二氧化钛光催化氧化水中腐殖酸的影响. 结果表明,在腐殖酸初始浓度C0=20 mg/L, [Ca2+]=80 mg/L, pH=7和TiO2=1 mg/ml实验条件下,经2.5 h的光催化反应,腐殖酸的脱色率为100%,氧化分解率接近100%,矿化率大于95%.     

混合偶合法一步合成活性黑染料

将对位酯重氮化，与J酸—三聚氯氰缩合物(0．003mol)、H酸—对位酯偶氮化合物(0．009mol)在同一个反应体系中用混合偶合法同时合成了C．I．活性黑5和一只橙色活性染料，改变偶合组分比例和反应条件，可得到色光不同的黑色活性染料。控制合成过程中产生的杂色染料，可以控制染料产品的色光和应用性能。     

TiO2光催化氧化降解偶氮染料废水的研究

以偶氮染料直接耐酸大红4BS模拟废水为研究对象,以TiO2为光催化剂,紫外灯作光源（80W）,探究了不同TiO2催化剂的用量、光照时间、溶液初始pH值及废水初始质量浓度等因素对偶氮染料废水降解率的影响。实验结果表明,偶氮染料直接耐酸大红4BS废水的最佳处理条件为：TiO2催化剂质量浓度1．2g／L,光照时间120min,初始pH值10,废水初始质量浓度20mg／L。在最佳处理条件下,对某染料厂的实际工业废水样进行了降解率的测定,得出其降解率在90％以上。     

Evaluation of polystyrene anion exchange resin for removal of reactive dyes from aqueous solutions

The Amberlite IRA-900 resin was tested to remove C.I. Reactive Black 5, C.I. Reactive Red 2 and C.I. Reactive Red 120 dyes from solutions. Batch adsorption studies concerning effects of the phase contact time, pH, temperature, the presence of salts and surfactants were run. A pseudo second-order kinetic model was used to evaluate the rate constants. The Langmuir equation provided good fit for the experimental data of the equilibrium adsorption. The studies of dyes uptake using the dynamic method were run. The treatment efficiency of Amberlite IRA-900 to model wastewaters was tested. Desorption experiments by the batch method were performed.     

Carbon Modified TiO2 Photocatalyst with Enhanced Adsorptivity for Dyes from Water

A new photocatalyst was obtained by modification of commercial anatase TiO₂ (Police, Poland) in a pressure reactor in an ethanol atmosphere at 120 °C for 4 h. The photocatalytic activity of the new material was tested during three azo dyes decomposition: monoazo (Reactive Red 198), diazo (Reactive Black 5) and poliazodye (Direct Green 99). The obtained photocatalyst had new bands at 1,440 cm^?1 attributed to CO groups. UV–Vis/DR spectra of the photocatalyst also were changing and had an insignificant decrease in the visible region of the spectra. The amount of hydroxyl radicals produced on carbon-modified TiO₂ was a little higher than for the pristine one. The carbon modification also changes the Freundlich model of dyes adsorption to Langmuir model of adsorption. Additionally, it increases the monolayer capacity of modified TiO₂. As a result we observed a clear increase of the photocatalytic activity of carbon-modified TiO₂ sample.     

季铵型阳离子聚丙烯酰胺的无盐染色行为

以季铵型阳离子聚丙烯酰胺作为一种新的阳离子助剂对棉纤维进行处理,应用于活性染料无盐染色,对染色过程中染料与处理后棉纤维之间的吸附类型、吸附热力学及吸附动力学进行了研究。结果表明,无盐染色过程符合Langmuir吸附模型;吸附过程是放热自发进行的,低温有利于染料的吸附;吸附动力学符合二级动力学模型,属于化学吸附过程。与传统有盐染色结果相比,染色后的阳离子化棉纤维色深增加,染料利用率提高。