室内空气中三氯乙烯在TiO_2/AC上的光催化氧化反应动力学

采用具有多层结构的蜂窝状整体式光催化净化块为催化材料 ,设计了室内空气净化光催化反应器 ,以三氯乙烯 (TCE)为模拟污染物 ,在 2 5℃、常压下 ,进行水、TCE的吸附等温线的测试和 TCE的光催化降解反应动力学研究。水与 TCE的平衡吸附采用 L angmuir吸附等温线表示 ;TCE在 Ti O2 表面的光催化反应采用简单的 L- H速率方程来表征 ;并进行了模型值与实验值的比较 ,结果令人满意     

气相甲苯光催化降解反应动力学及机理

以紫外光为光源,锐钛矿型TiO2为催化剂,研究了气相甲苯光催化降解过程,并探讨了降解机理. 结果表明,甲苯光催化降解过程符合一级反应动力学方程,甲苯初始浓度越高,反应速率常数越小. 甲苯光催化降解的主要中间产物为己烷和苯. 在紫外光和TiO2作用下,甲苯经脱甲基反应生成苯和甲基,甲基可与甲苯分解产生的3-戊烯炔生成2,4-己二烯,经加氢转化为己烷.     

Photodegradation of Methylene Blue in a Batch Fixed Bed Photoreactor Using Activated Carbon Fibers Supported TiO2 Photocatalyst

A batch fixed bed photoreactor, using felt-form activated carbon fibers (ACF) supported TiO2 photocatalyst (TiO2/ACF), was developed to carry out photocatalytic degradation of methylene blue (MB) solution. The effects of TiO2 particle size, loaded TiO2 amount, initial MB concentration, airflow rate and successive run on the decomposition rate were investigated. The results showed that photodegradation process followed a pseudo-first-order reaction kinetic law. The apparent first-order reaction constant kapp was larger than 0.047 min-1 with half reaction time t1/2 shorter than 15 min, which was comparable to reported data using suspended Degussa P-25 TiO2 particles. The high degradation rate was mainly attributed to adsorption of MB molecules onto the surface of TiO2/ACF. The photocatalytic efficiency still remained nearly 90% after 12 successive runs, showing that successive usage of the designed photoreactor was possible. The synergic enhancement effect in combination of adsorption with ACF and photodegradation with TiO2 was proved by comparing MB removal rates in the successive degradation and adsorption runs, respectively.     

Liquid-phase photocatalytic degradation over tio2 particles suspending in gas-liquid dispersion

The photocatalytic degradation over TiO2 particles suspending in the gas-liquid dispersion was modeled by taking the decay of the illumination intensity in the gas-liquid-solid fluidized bed in terms of Lambert-Beer law into consideration. For the sake of experimental verification of the proposed model, the oxidative degradation of an acid dye (C.I. Acid Blue 40) as a model compound, was carried out using a coaxial double cylinder-type reactor (internal cylinder part: quartz glass cylinder installing black light type fluorescent tube as UV light source; annular part: gas-liquid-solid fluidized bed) newly manufactured here. The reactor is operated continuously with respect to the gas phase and batchwise with respect to the solid phase, whereas the liquid phase is recirculated. The degradation rate could be expressed apparently as first-order in the concentration of acid dye. The observed relationship between apparent degradation rate constant and solid (TiO2) loading could satisfactorily be interpreted in terms of the proposed model.     

LIQUID-PHASE PHOTOCATALYTIC DEGRADATION OVER TiO2 PARTICLES SUSPENDING IN GAS-LIQUID DISPERSION

The photocatalytic degradation over TiO2 particles suspending in the gas-liquid dispersion was modeled by taking the decay of the illumination intensity in the gas-liquid-solid fluidized bed in terms of Lambert-Beer law into consideration. For the sake of experimental verification of the proposed model, the oxidative degradation of an acid dye (C.I. Acid Blue 40) as a model compound, was carried out using a coaxial double cylinder-type reactor (internal cylinder part: quartz glass cylinder installing black light type fluorescent tube as UV light source; annular part: gas-liquid-solid fluidized bed) newly manufactured here. The reactor is operated continuously with respect to the gas phase and batchwise with respect to the solid phase, whereas the liquid phase is recirculated. The degradation rate could be expressed apparently as first-order in the concentration of acid dye. The observed relationship between apparent degradation rate constant and solid (TiO2) loading could satisfactorily be interpreted in terms of the proposed model.     

粘土、活性炭、二氧化钛复合陶瓷球对染料废水的降解

将具有高吸附特性的活性炭和易加工成型的粘土作为TiO2光催化剂的载体，分别制成粘土／AC、粘土／TiO2、粘土／TiO2／AC复合陶瓷球，研究对酸性湖蓝A染料废水的净化效果。试验结果表明，粘土／TiO2复合陶瓷球的光催化降解率较低，而粘土／AC复合陶瓷球在多次利用后降解效率下降较大；但粘土／TiO2／AC复合陶瓷球吸附光催化降解后使染料废水变得无色透明，重复利用50次仍可使染料降解率达95％以上，并且可解决只以活性炭作为吸附剂饱和后黏度极大、难清理的问题。     

Fe3+/TiO2光催化剂降解孔雀绿染料的研究

采用快速溶胶法制备纳米TiO2光催化剂,用Fe^3 对其掺杂改性,并进行了催化剂的X-射线衍射分析(XPd3),傅立叶红外光谱分析(FT-IR),BET比表面积的表征,用于光催化降解水中孔雀绿染料的研究．研究了不同催化剂的光催化活性,确定了光催化剂的用量．结果发现60W紫外光辐射80min,孔雀绿可以彻底降解;可见光下,光催化剂对孔雀绿降解120h,其转化率为98%,COD的去除率为75．3%。可见光下孔雀绿的脱色率和COD的变化不一致,并对其产生的原因和孔雀绿的光催化降解机理作了探讨。孔雀绿的光催化降解符合一级动力学反应规律,反应速率常数随催化剂的用量增加而增大,但增大幅度逐渐减小。     

Influence of activated carbon upon titania on aqueous photocatalytic consecutive runs of phenol photodegradation

The photocatalytic degradation of phenol was performed at room temperature in aqueous suspended mixtures of TiO₂ and activated carbon (AC). The main objective of the present work was to verify the potential of TiO₂/AC system in the photocatalytic degradation of phenol and the principal intermediate products after performing three consecutive runs. The phenol disappearance follows a first-order kinetics. Therefore, the apparent first-order rate constant of phenol and total organic carbon photodegradations were selected to evaluate the photoefficiency of the system. From the present results it can be concluded that there is a synergistic effect between both solids which is determined by the numbers of photocatalytic runs. From a practical point of view, TiO₂/AC is able to photomineralize phenol and total organic carbon for three and two, respectively, consecutive runs more efficiently than TiO₂ alone.     

以十二烷基苯磺酸钠为模型反应物的Y2O3／TiO2复合催化剂的制备及光降解催化性能

采用浸渍法制备了Y2O3/TiO2复合氧化物催化剂，并用紫外可见光谱、SEM、BET等手段对其进行了表征，以水相十二烷苯苯磺酸钠（DBS）溶液的光催化降解反应为实验模型，考察了TiO2掺杂Y2O3后的光催化氧化活性，并探讨了Y2O3掺杂量、吸附性、焙烧温度及时间对Y2O3/TiO2复合氧化物催化剂光催化活性的影响，实验结果表明：复合氧化物催化剂Y2O3/TiO2存在某一最佳组分比值，当两者重量比为1：200时，其催化活性是同样条件下前体催化剂TiO2的2.4倍。     

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。     

Au掺杂水热均匀沉淀高温制备TiO_2的光催化性能

向水热均匀沉淀、800℃焙烧制得的高活性、易分离TiO2(TiO2-800)中掺杂金(Au),以光催化降解活性艳红染料X-3B作为模型反应,考察了掺Au量、制备条件、Au的价态等对Au/TiO2-800光催化性能的影响。结果表明,氨水作为沉淀剂,200℃焙烧的0.5%Au/TiO2-800的光催活性较TiO2-800有较大提高,染料X-3B的降解率由93%提高到了100%。还原实验显示,0.5%Au/TiO2-800表面存在的离子态Au能有效提高TiO2-800光催化活性。     

LDO负载纳米二氧化钛复合物的制备及其光催化性能研究

以碳酸根型镁铝层状双氢氧化物(LDH)为载体,采用溶胶-凝胶法利用酞酸丁酯水解负载纳米TiO2于LDH片层获得TiO2/LDH前驱体,通过低温焙烧前驱体获得纳米二氧化钛/层状双金属氧化物复合物(TiO2/LDO).以亚甲基蓝溶液模拟染料污染物,在波长291 nm紫外光条件下测定吸光度,评价了光催化剂不同投加量,体系pH值以及光照时间条件下对亚甲基蓝降解率的影响,研究了TiO2/LDO的光催化性能.结果表明:通过溶胶-凝胶法可以获得高分散纳米级(<10 nm)TiO2负载型TiO2/LDH复合物,TiO2/LDH中TiO2负载率达8.01wt%(质量分数);TiO2/LDO的光催化性能较纯LDO高,TiO2负载于LDO层板对亚甲基蓝具有协同催化作用;在pH值为9的80 mL亚甲基蓝溶液(浓度为5 mg/L)中投入0.20 g TiO2/LDO,催化反应8 h后降解率高达81.7%,TiO2/LDO对亚甲基蓝溶液的光催化反应符合一级动力学方程.     

Au掺杂水热均匀沉淀高温制备TiO2的光催化性能

向水热均匀沉淀、800℃焙烧制得的高活性、易分离TiO2（TiO2-800）中掺杂金（Au）,以光催化降解活性艳红染料X-3B作为模型反应,考察了掺Au量、制备条件、Au的价态等对Au／TiO2-800光催化性能的影响。结果表明,氨水作为沉淀剂,200℃焙烧的0．5％Au／TiO2—800的光催活性较TiO2-800有较大提高,染料X-BB的降解率由93％提高到了100％。还原实验显示,0．5％Au／TiO2-800表面存在的离子态Au能有效提高TiO2-800光催化活性。     

Photocatalytic degradation of gaseous trichloroethene using immobilized ZnO/SnO2 coupled oxide in a flow‐through photocatalytic reactor

The photocatalytic degradation of gaseous trichloroethene (TCE) was investigated on immobilized ZnO/SnO₂ coupled oxide in a flow‐through photocatalytic reactor. It was found that gaseous photocatalysis is an efficient method for volatile organic compounds' abatement and air purification. Degradation of ～100% was found for TCE at the concentrations examined, up to 400 ppmv, in a flow‐through dry synthetic gas stream. In our tested conditions, the flow rate had little influence on the photocatalytic degradation efficiencies of TCE, while the relative humidity had a significant influence on the photocatalytic degradation of TCE. The photocatalytic degradation efficiencies of TCE increased slowly below 20% relative humidity and then decreased as the relative humidity increased further. The deactivation of used immobilized photocatalyst was not observed within the 200 h testing period in the present experiment, although the surface of the photocatalyst changed greatly during the use of the photocatalyst. Copyright © 2004 Society of Chemical Industry     

固定式填充复合床光催化反应器降解亚甲基蓝的研究

设计了一种固定式填充复合床光催化反应器,以普通玻璃片和玻璃螺旋圈为载体,用溶胶-凝胶法制备了负载型TiO2薄膜光催化剂。利用紫外光为光源,采用难降解物质亚甲基蓝在不同初始浓度、pH值和光强等因素下的光催化降解脱色反应速率考察了该反应器的工艺特性,试验结果表明:该种反应器的最佳操作条件为反应器中同时放置普通玻璃片TiO2薄膜光催化剂和玻璃螺旋圈TiO2薄膜光催化剂,溶液pH值为7.5,光源光强为650W,光照时间为180min。当进水亚甲基蓝的质量浓度为8.0mg/L时,在此条件下的降解脱色效率为93.83%,且其设计易于实现产业化。     

光催化降解壬基酚聚氧乙烯醚的研究

研究了以悬浮态TiO2为催化剂,在H2O2存在的条件下,对壬基酚聚氧乙烯醚的光催化降解反应。分别考察了pH值、TiO2和H2O2的加入量、壬基酚聚氧乙烯醚的初始浓度以及光照时间对降解反应的影响。结果表明:在pH值为5,H2O2质量浓度为30mg/L的条件下,对初始质量浓度为50mg/L的壬基酚聚氧乙烯醚溶液光照4h后降解率达46.32%。     

改性膨润土制备二氧化钛复合材料的光催化性能

以改性膨润土和四氯化钛为原料,采用水热法制备TiO2/膨润土柱撑复合材料,以甲基橙的光降解为研究重点,探讨了催化剂光降解过程,对催化反应机理进行了研究。结果显示,用各种改性膨润土合成的TiO2/膨润土柱撑复合材料层间距都有不同程度的增大;各TiO2/膨润土柱撑复合材料对甲基橙的光催化遵循一级动力学方程机理;催化剂经H2SO4和H2O2处理,可重复使用。     

负载纳米TiO_2薄膜光催化还原氮气合成氨的研究

对负载纳米TiO2薄膜光催化还原氮气合成氨进行验证,分别讨论了pH值、光照、初始浓度、不同载气和催化剂用量等因素对溶液中氨氮浓度变化的影响,并对实验结果作出初步解释。对自制的TiO2/Ti光电极绘制了Mott-Schotty曲线,初步研究了光电极的半导体性质,计算了其载流子浓度ND、平带电位Фfb及能带弯曲量VB。研究了当下利用TiO2光催化还原氮气合成氨方法的可行性,对TiO2光催化还原性的利用提出相应的意见及建议。     

镱镧共掺杂二氧化钛光催化降解染料废水

采用溶胶-凝胶法制备镱镧共掺杂光催化剂Yb-La/TiO2,在紫外灯照射下,对罗丹明B模拟染料废水进行光催化降解研究,优化了光催化的反应条件。结果表明,催化剂用量2 g/L,溶液pH值为6,光照时间2.5 h,染料废水的起始浓度为10 mg/L时,染料废水的降解率可达96.71%;在上述体系中加入0.2 g/L的双氧水,在pH值为3⁴时,光照时间2 h,染料废水的降解率可达97.02%,可提高光催化效率。     

微波辐射法研制复合半导体光催化材料TiO2/ZnO

采用微波辐射法制备了复合型半导体光催化材料TiO2/ZnO,利用X射线衍射(XRD)测试技术对TiO2/ZnO复合型半导体光催化材料进行了表征。用甲基红模拟有机废水,在高压汞灯模拟日光光照的条件下,研究了复合型半导体光催化材料TiO2/ZnO光催化降解有机废水的过程,并在相同的条件下,与机械研磨法制备的复合型半导体光催化材料TiO2/ZnO的光催化性能进行了对比实验。研究结果表明,微波辐射法制备的复合型半导体光催化材料TiO2/ZnO具有很好的光催化性能,TiO2/ZnO投加量为0.5g.L-1时,其具有良好的光催化脱色性能,经1h光照,对甲基红的光降解效率可以达到100%。随着溶液初始浓度增加,甲基红的降解率增大。