纳米二氧化钛光催化活性影响因素的研究

以苯酚为模拟污染物,考察了不同晶型、溶液初始pH值、反应物初始浓度、氧气的协同作用对TiO2悬浮体系光催化活性的影响;并将TiO2负载到活性炭纤维上,制备了固定体系的TiO2/ACF复合催化剂.结果表明,具有混晶结构的P25降解速率比纯锐钛矿TiO2快;溶液pH=6及苯酚初始浓度为150 mg/L时,降解速度最快;通入氧气,可以提高催化剂活性;光催化降解苯酚表明,TiO2/ACF复合催化剂具有较好的光催化活性.     

B、N和Ce共掺杂TiO_2光催化降解染料废水研究

采用B、N和Ce共掺杂TiO_2降解酸性蓝BRL、活性金黄K-2RA、弱酸性黑RB和酸性大红GR 4种染料废水,考察了催化剂用量、染料初始浓度、光照时间和pH值等对其降解率的影响。结果表明:B、N和Ce共掺杂TiO_2除了能使染料快速褪色外,还能将其完全矿化为CO_2,SO_4~(2-)和NH~+_4等离子。酸性大红GR染料和酸性蓝BRL在pH=5、催化剂用量50mg、初始浓度50mg/L、光照180min时降解率分别为98%和94.2%。pH=1、催化剂用量50mg、初始浓度40mg/L、光照时间180min时,活性金黄K-2RA的降解率达94.5%。弱酸性黑RB在pH=2、催化剂用量60mg、初始浓度20mg/L、光照时间210min时,降解率达到最大,为92.6%。     

硫掺杂二氧化钛负载硅藻土复合光催化剂光降解苯酚的研究

以硅藻土为载体,采用溶胶-凝胶-低温烧结法制备了硫掺杂二氧化钛负载型微孔-介孔结构复合光催化剂.物相分析表明TiO2-xSx样品为纯的锐钛矿相,TiO2包覆在硅藻土载体表面形成了复合结构.紫外-可见漫反射谱图显示S掺杂后的TiO2-xSx(350℃)样品吸收带边发生了明显的红移,负载型复合光催化剂显示出比TiO2-xSx样品更强的可见光吸收性能.当复合光催化剂中硅藻土的负载量为30%(质量分数)、硫的掺杂量为0.03%(摩尔分数)时,以氙灯为辐照光源,光催化苯酚溶液的降解率最高.在pH=5.83、催化剂用量为2g/L、初始质量浓度为10mg/L的条件下,苯酚在光照2h后降解率达到85%.催化剂重复使用4次后,苯酚的降解率仍在80%以上.     

Eu~(3+)掺杂纳米TiO_2的制备及催化降解亚甲基蓝的研究

采用溶胶-凝胶法制备了Eu3+掺杂的纳米TiO2粉体,采用X射线衍射(XRD)和荧光光谱分析(PL)等手段对TiO2的相结构和TiO2中电子-空穴对的复合性能进行了表征,探讨了掺杂组分对光催化活性的影响机制。以紫外光下降解亚甲基蓝为探针反应,考察铕的掺杂对催化剂催化性能的影响。结果表明Eu3+的掺杂能够通过抑制催化剂晶粒长大从而减少团聚,并且通过降低光生电子-空穴的复合几率,提高催化剂的光催化活性。光催化实验表明,催化剂加入量为3g/L,亚甲基蓝溶液初始浓度为20mg/L时,掺杂1%Eu3+的催化剂催化性能最佳,反应3.5h降解率达到85.5%。     

大颗粒纳米晶TiO2的制备与降解硝基苯的研究

采用溶胶-凝胶法制备了大颗粒TiO2为光催化剂,并通过XRD、SEM、BET等方法对制备的催化剂结构进行了表征,研究了硝基苯溶液光催化降解的影响因素,并根据降解机理讨论了降解过程中的中间产物.结果表明:大颗粒TiO2催化剂有比较高的活性,同时硝基苯初始浓度、降解环境、溶液pH值方面对降解过程有影响.     

太阳光下Cr~(3+)掺杂TiO_2复合微粒光催化性能研究

利用酸催化的溶胶一凝胶法成功地合成了一系列不同CP3+掺杂量(x=0.01%～10%)的TiO2复合光催化剂(Cd3+/TiO2).在太阳光条件下,以亚甲基蓝溶液的光催化降解对复合材料的光催化性能进行了表征,并考察了催化剂投加量、Cr3+掺杂量和溶液pH值等因素对光催化降解反应的影响.结果表明,亚甲基蓝溶液在复合微粒上的光催化降解反应遵循Langmuir-Hinshelwood动力学模型,在催化剂投加量为lg/L、Cr3+掺入量为0.3%和pH=7时,Cr3+/TiO2复合微粒光催化活性达最佳,测得表观反应速率常数 K为7.27×10-3 rag(L·min)-1,t1/2为95min,反应4h后亚甲基蓝的降解率可达79%,与纯的TiO2相比较,反应速率提高了2倍,降解率提高了20%.中性或碱性条件下有利于亚甲基蓝溶液的光催化降解.     

Sm3+和Gd3+共掺杂TiO2粉体的制备和性能表征

采用溶胶-凝胶法制备了纯TiO2,1%Sm3+或2%Gd3+单掺杂和1%Sm3+/2%Gd3+共掺杂TiO2复合粉体,采用XRD和SEM/EDAX等技术进行表征。以对亚甲基蓝的光催化降解为目标反应,评价了TiO2复合粉体的光催化活性,探讨了Sm3+/Gd3+共掺杂、亚甲基蓝初始浓度和粉体投加量对TiO2粉体光催化活性的影响机制。结果表明,Sm3+/Gd3+共掺杂可以显著提高TiO2粉体的光催化活性;Sm3+/Gd3+共掺杂在TiO2粉体中产生协同作用,抑制了TiO2由锐钛矿相向金红石相转变,使TiO2粒径尺寸减小,增大了TiO2的晶格畸变。当亚甲基蓝初始浓度为4mg/L和粉体投加量为2g/L时,TiO2复合粉体的光催化活性最高,对亚甲基蓝光催化降解率达99.71%;降解亚甲基蓝反应符合Langmuir-Hinshelwood动力学方程。     

ZnS在TiO2纳米管上的分散对其光催化降解染料废水的影响

水热法制备了TiO2纳米管,并采用简单加热回流的方法制备了ZnS/TiO2纳米复合材料。采用TEM、XRD分析手段对产物进行表征,并对其光催化降解酸性玫瑰红B(AR)染料废水进行了研究。考察了反应物供给速率、硫化锌复合量、催化剂稳定性、光照对光催化降解效果的影响。研究表明控制反应物供给速率和硫化锌的负载量可使硫化锌在二氧化钛纳米管表面均匀分散。当染料废水初始浓度为10mg/L,ZnS:TiO2=8:1时,ZnS/TiO2复合材料光催化活性最高。且催化剂稳定性较好。     

TiO_2柱撑蒙脱土的制备及其光催化性能的研究

采用TiCl4在 HCl中的水解制备TiO2柱撑蒙脱土(TiO2-PILM)纳米光催化材料,通过X射线衍射和红外光谱对其进行了表征.考察了甲基橙的初始浓度、甲基橙溶液、pH值对光催化降解效果的影响.结果表明,TiO2-PILM具有大的晶面间距,TiO2-PILM 对甲基橙有较好的光催化活性,吸附动力学数据很好地符合Lagergren二级速率方程,在甲基橙初始浓度为10mg/L、投样量为0.02g、在酸性或碱性条件时,TiO2-PILM对甲基橙的降解率较高.     

T-ZnOw光催化降解甲基橙的动力学研究

研究了四针状氧化锌晶须在紫外光照射条件下对甲基橙的降解活性,考查了甲基橙溶液初始浓度、催化剂浓度及种类等对光催化降解的影响,并初步探讨了其反应动力学.实验结果显示,四针状氧化锌晶须光催化降解反应基本符合一级动力学规律,光催化效果随着甲基橙初始溶液浓度的增加而降低,最佳浓度为2g/L,是一种降解效果优异的光催化材料.     

失活钒钛基SCR催化剂性能表征及其再生

主要研究了钒钛基脱硝催化剂失活机理及再生。采用SEM、EDS、XRD、BET等手段对国内某家燃煤火电厂运行20000h的SCR脱硝催化剂进行表征,然后使用0.5mol/L的硫酸和0.01mol/L的氢氟酸对运行过的催化剂进行了清洗再生并通过烟气模拟-催化剂活性测试系统考察了催化剂的脱硝活性。结果表明,相比于新鲜催化剂,运行后的催化剂活性明显下降,孔容和比表面积有所下降,其表面存在着组成复杂的飞灰,飞灰主要成分为SiO2;采用0.01mol/L氢氟酸溶液清洗能够明显恢复催化剂的脱硝活性,这是因为氢氟酸可以有效清除失活催化剂表面的SiO2。     

Study on photocatalytic degradation of several volatile organic compounds

The gas-phase photolytic and photocatalytic reactions of several aromatics and chlorohydrocarbons were investigated. The experimental results revealed that chlorohydrocarbons like trichloroethylene, dichloromethane and chloroform could be degraded through either photolysis or photocatalysis under irradiation of germicidal lamp, and the elimination rate of chlorohydrocarbons through photolysis was quicker than that through photocatalysis. UV light from a germicidal lamp could directly lead to degradation of toluene but could hardly act on benzene. The photodegradation rate for these volatile organic compounds (VOCs) through photolysis followed an order: trichloroethylene>chloroform>dichloromethane>toluene>benzene>carbon tetrachloride, and through photocatalysis followed: trichloroethylene>chloroform>toluene>dichloromethane>benzene>carbon tetrachloride. Besides, a series of modified TiO2 photocatalysts were prepared by depositing noble metal, doping with transition metal ion, recombining with metal oxides and modifying with super strong acid. Activity of these catalysts was examined upon photocatalytic degradation of benzene as a typical compound that was hard to be degraded. It indicated that these modification methods could promote the activity of TiO2 catalyst to different extent. The apparent zero-order reaction rate constant for degrading benzene over SnO2/TiO2 catalyst had the highest value, which was nearly three times as that over P25 TiO2. But it simultaneously had the lowest rate for mineralizing the objective compound. In spite that Fe3+/TiO2 catalyst behaved slightly less active than SnO2/TiO2 for degradation of benzene, the mineralization rate over Fe3+/TiO2 was the highest one among the prepared catalysts.     

催化剂MnCe（y）Ox/TiO2的制备及其催化燃烧甲苯的活性

以TiO2为载体,采用浸渍法制备了不同配比的MnCe复合型催化剂,并采用X射线衍射(XRD)、氧气的程序升温脱附(O2-TPD)和氢气的程序升温还原(H2-TPR)对制备的催化剂进行表征,比较了催化剂催化氧化(燃烧)甲苯的活性。研究结果表明,所制备的催化剂MnCe(y)Ox/TiO2对甲苯有明显的催化活性。当Ce/(Mn+Ce)的摩尔比为0.1时,催化剂MnCe(0.1)Ox/TiO2的催化活性最高,甲苯的转化率达到90%时的温度为254℃。在催化剂MnOx/TiO2中掺杂少量的Ce元素,有利于活性组分Mn物种在载体表面上以更小颗粒而且更高的分散度存在,从而提高催化剂的催化活性。     

Effectiveness of UV-based advanced oxidation processes for the remediation of hydrocarbon pollution in the groundwater: a laboratory investigation

The effectiveness of advanced oxidation processes in a batch and a flow reactor was investigated for the remediation of hydrocarbon pollution in the groundwater underlying a petrochemical industrial site. The main organic contaminants present in the groundwater were MTBE, benzene, alkyl-benzenes and alkyl-naphthalenes. Experimental results with a batch reactor showed that for all the organic contaminants the removal efficiency order is UV/TiO2 approximately UV/H2O2>UV (medium-pressure) in a synthetic aqueous solution, compared to UV/H2O2>UV (medium-pressure)>UV/TiO2 for the real polluted groundwater. The much lower performance of UV/TiO2 with respect to UV/H2O2 was inferred to the matrix of the groundwater, i.e. the salt content, as well as the organic and particulate matter. In fact, it is likely that the salts and dissolved organic matter quench the superoxide anion O2(-) and hydroxyl radicals just formed at the surface of the TiO2 catalyst. MTBE was the hardest compound to remove with each of the investigated treatments. UV and UV/TiO2 treatments were not able to reach a residual concentration of 10 microg/L (set by Italian legislation) even after 180 min. As for the UV/H2O2 process, only the MTBE degradation rate resulted affected by the initial H2O2 concentration, while for other compounds a complete removal was obtained within 20 min even with the lowest H2O2 concentration used (0.13 g/L). Only after 120 min of treatment, with an initial H2O2 concentration of 0.13 g/L, did the residual MTBE concentration fall below the above reported maximum admissible concentration. Instead, by using an initial concentration of 2g/L a residual concentration lower than 5 microg/L was obtained after just 30 min of reaction. The UV/H2O2 process was also investigated with a flow reactor. Results showed that it was more efficient than the batch reactor for removing MTBE, in terms of reaction time and initial H2O2 concentration required. This is consistent with the higher power of the UV lamp and with the different geometry of the flow reactor, which has a much shorter optical path than the batch reactor. By-product characterisation was also performed showing that t-butyl-formate and low molecular weight organic acids are formed as intermediate and final by-products, respectively. Finally, a preliminary evaluation of the operational cost of the UV/H2O2 process showed a value of 1.7 euro/m3 under the optimised condition.     

TiO2／海泡石催化剂的光催化降解性能

以钛酸四丁酯为前驱体,采用水解．沉淀法制备纳米TiO2,再将其负载于海泡石上制得TiO2/海泡石催化剂,用X射线衍射和扫描电子显微镜对载体催化剂的形貌及晶型进行了分析．以紫外光为光源,在水溶液中以环境激素邻苯二甲酸二乙酯（DEP）为降解底物进行光催化性能的研究．结果表明：催化剂的用量和TiO2的负载量对光催化降解速率都有影响．其中TiO2/海泡石催化剂的用量起主要作用,更能影响其光催化速度及DEP的降解．当催化剂用量为4g/L、TiO2负载量为30％时,TiO2/海泡石催化剂的催化效果较好．     

稀土元素镧与铈对VOx／TiO2催化降解氯苯性能的影响

采用等体积浸渍法分别制备了不同稀土元素@阑或铈）添加量的VOx／TiO催化剂,通过XRD、EDS和TPR对样品进行表征,考察了它们催化燃烧氯苯的活性,结果表明,不同镧或铈添加量的催化剂样品仍保持TiO2税钛矿晶相。当LaOx与VOx的摩尔比为1：5时,会出现镧钒氧物种或镧钛氧物种的晶相;当CeOx与VOx的摩尔比为1．5时,会出现CeOx方铈矿萤石结构的晶相;镧和铈的添加会提高活性物种VOx在催化剂表面的含量和分数}生。当CeOx与VOx的摩尔比为1：13．7时,活性组分VOx绝大部分分布在载体表面;镧对于催化剂的氧化性能没有影响,而铈能提高催化剂的氧化性;适量镧或铈的添加对于VO／TiO2催化剂催化降解氯苯有促进作用。锏的添加对于催化剂催化活性的促进作用与催化剂表面活性物VOx含量有关,而铈的添加对催化剂催化活性的提高作用除此原因外,还与催化剂氧化洼的提高有关。     

Fe-F/TiO_2复合微球的制备与光降解部分水解聚丙烯酰胺机制

以Span-80为调控剂,钛酸四丁酯(TBOT)为钛源,采用低温水解-回流法制备了Fe-F共掺杂TiO_2介孔复合微球(Fe-F/TiO_2)。通过XRD、SEM、FTIR、TG-DTA、BJH和UV-vis DRS测试方法对样品进行了结构性能表征;以部分水解聚丙烯酰胺(HPAM)为目标降解物,研究了Fe-F/TiO_2复合催化剂的光催化性能。结果表明,制得的Fe-F/TiO_2是由直径为10~15nm的纳米粒子堆砌而成的锐钛矿型介孔微球,其中Fe3+可以有效促进锐钛矿而抑制金红石相的生成,使其具有较高的热稳定性;比表面积、孔容积及平均孔径分别是145.11 m2/g、0.26cm3/g和6.23nm。在光降解HPAM的过程中,Fe3+和F-的协同效应可以提升材料的光催化性能,使FeF/TiO_2具有最高的催化活性。在紫外光及可见光条件下,0.1g的Fe-F/TiO_2降解100mL浓度为500mg/L的HPAM溶液120min,其COD去除率分别为81%和74%。     

Studies on TiO(2)/ZnO photocatalysed degradation of lignin

The photocatalytic degradation of lignin obtained from wheat straw kraft digestion has been investigated by using TiO(2) and ZnO semiconductors. ZnO has been found to be a better photocatalyst than TiO(2). The different variables studied, include catalyst dose, solution pH, oxidant concentration and initial concentration of the substrate. The degradation of lignin was favorable at pH 11. Optimum values of catalyst dose and oxidant concentration were found to be 1g/l and 12.2 x 10(-6) M, respectively. The degradation of the organic compound was also evaluated as COD removal and increase in the COD removal was observed with increase in degradation rate. An attempt has also been made to explore the applicability of ZnO in immobilized mode for the degradation of lignin under solar light for industrial scale application. Further the comparative evaluation of ZnO in slurry/immobilized mode has been carried out.     

TiO2/ACF光催化再生复合材料的研究进展

总结近年来在TiO2与活性碳纤维复合光催化剂的合成方法、结构与性能,及对室内挥发性有机物光催化降解方面的研究,分析TiO2/ACF复合光催化剂对有机物吸附、富集、光催化、原位再生的过程,探讨活性碳纤维吸附材料对提高TiO2光催化剂量子产率的作用机制,认为低浓度污染物在催化剂表面的吸脱附速率提高是TiO2/ACF复合光催化剂具有较高降解能力的关健因素.