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.     

活性炭负载TiO2复合光催化剂的光催化活性研究

采用水热法将TiO2负载在不同活性炭上形成复合光催化剂,通过SEM和XRD对所得复合催化剂进行表征,并对亚甲基蓝(MB)进行光催化降解。结果表明:复合光催化剂具有很高的光催化降解率,其中椰壳活性炭载体优于煤质活性炭载体。负载的TiO2均为锐钛矿晶型,晶粒发育较完善、粒径小、分布均匀。TiO2负载量的提高未能改变光催化活性,反而降低了复合光催化剂的吸附能力。煅烧处理可以进一步提高光催化活性。     

炭表面改性对负载型TiO_2/活性炭复合光催化剂性能的影响

采用HNO3、H2O2和O3对商品活性炭进行表面改性处理,考察了改性处理对活性炭表面基团、负载TiO2以及所形成的TiO2/活性炭复合光催化剂性能的影响。利用傅里叶红外光谱(IR)、X射线光电子能谱(XPS)、扫描电镜(SEM)及氮气吸附等手段对材料进行了表征。结果表明,3种改性方法均可有效提高活性炭载体表面的含氧官能团数量,但是对活性炭的比表面积和孔容影响不大;H2O2和O3对活性炭载体改性后可以提高对钛前驱体的吸附性能,HNO3改性有利于TiO2颗粒在活性炭表面的分散。使用改性后的活性炭作为载体制备的TiO2/活性炭光催化降解甲基橙的性能均高于未改性的TiO2/活性炭催化剂,其中以HNO3改性后的TiO2/活性炭活性最高。     

高吸附性负载型TiO2光催化材料的制备与结构性能表征

采用分子吸附沉积工艺制备了活性炭纤维基TiO2光催化材料,利用SEM、XRD、BET比表面及紫外可见吸收光谱(Uv-vis)表征了该材料的结构与形貌、TiO2的晶体结构、比表面积及紫外吸收性能.实验表明活性炭纤维丝上已大规模地负载了厚约100nm的TiO2颗粒膜,沉积的TiO2颗粒尺寸小于100nm,纤维丝间保留的空间可使紫外辐射进入光催化剂内部,形成一个具有三维结构的光催化空间;800℃以下焙烧处理,均可获得唯一的锐钛矿相TiO2;负载TiO2颗粒膜后,光催化剂的比表面积可达321.4m2·g-1,具有很强的吸附能力.试验考察了制备的光催化材料对亚甲基蓝的光催化降解过程,显示了较高的光催化活性,连续试验中展示了很好的稳定性.     

TiO_2/AC复合光催化剂制备及性能研究

以TiCl4乙醇溶液为前驱物、煤质活性炭为载体,通过溶胶-凝胶法制备活性炭(AC)/TiO2复合光催化剂。利用扫描电子显微镜(SEM)、X-射线衍射仪(XRD)和BET比表面积孔径测定仪等对制备的样品进行表征。以光催化降解甲基橙溶液为模型反应,表征其光催化活性,考察了TiCl4/乙醇体积比、煅烧温度和煅烧时间等制备条件对光催化活性的影响。结果表明:在TiCl4/乙醇体积比为1∶20,500℃煅烧2h时,光催化降解甲基橙的活性最高,降解率达到95%;TiCl4/乙醇体积比和煅烧温度对光催化活性影响较大,煅烧时间对光催化活性影响甚小。含少量金红石相的TiO2有利于光催化降解甲基橙。     

活性炭负载N掺杂可见光型TiO2-xNy/AC光催化剂的制备及性能研究

将活性炭负载与N掺杂有效结合,采用酸催化水解法在粉状活性炭(AC)表面合成TiO2前驱体,在NH3/N2气氛中程序升温处理制得N掺杂TiC2-xNy/AC(TON/AC)光催化剂.以苯酚为模型物,考查了TON/AC紫外光区、可见光区及太阳光下催化活性以及分离性能、使用寿命.采用XPS、XRD、DRS、FTIR,SEM、低温氮物理吸附对光催化剂的表面特征,吸光特性、晶相结构等进行表征.结果表明,N以阴离子形式进入TiO2体相并置换晶格中的O,适量N掺杂的TON/AC在紫外光区、可见光区及太阳光下均表现出较高的活性.N掺杂在TiO2表面生成Ti-O-N键,形成新的能级结构,使催化剂的吸收红移至450～550nm,诱发TiO2可见光催化活性. AC负载可降低TiO2团聚体的尺寸,增加催化剂比表面积,为光催化降解提供高浓度环境,从而提高光催化效率同时还可改善催化剂分离性能,提高催化剂使用寿命.     

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.     

用超临界异丙醇流体制备TiO2/活性炭复合材料

在存在超临界异丙醇介质的条件下,将钛酸异丙酯与活性炭反应生成具有光催化与吸附性能协同效应的TiO2/活性炭复合材料.产生协同效应,可使低浓度污染物快速地表面富集和吸附净化,加快了污染物的光催化降解速率,TiO2的光催化作用又促使被活性炭吸附的污染物向TiO2表面迁移,使活性炭吸附能力得以恢复,实现了吸附剂的原位再生.     

活性炭负载纳米TiO2光催化降解气相丙酮

以钛酸四丁酯为前驱体,采用溶胶-凝胶法制得Fe、N离子共掺杂的以活性炭(AC)为载体的光催化剂(TiO2/AC),在紫外光照射下进行了气相丙酮的光催化降解研究。探讨了丙酮初始质量浓度、紫外光光强、催化剂用量、反应器内湿度等因素对其降解率的影响。结果表明,活性炭与TiO2的协同作用大大提高了对丙酮的降解效果;紫外光光强的增加对丙酮降解率有一定提高;使用3g光催化剂,丙酮的初始质量浓度为39.40mg/L;反应器内相对湿度为63%时,丙酮的降解效果最好,降解反应155min后丙酮的降解率达92.63%;催化剂循环使用6次后丙酮的降解率为83.91%。     

TiO_2/ACF复合光催化材料研究进展

将纳米TiO_2粉末负载于活性炭纤维(activated carbon fibers,ACF)上,可以解决纳米TiO_2颗粒的分离和再生等工业应用难题。通常,活性炭纤维负载TiO_2主要有两种途径;物理法(粉体烧结法、偶联法等)和化学法(溶胶-凝胶法、溶剂热、化学气相沉积法等)。综述了近年来TiO_2/ACF复合光催化材料的制备方法以及该类材料的研究进展,分析TiO_2/ACF复合光催化材料对污染物的降解过程,阐述TiO_2与活性炭纤维之间的协同作用机制,探索制备TiO_2/ACF复合光催化材料的最佳方法。     

TiO2/活性炭复合体超临界沉淀法制备及其光催化性能

以活性炭为载体、超临界二氧化碳为流体、钛酸丁酯为前驱体,用超临界流体沉积法制备TiO2/活性炭（TiO2/AC）复合体。用X射线衍射（XRD）、扫描电镜（SEM）、比表面积分析（BET）、热重-差热（TG-DTA）对TiO2/AC进行表征。以紫外灯为光源,偶氮类染料亚甲基蓝为标准降解物,考察TiO2/AC复合体的光催化...     

Synergy between surface adsorption and photocatalysis during degradation of humic acid on TiO2/activated carbon composites

A photocatalyst comprising nano-sized TiO(2) particles on granular activated carbon (GAC) was prepared by a sol-dipping-gel process. The TiO(2)/GAC composite was characterized by scanning electron microscopy (SEM), X-ray diffractiometry (XRD) and nitrogen sorptometry, and its photocatalytic activity was studied through the degradation of humic acid (HA) in a quartz glass reactor. The factors influencing photocatalysis were investigated and the GAC was found to be an ideal substrate for nano-sized TiO(2) immobilization. A 99.5% removal efficiency for HA from solution was achieved at an initial concentration of 15 mg/L in a period of 3h. It was found that degradation of HA on the TiO(2)/GAC composite was facilitated by the synergistic relationship between surface adsorption characteristics and photocatalytic potential. The fitting of experimental results with the Langmuir-Hinshelwood (L-H) model showed that the reaction rate constant and the adsorption constant values were 0.1124 mg/(L min) and 0.3402 L/mg. The latter is 1.7 times of the calculated value by fitting the adsorption equilibrium data into the Langmuir equation.     

TiO_2和活性炭纤维复合物光催化降解亚甲基蓝

以粘胶基活性炭纤维(VACF)为基体,钛酸丁酯为前驱体,通过溶胶-凝胶浸渍涂覆法将二氧化钛(TiO2)负载于粘胶基活性炭纤维上,制备活性炭纤维负载的TiO2光催化复合物,通过控制活性炭纤维在溶胶中的浸泡时间,制得不同TiO2负载量的复合物。采用扫描电子显微镜(SEM)表征了制备材料的形态结构,以质量浓度为20mg/L的亚甲基蓝溶液为目标降解物,测试了材料在紫外线光照下的催化性能。结果表明:紫外光直接照射对亚甲基蓝基本无降解作用,对活性炭纤维原样有一定作用;随着TiO2负载量的增加,复合物的吸附性能得到提高,对亚甲基蓝的降解作用也得到增强。     

Removal of dimethyl sulfide utilizing activated carbon fiber-supported photocatalyst in continuous-flow system

The present study investigated the adsorptional photocatalytic decomposition (APD) efficiency of activated carbon fiber-supported TiO(2) (ACF/TiO(2)) in a continuous-flow reactor for the removal of dimethyl sulfide (DMS). The SEM analysis identified that the ACF/TiO(2) exhibited the same tridimensional shape as uncovered ACF and that a TiO(2) photocatalyst could be embedded in the surface of the ACF. In the absence of UV light, the time-series removal efficiencies by ACF and the ACF/TiO(2) units exhibited a similar pattern, which decreased gradually as it reached close to zero. However, the APD efficiency determined via the ACF/TiO(2) with UV light remained at nearly 60% during the remaining courses of the 13-h period, after decreasing from a maximum APD of 80%. The APD efficiencies depended upon the weights of the TiO(2) embedded into the ACFs, the UV sources, the relative humidity, and DMS input concentrations. During a long-term (219-h) APD test, the APD efficiencies dropped from 80% to ca 60% within 1h after the initiation of the APD process and then fluctuated between 52% and 60%. No byproducts were measurable or observable in the effluent gas or on the ACF/TiO(2) surface. Consequently, the continuous-flow ACF/TiO(2) system could effectively be applied to control DMS without any significant functional deterioration.     

Magnetically separable composite photocatalyst with enhanced photocatalytic activity

A novel magnetically separable composite photocatalyst, anatase titania-coated magnetic activated carbon (TMAC), was prepared in this article. In the synthesis, magnetic activated carbon (MAC) was firstly obtained by adsorbing magnetic Fe₃O₄ nanoparticles onto the activated carbon (AC), and then the obtained MAC was directly coated by anatase titania nanoparticles prepared at low temperature (i.e. 75 °C). The prepared samples were characterized by XRD, SEM and vibrating sample magnetometer (VSM). The composite photocatalyst can be easily separated from solution by a magnet, its photocatalytic activity in degradation of phenol in aqueous solution also has dramatic enhancement compared to that of the neat titania.     

TiO2在微孔型活性炭纤维上的固载及其对苯酚的光催化降解

以环氧树脂作为TiO2与活性炭纤维(ACF)之间联结的前驱体，使TiO2粘附于纤维表面。后经氮气氛下400℃-580℃不同温度的煅烧处理，制得TiO2／ACF复合体。采用BET，SEM，XRD及UV—Vis光谱等手段对复合体的物理化学特性进行了表征。以水中苯酚为目标污染物考察了TiO2／ACF样品的光催化性能、结果表明，460℃煅烧品较其他样品对苯酚具有更好的去除能力。在其重复利用过程中，始终保持了高的光催化效率，直至第三次循环，其最终对苯酚的去除量仍与P25粉体相当。而且，牢固负载的TiO2更具实用性，易于从水中回收。     

Br-N共掺杂TiO_2/磁性炭复合材料的制备及其可见光催化性能

以活性炭(AC)为原材料,采用铁盐化学沉淀法耦合壳聚糖-戊二醛交联改性技术制备磁性活性炭(MAC)。以MAC为载体,采用溶胶-凝胶法制备不同Br/Ti掺杂比的Br-N共掺杂TiO_2/MAC可见光催化复合材料(Brx-N-TiO_2/MAC)。通过XRD、UV-Vis漫反射、BET吸附实验、SEM、XPS表征其结构和化学特征。以水杨酸为模型分子进行光催化降解,评价不同Brx-N-TiO_2/MAC材料的可见光催化活性。实验结果表明,相较于N-TiO_2/MAC可见光催化剂,Br-N共掺杂更能促进催化剂对可见光的吸收。Br_(0.35)-N-TiO_2/MAC对水杨酸的降解效果最好,暗吸附1h、光催化3h后,Br_(0.35)-N-TiO_2/MAC对水杨酸的降解率达到83%,高浓度水杨酸会对光催化反应产生一定的抑制作用,该催化材料重复利用三次后仍有78%的去除率,显示了较好的稳定性。