活性炭负载TiO2的制备及其光催化活性研究

采用溶胶-凝胶法制备TiO2/活性炭(AC)光催化剂,采用XRD分析了纳米TiO2晶型,SEM观察了活性炭负载前后表面形貌.正交试验分析了各因素对光催化降解甲基橙的影响.结果表明:制备的纳米TiO2为纯锐钛矿型,催化剂以不规则碎片包覆在活性炭表面.复合材料在TiO2浓度0.441 mol/L,50℃烘干后,pH=3的环境下降解甲基橙,脱色率达到95.5％.溶液pH值是催化降解的主要影响因素.     

Au/TiO2复合物的制备、表征及其增强光催化灭菌活性

为提升TiO₂光催化活性克服其可见光响应能力差的问题,采用沉积-沉淀法制备了Au/TiO₂复合物光催化剂,利用X射线衍射（XRD）、傅里叶红外光谱（FTIR）、X射线光电子能谱（XPS）、紫外-可见漫反射光谱（UV-vis DRS）、荧光发射光谱等对样品进行了表征。XRD、FTIR和XPS结果表明,Au/TiO₂中TiO₂为锐钛矿相且Au成功沉积至TiO₂。UV-vis DRS和荧光发射光谱结果表明,适量Au修饰不仅能提高TiO₂对可见光的吸收,还可促进TiO₂光生电子-空穴对分离,有利于增强其光催化活性。自由基捕获实验证实,形成?OH的数量与光照时间成正比且?OH生成量越多,光催化活性越高。对比考察了Au/TiO₂和TiO₂在氙灯光源照射下对大肠杆菌的光催化杀灭作用,并探讨了Au负载量、光照时间、光照强度、光催化剂浓度等因素对灭菌性能的影响。结果表明：Au/TiO₂的光催化灭菌活性优于TiO₂,且与光照时间和光照强度均成正比;Au的适宜负载量为3%（质量分数）;3%Au/TiO₂在光照时间60min、光照强度7mW/cm²、光催化剂浓度100μg/mL的条件下,对大肠杆菌的杀灭效率高达91.3%。     

二氧化钛-活性炭复合光催化材料的制备及表征

以二氧化钛纳米粉和环氧树脂为原料,制备了具有光催化活性的二氧化钛-活性炭复合材料.用热分析(TG-DSC)、X射线衍射(XRD)等手段对其表征,发现复合材料中的二氧化钛以锐钛矿晶型存在.通过扫描电镜(SEM)对复合材料进行分析,表明其颗粒直径约为100 nm.光催化氧化实验表明,复合材料对甲基橙溶液具有很好的光催化活性.研究结果表明,在实验条件下,甲基橙溶液的光催化脱色和矿化过程是同时进行的,而且活性炭的吸附作用使复合材料的催化效率比单纯的二氧化钛粉末有很大的提高.这是由于其对可见光的吸收(黑色),使复合材料不仅在紫外区,而且在可见光区域也有很好的催化效果.所以,复合材料可以解决二氧化钛作为光催化剂在实际应用中存在的太阳能利用率低的问题.     

Synthesis, characterization and photocatalytic reactivity of Ti-containing micro- and mesoporous materials

Ti-oxides incorporated within the framework of microporous zeolites and mesoporous molecular sieves were found to exhibit high and unique photocatalytic activity for the decomposition of NO into N₂ and O₂ as well as the reduction of CO₂ with H₂O to produce CH₄ and CH₃OH. Spectroscopic investigations of these catalytic systems using photoluminescence, UV-vis, XAFS (XANES and FT-EXAFS) and IR analyses revealed that the charge transfer excited state of the isolated tetra-coordinated Ti-oxides plays a vital role in these photocatalytic reactions. The reactivity of such Ti-oxides was found to depend strongly on their local structures which were controlled by the unique framework structures of the micro- and mesoporous material supports.     

Synthesis, characterization and photocatalytic reactivity of Ti-containing micro- and mesoporous materials

Ti-oxides incorporated within the framework of microporous zeolites and mesoporous molecular sieves were found to exhibit high and unique photocatalytic activity for the decomposition of NO into N₂ and O₂ as well as the reduction of CO₂ with H₂O to produce CH₄ and CH₃OH. Spectroscopic investigations of these catalytic systems using photoluminescence, UV-vis, XAFS (XANES and FT-EXAFS) and IR analyses revealed that the charge transfer excited state of the isolated tetra-coordinated Ti-oxides plays a vital role in these photocatalytic reactions. The reactivity of such Ti-oxides was found to depend strongly on their local structures which were controlled by the unique framework structures of the micro- and mesoporous material supports.     

Preparation of Ag nanoparticles loaded TiO2 nanoplate arrays on activated carbon fibers with enhanced photocatalytic activity

Ag loaded TiO₂ nanoplate array which grew on activated carbon fiber (ACF) was prepared in the present work. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–Vis diffuse reflectance spectra (DRS). The photocatalytic degradation of methylene blue (MB) was used to investigate the activity of the synthesized samples. Under both UV and visible light irradiation, the Ag loaded samples showed enhanced photocatalytic activity. Besides, the effect of the deposition dosage of Ag nanoparticles on the photocatalytic activity was also investigated. Under UV light irradiation, the Ag nanoparticles acted as electron traps, which enhanced electron–hole separation efficiency of TiO₂. Under visible light irradiation, the Ag nanoparticles showed surface plasmon resonance, which induced the visible light responsive photocatalytic activity for the obtained samples.     

Preparation and visible light photocatalytic activity of carbon quantum dots/TiO2 nanosheet composites

Carbon quantum dots (C QDs)/TiO₂ nanosheet (TNS) composites were prepared by a simple low temperature process in which TNS were dispersed in C QDs solution, and dried at 60 °C. The C QDs/TNS composites were characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscopy (TEM) and high-resolution TEM. The results indicated that C QDs were well combined with TNS through surface carbon–oxygen groups. The photocatalytic activity was investigated by degradation of rhodamine B under visible light irradiation. The photocatalytic activity of C QDs/TNS composites was significantly enhanced compared with that of C QDs/P25 composites and pure TNS, which indicated that the unique up-converted photoluminescence behavior of C QDs and highly reactive {0 0 1} facets of TNS both played important roles in the enhancement of photocatalytic activity of C QDs/TNS composites.     

Preparation and characterization of mesoporous activated carbon from waste tires

Activated carbons were produced from waste tires and their characteristics were investigated. Rubber separated from waste tires was first carbonized at 500 °C in N₂ atmosphere. Next, the obtained chars were activated with steam at 850 °C. As a result, fairly mesoporous activated carbons with mesopore volumes and BET surface areas up to 1.09 cm³/g and 737 m²/g, respectively, were obtained. To further improve the porous properties of the activated carbons, the char was treated with 1 M HCl at room temperature for 1 day prior to steam activation. This treatment increased mesopore volumes and BET surface areas of the activated carbons up to 1.62 cm³/g and 1119 m²/g, respectively. Furthermore, adsorption characteristics of phenol and a dye, Black 5, on the activated carbon prepared via acid treatment were compared with those of a commercial activated carbon in the liquid phase. Although the prepared carbon had a larger micropore volume than the commercial carbon, it showed a slightly lower phenol adsorption capacity. On the other hand, the prepared carbon showed an obviously larger dye adsorption capacity than the commercial carbon, because of its larger mesopore volume.     

Preparation, characterization and photocatalytic activity of Si-doped and rare earth-doped TiO2 from mesoporous precursors

Si-doped and rare earth-doped TiO₂ with large specific surface area were prepared by the hydrothermal method and sol–gel route, respectively, using C₁₈H₃₇NH₂ as template. The samples were characterized by XRD, FT-IR, low-temperature N₂ adsorption–desorption measurement, XPS and solid state UV–vis diffuse reflectance spectroscopy. The pore size for Si-doped TiO₂ exhibits both mesoporous and microporous distribution, and that for rare earth-doped TiO₂ exhibits a sharp and narrow distribution in microporous range. The photocatalytic activities were investigated with the degradation of phenol as probe reaction. Compared with pure TiO₂, the conversion of phenol and selectivity to CO₂ increases when adding rare earth elements, and the substitution of Si for Ti in an appropriate range also increases the conversion of phenol.     

N掺杂纳米TiO2的制备及其光催化性能

以钛酸四丁酯和乙醇为原料,尿素为氮源,室温下采用溶胶-凝胶法制备了氮掺杂的纳米TiO2粉末。采用XRD、TEM、UV-Vis DRS对样品进行了表征。结果表明：N掺杂使纳米TiO2的光谱响应范围拓展到可见光区。较佳制备条件是：n(钛酸四丁酯)∶n(尿素)为1∶3,400 ℃下煅烧3.5 h,所得样品为锐钛矿晶型,平均粒径为13 nm。光降解甲基橙实验中,溶液pH值为4.0时,降解率最大,反应3 h降解率可达70.5%。     

二氧化钛/铁酸钴磁性光催化材料的制备及表征

以化学共沉淀法制备的铁酸钴纳米粒子为磁核,采用硫酸氧钛水解法在铁酸钴磁性粒子表面包覆二氧化钛,制得顺磁性易于固液分离的二氧化钛/铁酸钴复合光催化材料,并运用X射线衍射（XRD）、透射电镜（TEM）和振动样品磁强计（VSM）技术进行了表征,以甲基橙为模拟污染物研究其光催化活性。结果表明：制备的复合光催化材料晶型较好,其中二氧化钛和铁酸钴分别以锐钛矿型和尖晶石结构存在,粒径为40～50 nm,且具有超顺磁性;二氧化钛/铁酸钴复合光催化材料具有较高的光催化活性同时具有良好的重复使用性能。     

纳米TiO_2的制备、表征及光催化降解酸性品红

以钛酸四正丁酯为原料,采用溶胶-凝胶法制备了纳米TiO2粒子,对其进行了TG-DTA,XRD,TEM和BET分析,并分别在紫外光和可见光下考察了其光催化降解酸性品红性能。结果表明,自制的纳米TiO2对酸性品红具有很好的光催化降解脱色能力,500℃的样品在紫外光下,20 min内即可将200 mg/L的酸性品红溶液完全降解脱色,在可见光下,210 min内酸性品红的脱色率达80%。     

Sn掺杂TiO2/ACF复合材料的制备、表征及光催化性能

以Ti(OC₄H₉)₄为前体,SnCl₄为Sn源,采用胶溶-回流法制备了Sn掺杂的TiO₂,利用浸渍提拉法将其负载到活性炭纤维(ACF)表面,并运用SEM、XRD、XPS、DRS等手段对TiO₂/ACF复合材料进行表征,考察了复合材料光催化降解气相甲醛的性能。研究结果表明,Sn元素掺入TiO₂晶格中,有利于抑制TiO₂晶粒的生长,促进TiO₂由锐钛矿型向金红石型的转化,光吸收范围发生一定程度红移;HNO₃的用量为0.015mol、掺锡量为6%、负载两层的TiO₂/ACF-50复合材料在紫外光照射下对甲醛的去除率复合材料可达85.2%,而在可见光下仅为65.3%。     

沥青基球形活性炭的制备研究

以煤沥青为主要原料采用水浴悬浮法制备沥青球。使用扫描电子显微镜和偏光显微镜对沥青球的表面形貌进行表征,探讨了减黏剂萘含量对调制沥青软化点的影响,成球温度对球形貌的影响以及沥青/水相的最大质量比。实验还采用Fluent软件对固液悬浮体系进行模拟。结果表明:所制得沥青球球形度好,表面光滑,粒径分布范围窄;相同原料沥青,萘含量越高调制沥青软化点越低;沥青/水相的最佳质量比为16;不同的搅拌器最佳速度有所不同。     

Preparation and photocatalytic activity of silver and TiO2 nanoparticles/montmorillonite composites

Ag–TiO₂/montmorillonite (Ag–TiO₂/MMT) was synthesized as photocatalyst using TiCl₄ hydrolysis to introduce nanosized TiO₂ into the interlayer space of the montmorillonite (MMT). Stable pillared TiO₂/MMT was obtained by calcination at 500 °C, then silver was loaded by reduction of silver nitrate. The physico–chemical properties of the photocatalyst were determined by X-ray diffraction (XRD), infrared spectroscopy (IR), atomic absorption spectrophotometer (AAS), nitrogen gas adsorption (BET method) and UV–Visible spectra. The photooxidation activity for methylene blue (M.B.) degradation was as follows: Ag–TiO₂/MMT > TiO₂/MMT > TiO₂(P25). Among them Ag–TiO₂/MMT had the highest photooxidation activity because of its larger specific surface caused by pillaring and loading of silver for improving its light absorption.     

Preparation,characterization, and photocatalytic degradation properties of polyacrylamide/calcium alginate/TiO2 composite film

Titanium dioxide (TiO₂) nanoparticles were dispersed in the sodium alginate and acrylamide aqueous solution to prepare the casting solution. The casting solution was spread on a glass plate by a glass rod enlaced with brass wires to control the thickness of the film. Then polyacrylamide/calcium alginate/TiO₂ (PAM/CA/T) composite film was obtained after UV irradiation and crosslinking by CaCl₂. The PAM/CA/T film was characterized by scanning electron microscopy and transmission electron microscope. The mechanical properties of the films were tested in wet form and the results showed that PAM/CA/T film had good strength and toughness. PAM/CA/T films did not rupture after swelling in 5.0 wt% NaCl solution and still had good mechanical properties. The PAM/CA/T hydrogel film provided a suitable carrier for TiO₂ in the photocatalytic degradation of dyes and the degradation rate of PAM/CA/T‐30 for methyl orange reached 80.8%. The PAM/CA/T film had good reusability and could degrade dyes in a high concentration of NaCl solution. POLYM. COMPOS. 37:1292–1301, 2016. © 2014 Society of Plastics Engineers     

氮铈共掺杂纳米TiO2的制备和光催化活性研究

采用水解沉淀法分别制备了未掺杂、氮掺杂和不同Ce^4＋浓度的氮、铈共掺杂纳米二氧化钛粉体,并利用XRD、TEM、XPS、UV-vis对其进行表征,以甲基橙的光催化降解为模型反应,考察其在太阳光下的光催化活性。结果表明,450℃下煅烧3h制备的纳米TiO2粉体均为锐态矿型,铈的掺入使衍射峰宽化;氮、铈共掺杂能抑制锐钛矿晶粒的生长,减少团聚,使晶粒细化。N取代了TiO2晶格中的部分氧原子形成N2p掺杂能级,而铈以Ce^4＋、Ce^4＋两种价态存在于TiO2中。氮、铈的协同作用不仅使TiO2的光吸收带边红移,也能明显提高TiO2在紫外光区的吸收强度。光催化降解甲基橙实验结果表明：当掺杂量为0．6％时,Ce-N-TiO2的光催化效率最高,约为纯二氧化钛的2倍。     

废菌渣基微/中孔活性炭的制备与结构表征

利用微波与碱液的协同作用脱除废菌渣中的含氮物质,脱氮后的滤渣用于制备活性炭,旨在减少氮氧化物排放,实现废菌渣的清洁化利用。分别以碘吸附值和亚甲基蓝吸附值为目标,采用响应面法（Box-Behnken）得到两种孔径活性炭的定向制备条件。①微孔活性炭：活化时间1h,活化温度425℃,ZnCl₂质量分数20%,浸渍比1：3.85。产品的碘吸附值为884.76mg/g,平均孔径为1.83nm。②中孔活性炭：活化时间2h,活化温度600℃,ZnCl₂质量分数30%,浸渍比1：4。产品的亚甲基蓝吸附值为448.65mg/g,平均孔径为3.15nm。利用扫描电镜、红外光谱等手段对活性炭结构进行表征,发现在活性炭表面形成了大量的表面官能团,包括羧基、羟基、内酯基等。