Low-temperature preparation and microwave photocatalytic activity study of TiO2-mounted activated carbon

TiO2 thin films were deposited on granular activated carbon by a dip-coating method at low temperature (373 K), using microwave radiation to enhance the crystallization of titania nanoparticles. Uniform and continuous anatase titania films were deposited on the surface of activated carbon. BET surface area of TiO2-mounted activated carbon (TiO2/AC) decreased a little in comparison with activated carbon. TiO2/AC possessed strong optical absorption capacity with a band gap absorption edge around 360 nm. The photocatalytic activity did not increase when the as-synthesized TiO2/AC was thermally treated, but was much higher than commercial P-25 in degradation of phenol by irradiation of electrodeless discharge lamps (EDLs).     

简单有效氮掺杂TiO2纳米微晶的制备、表征及其可见光活性

以尿素为氮源,采用简单的酸催化溶胶-凝胶法制备了氮掺杂TiO2纳米光催化剂,以甲基橙在可见光照射下的光催化降解为探针反应,评价了其光催化活性。运用XRD、XPS和UV-Vis DRS光谱表征技术考察了氮掺杂TiO2样品的微晶尺寸、晶相结构、表面组成及其吸光特性。结果表明氮掺杂减小了TiO2的带能隙,氮掺杂TiO2纳米微晶对400～530nm的可见光有较强的吸收,在降解甲基橙的实验中表现出良好的可见光催化活性。其中,400℃焙烧制得的具有单一锐钛矿相型,晶粒尺寸为14.94nm的TiO1.9904N0.0096样品的可见光催化活性最佳。     

Hydrothermal synthesis of nanostructured TiO2 particles and characterization of their photocatalytic antimicrobial activity

Nanostructured titania particles were synthesized by using hydrothermal processing and the photocatalytic antimicrobial activities were characterized. Both sol-gel synthesized and commercial TiO2 (anatase) samples were processed with two step hydrothermal treatments, under alkaline and neutral conditions. Scanning Electron Microscope (SEM) images showed that alkaline treatment yields nanofibers and lamellar structured particles from the commercial anatase and sol-gel synthesized samples respectively. Further treatment of nanofibers and nanostructured lamellar particles with distilled water results with crystal growth and the formation of nano structured bipyramidal crystalline particles. The photocatalytic antimicrobial activities of the samples were determined against Escherichia coil under irradiation. It was observed that the samples treated under alkaline conditions have improved activity than the original anatase samples. Limited activity and resulting time lag in bacterial inactivation were observed for hydrothermally treated samples with distilled water. However, a post treatment comprising the UV irradiation in aqueous conditions enhanced the photocatalytic activity.     

Synthesis and properties of carbons dispersed with α-iron particles from divinylbenzene-vinylferrocene

α-Iron-dispersed carbon was synthesized, through pressure pyrolysis of divinylbenzene-vinylferrocene above 750°C, and by reduction of magnetite-dispersed carbon. Divinylbenzenevinylferrocene copolymer was pyrolysed at 125 MPa above 750°C to yield carbons dispersed with α-iron accompanied by cementite. Magnetite in the carbon matrix was reduced to α-iron after heat treatments at 500°C in a flow of hydrogen. Carbons synthesized by the pressure pyrolysis of divinylbenzene-vinylferrocene at 800°C and 125 MPa contained iron-compound particles up to 200 nm, whereas the median diameter of α-iron particles in the carbon matrix after reduction treatments was 20 nm. α-Iron-dispersed carbon had a Curie temperature of 770°C. The saturation magnetization of iron-dispersed carbon increased with increasing the pyrolysis temperature of divinylbenzene-vinylferrocene copolymer, and reached a constant value of 183 e.m.u.g⁻¹ at 800°C. The saturation magnetization of α-iron-dispersed carbon after the reduction treatment revealed practically the theoretical value of α-iron. Carbons finely dispersed with only α-iron particles were synthesized successfully by reduction of magnetitedispersed carbons.     

Activated carbons containing TiO2: Characterization and influence of a preparation method on the state of TiO2 supported

In this study preparation procedure and characterization of coal-based activated carbons supporting TiO₂ is presented. Decomposition of titanium organic complex introduced into three raw coals of a different composition is described and illustrated by XRD patterns taken at different stages of the preparations. Influence of a coal rank and titanium supported on coals on the development of a mesoporous structure is shown. Titanium revealed a positive influence on the formation of mesopores in activated carbons. Titanium contents were higher in those carbons activated for a longer time. Loss of some part of Ti supported was observed during preparation and the loss remained in a straight relation with the activation time. As confirmed by TEM, size of TiO₂ particles supported on the activated carbons increased with the activation time. Distribution of the particles was irregular. Rutile was the only crystalline form of TiO₂ found in Ti-loaded activated carbons.     

多孔TiO2的制备表征及光催化研究

以钛酸四丁酯为前驱物，在溶胶-凝胶法和硬脂酸法的合成样品的过程中添加正硅酸乙酯，分别合成出纳米TiO2，焙烧成晶后通过HF除去硅，形成了多孔TiO2。通过XRD、SEM、UV-Vis、BET等测试手段，比较正硅酸乙酯对不同合成方法合成的样品的影响。在对甲基橙的紫外光催化试验中，添加正硅酸乙酯再由HF处理后合成的样品表现出较高的催化活性，这与此方法合成的样品的表面积较大有关。     

Surfactant-assisted solvothermal preparation of submicrometer-sized hollow hematite particles and their photocatalytic activity

Submicrometer-sized hollow hematite particles were prepared through a surfactant-assisted solvothermal process. The amount of FeCl₃·H₂O and cetyltrimethylammonium bromide, and the acidity of the solution were systematically altered to study their effects on the final results. Hollow hematite particles with shapes from sphere, ellipsoid to peanut were obtained. Their sizes range from 500 nm to 2 μm with shell thickness from 100 to 500 nm. Powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy and selected area electron diffraction were applied to investigate the products’ crystallinity, purity, morphology, size and structural features. Finally, the study on the photocatalysis of Fe₂O₃ for the destruction of diethyl phthalate in water was carried out. The result proved that Fe₂O₃ hollow particles were effective photocatalysts for the degradation of DEP, with 96.8% destruction ratio being obtained within 60 min.     

Facile preparation of Ag-coated TiO2 nanobelts and their photocatalytic activities

This article describes facile preparation of Ag nanoparticles coated on TiO2 nanobelts and their visible-light photocatalysis activity toward the degradation of Rhodamine B. An Ag complex was adsorbed onto the TiO2 nanobelts by impregnation of the nanobelts into an [Ag(NH3)2]NO3 aqueous solution, and subsequently the Ag precursor was reduced at room temperature by a glucose solution to form Ag nanoparticle-coated TiO2 nanobelts. The visible-light photodegradation of Rhodamine B on such nanocomposite was studied and showed much higher photocatalytic activity than commercial P-25 TiO2 nanoparticles and pure TiO2 nanobelts. Using a seeding preparation procedure through dropwise addition of fresh aqueous solution of NH2NH2 and AgNO3 alternately, larger Ag particles on TiO2 nanobelts were obtained.     

Preparation and high bacteriostatic action of the activated carbons possessing ultrafine silver particles

The new carbon composites possessing ultrafine silver particles (0.001 wt%, size 1.8–2.5 nm) show high bacteriostatic action toward bacteria such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis and a yeast fungus like Candida albicans. The present carbon composite was prepared by the steam activation of a mixture of a petroleum pitch and N,N-dimethylaminomethylphenylsilver (0.012 mg/g) at 930 °C for 15–19 min. The growth inhibitory effect for Gram-negative bacteria such as E. coli and P. aeruginosa varies greatly depending on the amount of ultrafine silver particles, while the Gram-positive bacteria show little effect by the amount of silver particles used. A yeast fungus like C. albicans exhibits relatively small biostatic action as compared with bacteria, but it shows enough activity when we used the carbon material possessing 0.01 wt% of Ag particles.     

粉状活性炭颗粒制备、脱色性能及再生性能研究

以粉末活性炭为原料,聚乙烯醇为粘结剂制备了颗粒活性炭,考察了干燥温度、干燥时间以及胶炭比对脱色性能的影响,并讨论了颗粒活性炭的再生性能.结果表明,颗粒活性炭的最佳后处理条件为:温度160℃,时间2h;其最佳胶炭比为1∶2.0.用酸洗涤法对脱色效果最好的颗粒活性炭进行了再生处理,其再生效果良好.对颗粒活性炭进行表征分析,其比表面积随胶炭比的增加而减小.SEM照片反映出颗粒活性炭内部粉末与胶粘剂的粘接和颗粒堆积产生的空隙.     

硝苯地平在球状活性炭中的吸附及缓释行为

采用球状活性炭作为硝苯地平药物载体,借助N2吸附仪表征了球状活性炭的比表面积和孔结构,利用SEM表征了球状活性炭的表面形貌,通过考察球状活性炭比表面积、孔隙结构与吸附性能和体外释放性能的关系,研究了球状活性炭对硝苯地平的吸附及缓释行为。结果表明:比表面积大、孔隙结构发达、孔径分布集中在2nm~5nm之间的中孔型活性炭,对硝苯地平的吸附能力较强,吸附量可达19.5mg/g;所制缓释微丸缓释效果良好,在接近人体胃液介质中累计释放率达到19.2%;球状活性炭对硝苯地平的释放动力学符合Higuchi模型,药物基本以恒定速率主动释放。     

Ultrafine dispersed CuO nanoparticles and their antibacterial activity

Copper oxide nanoparticles with a particle size ranging from 80 to 160 nm were prepared by a wet chemical procedure. Copper carbonate hydroxide and sodium hydroxide were used as raw materials. Copper hydroxide was generated as a precursor which was thermally decomposed to CuO nanoparticles. The nanoparticles were characterised using atomic force microscopy, X-ray diffraction and UV-visible spectrometry. The nanoparticles were tested for antibacterial activity against Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella paratyphi and Shigella strains.     

机械力化学效应在凹凸棒石/TiO2复合颗粒制备中的应用研究

用高能行星磨对凹凸棒石进行机械力化学活化,采用中和水解法制备了凹凸棒石/TiO2复合颗粒,通过热重分析、SEM和TEM分析,研究了机械力化学活化的凹凸棒石及所制备复合颗粒的热稳定性、粒度和微观形貌的变化情况。结果表明:凹凸棒石经粉磨后颗粒表面活性极大增强,颗粒变得扁平和细小,所制备的复合颗粒包覆效果理想,分散性好。     

丙三醇/羧甲基淀粉/改性氧化钛复合颗粒的电流变性能

结合改进的水解法和溶胶-凝胶法,制备了丙三醇/羧甲基淀粉/改性纳米氧化钛复合颗粒,分析表明羧甲基淀粉和纳米氧化钛之间存在有相互作用;同时,介电测试表明此颗粒配制的电流变液的介电极化特性有很大改善.经流变学测试,此复合颗粒电流变液的动态剪切应力在颗粒质量分数为25%,剪切速率为100s-1,3kV/mm DC下为960Pa,剪切增幅比为35.同时,此电流变液的静态屈服应力在更高浓度,5kV/mm DC下可达到18kPa,比同等条件下改性氧化钛和CMS电流变液的静态屈服应力均有所提高.此外,这种电流变液还表现出较好的抗沉降性能.     

Ce掺杂TiO2/SiO2的制备及其光催化降解罗丹明B

采用溶胶-凝胶法制备了纯TiO2和掺杂不同含量Ce的TiO2/SiO2复合纳米粒子.并用FT-IR,UV-Vis对样品结构进行了表征,并以罗丹明B(RB)的光催化降解为探针反应,评价了其光催化性能.结果表明,TiO2/SiO2催化剂中形成了新的Ti-O-Si键,Ce的掺杂使TiC2/SiO2光谱响应范围向可见光区拓展.与未掺杂的TiO2/SiO2相比较,掺杂的TiO2/SiO2具有更高的催化性能.Ce掺杂的最佳值为x(Ce)∶x(Ti)=0.0090,光催化剂最佳投放量为30mg.     

A continuous process for the ultrasonic spray pyrolysis synthesis of RuO2/TiO2 particles and their application as a coating of activated titanium anode

Synthesis and subsequent deposition of sub-micron spherical RuO₂/TiO₂ particles onto titanium were performed by continuous process in two connected reactors, exclusively applied for this purpose. Synthesis of particles was achieved by ultrasonic spray pyrolysis method in the first reactor. The deposition of thus produced RuO₂/TiO₂ onto an expanded titanium substrate was performed at 500 °C afterwards in the second, specially constructed, reactor equipped by high-voltage electrostatic field. Basic electrochemical properties of the obtained RuO₂/TiO₂ particles were checked in a form of the coating on Ti deposited from the suspension of the material produced in the first reactor. Thus prepared anode was investigated by cyclic voltammetry (CV), polarization measurements in O₂ (OER) and Cl₂ (CER) evolution and the accelerated stability test in diluted chloride solution. The morphology and composition of the deposited RuO₂/TiO₂ were checked by scanning electron microscopy/energy dispersive X-ray spectroscopy analysis. Analysis of the results obtained for OER and CER showed that Tafel slopes for these reactions were in accordance with the values for this kind of material. The CV response was of usual characteristics too. The accelerated stability test revealed acceptable anode stability.     

乳液聚合法制备TiO2/PS复合粒子及其性能研究

采用乳液聚合法制备了以纳米二氧化钛(TiO2)为核,聚苯乙烯(PS)为壳的复合粒子.利用正交实验研究了引发剂用量、单体用量、表面活性剂浓度对复合粒子包覆效率的影响;通过透光率和亲水亲油实验,检验复合粒子的分散性,并采用透射电镜(TEM),红外光谱(FTIR)表征了复合粒子的形貌和结构.     

Microwave absorbing behavior of metal dispersed TiO2 nanocomposites

Metal dispersed TiO₂ nanocomposites were prepared by milling process. The microwave absorbing characteristics of the prepared nanocomposites with epoxy were studied in the 8.2–12.4 GHz frequency range for the microwave absorption application. The measured relative complex permittivity of metal dispersed nanocomposite-epoxy indicates higher values in comparison to the pure TiO₂-epoxy nanocomposite. The Reflection loss (RL) values were calculated for thickness from 0.1 to 2.2 mm with an interval of 0.1 mm and the maximum value of RL found for TiO₂-epoxy nanocomposite was −4.96 dB at 10.21 GHz frequency for 2.0 mm thickness. Whereas, RL value is improved to a maximum value of −13.67 dB at 10.13 GHz with Al dispersion (1.8 mm thickness) and −7.24 dB at 10.38 GHz with Ni dispersion (1.3 mm thickness). This study suggests the effectiveness metal particles dispersion for the development of thin microwave absorbers as well as increasing the level of RL.