纳米TiO2光催化降解环境中有机污染物研究进展

有机污染物是目前生态环境中最主要的污染源,对这类物质的控制还缺少经济有效的技术处理手段。纳米TiO2光催化技术是一种绿色环保的污染治理技术,具有催化效率高、性质稳定、成本低和无二次污染等特点。探讨了纳米TiO2光催化原理和几种掺杂改性方法,介绍了纳米TiO2催化降解水中和空气中有机污染物的研究进展,并简要展望了纳米TiO2光催化技术的发展前景。     

纳米TiO2/SiO2负载棉织物的制备及其光催化降解染料的研究

将纳米TiO_2水溶胶和纳米SiO_2水溶胶复配制备环境净化整理剂,并通过轧烘焙工艺对棉织物进行后整理得到纳米TiO_2/SiO_2负载棉织物,然后将其用于不同结构有机染料的光催化降解反应中,重点考察纳米SiO_2的添加量对其在不同pH值反应体系中的光催化降解性能以及重复利用性的影响。结果表明,纳米TiO_2/SiO_2负载棉织物对不同结构的有机染料具有显著的光催化降解性能,能够促进染料分子的共轭体系和芳香环结构的降解反应。纳米SiO_2的添加不仅有利于纳米TiO_2/SiO_2负载棉织物在碱性介质中光催化降解性能的提高,而且也能够改善其重复利用性。     

以玻璃珠为载体制备纳米TiO2光催化膜滤料

研究了陈化时间及涂膜层数对纳米TiO2膜光催化性能的影响,结果表明:陈化3d时,膜的光催化性能最高;涂膜层数为3时,甲基橙的处理效率最高。同时研究了纳米TiO2膜对水和甲基橙的吸附性能,结果表明:水和甲基橙存在竞争吸附,随着加入甲基橙浓度的增加,光电催化测得的积分电量减少,膜的光催化活性降低。用制备的纳米TiO2膜光催化降解甲基橙,效率最高可达92.9%;在一定条件下累积运行93.8h,降解率均在83%左右,表明制备的纳米TiO2膜有较高的光催化性能及较长的使用寿命。     

纳米TiO2固相光催化降解PVC糊薄膜的研究

以纳米TiO2为光催化剂,以ATBC为增塑剂,制备了纳米-TiO2/PVC糊复合膜。研究了该薄膜在紫外光照射条件下的降解性能,并进行了GPC、SEM、FT-IR等分析,测试了复合膜经紫外光照射前后的质量变化、分子量变化、表面形貌的变化。结果表明,该复合膜在紫外光照射下,降解速率可提高128.43%左右。GPC测试结果表明,经紫外光照射720h后,数均分子量Mn和重均分子量Mw可分别降低24.75%和17.7%左右;SEM表明,降解后PVC糊复合膜表面有大量裂纹且部分裂解成碎片。     

阳极氧化制备TiO2纳米多孔膜

分别在氢氟酸和硫酸两种电解液体系下对纯钛(TA1)试样进行阳极氧化,在钛的表面获得TiO2纳米多孔膜.利用膜的颜色的不同来判断膜的厚度的变化,用FESEM观察了孔的形貌和结构并用XRD测试了TiO2膜的晶型,进而研究了阳极氧化电压对孔径和多孔膜晶型的影响并对多孔膜的形成机理进行了阐述.     

TiO2/活性炭复合纳米纤维膜的制备及表征

在聚丙烯腈(PAN)、N,N-二甲基甲酰胺(DMF)体系中加入钛酸四丁脂水解溶胶,通过静电纺丝技术得到纳米纤维膜,经预氧化、炭化、活化制备出TiO2/活性炭复合纳米纤维膜。采用扫描电子显微镜、X射线能谱、热分析、傅里叶红外光谱、X射线衍射以及测定Zeta电位和表面接触角等手段对TiO2/活性炭复合纳米纤维膜进行表征。结果表明,当V(PAN)∶V(DMF)∶V(Ti(OH)4)溶胶=3∶17∶3时,可制得纤维直径为600～700nm的TiO2/活性炭复合纳米纤维膜。纳米TiO2在TiO2/活性炭复合纳米纤维膜中分布均匀,晶型结构易于控制;TiO2/活性炭复合纳米纤维膜有较强的光催化活性和吸附活性,可以作为环境功能材料使用。     

TiO2/ZnO纳米复合材料的制备及表征

以钛酸正四丁酯及L-Cys为钛源和模板剂仿生合成纳米TiO2前体,采用水热合成法制备TiO2/ZnO纳米复合材料,并利用XRD、SEM、XPS、FT-IR以及比表面积及孔径分析等对TiO2/ZnO纳米复合材料进行表征。结果表明:合成TiO2/ZnO复合材料是由锐钛矿TiO2和纤锌矿ZnO组成,形貌是由许多几十纳米厚薄片组成的花状,直径在2～3μm之间,比表面积为219.54m2/g。     

腐植酸对纳米TiO2催化降解土壤中萘和菲的影响

化石燃料的采输和使用致使土壤中多环芳烃类污染物持续增加,影响了农作物的生长并威胁人类健康。腐植酸(HA)作为土壤中的有机质,含有多种官能团,在光催化降解有机污染物中具有敏化或抑制作用。将HA与TiO₂以不同质量比进行复配制备了复合催化材料,考察了材料组成、pH、光源等因素对多环芳烃降解率的影响。采用气相色谱-质谱联用仪(GC-MS)对降解情况进行定量分析,结合傅里叶变换红外光谱仪和X射线光电子能谱仪分析了HA影响TiO₂降解作用的机理。结果表明：复合催化材料有利于提高萘和菲的降解率,萘和菲的降解率分别为72.1%和83.3%;HA与纳米TiO₂之间产生了静电作用以及配合作用,提高了TiO₂表面的催化反应位点。     

聚丙烯基纳米TiO2的表面改性

针对纳米二氧化钛(TiO2)颗粒粒径小、表面活性大、易团聚的问题,采用硅烷偶联剂KH-560对TiO2进行表面改性,并与聚丙烯树脂(PP)在双螺杆挤出机上熔融共混得到改性PP;通过FT-IR、TG、SEM等测试手段对改性纳米TiO2颗粒进行了表征,讨论了纳米TiO2的改性程度及其在PP中的分散性。结果表明:硅烷偶联剂已经成功的包覆在纳米TiO2的表面;同时在碱性环境下纳米TiO2表面包覆的有机物含量最多;当在碱性环境下表面改性的纳米TiO2为PP质量的3%时,在聚丙烯树脂中分散较均匀。     

水杨酸原位表面改性纳米TiO2的制备及性能研究

通过控制四氯化钛(TiCl4)的水解速度,制备出水杨酸(SA)原位表面修饰的TiO2纳米颗粒(TiO2/SA).通过X射线衍射仪(XRD),高分辨透射电子显微镜(HRTEM),红外光谱仪(FT-IR),热分析(TG-DTA)和X射线光电子能谱(XPS)等实验分析手段对表面改性前后的TiO2纳米颗粒进行了表征,结果表明表面修饰水杨酸的TiO2纳米颗粒在乙醇中有良好的分散性,将TiO2/SA加入到光信息存储薄膜材料(PVA/AM)中,能大大提高材料的衍射效率,降低布拉格偏移.     

Large-sized nano-TiO2/SiO2 mesoporous nanofilm-constructed macroporous photocatalysts with excellent photocatalytic performance

Novel large-sized mesoporous nanofilm-constructed macroporous SiO₂ (LMNCMS) with two sets of well-defined 3D continuous pass-through macropores (pore size of 0.5–1.0 μm, wall thickness of 40–50 nm) was prepared through a dual-templating approach, and used as an advanced support for TiO₂ nanocrystalline photocatalyst. The structural and optical properties of the as-prepared materials were investigated by various characterization techniques in order to explore the connections between catalysts’ features and catalytic performance. The photocatalytic activities were evaluated by degradations of methylene blue (MB) and phenol under the simulated sunlight irradiation. To gain insight into the impact of preparation and operation conditions on photocatalytic degradation processes, experiments were conducted at wide ranges of the TiO₂ loading content, calcination temperature, solution pH, and photocatalyst dosage. Nano-TiO₂/LMNCMS exhibited high photocatalytic activity and stability. Rapid matter transport, good accessibility of pollutants to TiO₂ and high light harvesting could mainly account for the superior photocatalytic performance. The trapping experiments were performed to identify the main reactive species in the catalytic reactions.     

不同型号PVA对纳米TiO2/PVA复合材料性能的影响

用硅烷偶联剂γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH550)对纳米TiO₂进行改性, 将不同比例的聚乙烯醇(17-88与17-99)相混合制成胶液, 再采用直接共混法制备了纳米TiO₂/聚乙烯醇(PVA)复合材料, 并流延成膜。通过自制透水仪、 扫描电镜、 热失重分析、 拉伸强度、 耐水性能以及透明性对纳米TiO₂/PVA复合膜进行表征, 探讨不同含量的PVA 17-88对复合膜的性能影响。结果表明, PVA 17-88的质量分数为30%, 纳米TiO₂ /PVA膜厚度控制在25~30 μm, 透水量较大, 拉伸强度达到28.72 MPa, 耐水性能最佳。      

聚丙烯酸酯/纳米TiO2复合材料的制备与性能

通过无皂-原位乳液聚合法,以甲基丙烯酸甲酯、丙烯酸丁酯为原料,采用反应性乳化剂1-烯丙氧基-3-(4-壬基苯酚)-2-丙醇聚氧乙烯醚硫酸铵(DNS-86)制备聚丙烯酸酯/纳米TiO2复合材料。采用红外光谱(FT-IR)、动态激光光散射(DLS)、透射电镜(TEM)等检测手段对复合材料的结构进行了表征,通过力学性能、耐水性测试研究了纳米TiO2对复合材料性能的影响。FT-IR测试结果表明纳米TiO2与聚合物发生了相互作用,有少量的TiO2被接枝到聚合物分子中。DLS测试结果表明与纯聚丙烯酸酯相比,聚丙烯酸酯/纳米TiO2复合乳液乳胶粒的平均粒径和粒径分布都有所降低。TEM测试结果表明纳米TiO2分布在聚合物基体中。复合材料的性能测试结果表明,当纳米TiO2的加入量为0.5%时,聚丙烯酸酯/纳米TiO2复合材料的综合力学性能较好;纳米TiO2的加入可提高复合材料的耐水性。     

纳米TiO2 / 再生纤维素复合薄膜的制备及光催化性能

在1-烯丙基-3-甲基咪唑氯室温离子液体中, 将纳米TiO₂粉末与纤维素浆粕进行溶液共混, 所得纤维素用水再生后, 经过超临界CO₂干燥处理, 制备了不同TiO₂ 含量的纳米TiO₂ / 再生纤维素复合膜。通过扫描电子显微镜(SEM) 、X 射线衍射(XRD) 、傅立叶变换红外光谱( FTIR) 对所得薄膜的形貌、结构进行表征。利用PCC-2 型光催化活性检测仪测试薄膜在紫外光下光催化降解亚甲基蓝的能力, 评价薄膜的光催化活性。讨论了纳米TiO₂ 含量、超临界CO₂ 干燥和真空干燥对薄膜性能的影响。结果表明: 复合膜的光催化活性达到所用TiO₂粉体的90 %; 经超临界CO₂ 干燥处理所得复合膜的光催化活性明显高于真空干燥所得复合膜的活性; 纳米复合膜的光催化活性随TiO₂ 含量的增加先升高后降低, 含量为5 %时光催化活性最高。      

聚丙烯酸酯/纳米TiO2复合皮革涂饰剂的研究

以钛酸丁酯为纳米TiO2的前驱体,丙烯酰胺、醋酸乙烯酯、甲基丙烯酸甲酯、丙烯酸丁酯为单体,乙烯基三乙氧基硅烷(A-151)为偶联剂,采用双原位乳液聚合法制备聚丙烯酸酯/纳米TiO2复合涂饰剂。考察引发剂用量、反应时间及钛酸丁酯用量对乳液及其涂膜性能的影响,并采用红外光谱和透射电镜对复合涂饰剂的结构进行表征。结果表明,随着引发剂和钛酸丁酯用量的增加,涂膜的抗张强度先减小后增大,断裂伸长率先增大后减小,耐水性先增加后减弱;而随着反应时间的延长,涂膜的抗张强度及断裂伸长率呈现与引发剂和钛酸丁酯用量相反的趋势,耐水性基本呈现减弱趋势。红外光谱及透射电镜结果表明纳米TiO2存在于聚丙烯酸酯中,且主要存在于聚丙烯酸酯乳胶粒的表面。     

Effects of LDPE film on the properties of copper/LDPE composites for intrauterine contraceptive device

Copper/low density polyethylene (LDPE) composites covered with LDPE film on the surface were prepared for intrauterine contraceptive device (IUD). Cu²⁺ release rates of the composites were determined by absorbance measurements. The surface characteristics of the composites after incubated for 5 months were investigated by SEM and EDX techniques. The results show that the existence of LDPE film on the surface of the composites decreases the release rate of Cu²⁺, especially the burst release of Cu²⁺ at initial period. The undesirable deposits, which are observed on the surface of the composite without LDPE film, are not detected on the surface of the composite with LDPE film, indicating that the presence of LDPE film can effectively prevent the formation of deposits on the composite surface. Results obtained from this study suggest that the existence of LDPE film on the composite surface may alleviate the side effects (bleeding, abdominal pain and inflammatory complication) of IUD resulting from the burst release and the deposit formation.     

Hydrophilic properties of nano-TiO2 thin films deposited by RF magnetron sputtering

Microstructure and hydrophilicity of nano-titanium dioxide (TiO₂) thin films, deposited by radio frequency magnetron sputtering, annealed at different temperatures, were studied by field emission scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and water contact angle methods. It is found that the crystal phase transforms from amorphous to rutile structure with increase of annealing temperature from room temperature to 800 °C. It is also indicated that the organic contaminants on the surface of the films can be removed and the oxygen vacancies can be reduced by the annealing treatment. Annealed at the temperature below 300 °C, amorphous TiO₂ thin films show rather poor hydrophilicity, and annealed at the temperature range from 400 to 650 °C, the super hydrophilicity anatase of TiO₂ thin films can be observed. However, when the annealing temperature reaches 800 °C, the hydrophilicity of the films declines mainly derived from the appearance of rutile.     

聚丙烯/纳米二氧化钛复合材料的超临界流体微孔发泡

以聚丙烯(PP)/nano-TiO2复合材料为研究对象,采用快速降压超临界微孔发泡技术,制备了泡孔密度、泡孔直径分别为2.8×107cell/cm3~3.15×109cell/cm3,46.36μm~6.08μm的PP/nano-TiO2微孔复合材料。研究了复合材料中nano-TiO2的质量分数、饱和压力及发泡温度对PP/nano-TiO2复合材料发泡行为的影响,通过扫描电镜(SEM)对微孔形貌进行表征。结果表明,加入nano-TiO2可以改善PP的发泡性能,并得到泡孔分布均匀的闭孔发泡材料;随复合材料中nano-TiO2质量分数由1%提高到5%,泡孔密度增加,泡孔直径减小。对于nano-TiO2质量分数为3%的PP/nano-TiO2复合材料,随着饱和压力的增加,泡孔直径和泡孔密度都增加;随着发泡温度的升高,泡孔密度减小,泡孔直径变大。     

Investigation into real-time pressure sensing properties of SnO2, TiO2, and TiO2/ZnO thick films with interdigitated electrodes

The pressure sensing properties of nanocomposite SnO₂, TiO₂, and TiO₂/ZnO thick film capacitors with interdigitated electrodes are investigated. To form the dielectric layers, the metal oxides powders were respectively mixed with isopropanol, wet ball milled for 24 h, then the mixtures were dried at 120 °C and further the powders were placed under 2 tonnes of pressure to form pellets, which were fired at 1250 °C (rate of 5 °C/min) in a vacuum of 6 × 10⁻³ mbar for 5 h, followed by cooling (rate of 3 °C/min). After firing, the resultant nanopowders were mixed with 7 wt.% of polyvinyl butyral (binder) and suitable amount of ethylenglycolmonobutylether (solvent) to form the pastes. These were screen-printed over the Ag electrodes on alumina substrates to form SnO₂, TiO₂, and TiO₂/ZnO capacitor pressure sensors accordingly. The evaluation of pressure sensing properties of these sensors was performed using a HP 4192A Impedance Analyser, which recorded the changes in the values of the capacitances under different mechanical stresses. At the applied load of 5 kPa, the response times of 2.5 s, 5.6 s and 4 s were recorded for SnO₂, TiO₂, and TiO₂/ZnO sensors, respectively. In addition to instant response times, these pressure sensors have the advantage of being reusable, as their electrical properties were restored to the original value after annealing for 2 h at 80 °C. Moreover, one year later after the initial testing, the sensors were still operational and produced similar time responses to pressure.     

Porous SnO2 sputtered films with high H2 sensitivity at low operation temperature

Undoped and Pd-doped SnO₂ films were deposited at various substrate temperatures and discharge gas pressures using reactive magnetron sputtering. Structural factors of the films, such as crystallite size, grain size, and film density, were systematically investigated. The main objectives of this study are to clarify the operation temperature dependence of the H₂ sensitivity of these films as well as to clarify the dominant structural factor in the determination of the sensitivity. The operation temperature at which the sensitivity defined by (R_a−R_g)/R_g, where R_a and R_g are the resistances before and after exposure to H₂, showed a maximum decreased with decreasing film density. The highest sensitivity of 4470 was obtained for a Pd-doped film with the lowest density of 3.1 g/cm³ at 100 °C. It was found that the sensitivity correlated with film density rather than with crystallite size and grain size. The high sensitivity of a Pd-doped porous film at a low temperature was discussed in relation to the Schottky-barrier-limited transport as well as the chemical and electronic effects of Pd.