掺锌纳米TiO_2光催化性能研究

以钛酸四丁酯、硝酸锌为主要原料,采用溶胶-凝胶法制备掺锌纳米TiO2微粒.以罗丹明B为目标降解物,考察了掺锌纳米TiO2粉体的光催化活性.结果表明:300℃焙烧4.5 h时,得到的催化剂活性最高.在紫外光照射下,催化效果明显优于太阳光照射(在紫外光下,pH值为2时,用1 g/L掺锌2.7%纳米TiO2光照70 min,罗丹明B的降解率接近100%;在太阳光下,pH值为10时,用4 g/L掺锌3.0%纳米TiO2光照120 min,罗丹明B的降解率达93%).     

Development of an immobilization system for in situ micronutrients release

An immobilization system constituted by coated microcapsules was developed aiming at immobilizing probiotic bacteria capable of producing folate and release it in a sustained manner into the intestine. Despite no probiotic folate-producers have been immobilized so far, the system has been developed with this goal and this work reports its stability and ability to release folate under gastro-intestinal conditions.Microcapsules were made of alginate with three consecutive coatings of poly-l-lysine, sodium alginate and chitosan. Turbidity experiments showed a strong electrostatic interaction between these polymers. Fourier transform infrared spectroscopy (FTIR) and confocal analysis showed the stability of the coating materials when applied on the microcapsules, even after they were immersed in solutions simulating conditions in the stomach and small intestine (i.e. pH 2, 60 min and pH 7.2, 120 min, respectively). Coated microcapsules have an average diameter size ranged from 20 and 40 μm, and swelled upon exposure to a neutral medium, without dissolution as showed by microscopy analyses. Release experiments proved the ability of the coated microcapsules to release folic acid, at different rates, depending on the applied coating. Release experiments showed that the first coating (Ɛ-PLL) is characterized by Fickian diffusion as the main release mechanism of folic acid. Fickian rate constant (k_F) decreased with the number of consequent coatings, reflecting the decrease of predominance of Fick's behavior. Results showed that the developed coated microcapsules have suitable characteristics for encapsulation of folic acid aiming in situ release in the intestine.     

负载纳米TiO2后锦纶织物的染色性能分析

为了探讨纳米TiO2对锦纶染色性能的影响,采用活性染料雷马素艳蓝R在相同条件下,对负载纳米TiO2和未改性锦纶织物进行染色,测试它们的上染百分率,并借助扫描电镜和热重测试手段对染色刷洗前后的试样表面形貌和热学性能进行表征,测试织物的漫反射光谱、耐刷洗色牢度、耐摩擦色牢度、耐日晒和光泽度等性能.结果表明,负载纳米TiO2后锦纶的上染百分率小于未改性锦纶;刷洗后,负载纳米TiO2锦纶上的TiO2颗粒部分脱落;纤维热起始分解温度有所下降;紫外线吸收能力明显增强;耐刷洗色牢度、耐摩擦色牢度均为5级;日晒后K/S值降幅较小;两者光泽性变化不大.     

Development of antibacterial fabrics by treatment with Ag-doped TiO2 nanoparticles

This paper deals with the antibacterial properties of nonwoven Co/PET and PP fabrics and woven cotton fabrics treated with the pad-dry-cure (PDC) and electrospray processes. Firstly, the surface modification of nonwoven Co/PET and PP fabrics was carried out to obtain their hydrophilicity by RF-plasma system using acrylic acid as the monomer. Subsequently, Ag-doped TiO₂ nanoparticles prepared by sol–gel and chemical reduction processes using titanium isopropoxide and silver nitrate as precursor were applied to the fabric samples by PDC and electrospray processes. The effect of different synthesis processes of the nanoparticles and various application processes on their antibacterial efficiency was investigated. After RF-plasma pretreatment, the absorbency properties of the fabric samples were measured. The antibacterial activity of fabric samples against Escherichia coli and Staphylococcus aureus was determined qualitatively and quantitatively according to AATCC Method 147 and AATCC Method 100, respectively. The microstructural characteristics and surface morphology of the fabric samples were investigated by SEM-EDX and FTIR-ATR analyses. These results suggest that Ag-doped TiO₂ nanoparticles synthesized by the chemical reduction process imparted good and durable antibacterial activity to nonwoven Co/PET and PP fabrics and woven cotton fabrics for use in wall textiles.     

用壳聚糖/纳米TiO2对毛针织物进行功能性整理

文章应用壳聚糖/纳米TiO2和固化剂形成的溶液对羊毛针织物进行功能性整理,对壳聚糖和纳米TiO2在羊毛上的吸附率、染色性能、织物上染率和固色率以及抗菌性等进行了测试.经过整理的羊毛织物,既可达到防缩可机洗的效果,又具有抗菌性能,其染色性能也得到了提高.     

Evaluation of the content of TiO2 nanoparticles in the coatings of chewing gums

Titanium dioxide is a metal oxide used as a white pigment in many food categories, including confectionery. Due to differences in the mass fraction of nanoparticles contained in TiO₂, the estimated intakes of TiO₂ nanoparticles differ by a factor of 10 in the literature. To resolve this problem, a better estimation of the mass of nanoparticles present in food products is needed. In this study, we focused our efforts on chewing gum, which is one of the food products contributing most to the intake of TiO₂. The coatings of four kinds of chewing gum, where the presence of TiO₂ was confirmed by Raman spectroscopy, were extracted in aqueous phases. The extracts were analysed by transmission electron microscopy (TEM), X-ray diffraction, Fourier Transform Raman spectroscopy, and inductively coupled plasma atomic emission spectroscopy (ICP-AES) to establish their chemical composition, crystallinity and size distribution. The coatings of the four chewing gums differ chemically from each other, and more specifically the amount of TiO₂ varies from one coating to another. TiO₂ particles constitute the entire coating of some chewing gums, whereas for others, TiO₂ particles are embedded in an organic matrix and/or mixed with minerals like calcium carbonate, talc, or magnesium silicate. We found 1.1 ± 0.3 to 17.3 ± 0.9 mg TiO₂ particles per piece of chewing gum, with a mean diameter of 135 ± 42 nm. TiO₂ nanoparticles account for 19 ± 4% of all particles, which represents a mass fraction of 4.2 ± 0.1% on average. The intake of nanoparticles is thus highly dependent on the kind of chewing gum, with an estimated range extending from 0.04 ± 0.01 to 0.81 ± 0.04 mg of nano-TiO₂ per piece of chewing gum. These data should serve to refine the exposure scenario.     

Application of gold nanoparticles/TiO2 modified electrode for the electrooxidative determination of catechol in tea samples

A gold nanoparticles/TiO(2) composite modified Indium tin oxide (ITO) electrode has been constructed to study the electrochemical behaviour of catechol (CC) and hydroquinone (HQ) using cyclic voltammetry and differential pulse voltammetry (DPV). Increasing of separation of the oxidative peak potentials and peak current for CC and HQ in pH 6.0 phosphate buffer solution (PBS), make it suitable for selected determination of CC. After the optimization of the conditions, CC was determined by DPV and the linear range is from 1.0×10(-7) to 5.0×10(-4) mol L(-1) with a correlation coefficient of 0.999 and limit of detection as 5.0×10(-8) mol L(-1). Interference and stability study showed a satisfactory result. The proposed method has been applied to determine catechol in tea samples, and comparing with the chromatography the results are satisfactory.     

Plasma surface modified TiO2 nanoparticles: improved photocatalytic oxidation of gaseous m-xylene

Titanium dioxide (TiO(2)) is a preferred catalyst for photocatalytic oxidation of many air pollutants. In an effort to enhance its photocatalytic activity, TiO(2) was modified by pulsed plasma treatment. In this work, TiO(2) nanoparticles, coated on a glass plate, were treated with a plasma discharge of hexafluoropropylene oxide (HFPO) gas. By appropriate adjustment of discharge conditions, it was discovered that the TiO(2) particles can be either directly fluorinated (Ti-F) or coated with thin perfluorocarbon films (C-F). Specifically, under relatively high power input, the plasma deposition process favored direct surface fluorination. The extent of Ti-F formation increased with increasing power input. In contrast, at lower average power inputs, perfluorocarbon films are deposited on the surface of the TiO(2) particles. The plasma surface modified TiO(2) nanoparticles were subsequently employed as catalysts in the photocatalytic oxidation of m-xylene in air, as carried out inside a batch reactor with closed loop constant gas circulation. Both types of modified TiO(2) were significantly more catalytically active than that of the unmodified particles. For example, the rate constant of m-xylene degradation was increased from 0.012 min(-1) with untreated TiO(2) to 0.074 min(-1) with fluorinated TiO(2). Although it is not possible to provide unequivocal reasons for this increased photocatalytic activity, it is noted that the plasma surface treatment converted the TiO(2) from hydrophilic to highly hydrophobic, which would provide more facile catalyst adsorption of the xylene from the flowing air. Also, based on literature reports, the use of fluorinated TiO(2) reduces electron-hole recombination rates, thus increasing the photocatalytic activity.     

氨基改性TiO2纳米颗粒的制备及其在抗菌抗老化聚酰胺纤维的应用

以钛酸丁酯为前驱体,采用溶胶-凝胶法制备TiO2纳米颗粒,并在TiO2表面接枝氨基化合物,提高其分散性。在己内酰胺原位聚合的过程中,将改性TiO2纳米颗粒加入到聚合体系,制备氨基改性TiO2纳米颗粒聚酰胺切片,切片经过熔融纺丝得到改性聚酰胺纤维。经测试表明,TiO2纳米颗粒经过氨基改性后可提高聚酰胺纤维的抗菌和抗老化性能。     

Permeable environmental leaching capsules (PELCAPs) for in situ evaluation of contaminant immobilization in soil

We encapsulated radioisotope-spiked soil within a water-permeable polyacrylamide matrix cast in a small cylindrical geometry (approximately to 5 cm3) to measure the persistence of immobilized soil contaminants. As a proof-of-principle, soils contained within these permeable environmental leaching capsules (PELCAPs) were labeled with either 85Sr or 134Cs and were leached in both laboratory tests and continuously in situ with ground and streamwaters at two field sites on the Oak Ridge reservation. Groups of PELCAPs were retrieved, assayed nondestructively for radioisotopes via gamma spectroscopy, and then replaced in ground and surface water repeatedly over a 6-month period. PELCAPs that contained no soil readily and quantitatively leached either 85Sr or 134Cs into laboratory extractants or ground or surface water with effective diffusion coefficients (D(eff)) of (1.14 +/- 0.06) and (4.8 +/- 0.2) x 10(-6) cm2/s, respectively. PELCAPs containing untreated soil readily leached > 90% of 85Sr but < 1% of 134Cs during field leaching at both sites, whereas thermally treated soils quantitatively retained both isotopes under all conditions. Permeable polymer encapsulation methods, such as PELCAPs, offer the potential capability to conveniently test large numbers of soils and soil treatments for contaminant release and uptake under actual field environmental conditions.     

In situ Fenton reagent generated from TiO2/Cu2O composite film: a new way to utilize TiO2 under visible light irradiation

TiO2/Cu2O composite is prepared by a simple electrochemical method and coated on glass matrix through a spraying method. The obtained composite is characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of TiO2/Cu2O composite films with different ratio of TiO2 and Cu2O on photodegradation of the dye methylene blue under visible light is investigated in detail. It is found that the photocatalytic activity of TiO2/Cu2O composite film with the presence of FeSO4 and EDTA is much higher than that for the similar system with only TiO2 and Cu2O film respectively. Without the presence of FeSO4 and EDTA, there is no degradation for methylene blue. The exploration of the optimized parameters for the degradation of methylene blue by using TiO2/Cu2O composite film as catalyst under visible light was also carried out. The most significant factor is the amount of Ti02 in the composite, and the second significant factor is the concentration of FeSO4. During the degradation of methylene blue under visible light, TiO2/Cu2O composite film generates H202, and Fenton regent is formed with Fe2+ and EDTA, which is detected in this study. The mechanism for the great improvement of photocatalytic activity of TiO2/Cu2O composite film under visible light is proposed by the valence band theory. Electrons excitated from TiO2/Cu2O composite under visible light are transferred from the conduction band of Cu2O to that of Ti02. The formed intermediate state of Ti 3+ ion is observed by X-ray photoelectron spectroscopy (XPS) on the TiO/Cu2O composite film. Additionally, the accumulated electrons in the conduction band of TiO2 are transferred to oxygen on the TiO2 surface for the formation of O2- or O2(2-), which combines with H+ to form H2O2. The evolved H202 with FeSO4 and EDTA forms Fenton reagentto degrade methylene blue. Compared to the traditional Fenton reagent, this new kind of in situ Fenton reagent generated from TiO2/Cu2O composite film does not need to supply H202. It is expected to be easily recycled, which may reduce second pollution and the cost of wastewater treatment. Moreover, this TiO/Cu2O composite film with FeSO4 and EDTA provides a new way to take advantage of TiO2 under visible light.     

银纳米颗粒/二氧化钛/醋酸纤维素复合纤维的制备及其性能

以纳米TiO_2和Ag NO_3为添加剂,通过静电纺丝装置,成功制备了一种高性能抗菌复合纳米纤维。采用扫描电子显微镜、X射线能谱分析和琼脂平皿扩散法等手段对样品的形貌、纳米粒子的分布、化学态、抗菌性能等进行表征与分析。结果表明:Ag NO_3和TiO_2的质量分数都会对纤维的形貌产生影响,需选择合适的添加范围;在纤维中,醋酸纤维素中的氧原子与Ag之间存在着相互作用;银纳米颗粒的存在,使纤维在可见光区出现明显的吸收峰;银纳米颗粒和TiO_2良好的协同作用使纤维对大肠杆菌和金黄色葡萄球菌具有很好的抗菌效果。     

Recognition and effective degradation of 17beta-estradiol by anti-estradiol-antibody-immobilized TiO(2) nanoparticles

Polyelectrolyte polyacrylic acid (PAA), used in the chemical modification of titanium dioxide (TiO(2)) nanoparticles, allows TiO(2) nanoparticles to remain in suspension at neutral pH. The anti-17beta-estradiol (E2) antibody was immobilized on PAA-modified TiO(2) (PAA-TiO(2)) nanoparticles via covalent bonding between the carboxylic acid of PAA and the amino group of the antibody. The anti-E2-antibody-immobilized TiO(2) (E2Ab-PAA-TiO(2)) nanoparticles can form a suspension at neutral pH, with a particle size of less than 100 nm. The E2-PAA-TiO(2) nanoparticles caused the photocatalytic degradation of a typical TiO(2) substrate, methylene blue. The anti-E2 antibody immobilized on the TiO(2) surface recognized and bound E2 in the solution, thereby improving the efficiency of E2 degradation compared with that of PAA-TiO(2) nanoparticles. These results demonstrate that the E2Ab-PAA-TiO(2) nanoparticles developed in this study can be used in water treatment technology. Furthermore, this strategy of immobilizing proteins on nanoscale TiO(2) particles creates new applications not only in the treatment of environmental waste, but also in medical and public sanitation processes.     

A simple gold plate electrode modified with Gd-doped TiO2 nanoparticles used for determination of trace nitrite in cured food

A simple gold plate electrode (GPE) based on a gadolinium-doped titanium dioxide (Gd/TiO₂) ultrathin film was successfully constructed by using a surface sol-gel technique, and used for the detection of trace amounts of nitrite in cured foods. The Gd/TiO₂ nanoparticles were synthesised and characterised via scanning electron microscopy (SEM) and X-ray diffraction (XRD), indicating that the Gd-doped TiO₂ formed an anatase phase through roasting at 450°C, generating actively interstitial oxygen at the interface of the surface of TiO₂ lattice surrounded by Gd³⁺. The electro-catalytic effect for oxidation of nitrite on the modified electrode was investigated by cyclic voltammetry in 0.10?mol?l^?1 sulfuric acid media solution, showing that the modified electrode exhibited excellent response performance to nitrite with good reproducibility, selectivity and stability. The catalytic peak current was found to be linear with nitrite concentrations in the range of 8.0?×?10^?7 to 4.0?×?10^?4??mol?l^?1, with a detection limit of 5.0?×?10^?7?mol?l^?1 (S/N?=?3). The modified electrode could be used for the determination of nitrite in the cured sausage samples with a satisfactory recovery in the range of 95.5–104%, showing its promising application for food safety monitoring.     

Effect of TiO2 nanoparticles on basalt/polysiloxane composites: mechanical and thermal characterization

In the present investigation, a novel technique has been developed to fabricate composite materials containing TiO₂ nanoparticles, polysiloxane resin, and basalt fabric. A high-intensity ultrasonic probe was used to obtain a homogenous molecular mixture of TiO₂ nanoparticles and polysiloxane resin, thus the nanoparticles were infused into the resin through sonic cavitation. The loading effect of TiO₂ nanoparticles on the thermal and mechanical properties of basalt fabric reinforced polysiloxane composite materials has been investigated. Composite samples were prepared, each using two layers of basalt fabric with TiO₂ nanoparticles loading from 0.5, 1, 1.5, 2, 2.5, and 3% by weight. Size distribution of nanoparticles was observed by particle size analyzer and the prepared fabric nanocomposites were characterized by scanning electron microscopy, dynamic mechanical analysis (DMA), thermo gravimetric analysis (TGA), and differential scanning calorimetry (DSC). Tensile testing was performed as per American standard for testing of materials (ASTM) standards. The dependence of dynamic mechanical parameters E′, E′′, tan (delta), T _g, and heat distortion temperature (HDT) are associated with the filler content and can be controlled by the curing conditions. Tensile results show that 1.5 wt.% loading of TiO₂ nanoparticles in the nanocomposites resulted in highest improvement in tensile modulus compared to the neat system. DMA studies also revealed that 1.5 wt.% doped system exhibits highest storage modulus as compared to the neat and other loading percentages. DSC and TGA studies show that T _g and HDT of the composite increases with the increase in wt.% of nanofillers in the composite. Based on these results, it is clear that miscibility of nanoparticles in the resin is of prime importance with regard to performance.     

Ni2+-Co2+共掺杂TiO2光催化降解制浆黑液的研究

通过sol-gel法制备掺杂Ni2 、Co2 和Ni2 -Co2 共掺杂的纳米TiO2,利用X-射线衍射(XRD)、透射电子显微镜(TEM)和紫外-可见光谱(UV-Vis)对样品进行表征.结果表明:400℃时,粒子平均粒径为10nm左右,Ni2 、Co2 离子共掺杂抑制纳米TiO.晶粒的成长,使TiO2的光谱响应范围向可见光拓展.在紫外光照射下,Ni2 、Co2 离子共掺杂的TiO2能有效提高光催化降解制浆蒸煮黑液的效果,反应8h,体系中的CODCr可由反应前的480mg/I降至192mg/l,色度去除率可达到88.7%.     

Role of the air-water interface in the retention of TiO2 nanoparticles in porous media during primary drainage

The increasing use of nanomaterials in commercial products has resulted in increased concerns about their potential environmental impacts. The overall mobility of nanomaterials in the environment may depend in part on their mobility in the unsaturated zone of the subsurface, which may provide a sink for nanomaterials, preventing their spread, or a long-term contaminant source. The objective of this work was to study the dynamic unsaturated transport of titanium dioxide (TiO2) during primary drainage to examine the role of air-water interface formation on nanomaterial retention. A specialized automated system was used to track depletion of TiO2 in the pore solution of a porous medium during dynamic drainage, while simultaneously measuring capillary pressure (Pc) and saturation (S). A continuous mass balance was used to calculate the mass of retained TiO2 nanoparticles. Experiments were specifically designed to minimize TiO2 interactions with solid surfaces to allow direct assessment of the role of the air-water interface. Results indicate that the mass of retained TiO2 increases as saturation decreases at all drainage rates, with slower drainage rates corresponding to greater retention at a given saturation. Normalizing the retained mass (M) bythe measured air-water interfacial area (A) shows near-constant M/A values at high saturations (S > 0.4) and increasing M/A values with decreasing saturation as saturation drops below 0.4. This result may indicate air-water interfacial adsorption at high saturations, with increasing contributions from film straining at lower saturations.