用等离子体改性淀粉膜的处理条件分析

利用等离子体对淀粉膜进行表面改性,通过测量改性后丙烯酸接枝率,分析了等离子体放电功率、放电时的气压、放电时间和放电后静置时间对淀粉膜改性效果的影响.结果表明,丙烯酸接枝率在2.0%～7.0%之间;接枝率随等离子体放电功率增加有增加趋势,随真空腔气压升高呈下降趋势,随等离子体处理时间增加呈先增加后逐渐饱和态势,随静置时间延长呈下降趋势,且时间过长会大幅衰减,接枝率趋向于零.     

多孔TiO2薄膜在PET纤维上的负载及其光催化性能

采用浸渍法将低温制备的TiO2溶胶在普通和碱减量PET纤维上负载成膜,并以聚苯乙烯（PS）微球为模板剂使TiO2膜多孔化,制备了一系列TiO2/PET光催化纤维。采用XRD、SEM对TiO2和纤维进行了表征,并通过对甲基橙的降解来考察其光催化性能。结果表明：溶胶经室温陈化后可得到具有较高光催化活性的纳米锐钛矿型TiO2。PET纤维上TiO2的负载率随着溶胶在浸渍液中的含量增加而增大。PET纤维的碱减量有利于TiO2的负载和光催化活性的提高,且随着TiO2负载率的增加,甲基橙降解率具有先增加后缓慢减小的趋势。当碱减量纤维的TiO2负载率为4.2%时,光催化活性最好。利用PS为模板剂使TiO2薄膜多孔化可以进一步提高光催化纤维的比表面积和吸附能力,从而提高光催化活性。     

Surface coating of silver nanoparticles on polyethylene for fabrication of antimicrobial milk packaging films

In this study, antimicrobial packaging films were prepared by coating silver (Ag) nanoparticles onto the surface of low density polyethylene (LDPE) films modified by corona air plasma. The possibility of these films for use in the packaging of milk was studied. The influence of input power of the corona discharge treatment on the surface modification and performance of the fabricated Ag/LDPE nanocomposite films was also investigated. The prepared antimicrobial packaging films showed promising antimicrobial efficiency against micro‐organisms that are present in milk and were able to increase the microbial shelf life of the milk. Packages fabricated at corona input powers of 210, 500 and 800 W reached the maximum limit after 5, 8 and 14 days (respectively).     

Impact of aggregate size and structure on the photocatalytic properties of TiO2 and ZnO nanoparticles

Aggregation of photocatalytic semiconductors was determined to reduce the generation of free hydroxyl radicals in aqueous suspensions in a fashion dependent on aggregate size and structure. Static light scattering measurements were used to follow temporal changes in the fractal dimension of aggregating TiO(2) and ZnO nanoparticles. At length scales comparable to nanoparticle size, the structure of aggregated TiO(2) nanoparticles was independent of particle stability and the associated aggregation rate, consistent with the fused nature of TiO(2) primary particles in the initial suspension. In contrast, ZnO aggregates were characterized by smaller fractal dimensions when ionic strength, and the resulting aggregation rate, were increased. The photocatalytic activity of ZnO and TiO(2) in generating free hydroxyl radicals varied with aggregate structure and size, consistent with theory that predicts reduced reactivity as aggregates become larger and more dense.     

Secondary organic aerosol coating of synthetic metal-oxide nanoparticles

Secondary organic aerosol (SOA) from the α-pinene + ozone reaction readily coats TiO(2) and CeO(2) metal-oxide nanoparticles in smog-chamber experiments under atmospherically relevant conditions. Otherwise identical experiments compared bare nanoparticles and nanoparticles coated with poly(acrylic acid) (PAA). The PAA-coated particles result in significantly higher new-particle formation rates, suggesting that the SOA vapors coat bare metal oxide more readily than the PAA. After particles begin to grow via SOA coating, however, all particles, independent of size or the presence of a metal-oxide core, grow with a rate proportional to their surface area, modified to account for gas-phase diffusion in the transition regime between the kinetic and bulk-flow regimes. This suggests that SOA condensational growth may be modeled based on the size distribution of the condensational sink in the atmosphere.     

银/二氧化钛可见光催化自清洁织物的制备及其性能

为制备基于可见光光催化降解机制的自清洁织物,吡咯(Py)为单体,以硝酸银为银源,通过化学氧化聚合在商业化的纳米二氧化钛(TiO2 )表面形成聚吡咯掺杂银包覆层(PPy-Ag/ TiO2 ),然后高温焙烧去除PPy,获得可见光响应催化剂银/ 二氧化钛(Ag/ TiO2 )。通过共分散溶液用浸渍涂覆法将其涂覆到聚丙烯腈(PAN)纤维上,经加捻、合股织制成织物。借助扫描电子显微镜、红外光谱分析仪、热重分析仪、紫外可见分光光度计等测试织物的结构和性能。结果表明：Ag/ TiO2 粒子较均匀地负载到PAN 纤维表面,其负载率约为3. 17%;涂覆Ag/ TiO2 的织物对亚甲基蓝、罗丹明B 和红酒在可见光下具有良好的降解作用,表现出良好的自清洁效果;经多次洗涤后,该织物仍保持良好的光催化效果,具有良好的耐洗牢度。     

ZrO2-modified mesoporous nanocrystalline TiO2-xNx as efficient visible light photocatalysts

Mesoporous nanocrystalline TiO2-xNx and TiO2-xNx/ZrO2 visible-light photocatalysts have been prepared by a sol-gel method. The photocatalysts were characterized by XRD, N2 adsorption-desorption, TEM, XPS, UV/Vis, and IR spectroscopy. The photocatalytic activity of the samples was evaluated by the decomposition of ethylene in air under visible light (lambda > 450 nm) illumination. Results revealed that nitrogen was doped into the lattice of TiO2 by the thermal treatment of NH3-adsorbed TiO2 hydrous gels, converting the TiO2 into a visible-light responsive catalyst. The introduction of ZrO2 into TiO2-xNx considerably inhibits the undesirable crystal growth during calcination. Consequently, the ZrO2-modified TiO2-xNx displays higher porosity, higher specific surface area, and an improved thermal stability over the corresponding unmodified TiO2-xNx samples.     

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.     

Transparent thin-film TiO2 photocatalysts with high activity

A transparent, thin-film TiO2 layer prepared by sol-gel deposition is shown to be more active for photocatalytic oxidation (PCO) of acetaldehyde, acetic acid, and toluene than Degussa P25 thin films. The sol-gel TiO2 adsorbs 30-70% less organic, but the PCO activity per adsorbed molecule is 3.5-8.5 times higher on the sol-gel TiO2 than on Degussa P25. In addition, less-reactive intermediates do not appear to form as readily on the sol-gel catalyst as they do on Degussa P25, and thus the sol-gel catalyst deactivates slower during toluene PCO. Rates were measured in transient experiments for a monolayer of adsorbed organic, and transient experiments are shown to be an effective way to measure rates, selectivities, surface coverages, and formation of less-reactive intermediates in the same set of experiments.     

Improvement of catalyst durability by deposition of Rh on TiO2 in photooxidation of aromatic compounds

Gas-solid heterogeneous photocatalytic oxidation of aromatic compounds in air was carried out at room temperature with a fixed bed flow reactor. The deposition of Rh on TiO2 catalyst improved the catalyst durability in benzene photooxidation. The Rh deposition reduced the amounts of carbonaceous materials on the catalyst surface that were the cause of catalyst deactivation. The highest reaction rate was obtained at the Rh loading of 0.5-1.0 wt %. The Rh/TiO2 catalyst was gradually deactivated in prolonged benzene photooxidation, due to the increasing amount of carbonaceous materials on the catalyst surface. XPS studies showed that the gradual deactivation was related to the changes in the oxidation state of the surface Rh metals. The catalysts were regenerated by the treatment of hydrogen reduction after the photoirradiation in humidified air, indicating that Rh(0) was essential for the improvement of the catalyst durability. The catalyst was also regenerated by the heat treatment in N2 flow instead of the hydrogen reduction. Rh deposition was also effective for the improvement of catalyst durability in toluene photooxidation.     

TiO_2薄膜的制备及对罗丹明B光催化分解过程的影响

采用sol gel法在玻璃表面制备了TiO2 薄膜 .X射线衍射表明 ,该薄膜的结构为锐钛矿型 .通过考察罗丹明B的光催化分解过程 ,发现TiO2 薄膜对罗丹明B的光催化分解有很好的活性 ,可以完全分离罗丹明B .通过考察罗丹明B在TiO2 薄膜上的吸附性 ,发现当薄膜吸附罗丹明B达到一定量时 ,脱乙基反应将与降解反应同时发生     

Reactivity enhancement of 2-propanol photocatalysis on SO4(2-)/TiO2: insights from solid-state NMR spectroscopy

Solid-state NMR techniques have been employed to investigate the surface acidic properties of TiO2 and sulfated TiO2, as well as their photocatalytic activities toward 2-propanol. The multinuclear MAS NMR experiments clearly revealed that three different types of Br?nsted acid sites with much stronger acid strength were generated after the sulfation of TiO2. Due to the enhanced Br?nsted acidity, the protonation of 2-propanol can occur more easily, preferentially leading to the formation of Ti-bound 2-propoxy species on the SO42-/TiO2 catalyst The 2-propoxy species can be directly converted to CO2 and thus the photocatalytic activity of sulfated TiO2 catalyst is remarkably enhanced. For comparison, both hydrogen-bonded 2-propanol and Ti-bound 2-propoxy species are present on the TiO2 catalyst with the former being predominant The hydrogen-bonded 2-propanol species are oxidated into acetone molecules that are difficult to further convert into CO2, and the conversion of 2-propoxy species to 2-propanol hampers the direct mineralization of 2-propoxy species on the TiO2 catalyst.     

Photocatalytic surface reactions on indoor wall paint

The reduction of indoor air pollutants by air cleaning systems has received considerable interest, and a number of techniques are now available. So far, the method of photocatalysis was mainly applied by use of titanium dioxide (TiO2) in flow reactors under UV light of high intensity. Nowadays, indoor wall paints are equipped with modified TiO2 to work as a catalyst under indoor daylight or artificial light. In chamber experiments carried out under indoor related conditions itwas shown thatthe method works for nitrogen dioxide with air exchange and for formaldehyde without air exchange at high concentrations. In further experiments with volatile organic compounds (VOCs), a small effect was found for terpenoids with high kOH rate constants. For other VOCs and carbon monoxide there was no degradation at all or the surface acted as a reversible sink. Secondary emissions from the reaction of paint constituents were observed on exposure to light. From the results it is concluded that recipes of photocatalytic wall paints need to be optimized for better efficiency under indoor conditions.     

On the preparation of TiO2-sepiolite hybrid materials for the photocatalytic degradation of TCE: influence of TiO2 distribution in the mineralization

Hybrid structured photocatalysts based on sepiolite, an adsorbent, and TiO2 were prepared by extrusion of ceramic dough and conformed as plates. The influence of the photocatalyst configuration was studied either by including TiO2 in the extrusion process (incorporated materials) or by coating the sepiolite plates with a TiO2 film (coated materials). The influence of the OH- surface concentration in the photocatalytic performance was studied by treating the ceramic plates at different temperatures. The samples were characterized by N2 adsorption-desorption, MIP, SEM, XRD, and UV-vis-NIR spectroscopy and tested in the photocatalytic degradation of trichloroethylene (TCE) as a target VOC molecule. Most of the catalysts presented high photoactivity, but considerable differences were observed when the CO2 selectivity was analyzed. The results demonstrate that there is a significant effect of the catalyst configuration on the selectivity of the process. An intimate contact between the sepiolite fibers and TiO2 particles for incorporated materials with a corncob-like structure favored the migration of nondesirable reaction products such as COCl2 and dichloroacetyl chloride (DCAC) to the adsorbent, reacting with OH- groups of the adsorbent and favoring the TCE mimeralization.     

Antifungal activity of TiO2 photocatalysis against Penicillium expansum in vitro and in fruit tests

The antifungal activity of TiO2 photocatalytic reaction in the form of TiO2 powder and TiO2 coated on a plastic film against Penicillium expansum was investigated in vitro and in fruit tests. The mixture of P. expansum conidial suspension and TiO2 powder was added to potato dextrose agar (PDA) plates for vitro test. The TiO2 photocatalytic reaction reduced conidial germination of the fungal pathogen. It was found that the ability of the TiO2 photocatalytic reaction to suppress P. expansum growth correlated to the amount of TiO2 added. Lower numbers of viable colonies of P. expansum were observed with increasing amount of TiO2. Regardless of the kind of selected fruit inoculated with P. expansum, both TiO2 powder and TiO2-coated film exhibited antifungal activity to control fruit rot. Development of Penicillium rot in apple was significantly (P = 0.05) retarded by the TiO2 photocatalytic reaction. Similarly the TiO2 photocatalytic reaction was the only treatment where no tomato fruit rot was noticeable after 1 week of storage. TiO2-coated film also decreased brown lesions and Penicillium rot infection in lemons. The mean severity fruit rot scores (browning and softening flesh) were 3.2 and 1.9 for uncoated and TiO2-coated film, respectively. Our findings suggest that "TiO2 photocatalytic reaction" shows antifungal activity against P. expansum which may have potential for postharvest disease control.     

溅射功率对沉积纳米TiO2织物光催化性能的影响

室温条件下采用直流磁控反应溅射技术在涤纶纺粘非织造织物表面生长二氧化钛（TiO2）薄膜。采用X射线光电子能谱仪、X射线衍射仪和原子力显微镜对不同溅射功率条件下所制备TiO2薄膜的结构和表面形貌进行表征,研究溅射功率对薄膜沉积速率以及沉积纳米TiO2织物光催化性能的影响。实验表明：在一定范围内,溅射功率对沉积薄膜的化学结构影响不大,但溅射功率增加,薄膜的沉积速率和溅射效率提高,薄膜均匀性、致密性增加,沉积纳米TiO2织物光催化性能提高。但过高的溅射功率使靶材出现过温,不仅使薄膜沉积速率降低,均匀性下降,而且易损伤靶材。     

Pd修饰TiO2光催化材料在棉织物中的应用

为提高棉织物表面TiO2的光催化效果,以棉针织物为载体,纳米羟基磷灰石（HAP）为保护剂,纳米TiO2为光催化剂,实践Pd对光催化剂的表面改性,制备具有光催化功能的纺织装饰材料。并采用扫描电镜、气相色谱等测试手段,对整理剂在织物表面的沉积状况、织物对甲醛的催化降解效率等进行测试和分析。结果表明：经过Pd表面改性后,织物表面TiO2的光催化效果得到明显的改善,较改性前提高了49%,并具有很好的紫外防护效果;纳米HAP整理对织物表面光催化剂具有一定的吸附效果。     

Dramatic visible photocatalytic degradation performances due to synergetic effect of TiO2 with PANI

The dramatic visible light photocatalytic activity was obtained for the degradation of Methylene Blue (MB) and Rhodamine B (RhB) under visible light irradiation (lambda > 450 nm) after TiO2 photocatalysts were modified with monolayer dispersed polyaniline (PANI) via a facile chemisorption approach. Under visible light irradiation, PANI generated pi-pi* transition, delivering the excited electrons into the conduction band of TiO2, and then the electrons transferred to an adsorbed electron acceptor to yield oxygenous radicals to degrade pollutants. Also, the ultraviolet photocatalytic performance was enhanced to about two times compared with that of P-25 TiO2 photocatalyst. The high photocatalytic activity came from the synergetic effect between PANI and TiO2, which promoted the migration efficiency of photogenerated carriers on the interface of PANI and TiO2. Under ultraviolet light irradiation, photoinduced holes in TiO2 valence band could transfer into HOMO orbital of PANI and then emigrate to the photocatalyst surface and oxidize the adsorbed contaminants directly. The optimum synergetic effect was found at a weight ratio of 3.0 wt % (PANI/ TiO2).     

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.     

Substrate-specific photocatalytic activities of TiO2 and multiactivity test for water treatment application

The multidimensional aspects of the photocatalytic activity were investigated in a systematic way. The photocatalytic activities of eight commercial TiO2 samples were quantified by employing 19 test substrates (phenols, organic acids, amines, chlorohydrocarbons, dyes, inorganic ions, etc.) in terms of their degradation or conversion rates in water. The measured activities exhibited a complex behavior that depends on the test substrate. The photocatalytic activities are roughly correlated only among structurally related compounds. The photocatalytic activities can be represented in many different ways, and even the relative activity order among the tested photocatalysts depends on what substrate is used. Each TiO2 (among eight samples) showed the best activity for at least one test-substrate. This highly substrate-specific activity of TiO2 photocatalysts hinders the straightforward comparison of which catalyst is better than others. Even the common belief that anatase is more photoactive than rutile cannot be fully supported on the basis of the present data set. Although there seems to be no simple correlation between the activity and the common physicochemical parameters of photocatalysts, the substrate-specific activity was analyzed and discussed in terms of various parameters such as surface area, crystallinity, surface charge, and substrate adsorption. Finally, the multivalue photocatalytic activity test in relation with water treatment application was proposed to take the substrate-specificity into account.