Synergistic effect of hydrogen peroxide production and sonochemiluminescence under dual frequency ultrasound irradiation

The synergistic effect of H(2)O(2) production and sonochemiluminescence (SCL) was studied under both orthogonal and opposite dual irradiation at the frequencies of 28, 584 and 970 kHz and at various acoustic powers. The largest reduction in H(2)O(2) production was observed under opposite dual irradiation at a 28/28 kHz frequency without considering the acoustic power levels. The largest enhancement was observed under dual irradiation at a frequency of 28/970 kHz. This enhancement might be due to the increased number of bubbles that underwent violent collapse by low frequency ultrasound (28 kHz). These results were also confirmed by observing the SCL. Under dual irradiation at relatively high frequencies (i.e., 584 and 970 kHz), the synergistic effect was high at low acoustic power levels. However, the effect tended to decrease (to the equivalent of the calculation from the result of each single irradiation) with increasing acoustic power. Unlike dual irradiation coupled with a frequency of 28 kHz, the inhibition effect was not observed under dual irradiation at relatively high frequencies. With respect to H(2)O(2) production, the production rate constants of H(2)O(2) followed the order of 584/584>584/970>28/970≈28/584>28/28 kHz, which resulted from the fact that the production efficiency of H(2)O(2) at an irradiation frequency of 584 kHz was considerably higher than that at other frequencies.     

Enhancement of saccharin removal from aqueous solution by activated carbon adsorption with ultrasonic treatment

This study investigates the use of ultrasonication as a pretreatment process and its effect on the adsorption characteristics of saccharin onto activated carbon (AC). Ultrasonic decomposition of saccharin was performed at a frequency of 500 kHz under argon and O2/N2 (20/80 vol%) atmospheres. Adsorption was carried out using a commercial activated carbon. The behavior of total organic carbon (TOC) during ultrasonication was investigated. Saccharin removal after 180 min of ultrasonication under Ar and O2/N2 atmospheres are 38% and 26%, respectively, while the amount of saccharin removed by activated carbon adsorption without US pretreatment is 40% after 16 h. After 16 h of AC adsorption with 180 min of ultrasonic pretreatment under Ar and O2/N2 atmospheres, both removal ratios increased to 75%. These results indicated that the pretreatment of sonication under O2/N2 leads to the increase in the amount of saccharin adsorbed on AC. On the other hand, the TOC removal by decomposition by ultrasound is not more than 5% in both Ar and O2/N2 atmospheres after 180 min ultrasonication. However, the TOC removal increased to 54% and 69% after 16 h of adsorption of saccharin pretreated by ultrasonication for 180 min under Ar and O2/N2 atmospheres, respectively. About 13% and 16% TOC removal in Ar and in O2/N2, respectively, were achieved due to adsorption of the by-products. It is considered that the improvement in TOC removal is also brought about by the formation of the by-products that were adsorbed onto AC.     

水热法制备In2O3/ZnO异质结及其高的光催化性能

采用简单的两步水热法合成了不同In₂O₃质量比的In₂O₃/ZnO异质结复合材料．通过X射线衍射仪(XRD)、紫外-可见分光光度计(UV-vis)和扫描电子显微镜(SEM)对复合材料的结构、形貌和性能进行了表征．同时还使用UV-vis分光光度计测试了异质结降解罗丹明B(RhB)的光催化活性．实验结果表明,与纯ZnO和In₂O₃相比,In₂O₃的引入将ZnO的吸收光谱扩展到可见光区域,从而提高了其光生电子和空穴的分离．此外,In₂O₃/ZnO异质结在可见光照射对RhB具有较高的光催化活性．5 wt%-In₂O₃/ZnO异质结对RhB的降解率为84.3%,且具有良好的光催化稳定性．In₂O₃/ZnO异质结复合材料在有机染料废水的降解中有更广阔的应用前景．     

Influence of particles on sonochemical reactions in aqueous solutions

Numerous publications deal with the possible application of ultrasound for elimination of organic pollutants as a tool for water pollution abatement. Most of the experiments were performed in pure water under laboratory conditions. For developing technologies that hold promise it is necessary to investigate the effect of ultrasound in natural systems or waste water where particulate matter could play an important role. In this paper the influence of quartz particles (2-25 microm) on the chemical effects of ultrasound in aqueous system using a high power ultrasound generator (68-1028 kHz, 100 W, reactor volume 500 ml) is reported. In pure water in dependence on particle size, concentration and frequency the formation rate of hydrogen peroxide under Ar/O2 (4:1) shows a maximum using 206 kHz in presence of 3-5 microm quartz particles (4-8 g/l). Under these conditions the yield of peroxide is higher than without quartz. Additionally under N2/O2 (4:1) besides hydrogen peroxide the formation of nitrite/nitrate was measured. Compared to pure water quartz particle depressed the formation of nitrite/nitrate up to 10-fold but not the formation of H2O2. According to the results of H2O2 formation the elimination of organic compounds by sonolysis (206 kHz) and the influence of quartz particles were investigated. As organic compounds salicylic acid, 2-chlorobenzoic acid and p-toluenesulfonic acid were used. The influence of quartz on the oxidation of organic compounds (206 kHz) is similar to that on the formation of H2O2.     

一种新颖的稀土-2-羟基烟酸的配合物的结构和光谱性质研究

通过水热反应合成了一种新颖的稀土2-羟基烟酸的配合物{[LaL(HL)(H2O)3]1/3(SO4)2/3(H3O)2H2O}(H2L=2-hydroxynicotinic acid)。X-ray单晶衍射分析可知,2-羟基烟酸通过羧基O和羟基O原子桥连La离子,形成二维层状结构,层与层之间通过弱作用力拓展为三维结构。二维相关光谱分析表明N—H面外弯曲振动和C—H面外弯曲振动对磁微扰比较敏感,这可能是吡啶环上π电子云在磁微扰下变形引起C—H和N—H面外弯曲振动的响应,SO24-的ν4振动和羧基不对称伸缩振动对磁微扰也比较敏感;热微扰下N—H伸缩振动比较敏感。此外还对化合物进行了紫外和热重分析。     

A novel one-step electron beam irradiation method for synthesis of Ag/Cu2O nanocomposites

In this paper, a novel method for fabrication of silver/cuprous oxide (Ag/Cu₂O) nanocomposites is reported. The method involves the reduction of Ag⁺ and Cu²⁺ in the aqueous solution to Ag/Cu₂O without adding any reducing reagent under electron beam (EB) irradiation. Dye methyl orange is used as the pollutant model to investigate the photocatalytic properties of these nanocomposites. The results reveal that they have higher photocatalytic efficiencies than that of Cu₂O under visible light. These visible light-sensitive catalysts may have potential application in the field of environmental remediation.     

ZnO/Cu_2O异质结纳米阵列制备及光催化性能

利用湿化学法在FTO玻璃基底上制备了高度规整的ZnO纳米棒阵列(ZnO NRAs),以此为衬底,采用磁控溅射法在ZnO NRAs表面沉积Cu_2O薄膜。分别用X射线衍射仪、X射线光电子能谱、扫描电镜、光致光谱、紫外可见分光光度计和电化学工作站对样品的物相、形貌、吸收光谱、光电性能进行了表征,用甲基橙(MO)模拟有机物废水研究复合材料的光催化性能。结果表明:ZnO纳米棒为六方纤锌矿结构,其直径约为80~100 nm,长约2~3μm,棒间距约100~120 nm。立方晶系的Cu_2O颗粒直径约为100~300 nm,形成致密膜层并紧密覆盖在ZnO NRAs表面上,构成ZnO/Cu_2O异质结纳米阵列(ZnO/Cu_2O HNRAs)结构。与纯ZnO NRAs和Cu_2O相比,ZnO/Cu_2O HNRAs在可见光范围内的吸收显著增强,吸收波长向可见光方向偏移。ZnO/Cu_2O HNRAs的载流子传递界面的电荷转移速度快,有效促进了光生电子和空穴的分离。在紫外-可见光照射65 min后,ZnO/Cu_2O HNRAs的降解效率为94%,分别是纯ZnO NRAs和Cu_2O的18倍和1.7倍。     

ErP5O14非晶中从0秒到稳态的粒子数变化过程和发光强度

分别对五磷酸盐非晶材料(ErP5O14)在979.3,803.8,521.8,450.0,405.5和378.5nm等光激发下所有能级的动力学过程在改进能量传递理论前后进行了数值模拟比较。结果发现,应用改进后的能量传递速率进行计算模拟的结果才是合理的,其中在521.8,450.0和378.5nm光激发ErP5O14非晶时,4I 13/2→4I 15/2和4I 11/2→4I 15/2跃迁的相对荧光强度的比值分别是979.3nm光激发的2.11倍,2.82倍和2.99倍,均存在有效的4I 13/2→4I 15/2跃迁的红外量子剪裁效应。该研究对于提高锗太阳能电池的转换效率具有潜在的应用前景。     

Origin of the relaxor state in Pb(B{x}B{1-x}{'})O(3) perovskites

Molecular dynamics simulations of first-principles-based effective Hamiltonians for Pb(Sc{1/2}Nb{1/2})O(3) under hydrostatic pressure and for Pb(Mg{1/3}Nb{2/3})O(3) at ambient pressure show clear evidence of a relaxor state in both systems. The Burns temperature is identified as the temperature below which dynamic nanoscale polar clusters form, pinned to regions of quenched chemical short-range order. The effect of pressure in Pb(Sc{1/2}Nb{1/2})O(3) demonstrates that the stability of the relaxor state depends on a delicate balance between the energetics that stabilize normal ferroelectricity and the average strength of random local fields which promote the relaxor state.     

水在金属氧化物表面的吸附与解离

水(H2O)由H原子和O原子组成.地球上有大量的水,若能找到一种经济、实用的方法将H2O解离生成H2和O2,则在新能源的开发和应用方面,意义深远.水在固体表面的吸附现象极为普遍,在某些金属或金属氧化物表面,H2O被吸附并解离成OH-和H+.文章以有序氧化镁(MgO(100))薄膜和Pd/MgO(100)体系为例,在超高真空条件下,用光电子能谱和高分辨电子能量损失谱方法,研究了水在它们表面的吸附与解离.研究结果表明,H2O在MgO(100)表面可以被部分解离,而H2O在Pd/MgO(100)表面的解离与Pd的含量有关.了解水与固体表面的相互作用机理还需要做更多的基础研究工作.     

Sonocatalytic performance of Tb7O12/TiO2 composite under ultrasonic irradiation

A Tb(7)O(12)/TiO(2) composite was successfully synthesized through a hydrolysis-calcination process. The Tb(7)O(12)/TiO(2) composite catalyst was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy, UV-Vis absorption/reflection spectroscopy, and X-ray diffraction (XRD). The heterogeneous sonocatalytic oxidation of amaranth in water, containing dispersed pure TiO(2) and Tb(7)O(12)/TiO(2) composite, was investigated under ultrasonic irradiation. The activity of the Tb(7)O(12)/TiO(2) catalyst is higher than that of pure TiO(2) during the sonodegradation of amaranth. The enhanced sonocatalytic activity of the composite may be attributed to the increase in charge separation efficiency and the presence of surface acidity.     

Intensive green emission of ZnAl2O4:Mn2+ under vacuum ultraviolet and low-voltage cathode ray excitation

A series of Zn(1-x)Mn(x)Al(2)O(4) (x=0.001～0.08) phosphors were synthesized by a traditional solid-state reaction route. Their photoluminescence under vacuum ultraviolet (VUV, energy E>50000 cm(-1), wavelength λ<200 nm) and cathodoluminescence under low-voltage electron beam excitation were evaluated. The luminescence decays were also measured. The intense green emission was observed with a peak at about 510 nm upon 172/147 nm excitation. The luminescence of optimum phosphor Zn(0.99)Mn(0.01)Al(2)O(4) (ZAM) was compared with that of commercial green phosphor Zn(2)SiO(4):Mn(2+) (ZSM). The maximum emission intensity of ZAM is larger than that of ZSM under 172/147 nm and low-voltage electron beam excitation. The values of chromaticity coordinates reveal the phosphors can evidently enlarge the tricolor gamut. The results show that the ZnAl(2)O(4):Mn(2+) phosphors may be considered as candidates for Hg-free lamps, plasma flat backlights, and field emission backlights for liquid crystal displays.     

Synthesis of MCM-22 zeolite by an ultrasonic-assisted aging procedure

The synthesis of MCM-22 zeolite under hydrothermal crystallization conditions has been performed by an ultrasonic-assisted aging procedure. The ultrasonic-assisted aging of the initial aluminosilicate gel can shorten the crystallization time of MCM-22, decrease the amount of hexamethyleneimine (HMI) used, and broaden the range of SiO(2)/Al(2)O(3) ratios. By using the ultrasonic aging, pure phase of high-silica MCM-22 products with SiO(2)/Al(2)O(3)>100 can be obtained. When SiO(2)/Al(2)O(3) 相似文献   

燃煤流化床加入氧化钙的氮转化机理

实验研究了 ＣａＯ及与 ＣＯ对 Ｎ２Ｏ、 ＮＯ的催化还原作用。结果表明 ＣａＯ／ＣＯ对 Ｎ２Ｏ的作用表现在可以降低Ｎ２Ｏ的初始分解温度和提高Ｎ２Ｏ的转化率５只有在ＣＯ的共同作用下ＣａＯ可以提高ＮＯ的转化率。以此为基础,分析了不同规模的流化床燃烧不同挥发份含量的煤时加入ＣａＯ后影响Ｎ２Ｏ／ＮＯ排放的不同机理。     

近紫外荧光粉SrAl_2Si_2O_8∶Ce~(3+)的光致发光特性

采用高温固相反应法制备了xCe~(3+)(x=0.01%,0.05%,0.10%和0.30%)激活的Sr_(1-x)Al_2Si_2O_8近紫外荧光粉,利用X射线衍射(XRD)和扫描电镜(SEM)检测出荧光粉的物相结构,通过光致发光谱(PL)和激发光谱(PLE)表征了荧光粉的发光性质。结果显示,在中波紫外光激发下,发射峰位于长波紫外区,归属于Ce~(3+)的5d→2 F5/2和5d→2 F7/2跃迁。激发波长308nm时,观察到近紫外SrAl_2Si_2O_8荧光粉的发光强度随Ce~(3+)掺杂量增加而先增大后减小,同时发射峰位置红移。280和325nm波长选择性激发条件下的差异性发射行为表明SrAl_2Si_2O_8∶Ce~(3+)具有两种性质不同的发光中心,该结论由监测320和390nm发射时获得的形状具有明显区别的激发光谱亦可得以验证。离子半径的匹配性支持Ce~(3+)优先取代Sr~(2+),同时Van Uitert的经验公式估算结果推断出低浓度的Ce~(3+)生成九配位的Ce(Ⅰ)发光中心,高浓度掺杂情况下部分相互近邻的Ce~(3+)有效配位数减小,形成八配位的Ce(Ⅱ)发光中心。紫外280nm激发下峰位348nm的发射谱带源于Ce(Ⅰ)和Ce(Ⅱ)发光中心共同贡献,紫外325nm激发下发射峰位于378nm的发射带则主要对应于Ce(Ⅱ)发光中心。紫外光激发下Ce~(3+)发射出较强的近紫外光,表明SrAl_2Si_2O_8∶Ce~(3+)是一种适用于研发紫外荧光光源的荧光粉体材料。     

Enhancing The Efficiency of White Organic Light-emitting Diode Using Energy Recyclable Photovoltaic Cells

We demonstrate that power recycling is feasible by using a semi-transparent stripped Al electrode as interconnecting layer to merge a white organic light-emitting devices (WOLED) and an organic photovoltaic(OPV) cell. The device is called a PVOLED. It has a glass/ITO/CuPc/m-MTDATA∶V2O5/NPB/CBP∶FIrpic∶DCJTB/BPhen/LiF/Al/P3HT∶PCBM/V2O5/Al structure. The power recycling efficiency of 10.133% is achieved under the WOLED of PVOLED operated at 9 V and at a brightness of 2 110 cd/m2, when the conversion efficiency of OPV is 2.3%. We have found that the power recycling efficiency is decreased under high brightness and high applied voltage due to an increase input power of WOLED. High efficiency (18.3 cd/A) and high contrast ratio (9.3) were obtained at the device operated at 2 500 cd/m2 under an ambient illumination of 24 000 lx. Reasonable white light emission with Commission Internationale De L'Eclairage (CIE) color coordinates of (0.32,0.44) at 20 mA/cm2 and slight color shift occurred in spite of a high current density of 50 mA/cm2. The proposed PVOLED is highly promising for use in outdoors display applications.     

Migration of weakly bonded oxygen atoms in a-IGZO thin films and the positive shift of threshold voltage in TFTs

Amorphous indium-gallium-zinc oxide (a-IGZO) thin films are prepared by pulsed laser deposition and fabricated into thin-film transistor (TFT) devices. In-situ x-ray photoelectron spectroscopy (XPS) illustrates that weakly bonded oxygen (O) atoms exist in a-IGZO thin films deposited at high O₂ pressures, but these can be eliminated by vacuum annealing. The threshold voltage (V_th) of the a-IGZO TFTs is shifted under positive gate bias, and the V_th shift is positively related to the deposition pressure. A temperature variation experiment in the range of 20 K-300 K demonstrates that an activation energy of 144 meV is required for the V_th shift, which is close to the activation energy required for the migration of weakly bonded O atoms in a-IGZO thin films. Accordingly, the V_th shift is attributed to the acceptor-like states induced by the accumulation of weakly bonded O atoms at the a-IGZO/SiO₂ interface under positive gate bias. These results provide an insight into the mechanism responsible for the V_th shift of the a-IGZO TFTs and help in the production of reliable designs.     

超细Y2O3：Eu荧光粉的阴极射线发光和光致发光

本文首次报道由尿素溶胶法制备的球形、超细(120~250nm)高效Y2O3:Eu红色荧光粉的晶体结构及其阴极射线发光和光致发光性质.这种超细颗粒在254nm激发时的发光强度比商用的传统微米样品低.但在中等电压(≤10kV)的电子束激发下,其阴极射线发光强度超过商用微米样品.这种接近纳米的Y2O3:Eu超细颗粒已表现出较强的表面效应.对实验结果进行了分析和讨论.     

In situ XPS investigation of Pt(Sn)/Mg(Al)O catalysts during ethane dehydrogenation experiments

Calcined hydrotalcite with or without added metal (Mg(Al)O, Pt/Mg(Al)O and Pt,Sn/Mg(Al)O) have been investigated with in situ X-ray photoelectron spectroscopy (XPS) during ethane dehydrogenation experiments. The temperature in the analysis chamber was 450 °C and the gas pressure was in the range 0.3-1 mbar. Depth profiling of calcined hydrotalcite and platinum catalysts under reaction, oxidation and in hydrogen-water mixture was performed by varying the photon energy, covering an analysis depth of 10-21 Å. It was observed that the Mg/Al ratio in the Mg(Al)O crystallites does not vary significantly in the analysis depth range studied. This result indicates that Mg and Al are homogeneously distributed in the Mg(Al)O crystallites. Catalytic tests have shown that the initial activity of a Pt,Sn/Mg(Al)O catalyst increases during an activation period consisting of several cycles of reduction-dehydrogenation-oxidation. The Sn/Mg ratio in a Pt,Sn/Mg(Al)O catalyst was followed during several such cycles, and was found to increase during the activation period, probably due to a process where tin spreads over the carrier material and covers an increasing fraction of the Mg(Al)O surface. The results further indicate that spreading of tin occurs under reduction conditions.A PtSn₂ alloy was studied separately. The surface of the alloy was enriched in Sn during reduction and reaction conditions at 450 °C. Binding energies were determined and indicated that Sn on the particle surface is predominantly in an oxidised state under reaction conditions, while Pt and a fraction of Sn is present as a reduced Pt-Sn alloy.     

Activation Radionuclides in the Process of Irradiation of a Niobium Target at the Cyclone 18/9 HC Cyclotrone

Physics of Atomic Nuclei - The accumulation of long-lived radionuclides (LRNs) produced in water [18O]H2O under irradiation at the Cyclone 18/9 HC cyclotron with a niobium target and an input...