Nano-sized ZnO Powders Research Articles

Sonocatalytic damage of composite TiO2/ZnO powder to bovine serum albumin under ultrasonic irradiation

The composite TiO2/ZnO was prepared by mixing nano-sized TiO2 and ZnO powders directly, in the molar proportion of 4:6, followed by heat-treatment at 500°C for 40 min. The products were charactered by powder X-ray diffraction and transmission electron microscopy. The test of sonocatalytic activities of the composite TiO2/ZnO powders was carried out through the damage of bovine serum albumin (BSA). Otherwise, the effects of several factors on the damage of BSA molecules were evaluated by means of UV-vis and fluorescence spectra. It was found that the damage degree was aggravated with the increase of ultrasonic irradiation time and composite TiO2/ZnO addition amount. These research results were of great significance for driving sonocatalytic method to treat tumor in clinic application.

Baculoviral capsid display of His-tagged ZnO inorganic binding peptide

Virus-templated fabrication of compound structures can be made through incorporating the specifically inorganic-binding peptide into the viral scaffold, widely used is phage display system. Compared to prokaryotic phages, insect cell-based baculovirus has some strengths such as the adaptability to the proteins' posttranslational modification and non-replication in mammalian cells. As an attempt to explore the baculovirus-mediated bioconjugates, we show in this study that a genetically engineered baculovirus, with a hexahistidine (His(6)) tagged ZnO binding peptide fused to the N-terminus of the viral capsid protein vp39 of AcNPV, was constructed. It maintains both the viral infectivity and the fusion protein's activity. The presence of the fusion protein on the baculovirus particle was demonstrated by western blot analysis of purified budded virus. Its display on the virus capsid was revealed by virus fractionation analysis. The binding of nanosized ZnO powders to the virus capsid was visualized by transmission electron microscopy (TEM). This is the first report of the display of the inorganic-binding peptide on the capsid of eukaryotic baculovirus. Aimed at the nanomaterials' application in the biological field, this research could find useful in the biotracking of the baculovirus transduction process and the preparation of novel functional nanodevices.

Study on inorganic oxidants assisted sonocatalytic degradation of Acid Red B in presence of nano-sized ZnO powder

Because of the extensive use and excessive release of various dyes, the economical and efficient methods for treatment of wastewater and cleanup of dyes are needed. This study focuses on the sonocatalytic degradation of Acid Red B in aqueous solution assisted with different inorganic oxidants. The objective is to determine the potential degradation feasibility for Acid Red B and other some dyes in US/ZnO/oxidant systems. In this work, an integrated US/ZnO/oxidant system was used to degrade the Acid Red B in aqueous solution, and the concentration of Acid Red B was measured by UV–vis spectra at regular time intervals. It is found that some inorganic oxidants can effectively assist the sonocatalytic degradation of Acid Red B in the presence of nano-sized ZnO powder and the effect of oxidants changes as the order of KClO 4 > KClO 3 > Ca(ClO) 2. Otherwise, some operational parameters such as ultrasonic irradiation time, reaction kinetics, solution pH value, oxidant kind and concentration and systematic temperature have been examined. The possible degradation mechanism of Acid Red B was also presented. It is demonstrated that the degradation of Acid Red B was very obvious in US/ZnO/oxidants (US/ZnO/KClO 4, US/ZnO/KClO 3 and US/ZnO/Ca(ClO) 2) systems. In addition, the method of sonocatalytic degradation assisted with oxidants has many advantages such as convenience, safety, economy and high efficiency. If it can be applied extensively, the efficiency of wastewater treatment will be enhanced greatly.

Photocatalytic Removal of Cu Ions from Aqueous Cu-EDTA Solution Using Solution Combusted Zinc Oxide Nanopowder

Nano-sized ZnO powder was prepared by "solution-combustion method (SCM)." The ZnO powder using Zn(OH)2 and glycine as an oxidant and a fuel (F/O = 0.8), showed good powder characteristics, such as average grain size of 30 nm and the specific surface area of 120 m2/g. and it was used as a semiconductor photocatalyst to remove Cu ions from aqueous Cu-EDTA solution. The result was then compared with other semiconductor photocatalyst powders such as titanium dioxide (TiO2) powder (P25, Degussa) and TiO2 powder prepared by homogeneous precipitation process at low temperature (HPPLT). The SCM ZnO nanopowder showed excellent photocatalytic properties. The Cu++ ions were completely removed from the solution within 90 min. However, for the other two powders, no complete removal of the ions was observed within the reaction time of 180 min. The ZnO powder synthesized at the fuel/oxidant ratio of 0.8, showed higher PL intensity at UV region than the other photocatalytic powders. The superior photoreduction ability of SCM ZnO nanopowder might be due to its excellent UV absorption capacity.

Studies on alcohol sensing mechanism of ZnO based gas sensors

Nanosized ZnO powder was synthesized by using a chemical precipitation method, and loaded with different dopants through impregnation. The as-prepared ZnO powder was characterized by XRD and TEM. The characterization results show that the as-prepared sample is wurtzite polycrystalline ZnO, the mean grain size is 30–40 nm, and there are three types of adsorbed oxygen (O2−, O22−, and O2−) on the surface of the sample. The as-prepared ZnO powder shows excellent gas responses to alcohol and acetaldehyde, but no response to ethene. The sensing mechanism of ZnO was further studied with the help of gas chromatography (GC) associated with a fixed-bed reactor. The studies show that acetaldehyde, carbon dioxide and water are the only oxidation products of C2H5OH over ZnO. The gas response to C2H5OH is strongly dependent on the conversion ratio of C2H5OH to acetaldehyde. In addition, among all the dopants tested, Ru is the optimal dopant which can increase the response to C2H5OH, but cannot increase the conversion ratio of C2H5OH to acetaldehyde. Thus we suggest that the gas sensing mechanism of ZnO to C2H5OH is the mode controlled by chemisorption of negatively charged oxygen, and the sensitizing role of Ru in the ZnO sensor belongs to the electronic sensitization mechanism.

Sonocatalytic degradation of acid red B and rhodamine B catalyzed by nano-sized ZnO powder under ultrasonic irradiation

Nano-sized ZnO powder was introduced to act as the sonocatalyst after the treatment of high-temperature activation, and the ultrasound of low power was used as an irradiation source to induce nano-sized ZnO powder performing sonocatalytic degradation of acid red B and rhodamine B. At the same time, the effects of operational parameters such as solution pH value, initial concentration of dyestuff and addition amount of nano-sized ZnO powder have been examined in this paper. We found that the degradation ratios of acid red B and rhodamine B in the presence of nano-sized ZnO powder were much higher than that with only ultrasonic irradiation. However, the degradation ratio of acid red B was about two times higher than that of rhodamine B for the initial concentration of 10.0mg/L, addition amount of 1.0g/L nano-sized ZnO powder, solution acidity of pH 7.0 and 60min irradiation experimental condition. The difference of the degradation ratios can be illustrated by the difference of chemical forms of acid red B and rhodamine B in aqueous solution and the surface properties of nano-sized ZnO particles. In addition, the researches on the kinetics of sonocatalytic reactions of acid red B and rhodamine B have also been performed and found to the follow pseudo first-order kinetics. All the experiments indicated that the sonocatalytic method in the presence of nano-sized ZnO powder was an advisable choice for the treatments of non- or low-transparent organic wastewaters in future.

Removal of Heavy Metal Ions from Aqueous Pb-EDTA and Cu-EDTA Solutions Using Nanosized ZnO Powders by Solution-Combustion Method

ZnO nanopowder was prepared by a novel “solution-combustion method (SCM)” and it was used as a semiconductor photocatalyst to evaluate its photoreduction properties. Aqueous Pb-EDTA and Cu-EDTA solutions of heavy metal ions (Pb and Cu) were used for the photocatalysis reaction under UV illumination. The result was then compared with other semiconductor photocatalyst powder such as TiO2 powder (P25; Degussa) and TiO2 powder prepared by homogeneous precipitation process at low temperature (HPPLT). In the removal of Pb++ ions, the ZnO nanopowder showed 2.6 fold higher removal rate than P25 TiO2 powder and 1.8 fold higher than HPPLT TiO2. Also the ZnO nanopowder showed the highest removal rate of the Cu++ ions from the solution among the different photocatalyst powders compared. The superior photoreduction ability of the ZnO nanopowder appears to be due to its excellent UV absorption characteristics. This was confirmed by the photoluminescence (PL) measurement.

Synthesis of nano-sized ZnO powders by thermal decomposition of zinc acetate using Broussonetia papyrifera (L.) Vent pulp as a dispersant

Abstract Nano-sized ZnO powders were synthesized by thermal decomposition of zinc acetate and Broussonetia papyrifera (L.) Vent pulp. The pulp was soaked in zinc acetate solution for 24 h. The impregnated pulp was dried at 70 °C for 48 h. The mixture was calcined for 1 h at 600, 700, 800, and 900 °C. The reaction mechanisms to form the ZnO nanoparticles were evaluated using FT-IR spectroscopy. The calcined powders were characterized by XRD, SEM, and TEM. The values of surface area were calculated from BET data. The particle sizes of ZnO in the calcined powders ranged from 10 nm to 60 nm, and the surface area was 18.93 m 2 /g.

Preparation of nanosized ZnO and dielectric properties of composites filled with nanosized ZnO

Nanosized ZnO powder is prepared by a precipitation method that is simple, convenient manipulation and low energy consumption. The process can produce white ZnO powder of 50–90 nm in size. The dielectric constants of composites with nanosized ZnO filler are also studied in detail in a frequency range of 1–10 MHz by an impedance analyzer. Composites with more ZnO filler have relatively large dielectric constants and losses and they increase with increasing the frequency. High frequency has a remarkable effect on dielectric constants and losses of the composites. Finally, the high dielectric constants and losses of the composites appear under 10 MHz in experimental study. In addition, mixing temperature and time also play an important role on dielectric constants and losses. High temperature and long time during the mixing process might induce the structure change of low-density polyethylene (LDPE). Therefore, the composites have a high dielectric constants and losses.

Rapid Ag recovery using photocatalytic ZnO nanopowders prepared by solution-combustion method

The study of photocatalytic reactions is a recently emerging area out of the field of catalytic chemistry. In general, photocatalytic reaction is an interaction between molecules and surfaces including electron transfer between molecules and catalysts. Semiconductors are usually used for photocatalysts because their carrier concentration can be controlled [1, 2]. Recent studies have mainly concentrated on environmental problems such as purification of contaminated water or air [3, 4]. Semiconductors for photocatalytic reactions should have characteristics such as high optical activity, high optical stability, high sensitivity for UV-visible light and low fabrication cost [2, 5]. Many researchers have paid attention to oxide semiconductors because of their wide band gap energy and ease of handling [6–9]. Nano-sized particles have different physical and chemical properties compared to bulk materials. High catalyst activity may be expected because of their large surface area and different surface properties, such as surface defects, when these nano-sized particles are used as catalysts. The fabrication of nano-sized particles with high stability and dispersibility in solution is essential to obtain high photocatalytic activity [10, 11]. In this paper, synthesis of ZnO was tried to obtain the nano-sized semiconductor particles for photocatalytic application. Two methods are generally used to obtain such ZnO powder. One is vapor method and the other is sol-gel method. In the case of vapor method, the resulting powders contain agglomerates rather than separated particles because it is very difficult to control the reaction conditions during the process. This means that the vapor method is not a satisfactory method to obtain nano-sized ZnO powders. On the other hand, the sol-gel method could provide uniform ZnO powders. However, it is required to control the reaction condition strictly because of the violent hydrolysis reaction in the air during synthetic process. In addition, this method is not attractive because metal alkoxide as a starting source is very expensive. This is why the method is still not commercialized but is being tried only in a small laboratory scale [12, 13]. Park et al. proposed the solution combustion method to synthesize highly pure and fine ceramic powders. Using this method, the heating and evaporation of metal nitrate solution with glycine results in self-firing and generates intense heat by exothermic reaction [14]. This intense heat is used to synthesize the powders. In this study, nano-sized ZnO powders were prepared using this solution combustion method. Their characteristics and photocatalytic efficiency were also investigated. Zn(OH)2 (Junsei, Japan) powder solved in nitric acid was used as the starting material (oxidant), and glycine(H2NCH2COOH, Yakuri pure chemicals co. Ltd, Japan) was used as a fuel, in order to synthesize ZnO powder. The starting material was dissolved in distilled water in a beaker. Then the glycine was added to the starting solution in the beaker. The solution was then heated on a hot plate with stirring. As the distilled water evaporated, the solution became viscous and generated small bubbles. The nitric acid group (NO3 ) reacted with the fuel and intense heat was generated (the temperature rises to 1500–1800 ◦C). This high temperature resulted in a high pressure, which leads to an explosion. ZnO powder was formed by this high temperature and high pressure and was collected in a collector that was placed above the beaker. In this paper, this process is referred to the solution combustion method. In general glycinenitrate process (GNP), oxide powders are synthesized adding the fuel in equilibrium state (fuel/oxidant = 1). However, in this study after calculating the oxidation number by the general GNP method, ZnO powder was prepared by fuel lean state considering the vapor pressure of Zn or ZnO. Five different ZnO powders were prepared with the variation of the fuel/oxidant ratio. X-ray diffractometer (XRD) measurement was performed to examine the crystalline state of the prepared ZnO powder. As shown in Fig. 1, single phase ZnO was obtained by the above method; the ZnO powder with fuel/oxidant ratio of 0.8 showed the highest XRD peaks and hence was assumed to be the most crystalline. As shown in Fig. 2, the photoluminescence spectra of commercial ZnO powder showed two peaks: one is in the vicinity of 500 nm, and the other one is near 400 nm. The peak near 500 nm probably came from the energy transition between O vacancy level and Zn vacancy level as shown in Fig. 3. The UV peak near 400 nm might be from band to band transition. However, ZnO powder synthesized by the solution combustion method showed only one sharp peak near 390 nm that was slightly shifted to UV side. This peak is equivalent to the energy gap of ZnO (∼3.2 eV). These results indicate

Photocatalytic ZnO nanopowders prepared by solution combustion method for noble metal recovery

Nano-sized ZnO powder was synthesized by solution combustion method (SCM). Using this ZnO nanopowder as a photocatalyst, it was tried to recover silver from the silver-plating wastewater that was discharged by noble metal plating industries. The photocatalytic efficiency of ZnO nanopowder, as one of optical properties, was compared with other photocatalysts such as commercial TiO2 and commercial ZnO. The ZnO nanopowder showed three folds higher photocatalytic efficiency than any other commercial photocatalysts. Other electro-optical measurements such as photoluminescence (PL) measurement, electrical resistivity and carrier concentration measurement also showed very consistent results. The recovery of gold from gold plating wastewater was also tried. The recovery efficiency was improved by about 25% by adding methanol as a scavenger to the gold plating wastewater. It took 45 min to completely recover gold from the wastewater.

Synthesis and Ag Recovery of Nanosized ZnO Powder by Solution Combustion Process for Photocatalytic Applications

Nanometer-sized ZnO powders for photocatalytic applications were prepared by a solution combustion method with various starting materials and fuels. It was easy to obtain single-phase ZnO powders using the solution combustion method regardless of the starting materials and fuels. However, the particle size and shape of the synthesized ZnO powders were different than the used fuel. Using glycine as a fuel, the particle shape of ZnO powders was spherical with uniform nanosize. On the other hand, using carbohydrazide as a fuel, the particle shape was platelike. The ZnO powder synthesized using Zn(OH)2 and glycine as starting material and fuel, respectively, showed good powder characteristics, such as average grain size of 75 nm and the specific surface area of 94 m2/g. The average particle size and specific surface area were greatly dependent on the types of oxidants and fuels. Removal of silver ions from a used photo-film developing solution was attempted to examine the photocatalytic activity of the prepared ZnO powders. It also showed excellent photocatalytic properties in that the silver ions were completely removed from the solution within 3 min.