Electrodeposition of zinc coatings from the solutions of zinc oxide in imidazolium chloride/urea mixtures

To solve the inherent disadvantages in conventional processes for electrodeposition of zinc, it’s necessary to develop more high-efficiency and environmentally friendly electrolytes. In this work, it was found that the dissolution of ZnO was remarkably enhanced in some imidazolium chloride by the addition of urea, and the solubility of ZnO in 1:1 [Amim]Cl/urea mixture was as high as 8.35 wt% at 373.2 K. Electrochemical measurements showed that zinc could be readily electrodeposited from the solutions of ZnO. Bright, dense and well adherent zinc coatings with good purity were obtained from 0.6 M solution of ZnO in 1:1 [Amim]Cl/urea at 323.2 343.2 K. It’s expected that the solutions of ZnO in imidazolium chloride/urea mixtures have the potential to replace the traditional electrolytes, especially toxic zinc chloride-based ones for zinc electroplating, as well as preparation of zinc materials.     

Electrochemical formation of zinc selenide from acidic aqueous solutions

An investigation on electrochemical ZnSe thin film growth from acidic aqueous baths of Se(IV) and Zn(II) species is described. The range of co-deposition potentials is predicted on a thermodynamic basis according to a known electrochemical model. A study on the voltammetric behavior of Ti and Ni electrode substrates in the working solutions at various temperatures provides the main features of the applied electrochemical process. Cathodic electrodeposition at high temperatures (>65 °C) results in the formation of polycrystalline cubic, randomly oriented, ZnSe crystallites suffering, in general, from the presence of a crystalline Se phase in excess. Annealing of as-grown films adjusts the stoichiometry and leads to the production of semiconductive ZnSe with a band gap width of 2.7 eV. Electronic Publication     

Colloido-chemical characteristics of zinc oxide in electrolyte solutions

The electrosurface characteristics (total surface charge, electrokinetic potential, and positions of the point of zero charge and isoelectric point) of zinc oxide have been comprehensively studied as depending on pH and background electrolyte (NaCl) concentration. The constants of surface reactions and the adsorption potentials of potential determining of background electrolyte ions have been obtained in terms of the 2pK-model. The aggregation stability of aqueous zinc oxide suspensions has been studied in a wide range of concentrations of 1: 1 and 1: 2 electrolytes, and the threshold of sol coagulation has been found. Within the framework of the DLVO theory, the interaction energy between ZnO particles has been calculated as a function of the interparticle distance. It has been demonstrated that the experimental data can be qualitatively described in terms of the classical DLVO theory, which takes into account only ion-electrostatic and molecular (dispersion) forces of interparticle interaction.     

The study of thermal decomposition kinetics of zinc oxide formation from zinc oxalate dihydrate

This study is devoted to the thermal decomposition of ZnC₂O₄·2H₂O, which was synthesized by solid-state reaction using C₂H₂O₄·2H₂O and Zn(CH₃COO)₂·2H₂O as raw materials. The initial samples and the final solid thermal decomposition products were characterized by Fourier transform infrared and X-ray diffraction. The particle size of the products was observed by transmission electron microscopy. The thermal decomposition behavior was investigated by thermogravimetry, derivative thermogravimetric and differential thermal analysis. Experimental results show that the thermal decomposition reaction includes two stages: dehydration and decomposition, with nanostructured ZnO as the final solid product. The Ozawa integral method along with Coats–Redfern integral method was used to determine the kinetic model and kinetic parameters of the second thermal decomposition stage of ZnC₂O₄·2H₂O. After calculation and comparison, the decomposition conforms to the nucleation and growth model and the physical interpretation is summarized. The activation energy and the kinetic mechanism function are determined to be 119.7 kJ mol^?1 and G(α) = ?ln(1 – α)^1/2, respectively.     

The synthesis of zinc oxide nanostructures

It was proposed to synthesize quasi-one-dimensional nano-sized zinc oxide crystals by the vapor-liquid-crystal mechanism during the gas phase epitaxy. An array of nanowhiskers randomly distributed throughout the polished surface of silicon wafer was grown. The structure and properties of whiskers were determined.     

Hydrothermal synthesis of zinc silicates from borosilicate glasses and from mixtures of zinc oxide and silica

The formation of sauconite and hemimorphite from glasses and oxide precursors in aqueous solution at 150–200°C is described. A tentative schematic stability diagram for a portion of the system Na₂O-ZnO-SiO₂-H₂O at 150°C is presented. The relevance of this work to the use of a sodium zinc borosilicate glass as a matrix for the immobilization of nuclear fuel reprocessing wastes is discussed briefly.     

Microwave synthesis of zinc sulfite and porous zinc oxide microrods

ZnSO(3) microrods with uniform size and shape can be prepared under microwave irradiation at much higher speed than a conventional heating bath, usually in minutes. The annealing of ZnSO(3) microrods produced porous ZnO microrods with pore size between 50-200 nm.     

Aqueous pathways for the formation of zinc oxide nanoparticles

We examine the effect of reactant concentrations, temperatures and feeding methods on the morphology of ZnO formed when reacting solutions of ZnSO(4) and NaOH. The catalytic effect of hydroxide in excess relative to the stoichiometric ratio is considered. It is shown that, having fixed other reaction conditions, the end-products, particle structures and size strongly depend on the mole ratio of the precursors. The presence of zinc salt hydroxide species was confirmed at sub-stoichiometric ratios in slightly acidic conditions. At the stoichiometric ratio both zinc hydroxide and zinc oxide are formed, while only zinc oxide forms in an excess of hydroxide. The method of feeding the reactants into the reaction vessel also has a strong influence on the end-product properties, as does the reaction temperature. By control of these parameters the specific surface area could be varied from 10 to 33 m(2) g(-1), the particle shape could be varied from equiaxed, through to star-like and needle-like, and the particle size may be varied from 50 to over 300 nm.     

Amine-functionalized graphene oxide/zinc hexacyanoferrate composites for cesium removal from aqueous solutions

Journal of Radioanalytical and Nuclear Chemistry - Amine-functionalized graphene oxide/zinc hexacyanoferrate (amino-rGO/ZnHCF) composites were successfully synthesized for the removal of Cs+ from...     

Hydrothermal synthesis and crystal structure of a new two-dimensional zinc citrate complex

A new two-dimensional compound C₁₂H₁₄O₁₆Zn₃ (1), containing seven-coordinate zinc atoms was prepared by the hydrothermal technique. The compound obtained was characterized by TG-DTA, single crystal X-ray diffraction, elemental analysis and FT-IR analysis. Single-crystal X-ray diffraction analysis shows that compound 1 crystallizes with monoclinic symmetry in the space group P2₁/c, a?=?6.1552(13)?Å, b?=?14.546(3)?Å, c?=?9.581?Å, β?=?102.66(2)°, V?=?836.9(4)?ų, Z?=?2, R1?=?0.0311, wR2?=?0.0830.     

Thermochemical studies on the formation and constitution of the zinc oxide—aluminium oxide system

This study is based on thermogravimetric (TG), differential thermal analysis (DTA) and chemical analysis of the ZnOAl₂O₃ system. The coprecipitation from mixed nitrate salt solutions of zinc and aluminium results in the formation of zinc basic carbonate and aluminium hydroxide, and is also a precursor to aluminate spinel (2ZnO·3Al₂O₃) only in the samples in which aluminium is present in near or above stoichiometric quantities. Grinding of the mixtures of individual precipitates maintains the similarity with coprecipitates in forming a “precursor”, but to a lesser extent. The endothermic peak in DTA at 275°C in some coprecipitated and mixed samples hints at the formation of a precursor since the individual precipitate does not have a peak at this temperature. The “precursor” to spinel obtained in the precipitation stage in some coprecipitated samples is freely soluble in 1 M HCl, and that obtained at 450°C is partially soluble which cannot be detected by the usual X-ray technique due to its highly disordered structure in amorphous state. The “precursor” is converted around 800°C to an actual spinel structure, which is almost insoluble in M HCl and is detectable by X-rays.     

The impact of physiological buffer solutions on zinc oxide nanostructures: zinc phosphate conversion

Zinc oxide (ZnO) nanostructures have been widely used in biosensor applications. However, little attention has been given to the interaction of ZnO structures with physiological buffer solutions. In the present work, it is shown that the use of buffers containing phosphate ions leads to the modification of the ZnO tetrapodal micro/nanostructures when immersed in such solutions for several hours, even at the physiological pH (7.4). ZnO samples designed to be used as transducers in biosensors were immersed in phosphate buffers for several durations at pH = 5.8 and pH = 7.4. Their detailed morphological, structural and optical characterization was carried out to demonstrate the effect of the ZnO interaction with the phosphate ions. The pH had an important role in the ZnO conversion into zinc phosphate, with lower pH promoting a more pronounced effect. After 72 h and at pH = 5.8, a significant amount of the ZnO structures were converted into crystalline zinc phosphate, while immersion during the same time at pH = 7.4 resulted predominantly in amorphous zinc phosphate particles mixed with the original ZnO tetrapods. Photoluminescence spectra show remarkable changes with prolonged immersion times, particularly when the luminescence of the sample was investigated at 14 K. These findings highlight the importance of a careful analysis of the sensing results when phosphate-based buffer solutions are in contact with the ZnO transducers, as the changes observed on the transduction signal during sensing experiments may also comprise a non-negligible contribution from a phosphate-induced transformation of ZnO, which can hamper an accurate assessment of the sensing behavior.     

Specifics of hydrothermal synthesis of oriented zinc oxide nanorods on metallic zinc substrates

Zinc oxide nanostructures are prepared hydrothermally in the presence of ethylenediamine (EDA). The morphology and photoluminescent properties of final products are studied as functions of synthesis temperature, synthesis time, and EDA concentration. A decrease in EDA concentration to 30% favors the formation of more perfect and more ordered structures. Blank experiments show that hydrothermal synthesis without organic reagents does not produce nanostructures. When samples are sheltered from convective flows in the cell, the rod growth direction is dictated by the grain orientation in the foil. When nanorods are formed under low supersaturations (in the absence of convective flows), oxygen nonstoichiometry arises in the nanorods and appears in photoluminescence spectra as increased peak intensities in the green spectral range.     

Equilibrium oxygen fugacity for the synthesis of zinc ferrite solid solutions

Thermodynamic information is utilized to study the width of the zinc ferritemagnetite phase field, and to establish the oxygen fugacity in equilibrium with this solid solution. Information is provided for the specification of the phase boundaries and for the particular oxygen fugacity that corresponds to the 4/3 oxygen/ cation ratio in the strictly stoichiometric solid solution.     

Removal of contaminated oxide layer on carbon steel in hydrochloric acid disodium citrate solutions

The removal of contaminated high temperature grown magnetite on carbon steel in buffered HCl-disodium citrate solutions has been studied. Decontamination factors higher than 200 concomitantly with a dissolution of metal substrate lower than 1 m after 1 hour treatment have been obtained.     

燃烧合成法制备纳米氧化锌

采用燃烧合成法制备氧化锌纳米粉体，DTA结果表明用柠檬酸作为燃烧剂比用尿素为燃烧剂时进行燃烧反应放出的热量少，更易制得纳米级氧化物．利用XRD和TEM表征样品，确定了生产纳米氧化锌粉体的最佳条件：硝酸锌与柠檬酸按9：1．5(物质的量比)形成前驱体，600℃进行反应．得到球形粉体粒径为16．4nm。     

氧化锌纳米棒的水热合成及其光催化性能

以分析纯ZnO作为锌源、NaOH为矿化剂、盐酸为反应溶液pH调节剂,利用水热反应制备了花状ZnO纳米棒;采用扫描电子显微镜和X射线衍射仪分析了产物的形貌和结构,考察了水热温度以及Zn2+和OH-浓度比对产物形貌的影响;以甲基橙为目标降解物,采用紫外-可见分光光度计研究了ZnO纳米棒的光催化性能.结果表明,在水热反应温度80℃、Zn2+/OH-浓度比1∶7.5条件下所得ZnO纳米棒呈花状聚合,直径约为200nm,长度约为2μm,具有六方纤锌矿结构.当甲基橙初始浓度为30 mg.L-1、ZnO纳米棒的投放量为1.5g.L-1时,以300W紫外灯照射150min,甲基橙的降解率可达90%.     

Fluoride-conversion synthesis of homogeneous actinide oxide solid solutions

The synthesis of (U,Th)O(2) solid solutions at a relatively low temperature of 1100 °C using a new technique is described. First, separate actinide oxides were reacted with ammonium hydrogen fluoride to form ammonium actinide fluorides at room temperature. Subsequently, this fluoride was converted to an actinide oxide solid solution using a two-phase reaction process, which involved heating of the fluoride first at 610 °C in static air followed by heating at 1100 °C in flowing argon. Oxide solid solutions of UO(2) and ThO(2) were synthesized for a ThO(2) content from 10 to 90 wt %. Microscopic investigation showed that the (U,Th)O(2) solid solutions synthesized using this method had high crystallinity and homogeneity up to nanoscale.     

Sorption of 60Co(II) from aqueous solutions onto biosynthesized zinc oxide nanocomposites

Journal of Radioanalytical and Nuclear Chemistry - Nano ZnO is biosynthesized using Lactobcillus sp. Poly Acrylic acid-co-Acrylonitrile/ZnO, PAACAN/ZnO, and poly Acrylic acid-co-Maleic acid/ZnO,...