Unsteady radiative heat transfer within a suspension of ZnO particles undergoing thermal dissociation

An emitting, absorbing, and anisotropically scattering plain medium containing a suspension of ZnO particles is considered, in which the particles are directly exposed to high-flux irradiation and undergo shrinkage during their endothermic dissociation into Zn(g) and O₂ at above 2100 K. The unsteady energy equation that links the rate of radiative heat transfer to the rate of the chemical reaction is formulated and solved numerically by the finite volume technique and the explicit Euler time-integration scheme. The path-length Monte Carlo method is applied for modeling the radiative transfer within the suspension using the absorption/scattering coefficients and the scattering phase function obtained from the Mie theory. It is found that the particle suspension can be heated rapidly from its initial 300 K to over 1800 K in less than 0.1 s, resulting in a more uniform temperature profile as the reaction progresses, particles shrink, and the suspension becomes optically thinner. The chemical conversion increases with decreasing initial particle diameter and volume fraction due to the efficient radiative absorption.     

A novel high power symmetric ZnO/carbon aerogel composite electrode for electrochemical supercapacitor

We present, for the first time, a new material of symmetric electrochemical supercapacitor in which zinc oxide (ZnO) with carbon aerogel (CA) was used as active material. Physical properties of ZnO/CA composite were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that ZnO has single hexagonal structure and the grain size increases with increase of ZnO compository. The result of cyclic voltammetry indicates that the specific capacitance of ZnO/CA composite in 6 M KOH electrolyte was approximately 25 F/g at 10 mV/s for 2:1 composition. AC impedance analysis reveals that ZnO with carbon aerogel powder enhanced the conductivity by reducing the internal resistance. Galvanostatic charge/discharge measurements were done at various current densities, namely 25, 50, 75, and 100 mA/cm². It was found that the cells have excellent electrochemical reversibility and capacitive characteristics in KOH electrolyte. The maximum capacitance of the ZnO/CA supercapacitor was 500 F/g at 100 mA/cm². It has been observed that the specific capacitance is constant up to 500 cycles at all current densities, which implies that the dendrite formation was controlled.     

Ag-ZnO catalysts for UV-photodegradation of methylene blue

High surface area Ag-ZnO catalysts have been made by flame spray pyrolysis (FSP) and characterized by X-ray diffraction (XRD), nitrogen adsorption, UV–vis spectroscopy and electron microscopy (SEM and transmission electron microscopy (TEM)) combined with energy dispersive X-ray spectroscopy (EDXS) for elemental mapping. Silver metal clusters deposited directly on ZnO nanocrystals were obtained from this process. The Ag loading (1–5 at.%) controlled the Ag cluster size from 5 to 25 nm but did not influence the ZnO crystal size. Photodegradation of 10 ppm methylene blue (MB) solution was used to evaluate the performance of these FSP-made Ag-ZnO and was compared to wet-made Ag-ZnO and reference titania photocatalysts. The rate of photodegradation was optimal for Ag loading around 3 at.%. The best photocatalytic performance was exhibited by flame-made Ag-ZnO produced at the longest high-temperature residence times having high crystallinity as determined by XRD and UV–vis.     

高硅铸铝合金镀前浸锌液

针对高硅铸铝件在组成，组织与性能上的特点，研究了8种高硅铝合金镀前浸锌液。用扫描电镜（SEM）观察了8种不同的浸锌液配方浸锌的试片的表面浸锌膜的微观形貌，测定了浸锌后镀镍层与试片的结合力，优选了能获得良好结合力的最佳浸锌液配方。并研究了随浸锌时间的增加，锌晶核的析出与成长的过程，结果表明，当氢氧化钠140g/L，氧化锌14～20g/L、氯化镍1.5g/L时，试片镀镍后结合力良好。发现浸锌液能够溶解铝合金部分组织，并在铝表面造成孔洞，这种孔洞对镀层起着锚链作用，铝合金表面孔洞的均匀分散以及细小锌晶粒的高度弥散是得到良好结合力的前提。     

[Zn(BDC)(H2O)2]n: a novel blue luminescent coordination polymer constructed from BDC-bridged 1-D chains via interchain hydrogen bonds (BDC = 1,4-benzenedicarboxylate)

A novel coordination polymer [Zn(BDC)(H₂O)₂]_n 1 (where BDC = 1,4-benzenedicarboxylate), has been synthesized and characterized by X-ray diffraction. 1 crystallizes in the monoclinic space group C2/c, a=15.09(2) Å, b=5.058(7) Å, c=12.196(16) Å, β=103.62(2)°, , Z=4. The most striking feature of 1 is that it consists of a high-dimensional network structure constructed from BDC-bridged 1-D chains via interchain hydrogen bonds. The coordination sphere of the zinc(II) ion is a distorted tetrahedron completed by four oxygen atoms from two water molecules and two BDC ligands. BDC adopts the bis-monodentated (syn–anti) coordination mode linking two adjacent zinc(II) ions. 1 shows strong blue photoluminescence as the result of the fluorescence from the intraligand emission excited state.     

一次性使用无菌注射器用橡胶活塞的化学分析方法的改进

介绍一次性使用无菌注射器用橡胶塞的化学分析方法。在适宜的酸度条件下，用碘量法测定易氧化物；重金属含量通常是测其硫化物的含量来判定的，本方法是采用硫代乙酰胶试剂作沉淀剂；锌离子能与亚铁氰化钾溶液及应生成白色络合物沉淀，因此采用亚铁氰化钾比浊法测其锌含量；利用硫氰酸铵比色法测其铁含量。本方法操作具体，比色明显、定量明确，对试样的测定得到了满意的结果。     

Anodic behaviour of zinc in methanol solutions of lithium perchlorate

Anodic dissolution of poly- and single-crystals of zinc was performed in methanol solution of lithium perchlorate by means of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The mechanism of anodic dissolution of zinc in organic solvents occurs in two oxidation steps. It is the first step that surface anodic product is created. Stability of the surface product is much better in anhydrous organic environments than in aqueous media; because the product is stable, a barrier layer composed of is formed at low anodic overvoltage. The formation of the layer is much stronger on the low index than on the high-index plane (0 0 0 1), where the adsorption of anodic product is more difficult.     

固相法合成锌铁氧体及其光催化性能

采用硝酸锌、硝酸铁、草酸以及软模板剂聚乙烯醇,通过室温固相研磨反应,制备出二元草酸盐混合前驱体,经600℃灼烧3h,对所获红棕色粉末用SEM、XRD表征,结果表明合成了一维棒状的锌铁氧体（ZnFe2O4）。使用合成产物降解葸和芘以及有机染料亚甲基蓝,通过荧光和紫外分析法考察其光催化性能和效果。讨论了光催化降解机理,考察了光催化剂用量、作用时间以及自然光和紫外光不同光照条件对催化效果的影响。适宜条件下,蒽和芘的降解率分别达到94．51％和56．05％,对亚甲基蓝的降解率达到48．93％     

蒙脱石/粉煤灰复合材料吸附含锌废水的研究

以蒙脱石、粉煤灰为原料,添加一定量的粘结剂混合造粒制成复合颗粒吸附剂,用于处理含Zn2+废水,实验研究了吸附反应时间、吸附剂投加量、废水初始浓度及介质pH值对吸附性能的影响。研究结果表明:蒙脱石/粉煤灰复合颗粒吸附剂的最佳吸附工艺条件为:在室温下,吸附反应时间50 min,吸附剂投加量5.0 g/L,初始浓度40 mg/L,溶液pH值为5。在此条件下处理含Zn2+废水,吸附去除率为95.77%,处理后残余浓度为1.69 mg/L,达到国家一级排放标准(2.0 mg/L)。     

硫酸盐还原菌(SRB)处理含锌废水的基础研究

从选取菌种开始，通过富集、驯化以及分离等过程筛选出高效去除废水中锌离子的硫酸盐还原菌（SRB）单株菌YY4，并对其除锌机理进行了初步研究。实验结果表明：锌离子主要是结合了SRB的代谢产物S^2-从水溶液中被去除，SRB产生硫离子对于去除锌离子的贡献在72％左右。