Solubility of Zinc Silicate and Zinc Ferrite in Aqueous Solution to High Temperatures

Crystalline zinc silicate, Zn₂SiO₄, and zinc ferrite, ZnFe₂O₄, were prepared and characterized. The solubilities of these phases were measured using flow-through apparatus from 50 to 350 °C in 100 °C intervals over a wide range of pH. Both solid phases dissolve incongruently, presumably to form ZnO(s) and Fe₂O₃(s) (or the corresponding hydroxide phases at low temperature), respectively. The respective concentrations of zinc(II) and iron(III) matched those of ZnO(cr) and Fe₂O₃(s) (≥150 °C) reported in the literature, whereas the corresponding Si(IV) and Zn(II) concentrations were at least an order of magnitude below the solubility limits for their pure oxide phases. Therefore, the solubility constants for zinc silicate and ferrite were determined with respect to the known solubility constants for ZnO(cr) and Fe₂O₃(s) (≥150 °C), respectively, and the corresponding concentrations of Si(IV) and Zn(II) measured in this study. The results of independent experiments, as well as those reported in the literature provide insights into the mechanism(s) of formation of zinc silicate and ferrite in the primary circuits of nuclear reactors. D.A. Palmer is retired.     

难溶硫化物在水中溶解度计算的探讨

在讲授难溶硫化物溶解度的计算时,由于其阴离子在纯水中发生水解作用,会改变溶液的pH,计算此类弱酸盐在水中的溶解度时,要考虑其阴离子水解的影响。现行教材大都分两种情况来讨论:若沉淀的溶解度非常小,则认为由S2-水解产生的[OH-]很小,此时水解后溶液的pH与水相同,可按pH=7时的酸效应来计算沉淀的溶解度;若沉淀的溶解度较大,则水解后溶液的pH大于7,此时按阴离子第一级水解已经完全,而第二级水解基本上没有发生,作近似计算[1]。本文提出了一种计算难溶硫化物在水中溶解度的新方法,即通过分段考虑S2-离子水解后水的pH,逆向推出与之对应的难溶硫化物的Ksp范围,并给出了溶解度大小的近似计算公式。     

Electrochemical Determination of Sulfide at High Temperatures via Its Electrochemically Initiated Reaction with Diethyl‐p‐phenylenediamine in Dimethylformamide

The electrochemical oxidation of DEPD proceeds via an EC_revECE mechanism in dimethylformamide. It has been investigated at elevated temperatures up to 130 °C at both micro and macro platinum and glassy carbon electrodes. Kinetic and thermodynamic parameters for the reaction process have been calculated for each temperature. Further, the voltammetric response of DEPD shows enhanced limiting currents in the presence of sulfide. The analytical utility of the approach has been investigated with linear range from 50 to 850 μM sulfide concentration observed and a corresponding limit of detection of 20 μM achievable at temperatures of 70 °C.     

Manganese-Doped Zinc Sulfide Quantum Dots for Determination of Bisphenol A by Room Temperature Phosphorescence

Manganese-doped ZnS quantum dots were synthesized through a facile process in aqueous solution using L-cysteine as a surface modifying agent. The quantum dots were characterized by transmission electron microscopy and X-ray diffraction spectroscopy, and had a favorable room-temperature phosphorescence property, with a longer emission time and a narrower emission profile than fluorescence. The phosphorescence was quenched by bisphenol A. Based on these findings, a room temperature phosphorescence quenching method was developed for the sensitive and selective detection of bisphenol A. Under the optimized conditions, the detection limit was 0.2 ng · mL^?1, and the relative standard deviation was 1.14% (C = 10 ng · mL^?1, n = 11). The proposed method was successfully applied to plastic products with satisfactory results. The recovery of the method was in the range of 96% to 106%.     

硫化锌胶体标准溶液稳定性研究

采用去离子除氧水,由淀粉、乙酸锌、氯化钠、硫化钠等配制了硫化锌胶体标准溶液。实验结果表明,硫化锌胶体标准溶液的吸光度与硫化钠标准溶液基本一致,可以替代硫化钠标准溶液。采用t检验对硫化物胶体标准溶液稳定性进行了检验,表明该法配制的硫化锌胶体标准溶液在室温下可稳定保存2个月,解决了硫化物标准溶液只能现配现标现用的问题。     

Solubility of Carbon in Sulfide Melts of the System Fe-Ni-S

The solubility of carbon in iron-nickel sulfide melts at 1673 K was studied in the entire range of compositions of the Fe-FeS-Ni₃S₂-Ni tetragon. The boundaries of the stratification area were determined in this system upon its being saturated with carbon. Lines of carbon isosolubility are plotted in the tetragon field outside the stratification area.     

Solubility Product for Lithium Metaborate in Acid Solutions to Extreme Temperatures and Pressures

A recently developed model for predicting the thermodynamic properties of electrolytes to high temperatures and pressures, the unified theory of electrolytes, is used to calculate the solubility product of lithium metaborate in acid solutions from 298.15 K to T _c. The results are compared with the available high temperature experimental data in the literature. This study also establishes a value of Δ_f H ^○ (298.15 K,0.1 MPa) for LiBO₂(cr) that is in good agreement with the JANAF tables value.     

沉淀溶解法制备纳米硫化锌

以烷基黄原酸锌和硫化钠分别为锌源和硫源，采用烷基黄原酸锌沉淀溶解法制备了粒度可调、粒径分布比较窄的面心硫化锌纳米粒子，利用比表面积(BET)测定、透射电镜(TEM)、粉末X射线衍射(XRD)、傅里叶转换红外光谱(FTIR)等方法对合成的硫化锌纳米粒子进行了表征。结果表明随着烷基黄原酸锌链长的增长，通过添加硫化钠而生成的硫化锌纳米粒子的粒径逐渐减小。本文还对沉淀溶解法制备纳米硫化锌的溶液化学反应机理进行了探讨。     

Precipitation of Zinc Sulfide Particles from Homogeneous Solutions

Zinc sulfide particles were homogeneously precipitated by thermal decomposition of thioacetamide in acidic aqueous solutions in a one-step process. The influence of the operating conditions (initial concentration of zinc ion and TAA) on the nucleation time and number concentration of the generated particles was investigated. The experimental results show that the model of homogeneous nucleation previously developed and successfully tested for silver particle generation by a chemical reduction method can also be applied to the formation of zinc sulfide particles by homogeneous precipitation. Furthermore, in the particle formation method in which the nucleation time t* can be measured, the particle number concentration n* can be predicted by the simple relation n*=1/(4pir*Dt*) (r* is the critical nucleus radius, and D the monomer diffusion coefficient). Thus the particle number concentration can be easily predicted even if the rate expression and the critical supersaturation concentration are unknown. Copyright 2000 Academic Press.     

纳米硫化锌的原位制备及其对多孔硅复合体系发光的调控

Zn S的带隙较宽 ,欧姆接触较差 ,并不是一种理想的半导体 .但将多种材料与硫化锌复合 ,在一定程度上可以克服这种缺陷 [1] .相关的文献报道主要集中在 Zn S∶ M( M=Mn,Cu,Ag等 ) ,Zn S∶ RE( RE=Sm,Tb,Eu等 ) ,Zn S∶ Cd S和 Zn S∶ Zn Se等复合材料上 ,同时也有关于多孔硅 ( PorousSilicon,PS)掺杂稀土 [2 ] 和有机物 [3,4 ] 以及 PS- Cd S[5～ 7] 的报道 ,但是尚未见到在多孔硅基体上原位制备硫化锌纳米材料的报道 .本文利用一种新颖、简单的化学方法 ,通过多相反应 ,在多孔硅基体的表面和纳米孔内制得纳米级的 Zn S,从而…     

高频—红外吸收光谱法测定硫化锑精矿中总硫

硫化锑精矿出口合同常常要求出具硫的含量。ＧＢ/Ｔ32 5 2 - 1982和ＧＢ/Ｔ15 0 80 .8- 1994规定硫的测定用硫酸钡重量法和燃烧中和滴定法 ,前者测定准确 ,但耗时繁琐 ,后者准确、快速 ,但装置较复杂。本文用高频红外碳硫仪直接测硫化锑精矿中总硫量 ,方法快速 ,精密度、准确度满足预定要求 ,拓宽了高频红外碳硫仪测定高硫样品的范围。1　试验部分1.1　试剂与仪器瓷坩埚 : 2 5ｍｍ× 2 5ｍｍ(经 12 0 0℃灼烧 4ｈ ,冷却后保存于干燥器中 )助熔剂 :纯钨粒、纯铁屑、纯锡粒硫化锑标样 :ＧＳＢ4 4 2 0 0 1 3(广东商检局研制 )ＨＣＳ 140型高…     

硫化铟锌的改性合成及光催化特性

随着社会经济的高速发展,能源的短缺和生态的破坏引起了人们的关注。近年来,寻找合适的解决方案已成为关注的重点。作为一种绿色环保技术,光催化由于其高效、低成本等优点而成为能源和环境问题的研究热点。在许多光催化材料中,三元硫化物硫化铟锌(ZnIn₂S₄)由于具有可见光响应特性、简单的制备方法和出色的稳定性而表现出巨大的潜力。然而,较高的载流子复合率限制了其光催化性能。近年来,许多研究报道了改性ZnIn₂S₄以提高其光催化性能,在此,本文详细介绍了各种改性研究,包括ZnIn₂S₄单体的合成、半导体化合物的结构、贵金属沉积、碳元素改性、离子掺杂。然后,系统完整地总结了ZnIn₂S₄在光催化、降解有机污染物、去除六价铬、还原CO₂和有机合成等方面表现出的光催化特性和机理。最后,对ZnIn₂S₄的发展前景提出了展望,以期ZnIn₂S₄光催化剂得到更广泛和深入的研究,尽快在实际生产中得到应用。     

硫化物的快速分光光度法测定

提出了测定微量硫化物的快速亚甲蓝分光光度法，实验结果表明，在硫酸溶液中，Ｋ２Ｃｒ２Ｏ７＋对二甲氨基苯胺＋Ｓ＾－２迅速显色反应形成亚甲蓝，表现摩尔吸收系数为４．０６×１０＾４Ｌ．ｍｏｌ＾－１．ｃｍ＾－１；最大吸收波长为６６４ｎｍ；线性范围为０～０．８ｍｇ／Ｌ，实验了采用全差示光度法直接测定水中硫化物的条件，用于某江水中２１．６μｇ／Ｌ硫化物测定时，相对标准偏差为３．２％（ｎ＝６）；试样的标准加入回收     

Voltammetric Determination of Sulfide Ions

Procedures were proposed for the voltammetric determination of S^2– at a mercury-film electrode. They are based on the oxidation of S^2– at –0.79 to –0.80 V and on the reduction of HgS, the product of the oxidation of S^2–, at –0.76 to –0.96 V in a 1 M NaOH solution. The anodic and cathodic currents are linear functions of S^2– concentration in the ranges from 1 × 10^–5 to 1 × 10^–4 M and from 2 × 10^–6 to 1 × 10^–4 M, respectively.     

New Measurements of the Solubility of Zinc Oxide from 150 to 350°C

The solubility of zincite (ZnO) has been re-evaluated in noncomplexing solutions over a wide range of pH and from 150 to 350°C at pressures ranging from slightly above saturation vapor pressure to significantly higher pressures in NaOH, NH₃, F₃CSO₃H/F₃CSO₃ Na (HTr/NaTr), CH₃COOH/NaOH, and HTr/NH₃ solutions using a hydrogen-electrode concentration cell (HECC) and a flow-through cell with downstream acid injection. The new results, coupled with our earlier results at 75–100°C, indicate that the solubility of zinc oxide is higher than we recently reported,⁽¹⁾ but substantially lower than previous estimates available in the scientific literature. It is believed that deposition of ZnO or a zinc hydroxide phase must have occurred near the solubility minimum in the HECC sample lines in our earlier study; a problem that is overcome in the flow cell by injecting acid into the sample line before the solution is depressurized and cooled to room temperature.     

Properties of Zinc Oxide Adsorbent for Adsorbing Hydrogen Sulfide

Russian Journal of Applied Chemistry - The paper defines the conditions for the synthesis of hydrogen sulfide adsorbent based on zinc oxide from basic zinc carbonate in order to produce strong,...     

水热法合成单分散ZnS微球

以醋酸锌、硫代乙酰胺为原料, P123表面活性剂为模板, 采用水热法, 成功合成ZnS微球, 并提出其可能的形成机理. 通过XRD, TEM, FT-IR, N₂吸附-脱附表征, 发现该微球由ZnS纳米颗粒组成, ZnS纳米颗粒尺寸为6～7 nm; 微球直径500～600 nm, 具有单分散性, 表面光滑, 大小均匀; 在4000～400 cm^－1波段具有热红外透过性等特点, 有望在光、电、磁等领域发挥其潜在的应用价值.     

铜锌锡硫的合成及其光电应用

铜锌锡硫(CZTS)半导体常作为对电极材料被应用于量子点敏化太阳能电池(QDSCs)中,然而效率一直低于4%。本文采用热注入法合成出纳米尺寸的CZTS并制成对电极(CZTS/FTO),用其组装的Cd Se QDSCs和Cd Se Te QDSCs的效率(PCE)分别达到了5.75%和7.64%。电化学阻抗谱、塔菲尔极化等表征证明电池效率的提高与CZTS良好的导电性及催化活性联系密切。     

Gallium Sulfide Quantum Dots with Zinc Sulfide and Alumina Shells Showing Efficient Deep Blue Emission

Solution-processed quantum dot (QD) based blue emitters are of paramount importance in the field of optoelectronics. Despite large research efforts, examples of efficient deep blue/near UV-emitting QDs remain rare due to lack of luminescent wide band gap materials and high defect densities in the existing ones. Here, we introduce a novel type of QDs based on heavy metal free gallium sulfide (Ga₂S₃) and their core/shell heterostructures Ga₂S₃/ZnS as well as Ga₂S₃/ZnS/Al₂O₃. The photoluminescence (PL) properties of core Ga₂S₃ QDs exhibit various decay pathways due to intrinsic defects, resulting in a broad overall PL spectrum. We show that the overgrowth of the Ga₂S₃ core QDs with a ZnS shell results in the suppression of the intrinsic defect-mediated states leading to efficient deep-blue emission at 400 nm. Passivation of the core/shell structure with amorphous alumina yields a further enhancement of the PL quantum yield approaching 50 % and leads to an excellent optical and colloidal stability. Finally, we develop a strategy for the aqueous phase transfer of the obtained QDs retaining 80 % of the initial fluorescence intensity.     

铜锌锡硫的合成及其光电应用

铜锌锡硫(CZTS)半导体常作为对电极材料被应用于量子点敏化太阳能电池(QDSCs)中,然而效率一直低于4%。本文采用热注入法合成出纳米尺寸的CZTS并制成对电极(CZTS/FTO),用其组装的CdSe QDSCs和CdSeTe QDSCs的效率(PCE)分别达到了5.75%和7.64%。电化学阻抗谱、塔菲尔极化等表征证明电池效率的提高与CZTS良好的导电性及催化活性联系密切。