氰化镀银溶液中银含量测定方法的改进

本文分析了用佛尔哈德法对氰化镀银溶液中银含量的测定,给出了用硫氰酸盐滴定银时保持滴定终点清晰的实验条件,从而解决了因溶液浑浊等当点不易确定造成的分析精度降低的问题.该方法能及时准确地提供分析数据,指导镀液调整.     

火焰原子吸收光谱法测定碲化铜中低含量的银

本实验讨论了火焰原子吸收光谱测定碲化铜中银的含量，研究了试样溶解的最佳方法，介质的选择及加入量，确定了实验的最佳条件及工作曲线。加标回收率实验中银的回收率在97.3%～102%，相对标准偏差0.50%～1.35%。结果表明，采用火焰原子吸收光谱法测定碲化铜中银含量，方法准确度高，精密度好，具有较强的实用性。经标准物质验证，结果能满足日常检测的需求。     

自动电位滴定法测定米糠中维生素B1含量的方法研究

研究了以银电极为指示电极,饱和甘汞电极为参比电极,用自动电位滴定法测定维生素B1含量。探讨了该分析方法的工作电极的选择、滴定剂浓度等实验条件。在最佳实验条件下,对维生素B1含量进行测定,并与紫外分光光度法加以比较。实验均用AgNO3标准溶液滴定,通过电位突跃来判断滴定终点。该方法的标准偏差约为4.51×10-4,相对标准偏差为0.78%,加标回收率为99.2%~100.7%。     

测定饲料级磷酸氢钙中镁含量的分析方法

介绍了饲料级磷酸氢钙中测定镁含量的分析方法.试样经盐酸溶液溶解,在试验溶液中加乙二醇二乙醚二胺四乙酸(EGTA)溶液和三乙醇胺溶液,以孔雀绿指示液为指示剂,用氢氧化钠溶液调节溶液的pH值为12,加热溶液,形成沉淀.沉淀经热盐酸溶液溶解,过滤,滤液收集在250mL三角瓶中.加少量抗坏血酸和三乙醇胺溶液,加氨水-氯化铵缓冲溶液和适量酸性铬蓝K-萘酚绿B混合指示剂,用乙二胺四乙酸二钠(EDTA)标准滴定溶液滴定至溶液由红色变为纯蓝色为终点.平均回收率在98%～102%之间.     

砷钼杂多酸孔雀绿分光光度法测定硫磺中的砷

1 试验 　　(1)砷标准溶液的配制。 称取 0 1320g三氧化二砷溶于烧杯中,加 5mL饱和碳酸氢钠溶液,加热溶解,用水稀释,用硫酸中和至微酸性后移入 1 000mL容量瓶中,再用水定容,此溶液中砷含量为 100g/mL,用此溶液再稀释成 1μ g/mL的砷标准溶液。 试验用试样是以 PDS为主催化剂的 ADA法脱硫装置所得的工业硫磺。……     

连续滴定法测定甘氨酸铝锆中铝和锆的含量

采用连续滴定法测得甘氨酸铝锆中铝和锆的含量。采用EDTA络合滴定的实验方案,先将甘氨酸铝锆固体粉末配制成溶液,并将溶液的pH值调节在0.5～1之间,以二甲酚橙为指示剂,用EDTA滴定测得锆的含量;再将此溶液的pH值调节在5～6之间,然后加入过量的EDTA溶液,让铝离子与EDTA充分络合,最后过量的EDTA用硫酸锌标准溶液进行返滴定,从而测得铝离子的含量。实验证明,该法简便,结果准确。     

纤维级聚酯切片中羧基值测定方法的改进

对国标GB/T14190 93测定方法进行改进。为防止在滴定过程中玻璃电极表面成膜,搅拌速度调节到旋起的旋涡约1/5溶液高,加液速度为1mL/min,直接用在蒸馏水中浸泡的电极测样,连续测量2个平行试样之间,将电极用乙醇、氯仿清洗后在蒸馏水中浸泡6min以上,在样品溶液中预加3～4滴饱和氯化锂溶液等。回收率可达95%～105%,相对误差最大为3.1%。     

草酸盐重量法测氟碳铈矿中稀土含量

本实验采用草酸盐重量法,首先将氟碳铈矿试样用1+1盐酸溶解,经过氨水,草酸进行沉淀分离干扰元素,滴定后灼烧形成烧成物并称量,测得试样品位。结果表明,采用该分析方法测定焙烧矿中稀土含量,不仅准确度高,稳定性好,并且可以通过单因素条件实验确定滴定时溶液的较适pH。     

自动电位滴定法测定草酸银中的银含量

采用自动电位滴定法测定草酸银中的银含量,每个平行测定6次,滴定的相对标准偏差小于0.2%。方法的回收率为99.65%~100.10%。经过对比实验证明,此方法操作简便快捷、准确可靠,不仅能满足生产过程中大批量草酸银中银含量的快速分析,而且不受干扰离子的影响。     

回收氯化银中银含量的测定方法

以浓硫酸与氯化银在加热条件下反应,将氯化银转化为溶解度较大的硫酸银,而后采用佛尔哈德法定量分析氯化银中的银含量。当取样量为0.4~0.6 g,需要浓硫酸用量为4 cm3,铁铵矾指示剂为10 d,用0.1000 mol/L的硫氰酸钾标准滴定溶液滴定,即可准确分析氯化银中的银含量。滴定时,将三角烧瓶置于磁力搅拌器上,防止AgSCN吸附Ag+离子,近终点时振摇保持30 s至溶液出现微红色不退即为终点。     

氯化银直接熔炼法制备纯银的研究

本力法采用适当的熔炼剂,将AgCl直接转化成金属银,AgCl的转化率为97％,银的纯度为99％以上。     

银回收工程中的银泥脱水

介绍了几种银泥的脱水方法和技术 ,披露了“活性污泥脱水”研究的进展。     

银鳞釉及高银釉的研究

本文对日本银鳞釉及高银釉进行了系统的研究，选择适合这两种釉的组成系统，确定了其最佳化学组成，釉面效果达到日方产品水平。本文还对影响这两种釉的各种因素进行了较详细的分析讨论，并指出了高银釉的形成机理是熔体液－液分相。     

The Effect of Silver Chloride Formation on the Kinetics of Silver Dissolution in Chloride Solution

The precipitation and growth of AgCl on silver in physiological NaCl solution were investigated. AgCl was found to form at bottom of scratches on the surface which may be the less effective sites for diffusion or the favorable sites for heterogeneous nucleation. Patches of silver chloride expanded laterally on the substrate until a continuous film formed. The ionic transport path through this newly formed continuous film was via spaces between AgCl patches. As the film grew, the spaces between AgCl patches closed and ion transport was primarily via micro-channels running through AgCl patches. The decrease of AgCl layer conductivity during film growth were attributed to the clogging of micro-channels or decrease in charge carrier concentration inside the micro-channels. Under thin AgCl layer, i.e. on the order of a micrometer, the dissolution of silver substrate was under mixed activation-Ohmic control. Under thick AgCl layer, i.e. on the order of tens of micrometers, the dissolution of silver substrate was mediated by the Ohmic resistance of AgCl layer.     

One-Pot Silver Nanoring Synthesis

Silver colloidal nanorings have been synthesized by reducing silver ions with NaBH₄ in trisodium citrate buffers. pH increase, by addition of NaOH, was used to speed up reduction reaction. The UV–vis absorption spectra of resulting silver nanorings showed two peaks accounting for transverse and longitudinal surface plasmon resonance, at ≈400 nm, and between 600 and 700 nm, respectively. The shapes of these silver nanoparticles (nanorings) depended on AgNO₃/NaBH₄ ratio, pH and reaction temperature. Particles were analysed by transmission electron microscopy, scanning electron microscopy and X-ray diffraction. A reaction pathway is proposed to explain silver nanoring formation.     

Silver electrocrystallization at polyaniline-coated electrodes

The initial stage of silver electrocrystallization is studied at polyaniline (PANI)-coated platinum electrodes by means of potentiostatic current transients and electron microscopic observations. Data for the nucleation frequency and the number of active sites for nucleation are obtained by interpreting of current transients according to the theory for nucleation and 3D growth under diffusion limitations. It is found that depending on the PANI layers thickness, d, two different regimes for silver nucleation and growth exist. For thin PANI coatings (d<0.3 μm), the crystallization occurs with high nucleation frequency at active sites located at the polymer layer/metal electrode interface, the number of active sites decreasing sharply with increasing PANI coverage. For thick PANI layers (d>0.3 μm), silver nucleation occurs with a two orders of magnitude lower nucleation frequency at active sites located most probably at the polymer surface, their number remaining constant for thicknesses up to 1.4 μm. It is established that reduction of the PANI layer occurring in parallel with the silver electrodeposition does not influence the number of active sites for nucleation. The results obtained by interpretation of current transients are in good agreement with results for the number of crystals obtained by microscopic observation.     

银影分散法增强照相影像

银影分散法增强照相影像是基于通过氧化还原反应 ,使再次形成的银影像颗粒缩小到原颗粒的约 1/100,提高银遮盖力从而增强照相影像。明胶层中来自卤化银晶格的银离子 Ag＋ 在非催化还原过程中的络合作用决定银颗粒缩小程度,因而也是决定银遮盖力的关键因素。银离子的络合作用受乳剂层结构和经常规方法显影后生成的影像银氧化还原条件的影响。 本方法突出的特点是通用性和高效性 ,各种用途的黑白卤化银感光材料 ,包括工业和医用胶片,它们对电离辐射感光度可以提高 6～ 8倍 ,并保持影像原有的细部的分辨能力。     

新型银变色抑制剂的研究

本文论述了以邻甲基苯胺，α－溴乙酸以及硫氰酸铵为等为原料，制备Ar-NH-CO-CH2-SH的最佳工艺条件，并对该产物的抑制银变色的机理进行了探讨。经实验证明，该化合物具有优良的防银变色性和可焊性。     

银镜反应影响因素探讨

银镜反应是中学及大学有机化学实验中的一个典型反应，但由于操作方法及种种因素的影响，往往得不到理想的实验结果。本文在反复实验的基础上，对影响银镜反应的因素进行了讨论。     

Silver Nanoparticles and Graphitic Carbon Through Thermal Decomposition of a Silver/Acetylenedicarboxylic Salt

Spherically shaped silver nanoparticles embedded in a carbon matrix were synthesized by thermal decomposition of a Ag(I)/acetylenedicarboxylic acid salt. The silver nanoparticles, which are formed either by pyrolysis at 300 °C in an autoclave or thermolysis in xylene suspension at reflux temperature, are acting catalytically for the formation of graphite layers. Both reactions proceed through in situ reduction of the silver cations and polymerization of the central acetylene triple bonds and the exact temperature of the reaction can be monitored through DTA analysis. Interestingly, the thermal decomposition of this silver salt in xylene partly leads to a minor fraction of quasicrystalline silver, as established by HR-TEM analysis. The graphitic layers covering the silver nanoparticles are clearly seen in HR-TEM images and, furthermore, established by the presence of sp² carbon at the Raman spectrum of both samples.