非水电位滴定法测定甲烷氯化物微量酸度

介绍了用全自动电位滴定仪测定二氯甲烷、三氯甲烷和四氯化碳产品中微量酸度。此方法实现了从取样到分析的全封闭操作过程,方法的相对标准偏差为1.9%-6.5%。本方法准确、快速、简便,弥补了萃取法测定酸度时操作繁琐、测试误差大等缺点,完全能够满足甲醇法甲烷氯化物产品中微量酸度的测试需要。     

NaOH间接滴定法快速测定高岭土中全硫

本文研究了快速测定高岭土中全硫的NaOH间接滴定法。样品用碱性熔剂半熔,在熔块用水浸取后的微酸性溶液中,先将转化后的硫酸盐沉淀为硫酸联苯胺,沉淀过滤并溶于热水后,再以酚酞作指示剂,用NaOH标准溶液滴定至终点。结果表明：改进后的本法操作简单、测定快捷、准确度高、干扰小,可满足生产要求,测定结果的相对标准偏差（RSD）仅为2．09％,加标回收率（R）在94．3％～101．6％之间。     

氧化锌主含量测定的改进

对氧化锌主含量的测定方法进行了改进：使锌呈锌氨络离子状态与干扰元素分离,pH值由原方法的10变为6,并加入相应的缓冲溶液,指示剂由铬黑T改为二甲酚橙,使滴定终点更易掌握,测定结果更加准确。     

Carbon and sulphur on Pd(111) and Pt(111): Experimental problems during cleaning of the substrates and impact of sulphur on the redox properties of CeOx in the CeOx/Pd(111) system

The X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and CO titration has been used to detect common impurities like carbon and sulphur on Pd(111) and Pt(111) surfaces. Different experimental problems are discussed and practical tips for the cleaning of Pd(111) and Pt(111) are given. A mechanism for the carbon oxidation on closed packed platinum group metals like Pt(111) and Pd(111) is presented. The bulk carbon concentration of Pd(111) was estimated based on the Langmuir-McLean theorem. Additionally it was shown that the titration with CO and subsequent XPS measurement is a powerful yet convenient method for quantitative detection of impurities and ceria coverage determination. A CeO_x/Pd(111) inverse model system was prepared by evaporation of cerium in an oxygen atmosphere. The comparative study has shown that sulphur contamination changes the redox properties of the CeO_x in the CeO_x/Pd(111) system.     

Synthesis and characterization of new sulfonated polytriazole proton exchange membrane by click reaction for direct methanol fuel cells (DMFCs)

Sulfonated polytriazole (SPTA) in which the acidic sulfonic acid and basic triazole groups act as physical crosslinking sites within a polymer backbone has been successfully prepared, for use as a proton exchange membrane, using the click reaction. The acid-base interactions of the SPTA membranes leads to the formation of well-dispersed ionic clusters and the random distribution of ion channels with good connectivity resulting in lower methanol permeabilities at ambient temperatures and similar or higher proton conductivities than Nafion 117 at 80 °C in conditions of near zero relative humidity. Proton conductivities (σ) of 0.149 S cm⁻¹ at 80 °C and 9 × 10⁻⁵ S cm⁻¹ in anhydrous conditions together with low methanol permeability (P) at 0.1 × 10⁻⁶ cm² s⁻¹ that are comparable or superior to Nafion 117 (σ_T=80 : 0.151 S cm⁻¹; σ_RH=0 : 3 × 10⁻⁵ S cm⁻¹; P_T=30: 1.31 × 10⁻⁶ cm² s⁻¹) were achieved. Additionally, the selectivity of SPTA is approximately four times higher than that of Nafion 117, thus it may have potential for use in direct methanol fuel cells (DMFCs).     

关于汽油规格中硫醇测定方法的讨论

针对汽油产品中硫醇的分析问题进行了讨论,包括不同硫醇博士法含硫试验的灵敏度烯烃对硫醇测定的影响以及产品标准中博士法含硫试验和电位滴定的关系等,并采用气相色谱法对催化裂化汽油中的单体硫酏进行了表征。从试验结果看,采用电位滴定法确定硫醇硫的含量比博士法含硫试验更客观一些。     

胶体滴定法测定采油污水中部分水解聚丙烯酰胺的浓度

应用胶体滴定技术建立了采油污水中部分水解聚丙烯酰胺（HPAM）浓度的分析方法。探讨了pH值、水解度、矿化度、含油量、粘均相对分子质量和滴定速度对胶体滴定法的影响。实验结果表明,在pH值为9～10．HPAM溶液浓度在5mg／L～200mg／L时,其电荷量（以滴定值表示）与对应浓度呈良好的线性关系。采出液中水相的矿化度和低于50mg／L的含油量以及HPAM的粘均相对分子质量对胶体滴定值无明显影响,但水解度会影响胶体滴定值。滴定速度应控制在0．02mL／S左右。HPAM的平均回收率为99．89％,相对标准偏差为5．35％。胶体滴定法和淀粉一碘化镉法测定的油田采出液中HPAM的浓度差值小于5mg／L。与淀粉一碘化镉法相比,胶体滴定法具有所用试剂无毒、对环境无污染、操作简便快速、结果准确、适合在现场监测使用的特点。     

增量电位滴定模式在低浓度磺酸盐阴离子测定中的应用

在两相电位滴定中,采用增量模式和动态模式两种滴定剂添加方式测定了阴离子表面活性剂有效物浓度.实验表明,试样质量分数在0.3％～0.09％,阳离子滴定剂质量浓度为0.004 mol/L,V(萃取剂水)∶V(无水乙醇)∶V(MIBK)=2 ∶ 1∶1时,标样的增量添加模式的准确度和精密度0.09％优于动态添加模式的0.29...     

采用非水滴定法测定羧基丁腈橡胶中的羧基含量

建立了一种采用非水滴定法测定羧基丁腈橡胶中羧基含量的方法,并考察了该方法的准确度和精密度。该方法以非水溶剂丁酮溶解试样,然后以KOH-乙醇标准溶液中和,滴加酚酞作指示剂,并用盐酸标准溶液返滴定过量的KOH。测试结果表明,该方法的回收率为97.3%～103.4%,标准偏差不大于0.040%。