倒数示波计时电位滴定法测定鞣液中铬

倒数示波计时电位滴定法测定鞣液中铬郑建斌，白育伟，胡娟，朱俊杰，高鸿（西北大学化学系西安，７１００６９）（南京大学化学系南京，２１０００８）关键词倒数示波计时电位滴定，皮革鞣液，铬在皮革鞣制过程中，鞣液中铬含量的高低直接影响成革或毛皮板的质量和规格。...     

聚合物—皮革复合材料的研究：Ⅰ.丙烯酸酯单体在铬鞣猪皮中的聚合过程

采用Ｋ＿２Ｓ＿２Ｏ＿８－ＮａＨＳＯ＿３引发体系，研究了丙烯酸乙酯（ＥＡ）、甲基丙烯酸丁酯（ＢＭＡ）及其二元混合单体（ＥＡ－ＢＭＡ）在铬鞣猪皮中的聚合过程，考察了反应温度、时间、单体浓度和铬鞣猪皮的部位不同对反应的影响，初步探讨了改性过程的反应机理。     

铬的化学形态分析进展

有关痕量元素形态的研究已成为当今科学领域的活跃领域之一,是分析工作者必须面对的新课题.同一元素不同的化学形态导致不同的环境毒害、生物效应和对人体健康有不同的影响.铬是VIB族元素,在地壳中的平均含量为 0.010%～0.011%,分布广泛.工业上主要用于制造各种优质合金,也广泛用于皮革、印染、电镀等工业,受腐蚀后以各种排放液进入环境.铬有多种价态,最常见的是三价和六价.研究表明,铬表现为必需元素还是有害元素,其价态起决定性作用.三价铬是人体必需的微量元素,是正常糖脂代谢所不可缺少的,缺铬会引起动脉硬化等多种疾病.六价铬由于其氧化性和对皮肤的高渗透性,毒害很大,被确认有致癌作用.铬形态分布也影响铬在环境中的迁移转化规律.因此铬的形态分析在环境科学、生命科学、生理医学等方面都有重要的意义.     

富铬酵母中铬的化学种态及结合形态研究

对富铬酵母中铬的化学种态进行了分析和初步探讨。在铬的化学种态测定中铬的使用离子交换和火焰原子吸收法测定了富铬酵母中的Ｃｒ（Ⅲ）,方法快速简便、定量回收,结果表明,总铬呈为１５８２μｇ／ｇ的富铬酵母中,无机态铬占１６％,其中Ｃｒ（Ⅲ）为２３２μｇ／ｇ,Ｃｒ（Ⅵ）为２４．５μｇ／ｇ。酵各过程中的８４％以上的无机铬化合物转化成有机铬。说明铬参与了酵母细胞的生物合成,促进生物转化,对提高富铬酵母的生物疚极     

催化电位滴定法测定铬鞣中铬（III）

报道了以氨三乙酸存在下锰（II）催化KIO4氧化结晶紫的反应指示终点,结晶紫电极作指示电极用催化电位滴定法测定的铬鞣剂中Cr(III)的方法,该法终点灵敏,准确度高,重现性好,结果满意,用标准加入法测得的平均回收率为100．03％,RSD为0．24％。     

空气-乙炔火焰原子吸收测定铬时与浓度有关的化学干扰的研究——Ⅰ、铁、钴对铬的干扰

本文较详细地研究了在Fe、Co基体中测定铬时出现的与浓度有关的化学干扰,铬的价态对干扰的影响,并讨论了干扰的机理及克服干扰的办法。     

多糖铬配合物的研究进展

从铬配合物的性能、种类与功能,多糖铬和寡糖铬配合物的合成方法及其铬含量的检测、糖铬配合物的生物活性与毒性研究等方面进行了综述,分析了多糖铬配合物研究和应用等方面存在的问题。     

流动注射—分光光度分析鉴别铬的化学形态的研究

提出了一个FI-SP连续分析水中Cr(Ⅵ)和T-Cr的方法。Cr(Ⅵ)直接用二苯碳酰二肼试剂显色测定;T-Cr在PbO_2柱氧化Cr(Ⅲ)后显色测定。本法测定Cr的浓度范围是0.05～3.0mg·L~(-1),进样颇率为Cr(Ⅵ)200h~(-1)、T-Cr 120h~(-1)。方法用于实际样品分析获得了令人满意的结果。     

聚合物－皮革复合材料的研究Ⅱ．丙烯酸酯类聚合物改性铬鞣猪皮的性能研究

采用ＩＲ、酸水解及氮含量测定等方法，研究并发现改性猪皮中聚合物与皮胶原的结合以聚合物扩散渗入原纤维的微细结构区域的形式为主。考察了聚合改性对改性猪皮性能的影响。结果表明，当沉积聚合物（Ｄ）≤４０％时，其收缩温度（Ｔｓ）较铬鞣猪皮仅下降１～３℃。吸水率和酸膨胀率均随Ｄ的增加而呈线性下降；当Ｄ＝２０％时，吸水率的线性变化呈现一拐点，斜率变大；酸膨胀率变化的拐点则出现在Ｄ＝１０％左右。Ｄ＝５０％时，对ＥＡ、ＥＡ－ＢＭＡ和ＢＭＡ三个改性体系，增厚率分别约为２１、２８和３４％；本文所述的聚合改性法对不同部位的皮块具有一定的选择性增厚作用，有利于厚度部位差的下降。     

利用聚四氟乙烯为化学改进剂降低电热原子吸收测定铬的基体干扰

本文研究了电热原子吸收光谱测定痕量铬时几种常见的金属离子的干扰作用。     

Synthesis of Citric Acrylate Oligomer and Its In-Situ Reaction with Chrome Tanned Collagen (Hide Powder)

Summary: The purpose of this study was to formulate the new combined system of acrylic and citric acids, which was prepared by free radical polymerization and esterification reaction at the same time to form citric-acrylate CAC oligomer. The presumable chemical structure of this oligomer and the reaction mechanism were investigated by different spectroscopic tools (¹H,¹³C-NMR and ATR-IR), GPC and TGA/DTA. The effect as masking agent of the eco-friendly oligomer (CAC) in the chrome tanning of the collagen and the pickling of the hide was approached by the study of the hydrothermal and mechanical properties of in-situ treated/grafted chrome tanned collagen (hide powder) and pickled hide, respectively. The use of citric acrylate CAC oligomer instead of the traditional strong acids resulted in significant improvement in chrome exhaustion and physical properties of the leather.     

The Interaction between Collagen and an Aluminum Tanning Agent

The interaction between collagen and organometallic aluminum complexes was studied. From the analysis of the IR and UV spectra, the viscosity of collagen, and the treated collagen, a possible interaction model of the collagen with the aluminum tanning agent has been found. It indicates that such an aluminum tanning agent could be used as a cleaner tanning agent in leather tanning.

Viscosity curves of the untreated collagen solution (a) and the collagen solution treated with aluminum tanning agent (b).     

Interaction of Maleic Acid Copolymers with Collagen

One of the present trends to increase the efficiency of the chrome tanning process is the use of chemicals which change the affinity and induce a better binding of the chromium ions in the hides. Recently, some anionic polyelectrolytes based on poly(acrylic acid) or maleic acid copolymers were developed as additives in the chrome tanning. The effect of polyelectrolytes could be explained by their interaction with the collagen from hide. In our work four maleic acid copolymer/collagen systems were investigated by turbidimetric, conductometric and potentiometric titrations. The interaction between the two macromolecular compounds was clearly evidenced, and its dependence on the chemical structure of the maleic acid copolymer and on the amount of added chromium ions was studied. Homogeneous systems or turbid dispersions were observed depending on the hydrophilic or hydrophobic character of the maleic copolymer, on the [CH]/[MP] ratio, and on the concentration of the chromium ions.     

Vegetable Tanning Agents

The distribution and structure of hydrolyzed tannins, the separation of tanning agents and their quantitative determination, methods for preparing tanning extracts, methods for increasing the efficiency of extracting raw material, and the chemical processes during tanning of hides are discussed. The literature from 1950 to 1999 is reviewed     

Some Advances in the Inorganic Chemistry of Bromine

Recent advances in the chemistry of bromine and its inorganic compounds are covered under the headings of technology, properties and reactions, liquid bromine as an inorganic solvent, analysis, and new or newly studied compounds. Much of what is new is bromine chemistry is characteristic also of what is new in inorganic chemistry as a whole. That is, more detailed information about compounds and reactions is becoming available from the application of new instrumental and theoretical techniques.     

翻白草中鞣质的微波提取工艺研究

采用微波辅助提取方法,以提取剂浓度、pH值、液固比、微波提取时间、温度等为考察因素,并以提取物中总鞣质的提取率为评价指标,使用磷钼钨酸-干酪素分光光度法为定量测定方法,在单因素实验的基础上,通过正交实验优化翻白草中鞣质的提取工艺.实验结果表明,最佳提取条件为:使用70%甲醇作为提取剂、液固比40∶1、提取液pH为8.0、提取温度为40℃、提取时间为10 min.还对翻白草不同部位(根、茎、叶)的鞣质含量进行分析,发现根部中鞣质的含量最大,其次为茎和叶.此外,采用高效液相色谱法对翻白草中鞣质的种类进行定性分析.     

Kinetics of Direct Reduction of Chrome Iron Ore

The kinetics of direct reduction of artificial chrome iron ore was studied by isothermal and non-isothermal methods. In the initial, middle and final periods, the reaction is controlled by nucleation and growth, a phase boundary reaction, and diffusion, respectively. In the main reaction region, the kinetic equation is 1–(1–)^1/3=kt and the apparent activation energy is 270 kJ mol^–1. The kinetic mechanisms found with the isothermal and non-isothermal methods do not differ, and the activation energy values are approximately the same. However, the non-isothermal method can demonstrate the kinetic process completely.This revised version was published online in November 2005 with corrections to the Cover Date.     

Crystal Chemistry of Complex Carbides and Related Compounds

Numerous metal carbides can be discussed in a rather uniform way by means of structural features, mainly characterized by the mode of linking of octahedral and occasionally trigonal prismatic [M₆C] groups (M = transition element). From this point of view perovskite carbides (M₃M′C, M′ = another transition or A-group element) and derivatives, β-Mn carbides (M₃M′₂C), κ-carbides, carbides with V₃AsC- and Cr₂AlC type structures and derivatives, η-carbides (M₃M′₃C) and carbides having the filled Mn₅Si₃ type structure will be treated. The high stability of these complex carbides is due to the strong bonding M? C and additional bonding of M? M′ atoms forming an ordered parent lattice. Besides the interstitial principle of filling of lattice holes (by isolated carbon atoms), substitution with A-group elements may also take place. Thus in borocarbides extended structural elements occur.     

超分子体系的物理化学研究进展

本文介绍了超分子化学领域的研究进展, 评述了其中与物理化学有关的研究成果, 并从化学热力学、电化学、化学动力学、胶体与界面化学等几个主要方面加以讨论, 描述了超分子物理化学的基本框架。     

第32届江苏省化学竞赛选拔赛有机化学试题解析*

利用有机化学基础知识和理论对第32届江苏省化学竞赛选拔赛试题有机化学部分进行详细解析,为指导老师和参赛学生提供参考。