锡铅焊料中高含量镉的测定-EDTA络合滴定法

研究了用EDTA络合滴定测定锡铅焊料中高含量镉的方法。对测定条件、溶液酸度、共存离子干扰情况、加标回收率、方法的准确度和精密度考察进行了较全面的讨论。本法可用于锡铅焊料中10％～20％（质量分数）镉的测定。     

镁钙锌铝四元类水滑石金属含量的测定研究

论述了镁-钙-锌-铝四元合成类水滑石中含量相差悬殊的4种金属元素含量的测定方法:第一份试液,以氟化铵掩蔽铝、镁、钙离子后,用乙二胺四乙酸二钠(EDTA)标准溶液滴定锌离子;第二份试液,用缓冲溶液调节pH为3.5,加过量EDTA煮沸处理,再调节pH为4.2,促使铝离子和锌离子全部与EDTA络合,以铜离子标准溶液滴定剩余的EDTA后,用取代络合滴定法测定铝离子;第三份试液,用小体积沉淀法处理,形成碳酸钙和氢氧化镁沉淀,与溶于水的偏锌酸根(ZnO2-2)和偏铝酸根(AlO-2)分离,再使碳酸钙与氢氧化镁溶于盐酸溶液,用EDTA滴定钙-镁总量;向第四份钙-镁溶液中加入乙二醇二乙醚二胺四乙酸钡(Ba-EGTA)-硫酸钠溶液掩蔽钙离子,用EDTA标准溶液滴定镁离子,以差减法计算钙离子含量.该法准确度和精密度均较高,能满足工业分析要求.     

络合滴定法和电位滴定法测定自来水中Ca^2＋、Mg^2＋比较

通过络合滴定诸和电位滴定法对自来水中Ca^2＋、Mg^2＋离子总含量的分析,得出电位滴定法较传统的络合滴定法的分析周期更短,揉作过程容易控制,相对偏差小且分布范围窄,有效避免了络合滴定法中对终点颜色判断带来的偶然误差。     

聚乙烯亚胺与钴离子的络合行为

采用光谱法研究了聚乙烯亚胺(PEI)与钴离子在水溶液中络合的行为.研究了不同温度下水溶液中生成的PEI-Co络合物浓度随时间的变化,发现随温度升高,达到络合平衡所需要的时间缩短,而生成的PEI-Co络合物浓度增加.分别在钴离子或PEI中亚胺基过量的情况下,研究了PEI与钴离子络合的初始速率与亚胺基或钴离子浓度的关系,发现PEI与钴离子的络合反应对钴离子和PEI中亚胺基均是一级反应.求出了不同温度下PEI与钴离子络合反应和解络合反应的速率常数,以及络合反应的平衡常数.根据Arrhenius方程计算得到PEI与钴离子络合反应的活化能为21.2 kJ·mol-1.基于Van't Hoff方程,求出了络合反应的摩尔反应焓和熵,其值分别为55.3 kJ·mol-1和218 J·mol-1·K-1.     

直接络合滴定法测定磷矿石中的钙

本文报导了ＥＤＴＡ直接络合滴定磷矿石中钙的分析方法。本文对磷矿石中常见离子作干扰实验，证明用ＴＥＡ－淀粉可掩蔽之。本试验用王水溶解试样，溶液在ｐＨ＞１２．５的碱性介质中，钙黄绿素－百里香酚酞与Ｃａ２＋形成绿色荧光络合物。用ＥＤＴＡ滴定至绿色荧光消失为终点，已用于标准物质及实际矿样分析。本法简便快速，结果可靠。     

磷化废水中锌含量的测定

过去,我厂油漆磷化工艺的含锌废水排放浓度高达70～100毫克/升,废水成份以锌离子为主,需要测定其锌含量时,用铬黑丁作指导剂,添加掩蔽剂以消除铁离子干扰,用EDTA络合滴定便可解决。但自从我厂油漆车架大楼建成并使用后,磷化工艺已有改革,其含锌废水的浓度发生了很大的变化,锌离子浓度大大降低,废水中所含Ca~(++)量大于Zn~(++)量。由于受大量钙离子的干扰,用铬黑丁为指示剂,以EDTA络合滴定锌的老方法测定废水中锌含量     

用Pb(NO3)2-EDTA络合滴定法测定硫黄纯度

提出了用Ｐｂ（ＮＯ３）２－ＥＤＴＡ络合滴定法测定硫黄纯度的分析方法，试样经处理转化为硫酸根，用铅离子溶液沉淀，再以二甲酚橙为指示剂，用ＥＤＴＡ标准溶液滴定滤液中过量的铅离子，间接求得硫黄纯度。该法操作简便，分析时间短，试验结果的精密度比二硫化碳溶解法高，试样分析获得了满意结果。     

用络合滴定法测定铝粉浆中铝含量

浮型与非浮型铝浆中的金属铝含量分析,我们采用常规EDTA络合滴定,都以失败而告终。发现铝离子与EDTA络合速度比其他离子与EDTA络合速度慢,是造成常规络合滴定失败的原因。本文介绍了解决这个分析问题的方法。该方法的要点是:在偏酸性的条件下,让铝离子和EDTA一起煮沸数分钟使络合充分,定量地与EDTA反应,用NaF置换被铝离子定量络合的EDTA,滴定被置换出来的定量EDTA来计算铝含量。     

陶瓷原料中SiO_2的钼酸银沉淀法测定

通过实验,发现络合滴定用的指示剂——偶氮胂—Ⅲ,可用作本测定中的沉淀滴定指示剂。根据标准 AgNO_3溶液同 MoO_4~(2-)的定量反应,计算出以硅钼黄 Hg[Si(Mo_2O_7)_6]形式存在的MoO_4~(2-)量,再据以算出硅酸盐中 SiO_2的含量。     

铬黑T作为络合滴定指示剂稳定性的研究

用络合滴定法和分光光度法对铬黑T在三乙醇胺和无水乙醇溶液中的稳定性进行了研究,认为铬黑T在三乙醇胺和无水乙醇溶液中作为络合滴定指示剂至少在一年中有效。     

萃取分析时最低掩蔽剂浓度的简便计算方法

提出一种萃取分析时掩蔽剂最低浓度的简便计算公式:lg[R]=1b[lgKe+nlg[HLn(o)]+npH-lgβb+3+lgVV((wo))],式中Ke为干扰金属离子与萃取剂配合物的萃取平衡常数,[HLn(o)]为萃取剂在有机相的浓度,V(o)和V(w)分别为有机相和水相的体积,n、b分别为干扰金属离子与萃取剂配合物的最大配位数和溶液中干扰金属离子与掩蔽剂配合物浓度最大配离子的级数。β为干扰金属离子与掩蔽剂配合物的累积稳定常数。求解时,我们从第一级配离子浓度最大开始,若计算出的[R]位于第一级配离子浓度最大的自由配体浓度范围,则此时的[R]即为计算结果;否则试探下一级配离子直至位于其浓度范围。得到了[R]后,由酸效应系数可计算出掩蔽剂的最小浓度。     

分子光化学贮存太阳能 III.双环[2,2,1]-2,5-庚二烯的光诱导电子转移敏化异构化反应

以N,N,N′,N′-四甲基联苯二胺、2,6-二甲氧基萘和2,7-二甲氧基萘为光敏剂,在正己烷溶液中实现了双环[2,2,1]-2,5-庚二烯到四环[2,2,1,0~(2,6),0.(3,5)]庚烷的异构化。测定了反应的量子产率。讨论了反应机理。通过激发态的光敏剂与二烯之间的电子转移反应,形成单重态和三重态处于平衡状态的离子自由基对中间体。处于溶剂笼中的三重态离子自由基对经电子反传,产生激发三重态二烯。最后该激发态二烯经分子内[2+2]环合加成反应异构化为四环烷。     

Complexation Equilibrium Constants of Poly(vinyl alcohol)-Borax Dilute Aqueous Solutions – Consideration of Electrostatic Charge Repulsion and Free Ions Charge Shielding Effect

Equilibrium dialysis experiments of dilute poly(vinyl alcohol) (PVA) in borax aqueous solution (PVA concentration was 2 g/L and borax concentration ranged from 0.0 M to 0.05 M) were carried out to determine the concentration of free borate ions in equilibrium with the PVA-borate complex at 25°C, and hence the amount of borate bound to PVA. The binding isotherm of borate ion on PVA molecules was investigated. The concentration of borate ion bound on PVA was found to increase with increasing borax concentration and reached an asymptote at high borax concentrations. The complexation equilibrium constant between borate and PVA diol was found to decrease initially then increases and finally decreases with increasing borax concentration while PVA concentration was fixed in a constant value. The equlibrium constant of free borate ion with borate-PVA diol complex was a balance result of excluded volume of PVA molecular chains, electrostatic charge repulsion between free borate ions and borate-PVA diol complexes, and electro-shielding of free Na⁺ ions on negatively charged PVA-borate complexes. In this study, the electrostatic charge repulsion between free borate ions and borate-PVA diol complex ions and free Na⁺ ions shielding effect are considered in the estimation of equilibrium constants of PVA diol-borate complexation. A fixed value of equilibrium constant is obtained with increasing borax concentration while borax concentraion is below a critical concentration [borax]_crt. As borax cocentration is higher than [borax]_crt, a lots of PVA diols form complexes with borate ions and a high shielding of free Na⁺ ions on negatively charged borate-PVA diol complexes causes the PVA-borate complexes to behave like neutral polymers. Few free PVA diol binding sites are available for reaction with free borate ions while borax concentration is higher than [borax]_crt resulting in a decrease in equilibrium constant with increasing borax concentration.     

Adsorption properties of a chelating resin containing hydroxy group and iminodiacetic acid for copper ions

A chelating resin, PSGI, was synthesized by the radical polymerization of GMA‐IDA, DVB, and styrene for the removal of Cu(II), Co(II), and Cd(II) from an aqueous solution. The characteristic functional groups and chemical composition of PSGI were analyzed by Fourier transform infrared spectroscopy and elemental analysis of C, H, and N. The equilibrium adsorption capacities of PSGI from their single‐metal ion solutions were 1.46 mmol/g for Cu(II), 1.02 mmol/g for Co(II), and 1.10 mmol/g for Cd(II). The adsorption isothermal of Cu(II) by PSGI followed the Langmuir isotherm. Increasing the concentration (0–0.1 M) of KCl in Cu(II) solution affected the adsorption behavior slightly. Within the pH range of 2–5.5, decreasing the pH of the Cu(II) solution did not produce remarkable changes in the equilibrium adsorption capacities. The adsorption capacities of PSGI for Cu(II) did not cause significant change during the repeated adsorption–desorption operations. The competitive adsorption tests verified that this resin had good adsorption selectivity for Cu(II) with the coexistence of Co(II) and Cd(II). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2123–2130, 2004     

甲醇-乙酸甲酯-1-丁基-3-甲基咪唑双三氟甲磺酰亚胺盐的等压汽液平衡

测定了101.3 kPa下甲醇-乙酸甲酯-1-丁基-3-甲基咪唑双三氟甲磺酰亚胺盐（[BMIM］［Tf2N］）体系的汽液平衡,并用NRTL方程对测得的汽液平衡数据进行了回归,得到方程的二元参数。实验表明［BMIM］［Tf₂N］能够显著提高甲醇对乙酸甲酯的相对挥发度,并且随着［BMIM］［Tf₂N］含量的增加,甲醇对乙酸甲酯的相对挥发度增大。将萃取剂［BMIM］［Tf₂N］与1-辛基-3-甲基咪唑六氟磷酸盐（［OMIM］［PF₆］）进行了对比,结果表明对于甲醇-乙酸甲酯体系,［BMIM］［Tf₂N］具有更高的分离效率。     

Solvent extraction with LIX 973N for the selective separation of copper and nickel

LIX 973N diluted with Iberfluid was used to co‐extract copper and nickel from ammoniacal/ammonium carbonate aqueous media. The influence of equilibration time, temperature, equilibrium pH and extractant concentration on the extraction of both metals has been studied. It was observed that neither copper nor nickel extraction is sensitive to temperature and equilibrium pH, however nickel extraction equilibrium is reached at a longer contact time (20 min) than that of copper (5 min), in addition nickel extraction depends greatly on the extractant concentration in the organic phase. For a solution containing 3 g dm⁻³ each of copper and nickel and 60 g dm⁻³ ammonium carbonate, conditions were established for the co‐extraction of both metals, ammonia scrubbing and selective stripping (with H₂SO₄) of nickel and copper. Using the appropriate extractant concentration the yield (extraction stage) for both metals is near 100%, whereas the percentage of nickel and copper stripping is also almost quantitative. © 1999 Society of Chemical Industry     

3种离子交换相平衡模型在Tau/OH~-体系中的比较

在牛磺酸/氢氧根相平衡体系下,对计量置换模型、异质作用模型和改进的Langmuir模型的计算精度等特性进行了比较。采用静态法进行牛磺酸/氢氧根体系的离子交换平衡实验,测定30℃下的离子交换等温线;分别使用计量置换模型、异质作用模型和改进的Langmuir模型方程对相平衡数据进行拟合得到相关模型参数。结果表明:改进的Langmuir模型在一定牛磺酸浓度范围内可以正确地描述Tau/OH-体系的相平衡,拟合结果优于计量置换模型和异质作用模型。     

Kinetics and equilibrium of cobalt ion adsorption on cross‐linked polyethylenimine membrane

The kinetics and equilibrium of cobalt ion adsorption on crosslinked polyethylenimine (PEI) membrane were studied by the spectroscopic method in terms of time, cobalt ion concentration, and temperature. It was found that the adsorption of cobalt ion on crosslinked PEI membrane obeyed the pseudofirst‐order kinetic model and the equilibrium adsorption amount of cobalt ion on crosslinked PEI membrane was closely related to the initial cobalt ion concentration. The equilibrium adsorption amount increased with the decrease of temperature and obeyed a Langmuir isotherm to give the equilibrium constant for the adsorption of cobalt ion on crosslinked PEI membrane under various temperatures. Based on Van't Hoff equation the enthalpy and entropy of the adsorption of cobalt ion on crosslinked PEI membrane were determined to be ?12.9 kJ mol^?1 and ?107 J mol^?1 K^?1, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

多级串联等体积全混流反应器与平推流反应器等效性研究——以二级可逆反应为例

在多级串联全混流反应器中,在等温等容条件下给出了二级可逆反应第Ⅳ级反应器的出口浓度表达式.讨论了在相同操作条件下,达到平推流反应器的转化率所需要的等体积串联全混流反应器的级数Ⅳ;主要考察了正反应速率常数k1、平衡常数K、反应物初始浓度之比M、停留时间τ等因素对N的影响,得出了N与正反应速率常数k1、相平衡常数K以及停留...     

Trace-Level Extraction Behavior of Actinide Elements by Aliphatic Alcohol Extractants in Mineral Acids: Insights into the Trace Solution Chemistry of Protactinium

The extraction of actinide elements thorium, protactinium (Pa), uranium, neptunium, and americium by aliphatic alcohols (1-octanol, 2-ethyl-hexanol, and 2,6-dimethyl-4-heptanol) was investigated with solvent extraction and extraction chromatographic techniques from hydrochloric and nitric acid solutions. These systems provide the potential for low-cost, high quality methods for the isolation of Pa from complex matrices. Acid dependency experiments demonstrate the selective extraction of protactinium from hydrochloric and nitric acids, relative to the other actinides explored. Experiments were conducted to elucidate the equilibrium chemical stoichiometry of the protactinium complex that underlies this unique extraction behavior. Slope analysis with respect to the alcohol concentration infers a stoichiometric relationship of 2:1 for the alcohol extractant to the protactinium ion. Slope analysis with respect to the chloride ion (when [H⁺] = 0.1, 1, and 4 M) suggests that the stoichiometric identity of the protactinium chloro-complexes depends on the [H⁺] (0.1 M to 4 M). Extraction of Pa increases as the Pa:Cl ratio increases from 1:2, at low acid concentration, to 1:6 at high acid concentration. With respect to the nitrate ion (when [H⁺] = 1 and 4 M), the stoichiometric relationship was determined to be 2:1 nitrate to protactinium throughout the range investigated. The sum of these findings and observations contribute to a deeper understanding of the unique chemistry of protactinium compared to the other members of the actinide group.