呈钼(Ⅵ)-羟胺-EDTA络合物的钼络合滴定

Pecsok和Samer研究了钼与EDTA络合物的特性和Lassner和Scharf提出钼的络合滴定法以来,这方面有了很大的发展.但绝大多数方法基于用硫酸肼把钼还元为五价,与EDTA形成深黄色的2:1络合物。由于络合物颜色较深,应用受到一定的限制。矢口裕彦、梶原武用盐酸羟胺作还原剂,钼(Ⅴ)与EDTA形成淡黄色的1:1络合物的新方法。Lassner等认为盐酸羟胺是络合剂,钼(Ⅵ)与羟胺、EDTA形成三元络合物。本     

EDTA作为螯合剂应用于棕地修复的研究综述

乙二胺四乙酸(Ethylenediaminetetraacetic acid,简称EDTA)是一种高效的螯合剂,可以应用于棕地修复中,具体体现在棕地空间(土壤、水体和空气)中重金属污染物含量的测定、清除,促进环境中的微生物反应等方面。首先介绍棕地相关的概念,重点从以EDTA为螯合剂制备的化学淋洗制剂、电化学絮凝剂、络合纳滤剂及EDTA分析滴定法2个角度阐述了EDTA对于棕地修复的应用。结合一个棕地治理工作的成功案例,总结螯合剂EDTA和配位反应的使用在棕地修复中的效果和我国棕地治理的现状,可以为EDTA与其相关反应在棕地修复中的实践应用提供一些参考。     

EDTA滴定法直接测定镍铁中镍量

测定常量镍常采用丁二酮肟重量法或氨性分离-EDTA滴定法.但两者分析流程均较长而不适于快速分析.EDTA滴定法测定镍的应用已较为广泛[1-3].本工作采用氟化钠掩蔽铁、铝,六偏磷酸钠掩蔽锰,在过量的EDTA存在下,于pH约4.6的乙酸-乙酸盐缓冲介质中,以PAN作指示剂,用硫酸铜标准溶液返滴定过量EDTA的方法直接测定镍铁中镍.方法简便,分析结果满意.     

基准试剂BaCl2纯度的测定

采用EDTA络合滴定法对BaCl2基准试剂的纯度进行测定.在滴定过程中加入EDTA-Mg,通过置换反应,以EDTA滴定Mg2 指示滴定终点,用ICP-MS法对该试剂中主要杂质如Fe、Eu、Yb、Lu等元素进行测定.EDTA络合滴定法结果与ICP-MS、GDMS杂质扣除法测定结果基本一致.该方法操作简单、快速,滴定时变色灵敏,测定结果精确度高.     

乙醛酸化学镀铜的电化学研究

以乙醛酸作还原剂,Na2EDTA.2H2O为络合剂,亚铁氰化钾和2,2'-联吡啶为添加剂组成化学镀铜液体系,应用线性扫描伏安法研究分析了络合剂、添加剂对该镀铜体系电化学性能的影响.结果表明,络合剂Na2EDTA对乙醛酸的氧化和铜的还原有阻碍作用.亚铁氰化钾和过量(20 mg/L)的2,2'-联吡啶对乙醛酸的氧化起较明显的抑制作用.     

硅钡铝合金中铝的测定

硅钡铝合金具有较强的脱氧和脱硫能力 ,对改变钢中夹杂物形态分布 ,细化晶粒 ,改善钢的加工性能 ,提高钢材质量具有重要作用。与纯铝、硅铁等单一合金相比效果更显著 ,因而在炼钢生产中受到越来越广泛的应用。但迄今尚无硅钡铝合金分析的标准方法。本文在 p H 4.5时 ,铝与 EDTA完全络合 ,以 PAN为指示剂 ,用 Cu SO4 标准溶液返滴定过量的 EDTA,从而求出铝的含量。本法操作简便 ,重现性好 ,结果满意。1　试验部分1 .1　主要试剂EDTA、Cu SO4 标准溶液 :均为 0 .0 2 mol· L-1乙酸 -乙酸钠缓冲液 :p H4.5铝标准溶液 :0 .1 mg· ml-1…     

在锌矿石粉(ZnS)存在下的粗氧化锌产品中的氧化锌EDTA容量法测定

粗氧化锌中氧化锌的测定通常采用王水分解样品,在碳酸铵存在下的氨性介质中分离Pb、Fe、Mn等干扰元素,在硫脲等掩蔽剂存在下,EDTA容量法测定Zn(1).由于方法快速,准确,在化工部门得到了广泛的应用.     

碱土金属离子与EDTA对纯铝在碱性溶液中的协同缓蚀作用

通过集气实验、极化曲线和电化学阻抗谱等方法研究了碱土金属离子与乙二胺四乙酸(EDTA)对纯铝在4 mol•L-1 KOH溶液中的协同缓蚀作用. 实验结果表明铝在含0.02 mol•L-1 EDTA和饱和Ca(OH)2、Sr(OH)2的溶液中具有最小的腐蚀速率. EDAX分析表明碱土金属离子和EDTA没有参与到铝表面氧化膜的组成中, 说明缓蚀剂是通过吸附在铝表面起作用的, 这表明它们是界面型缓蚀剂而非相间型缓蚀剂.     

EDTA对均匀胶体粒子形成的影响

特殊阴离子是决定金属盐升温水解制备均匀胶体粒子形态的重要因素之一. EDTA的存在强烈影响三价铁盐水解产物-均匀α-Fe_2O_3和β-FeOOH胶体粒子的形态. 其影响机理是EDTA在成长中的微粒子上络合吸附和溶液中的EDTA与Fe~(3+)离子间络合反应的复合结果. 前者趋于形成较大的聚合粒子; 后者趋于形成较小粒子. 进而, 凡是能够改变EDTA络合吸附状态和吸附量的. 存在于陈化液中的一切其它阴离子均会改变EDTA的作用程度.     

EDTA滴定法快速测定铝锰镁合金中铝和镁方法探讨

以HCl溶解HClO4冒烟使试样完全溶解后,利用铝是两性元素的特性,加入过量的NaOH使Mg、Fe、Mn生成氢氧化物沉淀,过滤与铝分离.将滤液定容,移取部分在过量EDTA存在下,用HCl调节pH 4左右,加热煮沸使铝与EDTA配位络合,以PAN为指示剂,用CuSO4标准溶液返滴定过量的EDTA,加氟化钠取代出与铝定量配位络合的EDTA,再用CuSo4标准溶液滴定取代出的EDTA,求得铝量.将过滤出的Mg、Fe、Mn等氢氧化物沉淀,用热的稀HCl及H2O2溶解后,用NH3·H20(1+1)调节pH 5～6,加入铜试剂使Fe、Mn沉淀与Mg分离,于滤液中加NH4Cl缓冲液,以铬黑T为指示剂,用EDA标准溶液滴定镁量.     

Influence of chemical dealumination on the properties of USY zeolite

Three series of dealuminated Y zeolites have been prepared by chemical extraction ofhydrothermally dealuminated Y zeolite(USY)with H_2Na_2EDTA,HCl and H_4EDTA.The unitcell constant,mesopore distribution,acidity and extraframework aluminum(EFAL)of thezeolites were studied with XRD,chemical analyses,adsorption,IR and NH_3-TPD techniques.It was shown that H_2Na_2EDTA only removed EFAL species deposited in the pores of USY,by contrast,HCl and H_4EDTA extract both extraframework and framework aluminum,andmake the zeolite framework further dealuminated.Adsorption tests gave evidence that a second-ary pore system exists in these dealuminated zeolites.H_2Na_2EDTA extraction increased bothmicropore and mesopore volumes,but after HCl and H_4EDTA treatments,new mesopores formedand the micropore volume was decreased.The pyridine-IR and NH_3-TPD measurements demon-strated that EFAL had no evident contribution to the zeolite acidity.     

Suitability of Stripping Chronopotentiometry for Heavy Metal Speciation Using Hydrogen Peroxide as Oxidant: Application to the Cd(II)‐EDTA‐PMA System

The possibilities of stripping chronopotentiometry (SCP) for heavy metal speciation have been tested in the modality of chemical oxidation using the model systems Cd(II)‐polyacrylic acid (PMA), Cd(II)‐EDTA and Cd(II)‐PMA‐EDTA. The use of 0.03% H₂O₂ as a chemical oxidant provides reliable results from transition times, but peak potentials are dramatically affected by the presence of this reagent. The study suggests that chemical‐oxidation SCP can be a technique complementary to other stripping modalities in the study of inert and macromolecular labile metal complexes.     

甲烷生物催化氧化制甲醇——几种化学物质对Methylosinus trichosporium 3011甲醇累积的影响

本文报导了在 Methylosinus trichosporium 3011细胞反应液中加入一些化学物质对甲醇累积的影响。结果表明,Na~+抑制甲烷单加氧酶的活性。当 M.trichosporium 3011细胞反应液中含高浓度磷酸根时,只有很少量甲醇累积下来。EDTA 和 Na_2EDTA 甲醇累积的促进作用小于甲酸钠或甲酸的作用。但由于 EDTA 不仅可以抑制甲醇脱氢酶的活性,而且可以螯合 Na~+,而甲酸则可使 NADH 辅酶再生。因此,反应液中含有2mM EDTA 和20mM 甲酸时甲醇累积量最高。     

SDY型沸石的浸取处理及其对催化性能的影响

分别用Ｎａ２Ｈ２ＥＤＴＡ、Ｈ４ＥＤＴＡ和Ｈｃｌ对ＳＤＹ型沸石的非骨架铝进行了浸取处理，并应用化学分析、ＸＲＤ、高真空苯吸附、低温Ｎ２吸附、ＮＨ３－ＴＰＤ和正庚烷裂解脉冲微型反应等物理和化学实验技术对浸取前后样品的结构、酸性和催化性能进行了研究。发现Ｎａ２Ｈ２ＥＤＴＡ能选择地浸取沉积于沸石微孔和二次孔中的非骨架铝碎片，且不损伤沸石骨架，浸取出部分非骨架铝后的样品，其正庚烷裂解和抗氮性能均有所提高。     

示差脉冲极谱法研究(Ⅹ)——受扩散和后行化学反应控制的极谱电流理论

受前行化学反应和平行化学反应的示差脉冲极谱电流理论已有论述。本文报道了受扩散和后行化学反应(EC过程)控制的示差脉冲极谱电流方程式并用实验进行了验证,应用该理论求得的动力学参数与文献值一致。     

Influence of the post-synthesis method on the number and size of secondary mesoporous structure of NaY zeolite and its effect on catalyst loading. An efficient and eco-friendly catalyst for synthesis of xanthenes under conventional heating

Several identification techniques have been used to study the effect of the preparation method of dealuminated Y zeolite on catalyst loading. In this paper, NaY zeolite was dealuminated by chemical operation with ethylenediaminetetraacetic acid (H₄EDTA) treatment. In this method, extra-framework aluminum species removed from the supercage of zeolite and therefore increases the Si/Al ratio and pore volume. Consequently, the loading of the molybdophosphoric acid (MPA) in the supercage of zeolite is increases (0.1 g/g equal 0.049 mmol/g support) in EDTA treatment (MPA-MDAZY) in comparison with (0.0875 g/g equal 0.043 mmol/g support) in hydrothermal method (MPA-DAZY). These results were also confirmed by XRF, AAS, FTIR, SEM, BET, XRD and WDX analysis. Reducing of the reaction time and increasing of the catalytic activity of EDTA treatment toward hydrothermal method can be related to the high catalyst loading based on removing of extra-framework aluminum. The catalytic activity of two catalysts has been compared in the xanthenes synthesis reactions.     

Efficient decomposition of liquid waste containing EDTA by advanced oxidation nanotechnology

Degradation of ethylenediaminetetraacetic acid (EDTA) present in the liquid waste was demonstrated by photocatalytic oxidation route by using nanoparticles of anatase titania. Nano sized titania photocatalyst was synthesized using sol–gel method coupled with ultrasonication mode and characterized using X-ray diffraction, transmission electron microscope, BET, Fourier transform infrared spectroscopy and TG–DTA. A cylindrical photoreactor was employed for the degradation studies. Five milligram of the nano anatase TiO₂ + 0.5 ml of 30% H₂O₂ were employed as catalysts for the degradation studies of 1,000 mg/L EDTA. EDTA degradation was followed by a complexometric titration method. Complete degradation of 1,000 mg/L EDTA could be achieved in 90 min and the photocatalytic efficiency of the synthesized titania photocatalyst was higher than that of P-25 TiO₂ for EDTA degradation. The influence of pH on the degradation of EDTA follow the order acidic > neutral > alkaline. More than ten fold increases in the decontamination factors were obtained for the chemical precipitation step for the liquid waste containing degraded EDTA compared to liquid waste without EDTA degradation.     

Simple pulse-acquire NMR methods for the quantitative analysis of calcium, magnesium and sodium in human serum

Simple pulse-acquire NMR methods are presented for accurate quantitation of calcium (Ca(2+)), magnesium (Mg(2+)) and sodium (Na(+)) in human serum. Ca(2+) and Mg(2+) can be determined simultaneously by (1)H NMR via their EDTA (ethylenediaminetetraacetic acid) complexes. Spectra are acquired before and after addition of EDTA, and the difference spectrum is used for integration of the signals from the complexes relative to an internal reference. Serum sodium can also be determined through pulse-acquire (23)Na NMR by integration of the free sodium signal relative to a reference signal (Na(+)+EDTA in a coaxial capillary tube). The method shows excellent accuracy and precision for all three metal ions. Slow chemical exchange between complexed and free EDTA at the natural pH of serum does not limit the accuracy of the determination of Ca(2+) and Mg(2+), and the large errors associated with spin-echo spectral editing methods are avoided.     

Antimicrobial,mechanical, optical and thermal properties of PVC/ZnO‐EDTA nanocomposite films

Covalent surface functionalization of synthesized ZnO nanoparticles (NP)s with ethylenediaminetetraacetic acid (EDTA) was successfully carried out. Modified ZnO‐EDTA NPs as a viable and inexpensive filler were incorporated into poly(vinyl chloride) PVC matrix after their chemical modification to investigate the agglomeration behavior. All prepared materials including modified NPs and PVC/ZnO‐EDTA nanocomposites (NC)s were analyzed by Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, thermogravimetric analysis, X‐ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. Fabricated PVC/ZnO‐EDTA NCs were reported to have high transparency and improved mechanical properties compared with PVC. Modified ZnO and the fabricated NCs were shown to exhibit excellent antibacterial activity against two bacteria species: Escherichia coli and Staphylococcus aureus. The obtained NCs could be considered as self‐extinguishing materials on the basis of the LOI values. Copyright © 2016 John Wiley & Sons, Ltd.     

Nuclear magnetic resonance studies of edta in the presence of excess calcium or strontium

The equilibria which exist between metal ions, ethylenediaminetetraacetic acid (EDTA), and the resulting chelates have been thoroughly investigated by many techniques, emphasis being placed on the study of complexes containing a 1:1 ratio of metal ion to ligand. The results presented here are concerned with the observation of the chemical shift of the nonlabile protons of EDTA when excess calcium or strontium ions are present. The results yield evidence for a 2:1 complex. Formation constants for the equilibria believed to be in effect are given and a possible structure of the 2:1 complex is discussed.