Synthesis of EDTA-modified magnetic activated carbon nanocomposite for removal of permanganate from aqueous solutions

In this study, activated carbon particles were magnetized by different amounts of maghemite in different temperatures using co-precipitation method and the resultant nanocomposite were modified with ethylenediaminetetraacetic acid (EDTA) to increase the permanganate contaminants adsorption capacity and to prevent degradation and oxidation of maghemite nanoparticles. Various properties of nanocomposite were investigated using different techniques including, vibrating sample magnetometer, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectrometer. Different kinetics, isotherms and thermodynamic models of adsorption process were investigated. Comparing data with kinetic models showed that the adsorption process complies with the pseudo-second-order kinetic model. The study of equilibrium isotherms data at different temperatures indicated that the adsorption process is more compatible with Langmuir model. Negative values of ΔG and positive values of ΔH revealed that adsorption process is spontaneous and endothermic. Response surface methodology was used to determine optimal parameters of an adsorbent dose of 1 g L⁻¹, pH = 2 and initial permanganate concentration of 50 mg L⁻¹, according to which, the maximum capacity of permanganate adsorption obtained under optimal conditions was 93.86 mg g⁻¹.     

EDTA滴定法测定锰矿石中的氧化钙和氧化镁

锰矿石中含有大量的锰,锰对络舍滴定法测定氧化钙、氧化镁有干扰,所以要先用HNO3-KClO3将大量锰分离,再用六次甲基四胺和铜试剂将滤液中残留的少量锰以及铁和铝等分离除去,最后用EDTA滴定法连续测定氧化钙和氧化镁.     

Chemical composition and antioxidant activity of Borago officinalis L. leaf extract growing in Algeria

The aqueous and hydroalcoholic extracts of borage (Borago officinalis) leaves from Annaba region (Algeria) were preliminary analyzed for their phenolic profile (total phenolics, total flavonoids, total flavonols, total tannins and total anthocyanins). These extracts were evaluated for their antioxidant properties by different methods such as DPPH radical scavenging, test NBT and total antioxidant activity. The two extracts have exhibited a high antiradical capacity. Indeed, the ethanolic extract showed the lower IC50 values and the highest amount of phenolics (94.09 ± 1.72 mg gallic acid/g dry extract). Using LC-MS/MS analysis, it was possible to identify phenolic acids, flavonoids, sterol and for the first time oleuropein was identified in the aqueous extract of the plant. The obtained results have demonstrated that phenolic compounds are the major contributor to the antioxidant activity of plants.     

Fe(OH)2悬浮液在EDTA作用下氧气氧化生成δ-FeOOH的机理研究

At room temperature and in the presence of trace EDTA, the formation of δ-FeOOH was studied by the rapid oxidation of Fe(OH)2 suspension with O2. The structural and morphological changes were characterized by various techniques such as XRD, FTIR and TEM. γ-FeOOH and δ-FeOOH formed simutaneously in the early period of oxidation. But as the rate of mass transfer was in equilibrium, trace γ-FeOOH vanished gradually. Accordingly, pure phase δ-FeOOH was obtained. At the same time, critical amount ratio K of EDTA to Fe^2 was verified. The experiments show that the reactivity, rate of the oxidizing agent and pH of the initial medium were important factors for the formation of pure phase δ-FeOOH. Under the auxiliary effect of EDTA, the reactivity of O2 was nearly improved to that of H2O2. And the process of the oxidation that Fe(OH)2 suspension was oxidized by O2 under that condition was discussed.     

阻抑催化动力学光度法测定板栗罐头中痕量EDTA

在硫酸介质中,Fe(Ⅲ)对过氧化氢氧化中性红的褪色反应具有强的催化作用,EDTA对上述指示反应具有灵敏的阻抑作用,从而提出了一种阻抑催化动力学光度法测定板栗罐头中痕量EDTA的方法。优化的试验条件如下:①过氧化氢用量为1.0mL;②0.1g.L-1中性红溶液用量1.0mL;③50.0mg.L-1 Fe(Ⅲ)溶液用量为0.12mL;④反应温度为沸水浴;⑤反应时间为10min。EDTA的质量浓度在900μg.L-1以内与ΔA呈线性关系,检出限(3s/k)为8μg.L-1。方法用于板栗罐头中EDTA的测定,测定值的相对标准偏差(n=6)小于3.0%,加标回收率为93.0%～96.0%。     

乙二胺四乙酸辅助水热法合成NaYF_4纳米晶

用络合剂乙二胺四乙酸(EDTA)辅助水热法合成了NaYF4纳米球和微米棱柱,通过控制反应条件得到了立方相和六方相纳米晶体;采用X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)及荧光光谱仪(PL)分析了产物的结构、形貌及发光性能.结果表明,络合剂EDTA和氟化物的物质的量对NaYF4的形貌和粒度有很大影响,且产物的荧光性能呈现出尺寸依赖性.     

Determination of ethylenediaminetetraacetic acid in sea water by solid-phase extraction and high-performance liquid chromatography

The chelating agent EDTA is widely used, and as a result is showing up widely in the aquatic environment. Here we describe a preconcentration procedure for measuring EDTA concentration in sea water samples by HPLC. The procedure consists of forming an Fe(III) complex followed by solid-phase extraction using an activated carbon cartridge. After the preconcentration, EDTA was quantified by HPLC with ultraviolet detection (260 nm). The enrichment permitted the determination of EDTA at concentrations as low as 1 nM. Good recoveries were obtained for both brackish and full-strength sea water with high repeatability (RSD < 6%). The method was applied to sea water samples taken from near the mouth of the Oyabe River in Japan.     

Complexometric Determination of Mercury(II) Using 2-Mercaptopropionylglycine as a Selective Masking Reagent

 A selective complexometric method for the determination of mercury(II) in the presence of associated metal ions is reported, based on the selective masking ability of 2-mercaptopropionylglycine (MPGH₂) towards mercury. Mercury, along with other associated metal ions, is first complexed with excess of EDTA and the surplus EDTA is back titrated at pH 5–6 (hexamine buffer) with standard zinc sulfate solution using xylenol orange as indicator. An aqueous 1% solution of MPGH₂ is then added to displace EDTA selectively from the Hg-EDTA complex and the released EDTA is titrated with the same standard zinc sulfate solution. Reproducible and accurate results are obtained for 4–85 mg of mercury with a relative error of ≤ 0.26% and coefficient of variation not exceeding 0.42%. The interferences of various cations and anions are studied. The method is used for the analysis of mercury in its complexes and alloy samples. Received August 30, 2000. Revision January 15, 2001.     

Experimental and theoretical study of recovery mechanism of impurity effect by the addition of EDTA

The impurity effect by trivalent metal ion such as Al³⁺, Fe³⁺ and Cr³⁺ during crystal growth of KDP is reasonably well documented. If a metal ion is adsorbed onto the crystal surface, it prevents the step propagation relevant to the crystal growth rate. However, this impurity adsorption mechanism is still not well understood. Recently, in our work on the addition of chelate agents, a recovery effect of the metal ion adsorption was discovered. However, its recovery mechanism is not clearly understood both theoretically and phenomenally. In this research, ethylene‐diamine‐tetra‐acetic acid, EDTA, which is the most common chelate agent, was used as a recovery agent. The recovery mechanism was considered from the correlation of experimental data and the interfacial distribution model that we proposed in our former study. Furthermore, quantum calculation of EDTA metal complex can explain the relaxation of impurity adsorption by the addition of EDTA. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

氯化稀土与丙氨酸配合行为的研究

用半微量相平衡方法研究了SmCl~3-Ala-H~2O三元体系在25℃时的溶解度。结果表明体系中形成了两种配合物: Sm(Ala)~2Cl~3.3H~2O和Sm(Ala)~3Cl~3.3H~2O,合成了RE(Ala)~3Cl~3.3H~2O(RE=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy),RE(Ala)~2Cl~3.nH~2O(RE=La, Ce, Pr, Nd, Sm, n=3; RE=Ho, Yb,Y, n=4)与RE(AlA)Cl~3.6H~2O(RE=Eu, Gd,Tb, Dy, Ho, Yb, Y)二十四种固体配合物, 用化学分析、IR、UV、X射线分析及TG-DTG对配合物进行了表征, 发现了RECl~3与Ala形成配合物的规律性。