四羟基蒽醌修饰活性炭碳糊电极阳极溶出法测铜

报道了将四羟基蒽醌吸附在稻壳基活性炭上,用直接混合法制成碳糊化学修饰电极及其在测定Cu(Ⅱ)中的应用。实验确定了阳极溶出法测定Cu(Ⅱ)的最佳操作条件。支持电解质为0.03 mol/L H2SO4,富集电位在-0.8V,该电极对Cu(Ⅱ)在5.0×10-8~1.0×10-2mol/L范围内分段有良好的线性响应;实际样品分析浓度小于1.0×10-2mol/L的均不需要稀释,高浓度的样品可不设富集时间,从-0.8 V处直接做阳极扫描,低浓度的样品则需设相应的富集时间,富集时间300 s时,检出限为5.0×10-9mol/L,Mg2+、Mn2+、A l3+和Fe3+等十余种共存离子基本不干扰。用本法分析人发中的铜与光谱法对照,结果令人满意。     

Electrochemical oxidation of cyclooctatetraene in the presence of allyltrimethylsilane. Anodic trialkylation with bicyclization

Anodic oxidation of cyclooctatetraene (COT) was carried out in acetonitrile containing excess allyltrimethylsilane. Under these conditions COT is oxidized preferentially to afford the COT cation radical, which then undergoes nucleophilic attack by the silane followed by further anodic oxidation. The process results in a substance in which the original eight carbons of COT are highly differentiated by the addition of three allyl groups and the formation of two new rings.     

Voltammetric and Coulometric Studies on Eugenol and Related Compounds

Abstract

Anodic processes were studied for eugenol, isoeugenol and 2,6-dimethoxy-4-allylphenol by cyclic voltammetry at a glassy carbon electrode in methanol. Preparative electrolyses were also applied coulometrically to these phenols, followed by the separation and the determination of the structures of -e, -2e and -4e products. It was indicated that both radical and cationic reactions were controlled by the applied potentials, the solvent media and the substituents on the aromatic rings.     

Determination of Vitamin K1by Adsorptive Stripping Square-Wave Voltammetry

Abstract

The adsorption of vitamin Ki at a hanging mercury drop electrode at pH 4.2 allows the determination of this compound in the 1 × 10^?6 M ^? 1 × 10^?9 M concentration range. Applying a square-wave potential scan provides a 200-fold increase of the peak current compared to differential pulse stripping voltammetry. The influence of several operational parameters such as the nature and the pH of the supporting electrolyte, the deposition time and the potential are discussed. Interactions between the adsorbed molecules occur during the deposition step.     

Recent Advances in Voltammetry

Recent progress in the theory and practice of voltammetry is surveyed and evaluated. The transformation over the last decade of the level of modelling and simulation of experiments has realised major advances such that electrochemical techniques can be fully developed and applied to real chemical problems of distinct complexity. This review focuses on the topic areas of: multistep electrochemical processes, voltammetry in ionic liquids, the development and interpretation of theories of electron transfer (Butler–Volmer and Marcus–Hush), advances in voltammetric pulse techniques, stochastic random walk models of diffusion, the influence of migration under conditions of low support, voltammetry at rough and porous electrodes, and nanoparticle electrochemistry. The review of the latter field encompasses both the study of nanoparticle-modified electrodes, including stripping voltammetry and the new technique of ‘nano-impacts’.     

Differential Pulse Anodic Stripping Voltammetric Determination of Bismuth(III) with 1‐(2‐Pyridylazo)‐2‐naphthol and Ionic Liquid Modified Carbon Paste Electrode

In this paper 1‐(2‐pyridylazo)‐2‐naphthol (PAN) and ionic liquid 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIMBF₄) were mixed with graphite powder to get a modified carbon paste electrode (PAN‐IL‐CPE), which was further used for the sensitive determination of bismuth(III). By the co‐contribution of the formation of PAN‐Bi complex and the accumulation effect of IL, more bismuth(III) was electrodeposited on the surface of the PAN‐IL‐CPE. Then the reduced Bi was oxidized and detected by differential pulse anodic stripping voltammetry (DPASV) with the oxidation peak appeared at 0.17 V (vs. SCE). Under the optimal conditions the oxidation peak current was proportional to the bismuth(III) concentration in the range from 0.04 to 7.5 μmol L^?1 with the detection limit as 3.9 nmol L^?1. The proposed method was successfully applied to the stomach medicine sample detection with good recovery.     

Preparative access to transformation products (TPs) of furosemide: a versatile application of anodic oxidation

Furosemide, a pharmaceutical prescribed for the treatment of edema and hypertension, is a known contaminant of water. In this study, chemoselective anodic oxidation was implemented to assist in the identification and the preparation of furosemide transformation products (TPs), i.e., compounds deriving from furosemide and likely to appear in the environment. An aniline and a pyridinium are proposed as plausible TPs and an analytical study of the pyridinium is presented.     

从含镁二壬基萘磺酸-磺化煤油溶液中反萃取镁的研究

采用简单的反萃取法回收二壬基萘磺酸-磺化煤油溶液中的镁。考察了反萃剂种类、反萃时间、反萃转速、反萃剂浓度、反萃相比(有机相与水相的体积比)O/A值对反萃取率的影响。研究结果表明:在常温下,以硫酸作反萃取剂,反萃剂浓度为4 mol·L-1,反萃时间为20 min,反萃取震荡转速为200 rpm,反萃相比O/A值为5时,镁的反萃率可达93.98%,经过反萃后得到的二壬基萘磺酸-磺化煤油溶液可以重复萃取冶金废水的镁离子,镁的萃取率保持不变。这一研究结果对于冶金行业废水的处理与综合利用具有重要参考价值。     

Carbon Nanotubes Heavy Metal Detection with Stripping Voltammetry: A Review Paper

The challenge of heavy metal detection for environmental, industrial and medical purposes has led to the development of many analytical techniques. Stripping voltammetry is a very sensitive electrochemical method and has been widely used for heavy metal detection. Carbon nanotubes, a well‐studied carbon material with physical and chemical properties suited for electrode material is commonly employed for sensitive and selective metal detection in electrochemistry. This article reviews the recent (2011–2016) applications of carbon nanotubes as an electrode or electrode surface modifier for heavy metals detection with stripping voltammetry.     

A Study on the extraction of uranium(VI) from sulphate leach liquor using LIX63

The sulphate leach liquor obtained from the sulphuric acid leaching process of Egyptian monazite was treated using solvent extraction to recover U(VI) by LIX63. The influence of various basic variables such as pH, concentration of LIX63, temperature, different stripping agent, phase ratio and diluents was examined. Using 10% LIX63 with the aqueous solution at equilibrium pH 5.5 and a phase ratio A/O?=?1/1, a four-stage McCabe-Thiele plot was constructed, which showed 85.57% of U(VI) extraction. The thermodynamic data showed that the extraction process is exothermic with enthalpy change ΔH?=???43.866?kJ/mol, the stripping of U(VI) was quantitative using 4?M HNO₃. The stable complex UO₂(HSO₄)R_org formed during extraction which supports the cation exchange mechanism was confirmed by FTIR spectral analysis. Uranium cake was finally obtained from the strip solution by the addition of hydrogen peroxide and ammonium hydroxide as precipitating agents, and a workable flowsheet was then formulated.