共查询到20条相似文献,搜索用时 15 毫秒
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Martin Pumera Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(20):4970-4978
Electrocatalytic or not? Carbon nanotubes (CNTs; see figure) are at the forefront of electrochemical research, but care should be taken when describing the electrochemistry, which is often caused by defects or impurities. A discussion on this aspect of their chemistry as well as important applications of CNTs for sensing and energy storage are presented.
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Over the last years, aqueous two-phase systems (ATPS) regained an increasing interest due to their potential in the downstream processing of biomolecules. After many years with only a few articles published, a lot of effort and work has been put into studying these systems for the partitioning of a range of compounds including proteins, organic low-molecular weight molecules or metal ions. Although several research and review articles appeared, a background review on ATPS partitioning fundamentals is needed. In this article, partitioning theories and main effects of several important factors for partitioning, such as molecular weight of the polymer, effect of added salts, pH, electrical charges, and temperature on phase diagrams, tie-line lengths, interfacial tension and settling time of the two aqueous phases are extensively reviewed. The trend in ATPS research is given compiling the recent 2008–2013 research articles published in the field. 相似文献
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Grégoire C. Gschwend Astrid Olaya Pekka Peljo Hubert H. Girault 《Current Opinion in Electrochemistry》2020
Charge transfer phenomena at the interface between two immiscible electrolyte solutions (ITIES) are electrochemical reactions taking place in soft media. Owing to their liquid nature, the ITIES shows a large panel of electrochemical reactions including electron transfer reactions, ion transfer reactions, coupled electron–ion transfer reactions or biomimetic redox reactions. Nevertheless, the mechanisms by which these reactions proceed are yet to be fully understood. The goal of this short review is to summarise the work accomplished over the past decades towards the elucidation of the structure and reactivity at the ITIES, highlighting the main questions still to be answered. 相似文献
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从学生实验能力培养出发,以"液-液萃取"实验内容为例,对较为常见的教学内容"乙醚萃取醋酸水溶液中醋酸"和"四氯化碳萃取碘水中碘"进行比较,提出选用"四氯化碳萃取碘水中碘"作为"液-液萃取"教学内容。并在此基础上,增加"四氯化碳回收"和"碘水中碘的含量测定"为拓展教学内容。教学实践表明:重组的"液-液萃取"项目,不仅丰富了教学内容,增强了实验项目的趣味性和综合性,更重要的是增加了学生课堂动手训练机会,同时对于培养学生化学实验素养、提高对环境保护的意识和自主探究学习精神起到了积极推进作用。 相似文献
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液-液(油-水)界面合成是近几年发展起来的一种制备纳米材料的有效方法,具有温和、低廉、操作简便且不需要模板等特点。 液-液界面特殊的物理化学性质使其在制备纳米材料和薄膜方面拥有独特的优势。 本文主要就近几年应用液-液界面进行纳米材料的制备及应用研究进行了综述。 所制备的纳米材料包括金属单质、氧化物、硫族化物、聚合物、异质二聚体和金属有机框架材料等。 并特别对新发展的离子液体-水界面可控合成技术进行了评述。 最后,对液-液界面合成在纳米材料制备方面的优点、存在的问题和未来的发展进行了评述和展望。 相似文献
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建立了以分散液液微萃取技术作为分离富集手段,以测汞仪分析水产品中的甲基汞的方法。以测汞仪直接测定样品中总汞,并用差减法计算出无机汞的含量。实验优化了分散液相微萃取的条件。实验表明,以二氯甲烷为萃取剂,乙醇为分散剂,二者体积比为1:5,HCl浓度为1 mol/L,NaCl浓度为120 g/L时,可以得到较为理想的结果。本方法的动态线性范围为0.2~20μg/L,检出限为0.10μg/L,相对标准偏差6.0%,富集倍数为8。仪器测定总汞的检出限为0.1 μg/kg,线性范围0.2~50μg/kg,相对标准偏差2.4%。本方法简单、快速,溶剂消耗量少。以标准参考物质验证本方法的准确性,其测定结果与标准值吻合较好。将本方法应用于实际水产制品的分析,得到较满意的结果。 相似文献
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Ionic liquids are possible alternative solvents for the separation of aromatic and aliphatic hydrocarbons by liquid-liquid extrac- tion. Interfacial tension is an important property to consider in the design of liquid-liquid extraction processes. In this work, the liquid-liquid interfacial tension and the mutual solubility at 25 °C have been measured for a series of biphasic, equilibrated mixtures of an ionic liquid and a hydrocarbon. In particular, the ionic liquids 1-alkyl-3-methylimidazolium bis(trifluorome- thanesulfonyl)imide (with the alkyl substituent being ethyl, hexyl or decyl), 1-ethyl-3-methylimidazolium ethylsulfate, and 1-ethyl-3-methylimidazolium methanesulfonate have been selected, as well as the hydrocarbons benzene, hexane, ethylben- zene, and octane. The selected sets of ionic liquids and hydrocarbons allow the analysis of the influence of a series of effects on the interfacial tension. For example, the interfacial tension decreases with an increase in the length of the alkyl substituent chain of the cation or with an increase of the degree of charge delocalisation in the anion of the ionic liquid. Also, the interfa- cial tension with the aromatic hydrocarbons is markedly lower than that with the aliphatic hydrocarbons. A smaller effect is caused by variation of the size of the hydrocarbon. Some of the observed trends can be explained from the mutual solubility of the hydrocarbon and the ionic liquid. 相似文献
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Grgoire Herzog Brian McMahon Myriam Lefoix Nicholas D. Mullins Courtney J. Collins Humphrey A. Moynihan Damien W.M. Arrigan 《Journal of Electroanalytical Chemistry》2008,622(1):109-114
The homo-oxo-calix[3]arene-facilitated electrochemistry of dopamine at the polarised liquid|liquid interface is presented. Cyclic voltammetry indicated that the dopamine: homo-oxo-calix[3]arene complex formed at the interface between water and 1,2-dichloroethane had a 1:2 stoichiometry, which was confirmed by 1H NMR titration. The electrochemically-determined association constants for the homo-oxo-calix[3]arene complexes with dopamine (log β 8.3), Na+ (8.0) and K+ (7.5) showed that the ionophore was more selective for dopamine over the two alkali metal cations than the dibenzo-18-crown-6 ionophore. Square wave voltammetry was employed for assessment of low concentration measurements, with a limit of detection of 3.8 μM dopamine achieved. These results show that oxo-calixarene-based ionophores are useful reagents for the detection of dopamine at the interface between two immiscible electrolyte solutions. 相似文献
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A simple and rapid sample preparation method of dispersive liquid-liquid microextraction(DLLME) was applied in the simultaneous determination of six parabens in the aqueous cosmetics. The analysis was performed on gas chromatography coupled with a flame ionization detection(GC-FID). The mixed solution containing 30 μL of chloroform(extraction solvent) and 300 μL of tetrahydrofuran(dispersive solvent) was rapidly injected into the sample solution for the purpose of microextraction. After that, the solution mentioned above was centrifuged at 4000 r/min for 10 min, and then the organic sediment phase was detected by GC-FID. The effects of experimental parameters, such as the extraction solvent and the volume of it, and the dispersive solvent and the volume of it, on the yield of the extraction were studied in detail. Under the optimum conditions, the enrichment factors of the target analytes range from 87 to 214. Linearity ranges are 0.05-10.0μg/mL for methylparaben and 0.025--5.0 μg/mL for the other five parabens. The relative standard deviations(RSDs) are lower than 8.2%(n=6). The proposed method was applied to the analysis of six parabens in eleven aqueous cosmetics. The recoveries of the target analytes in the spiked real samples are in the range of 81.0%-103%. 相似文献
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DongPingZHAN BingLiangWU 《中国化学快报》2002,13(3):273-276
A novel micro-hole electrode was fabricated to investigate the electron transfer reaction at the interface between two immiscible electrolyte solutions (ITIES). The electron transfer reaction between feero/ferricyanide in aqueous phase(W) and ferrocene in 1,2-dichloroethane (O) phase was studied as a test experiment. The results showed that the diffusion coefficient obtained from the micro-hole electrode was consistent with that obtained at macro-interface. Due to its simplicity and the very small IR drop it will be a useful tool for the study of ITIES systems. 相似文献
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Liquid-liquid phase equilibria of aqueous two-phase systems containing salts and polyethylene glycol 总被引:2,自引:0,他引:2
Liquid-liquid phase equilibria of the ternary systems: (a) polyethylene glycol - ammonium sulfate- water and (b) polyethylene glycol - sodium carbonate -water have been determined experimentally at 15°, 25°, 35° and 45°C and for two different molecular weights of the polymer (Avg. M.W. 1000 and 2000). Details of the glass cell and of the equilibration and analytical procedures used are described. Equilibrium data along with phase diagrams are presented. Finally the effect of temperature and of the molecular weight of the polymer are also discussed. 相似文献
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A new molecularly imprinted solid-phase extraction(MISPE) monolithic cartridge was synthesized, and MISPE-DLLME(DLLME=dispersive liquid-liquid microextraction) was developed for purification of astaxanthin in shrimp waste. The eluent(methanol) from MISPE was used as the dispersive solvent in subsequent DLLME for further purifying and enriching the analyte prior to high-performance liquid chromatography(HPLC) analysis. The mobile phase was methanol-acetonitrile-water-dichloromethane(85:5:5:5, volume ratio), flow rate was 0.7 mL/min and UV wavelength was 476 nm. Under optimal conditions, good linearity was obtained in a range of 0.2―200.0 μg/mL(r2=0.9998) with a limit of detection(LOD) of 0.08 μg/mL, and the extraction recoveries at three spiked levels ranged from 88.3%―92.5% with a relative standard deviation(RSD) less than 4.3%. Moreover, the mean contents of astaxanthin in the three batches of shrimp waste were 95.9, 85.4 and 77.2 μg/g, respectively. This method combining the advantages of MISPE and DLLME results in high selectivity and low cost, which was applied to determining the astaxanthin level in shrimp waste samples. 相似文献
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S. Trasatti 《Russian Journal of Electrochemistry》2005,41(12):1255-1264
This Award Lecture, delivered on the occasion of the presentation of the 2003 Frumkin Memorial Medal to the Author, consists of three parts: A brief introduction, a memorial section where the events in which Professor Frumkin and the author were jointly involved, and a scientific section where the main concepts at the basis of the scientific contacts between Frumkin and the author are illustrated. Among the latter, emphasis is placed on the relationship between the potential of zero charge and the electron work function of metals. 相似文献