排序方式: 共有126条查询结果,搜索用时 15 毫秒
71.
This article represents a step towards how to choose an ionic liquid as the solvent to improve metal ion (Ag+ and Pb2+) extraction. The liquid-liquid solvent extraction is proposed with the following imidazolium ionic liquids (ILs): 1-ethyl-3-ethylimidazolium,
or 1-butyl-3-ethylimidazolium, or 1-hexyl-3-ethylimidazolium bis{(trifluoromethyl)sylfonyl}imide [EEIM][NTf2], or [BEIM][NTf2], or [HEIM][NTf2], or 1-butyl-3-ethylimidazolium hexafluorophosphate [BEIM][PF6], or 1-hexyl-3-ethylimidazolium hexafluorophosphate [HEIM][PF6] and the popular 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6] for comparison. The effect of anion type (NTf2− versus PF6−) and the effect of structural components of an ionic liquid including alkyl chain length at the cation and the ethyl substituent
instead methyl at the cation, on the extraction and re-extraction processes by using dithizone as a metal chelator, were studied
at 296 K. Dithizone was employed to form neutral metal-dithizone complexes with heavy metal ions to extract them from aqueous
solution into the ILs.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users.
Presented at the 236th ACS National Meeting, August 17–21, Philadelphia, USA. 相似文献
72.
Eri Yoshida 《Colloid and polymer science》2009,287(7):767-772
The novel photo-living radical polymerization of methyl methacrylate (MMA) was determined using 2,2’-azobis(4-methoxy-2,4-dimethylvaleronitrile)
(AMDV) and 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (MTEMPO) in the presence of bis(alkylphenyl)iodonium hexafluorophosphate
(BAI). The polymerization provided a comparatively narrow molecular weight distribution in the range of 1.4–1.7. The resulting
PMMA contained no BAI fragments in its structure and had the 1-cyano-1,3-dimethyl-3-methoxybutyl radical and MTEMPO at the
1:1 molar ratio. The experimental molecular weight was in close agreement with the theoretical one when the initiator efficiency
was taken into consideration. The plots of ln([MMA]0/[MMA]) vs. time and the molecular weight of PMMA vs. the conversion and vs. the reciprocal of the initial concentration of
AMDV showed linear correlations, indicating that the polymerization proceeded in accordance with a living mechanism. It was
found that the polymerization had a photo-switching ability, because the polymerization was interrupted by turning off the
irradiation, and then restarted by the irradiation again. 相似文献
73.
Temperature dependence of viscosity and relation with the surface tension of ionic liquids 总被引:1,自引:0,他引:1
Viscosities of ionic liquids were correlated with two linear relations. The first one presents the temperature dependence of imidazolium-, pyridinium-, pyrrolidinium-, quaternary ammonium-, and nicotinium-based ionic liquids with high accuracy. The second one is a linear relation between logarithm of surface tension and fluidity involving the characteristic exponent ?, and fits the ionic liquids uniquely with ? = 0.30. Our previously measured surface tension data of ionic liquids and literature's were used in this study. The dependence of surface tension–fluidity relation of the imidazolium-based ionic liquids on the anion type is likely disappeared as alkyl chain length increases. 相似文献
74.
Ruyi Zou Xiaobao Li Guiling Luo Yanyan Niu Wenju Weng Wei Sun Jingwen Xi Yong Chen Guangjiu Li 《Electroanalysis》2019,31(3):575-581
An ionic liquid modified carbon paste electrode (CILE) was prepared with 1‐hexylpyridine hexafluorophosphate (HPPF6) and used as a substrate electrode. Then hexagonal boron nitride (BN) nanosheet, myoglobin (Mb) and Nafion were fixed on the electrode surface by coating method to get a new‐style chemically modified electrode (Nafion/Mb/BN/CILE). The morphology and crystal phase of BN nanosheet were characterized by SEM, TEM and XRD. UV‐Vis and FT‐IR results showed that Mb retained its original conformation in the composite modified film. In phosphate buffer solutions (PBS) with pH 3.0, cyclic voltammetry (CV) was performed to investigate the direct electrochemical behaviour of Mb. A pair of quasi‐reversible redox reaction peaks was obtained on the CV curve, proving that BN nanosheet had good biocompatibility and could accelerate electron transfer between Mb and electrode surface. Electrocatalytic reduction of trichloroacetic acid (TCA) was investigated, which was further applied to TCA detection. The catalytic reduction peak current at ?0.355 V depended linearly on the TCA concentration in the range of 0.2~30.0 mmol/L with the equation of Ipc (μA)=6.340 C (mmol/L)+0.305 (r=0.998), and the detection limit was 0.05 mmol/L (3 σ). 相似文献
75.
Jin Lou Wencheng Wang Lijun Yan Xiaohuan Sun 《International journal of environmental analytical chemistry》2015,95(10):911-921
In this article, a carbon ionic liquid electrode (CILE) was fabricated by using ionic liquid N-hexylpyridinium hexafluorophosphate as the binder and the modifier. Then urchinlike MnO2 microsphere and chitosan (CTS) was further casted on the CILE surface step-by-step to get a modified electrode that was denoted as CTS/MnO2/CILE. Cyclic voltammetric studies indicated that bisphenol A (BPA) exhibited a well-defined oxidation peak at 0.486 V in 22.83 g L?1 pH 8.0 Britton?Robinson buffer solution, which was attributed to the electro-oxidation of BPA on the modified electrode. The presence of urchinlike MnO2 microsphere on the electrode surface could increase the oxidation peak current (Ipa) greatly, which may be due to the larger surface area that could adsorb more BPA on the electrode surface. Electrochemical parameters of BPA on the modified electrode were calculated with the electron transfer coefficient (α) as 0.66 and the apparent heterogeneous electron transfer rate constant (ks) as 0.50 s?1. Under the optimal conditions, a linear relationship between the Ipa of BPA and its concentration was obtained in the range from 1.37 × 10–1 mg L?1 to 182.6 mg L?1 with the detection limit as 7.31 × 10–3 mg L?1 (3σ). The CTS/MnO2/CILE was applied to the detection of BPA content in different kinds of samples with satisfactory results. 相似文献
76.
《Electroanalysis》2017,29(8):1854-1859
A carbon paste electrode modified with 1‐butyl‐3‐methylimidazolium hexafluorophosphate ionic liquid (BMIPF6) and CuO nanoparticles (CuO/NPs) (CPE/BMIPF6/CuO/NPs) was fabricated and used for square wave voltammetric analysis of levodopa in the presence of vitamin B6. The elemental analysis, SEM and XRD methods were used for characterization of synthesized CuO nanoparticle. CPE/BMIPF6/CuO/NPs exhibited high electrical conductivity toward the electro‐oxidation of levodopa at a pH=7.0 as best experimental condition. Using CPE/BMIPF6/CuO/NPs the levodopa and vitamin B6 peaks are separated and oxidized at potentials of 0.565 V and 0.835 V, respectively; hence levodopa can be detected in the presence of vitamin B6. The electrochemical response shows a linear relationship from concentration of levodopa and vitamin B6 in the ranges of 0.06‐1000 μM and 0.1‐700.0 μM, respectively. Finally, CPE/BMIPF6/CuO/NPs were applied as high performance tool for determination of levodopa and vitamin B6 in real samples. 相似文献
77.
研究了双酚A(BPA)在十二烷基硫酸钠(SDS)现场自组装膜与离子液体N-丁基吡啶夫氟磷酸盐([ bupy]PF6)复合修饰碳糊电极(SDS-[ bupy]PF6/CPE)上的电催化氧化行为和电化学动力学性质.实验结果表明,在SDS-[ bupy]PF6/CPE上BPA发生了一受扩散控制的不可逆电化学氧化过程,用循环伏安(CV)法和计时电流(CA)法测得BPA在SDS-[bupy]PF6/CPE上的电极反应过程动力学参数.用方波伏安(SWV)法测得BPA氧化峰电流(Ipa)与其浓度在1.0×10-5~ 1.0×10-3 mol/L范围内呈良好的线性关系,线性方程为Ipa(μA) =2.635 +51.30c( 10-3 mol/L),r =0.998 1,检测限(S/N=3)为3.01×10-7 mol/L,同时运用SWV法对湖水样品中双酚A的含量进行了电化学定量测定. 相似文献
78.
《Analytical letters》2012,45(11):1738-1750
A new, simple, and rapid ionic liquid based dispersive liquid-liquid microextraction method is reported for the determination of copper with flame atomic absorption spectrometry. The ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate, was used to extract a copper(II)- curcumin complex. The optimum extraction efficiency of copper was obtained after optimization of the ionic liquid volume, pH, centrifugation speed and time, ultrasonic bath time and temperature, and mass of curcumin. The effects of various ions on the recovery of copper(II) were also investigated. The preconcentration factor was 135. In the optimum experimental conditions, the limit of detection and the relative standard deviation were 0.19 microgram per liter and 4.1 percent, respectively. The method was validated by the analysis of certified reference materials and applied to food and water. 相似文献
79.
The paper described a new ionic liquid, 1,3-dibutylimidazolium hexafluorophosphate, as extraction solvent for extraction and preconcentration of organophosphorus pesticides (fenitrothion, parathion, fenthion and phoxim) from water and fruit samples by dispersive liquid–liquid microextraction combined with high-performance liquid chromatography. The effects of experimental parameters, such as extraction solvent volume, disperser solvent and its volume, extraction and centrifugal time, sample pH, extraction temperature and salt addition, on the extraction efficiency were investigated. An extraction recovery of over 75% and enrichment factor of over 300-fold were obtained under the optimum conditions. The linearity relationship was also observed in the range of 5–1000 μg L−1 with the correlation coefficients (r2) ranging from 0.9988 to 0.9999. Limits of detection were 0.01–0.05 μg L−1 for four analytes. The relative standard deviations at spiking three different concentration levels of 20, 100 and 500 μg L−1 varied from 1.3–2.7, 1.4–1.9 and 1.1–1.7% (n = 7), respectively. Three real samples including tap water, Yellow River water and pear spiked at three concentration levels were analyzed and yielded recoveries ranging from 92.7–109.1, 95.0–108.2 and 91.2–108.1%, respectively. 相似文献
80.