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1
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Kinetic and spectroscopic investigations of aqueous micelles of cationic surfactants

100%
Luchetti L.
Open Chemistry
|
2010
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vol. 8
|
issue 6
1318-1322
EN
The aqueous micellar solutions of monocationic surfactants N-hexadecyl-N,N,N-trimethylammonium bromide (CTABr), N-hexadecyl-N,N,N-trimethylammonium nitrate (CTANO3), N,N,N-tributyl-N-hexadecylammonium bromide (CTBABr) and gemini surfactants 1,4-bis(N-hexadecyl-N,N-dimethylammonium)ethane dibromide (C-E-C2Br), 1,4-bis(N-hexadecyl-N,N-dimethylammonium)propane dibromide (C-P-C2Br), and 1,4-bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide (C-B-C2Br) were studied with a solvatochromic probe, 2,6-diphenyl-4-(2,4,6-triphenylpyridinium-1-yl)phenolate, better known as Reichard’s ET-30 dye. The local polarity at the probe site (ET) was calculated from the wavelength maximum of the lowest-energy intramolecular charge-transfer ϖ-ϖ* absorption band of ET-30. The results were compared with a kinetic investigation of the cyclization of 2-(3-bromopropyloxy)phenoxide (PhBr7) in micelles; this reaction is a model for SN2 reactions and it depends on medium polarity.
2
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Optimization of process parameters using response surface methodology for the removal of phenol by emulsion liquid membrane

100%
Balasubramanian A., Venkatesan S.
Polish Journal of Chemical Technology
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2012
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vol. 14
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issue 1
46-49
EN
Emulsion liquid membrane technique (ELM) was used for the extraction of phenol from synthetic and industrial effluents. In this study, the liquid membrane used for phenol removal was composed of kerosene as the solvent, Span-80 as the surfactant and Sodium hydroxide as an internal reagent. Statistical experimental design was applied for the optimization of process parameters for the removal of phenol by ELM. The effects of process parameters namely, Surfactant concentration, membrane or organic to internal phase ratio (M/I) and emulsion to an external phase ratio (E/E) on the removal of phenol were optimized using a response surface method. The optimum conditions for the extraction of phenol using Response surface methodology were: surfactant concentration - 4.1802%, M/I ratio: 0.9987(v/v), and E/E ratio: 0.4718 (v/v). Under the optimized condition the maximum phenol extraction was found to be 98.88% respectively.
3
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PbS nanostructures synthesized via surfactant assisted mechanochemical route

100%
Baláž P., Pourghahramani P., Dutková E., Fabián M., Kováč J., Šatka A.
Open Chemistry
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2009
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vol. 7
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issue 2
215-221
EN
PbS nanocrystals using surfactant assisted mechanochemical route has been successfully prepared. The methods of XRD, SEM, surface area and particle size measurements were used for nanocrystals characterization. The XRD patterns confirmed the presence of galena PbS (JCPDS 5–592) whatever treatment conditions were applied. The strong observable peaks indicate the highly crystalline nature in formation of PbS nanostructures where preferential crystal growth in the (200) direction after chelating agent (EDTANa2•2H2O) addition has been observed. The mean volume weighted crystallite size 4.9 nm and 35 nm has been calculated from XRD data using Williamson-Hall method for PbS synthesized without and/or with chelating agent, respectively corresponding with surface weighted crystallites sizes of 2.9 and 18.8 nm. The sample prepared without surfactant yields the smaller crystallites and the higher microstrain compared with surfactant assisted synthesis. The obtained results illustrate a possibility to manipulate crystal morphology by combining effect of milling and surfactant application. [...]
4
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Spectroscopic route to monitoring individual surfactant ions and micelles in aqueous solution: A case study

88%
Geng J., Johnson B., Wheatley A., Luo J.
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issue 3
307-311
EN
Using a very popular and commonly used surfactant sodium dodecylbenzene sulfonate (SDBS, C18H29SO3Na) for a case study, we report a new method of monitoring different forms of surfactant molecules in aqueous solution and measuring their critical micelle concentration (CMC) by ultraviolet-visible (UV-Vis) spectroscopy. The forms of SDBS micelles are also investigated by synthesizing and characterizing NiB nanoparticles using the micelles as molecular templates. In addition, the observed shifts of UV-Vis bands are analysed from the viewpoint of the electrons locations and distributions within the molecules and the possible overlap of their electronic orbitals between neighbouring molecules in each micelle.
5
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Spontaneous oscillations due to solutal Marangoni instability: air/water interface

88%
Kovalchuk N.
Open Chemistry
|
2012
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vol. 10
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issue 5
1423-1441
EN
Systems far from equilibrium are able to self-organize and often demonstrate the formation of a large variety of dissipative structures. In systems with free liquid interfaces, self-organization is frequently associated with Marangoni instability. The development of solutal Marangoni instability can have specific features depending on the properties of adsorbed surfactant monolayer. Here we discuss a general approach to describe solutal Marangoni instability and review in details the recent experimental and theoretical results for a system where the specific properties of adsorbed layers are crucial for the observed dynamic regimes. In this system, Marangoni instability is a result of surfactant transfer from a small droplet located in the bulk of water to air/water interface. Various dynamic regimes, such as quasi-steady convection with a monotonous decrease of surface tension, spontaneous oscillations of surface tension, or their combination, are predicted by numerical simulations and observed experimentally. The particular dynamic regime and oscillation characteristics depend on the surfactant properties and the system aspect ratio. [...]
6
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Preparation and shape control of β-Ni(OH)2 nano-particle

88%
Gao Y., Liu H., Ma M.
Open Chemistry
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2008
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vol. 6
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issue 1
23-25
EN
A simple and convenient method for the preparation of needle-shape nanoparticles of β-Ni(OH)2 has been developed. Results show that a needle-shaped β-Ni(OH)2 can be easily obtained in the presence of ethylenediamine and sodium dodecylbenzene sulfonate within a size from 100 to 200 nm. The shape and structure of the product were characterized by XRD, TEM and FT-IR. It is noteworthy that the formation of needle-shape β-Ni(OH)2 benefits from the addition of sodium dodecylbenzene sulfonate. The optimum preparation conditions and the possible mechanism are also discussed. [...]
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