Papers by Keyword: Reverse Micelle

Abstract: YCr_xAl_1-xO₃ nanoparticles were synthesized by a reverse micelle processing for inorganic pigment. Y(NO₃)₂·6H₂O, Cr (NO₃)₂·6H₂O and Al (NO₃)₃·9H₂O are used for precursors in order to synthesis YCr_xAl_1-xO₃ nanoparticles. The aqueous solution consists of mixing the molar ratio of Y/Cr/Al at 1:x:1-x and heat treated at 900~1300°C for 2h. The average size and distribution of synthesized YCr_xAl_1-xO₃ powders was in the range of 10-20nm and narrow, respectively. The average size of the synthesized YCr_xAl_1-xO₃ powders increased with increasing water to surfactant molar ratio and heating temperature. The crystallinity of synthesized YCr_xAl_1-xO₃ powder increased with increasing heating temperature. The synthesized YCr_xAl_1-xO₃ powders were characterized by X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FE-SEM) and color spectrophotometer. The properties of the synthesized powders were affected by such variables as molar ratio, heating temperature etc.

Abstract: The Ru core SiO₂ shell nano size particles have been synthesized within reverse micelle via metal alkoxide hydrolysis and condensation. The size of the particles and the thickness of the coating can be controlled by manipulating the relative rates of the hydrolysis and condensation reactions of tetraethoxysilane (TEOS) within the micro-emulsion. The average size of synthesized Ru core SiO₂ shell particles was about in the size range of 15-40 nm. The average size and distribution of the synthesized Ru core SiO₂ shell particles increased and narrow with R value increased. Otherwise, the average size and distribution of the synthesized Ru core SiO₂ shell particles decreased and narrow with H value increased. TEM studies of particle formation indicate that the reaction process in the complex system containing reverse micelles and TEOS is governed by a diffusion-controlled process. The effects of synthesis parameters, such as the molar ratio of water to TEOS, and the molar ratio of water to surfactant, are discussed.

Abstract: CoMn₂O₄ nanoparticles were synthesized by reverse micelle processing from the mixed precursor (consisting of Co (NO₃)₂ ·6H₂O and MnCl₂·4H₂O). The CoMn₂O₄ was prepared by mixing the aqueous solution at a molar ratio of Co : Mn = 1 : 2. The synthesized powders were calcined at 600°C for 2h. The average size and distribution of synthesized powders were in the range of 10-20nm and narrow, respectively. The average size of the synthesized powders increased with increasing water to surfactant molar ratio. The XRD diffraction patterns show that the phase of CoMn₂O₄ was spinel (JCPDS no.77-0471). The synthesized and calcined powders were characterized by thermogravimetry-differential scanning calorimeter (TG-DSC), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The magnetic property of the powder was measured by Vibrating Sample Magneto-meter (VSM) at 298K. The effect of synthesis parameter, such as the molar ratio of water to surfactant, is discussed.

Abstract: Reverse micelle extraction has received considerable attention in recent years due to its ability to selectively solubilise solutes from an aqueous phase, and in the case of biomolecules to maintain their biological activities. The apparent success of research on protein extraction from the aqueous phase using reverse micelle provides motivation to study the solubilisation of antibiotic. The objective of this study is to investigate the extraction of antibiotic (penicillin G is chosen as model antibiotic) from aqueous solution (forward extraction) and from the reverse micelle to a new aqueous solution (backward extraction). Sodium di(2-ethylhexyl)sulfosuccinate (AOT) is chosen as the surfactant and isooctane as the organic solvent. The UV-Vis spectrophotometer is used to determine the mass of penicillin G in solution after the extraction process. The extraction is expected to be influenced by the initial penicillin G concentration, the salt type and concentration in the aqueous phase, pH, and surfactant concentration. It is expected that as penicillin is an interfacially active compound that will interacts with AOT surfactant, the interfacial association will be dependent on both pH and surfactant concentration.

Abstract: Sn doped SiO₂ nanoparticles have been synthesized using a reverse micelle technique combined with metal alkoxide hydrolysis and condensation. The size of the particles and the thickness of the coating can be controlled by manipulating the relative rates of the hydrolysis and condensation reactions of tetraethyl orthosilicate (TEOS) within the micro-emulsion. The properties of the Sn doped SiO₂ nanoparticles were studied as a function of various processing parameters such as R and H value. The average size of synthesized Sn doped SiO₂ nanoparticles was about in the size range of 20-40 nm and core particle (Sn) 1-5 nm. The Sn doped SiO₂ nanoparticles were characterized by X-ray diffraction (XRD) and Transmission electron microscopy (TEM).

Abstract: his paper describes the rules of change of reverse micelle phase separation under acid conditions. Using acetic acid, the reverse micelle system can be separated into an upper and lower phase. After separation with acid, the continuous phase is an organic solution and the polarity of upper phase is lower than that of lower layer. The separation formula is y=1.62+20.84e-x/5.31, where x is the W0 value of ^{Superscript text}the original micelle system, y is the concentration of acetic acid required to separate the reverse micelle system into two phases of equal volume and it can be used to check the formula. Applying this formula to calculate the concentration of acid required to affect separation, the protein of rat serum can be separated under acidic conditions by the reverse micelle extraction method. In this way serum protein of rat can be further separated.

Abstract: Nanosized TiO₂-SiO₂ particles were prepared by controlled hydrolysis of titanium tetraisopropoxide (TTIP) and tetraethylorthosilicate (TEOS) in microemulsions stabilized by anionic surfactants. Anionic surfactants ammonium carboxylate perfluoropolyether (PFPE-NH4) and sodium bis (2-ethylhexyl) sulfosuccinate (AOT) were used for formation of stabilized microemulsions in the W/C and W/O systems, respectively. The physical properties of the prepared particles have been investigated by TG-DTA, FT-IR, XRD and HRTEM. It is shown that the XRD pattern of the TiO₂-SiO₂ particles dried at 105 °C without calcination indicates amorphous. The particles calcined at 500 °C were identified as nanocrystalline anatase regardless of TTIP/TEOS molar ratio. The crystallite size of prepared particles decreased with increasing the silica content. From FT-IR analysis, the band for Ti-O-Si vibration was observed. The micrographs of HRTEM shown that the TiO₂-SiO₂ nanoparticles have a spherical morphology with a narrow size distribution and then the lattice fringe was 3.5 Å, which corresponds to the lattice spacing of (101) plane in the anatase phase.

Abstract: The non-ionic reverse micelles used for dyeing wool were prepared with a non-ionic surfactant Triton X-100 (TX-100) by injecting small amount of acid dye aqueous solution. And the adsorption properties of three water-soluble anionic acid dye including Mordant Black 9, Acid Black 234 and Acid Orange 156 onto wool in TX-100 reverse micelle were studied and compared. Then effect of W value (molar ratio of the injected water to TX-100) and pH level on dye adsorption was also investigated. The results indicate that Higher W value and Low pH level would increase the adsorption amount of the dye onto wool. The adsorption of the dye onto wool showed better agreement with Langmuir isotherm equation. Mordant Black 9 with lower molecular weight and one sulfonic group exhibited the higher adsorption capacity than the other dyes.

Abstract: Structure of nonionic surfactant diglycerol monolaurate (C12G2) reverse micelles in squalene at different surfactant concentrations and temperatures is presented. For the structural characterization of the micelles, small-angle X-ray scattering (SAXS) technique is used. The scattering data is evaluated by virtually model free generalized indirect Fourier transformation (GIFT) method. GIFT analysis of the SAXS data has shown the clear evidence on the formation of rod-like micelles in the C12G2/squalene system at higher temperatures. At fixed temperature, increasing surfactant concentration induces one-dimensional micellar growth; the maximum length of the micelles increases with concentration, but the micellar cross-section remains essentially the same. On the other hand, at fixed concentration, the maximum length of the micelles decreases with the rise of temperature. It is found that the length of micelles decreases by ~ 35% keeping cross-section diameter unchanged with the rise of temperature from 60 to 80 °C in 5 wt% wt% C12G2/squalene system.

Abstract: Ga doped SiO2 nanosized particles have been synthesized using a reverse micelle technique combined with metal alkoxide hydrolysis and condensation. The size of the particles and the thickness of the coating can be controlled by manipulating the relative rates of the hydrolysis and condensation reactions of tetraethyl orthosilicate(TEOS) within the micro-emulsion. The average size of synthesized Ga doped SiO2 nanoparticles were about in the size range of 10-15 nm and Ga particles 2-5 nm. The effects of synthesis parameters, such as the molar ratio of water to TEOS, and the molar ratio of water to surfactant, are discussed.