Uniform Rice-like CdS Particles Prepared from Water-in-oil Microemulsions

Uniform rice-like CdS particles were synthesized in cyclohexane/Triton X-100/n-pentanol/water quaternary microemulsions. The as-prepared samples were characterized by X-ray diffraction, transmission electron microscopy, and electron diffraction. The results indicate that the size and the shape of the rice-like CdS particles can be influenced by the molar ratio of water to the surfactant（w value） and the reactant concentrations.

Synthesis of Cu_2O nanowhiskers with CTAB as a template in water-in-oil microemulsion system

Dispersed cuprite （Cu2O） nanowhiskers were synthesized in a water/butanol/cyclohexane/cetyl trimethyl ammonium bromide （CTAB） water-in-oil microemulsion system at 25℃. The nanowhiskers with a diameter of about 8 am exhibit a well-crystallized one-dimensional （1D） structure over several hundreds nanometers in length and mainly grow along the 〈111〉 direction. However, without CTAB, only cubic and hexagonal bulks are obtained. Without emulsifier, short and thick nanowhiskers can be prepared but they are apt to agglomerate. The possible growth mechanism of Cu2O nanowhiskers is speculated. The surfactant and the microemulsion system are related to the 1D shape formation and the even dispersion of Cu2O nanomaterials, respectively.

Formation and Solubilization Property of Water-in-Oil Microemulsions of Alkyl Glucosides

The dependence of solubilization properties on the alkyl chain length of alkyl glucosides (AG) in AG/isooctane/ n-butanol/water system was investigated. The stable Winsor II system consisting of a water-in-oil (w/o) microemulsion phase and an aqueous phase was formed in AG/isooctane/n-butanol/water system. The apparent critical micelle concentration of AG reverse micelles in organic phases was markedly dependent upon the alkyl chain length of AG. The limiting amount of solubilized water increased with an increase in the alkyl chain length of AG. The solubilization capacity of methyl orange (MO) was superior to that of methylene blue (MB), and the solubilization capacities of MO and MB tended to increase with increasing the alkyl chain length of AG. Reverse micelles of dodecyl glucoside (AG12) exhibited the significant solubilization capacities of cytochrome c and lysozyme, while ribonuclease A was not solubilized by AG12 reverse micelles.

Electrochemical behavior of K_3Fe(CN)_6 in water-in-oil microemulsion

A water-in-oil (W/O) microemulsion composed of Triton X-100, n-hexanol, n-hexane and water solution with hydrochloric acid was prepared. K3Fe(CN)6 was added in as a water-soluble electroactive probe, and its electrochemical behavior was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It is found that the H+ concentration of the water phase has a great effect on the conductivity of the W/O microemulsion, and hence influences the electrochemical behavior of K3Fe(CN)6. When the pH value of water phase is about 7, the electrical conductivity of the W/O microemulsion is only 1.2×10-6 S/cm, and K3Fe(CN)6 almost cannot react at the glassy carbon electrode. But when the H+ concentration is more than 3 mol/L, the W/O microemulsion has a good electrical conductivity and K3Fe(CN)6 shows good electrochemical performance in it. The results of CV and EIS studies indicate that the electrochemical behavior of Fe(CN)63-/Fe(CN)64- in the W/O microemulsion is different from that in the aqueous solution. This may be due to the unique liquid structure of the W/O microemulsion and the unique mass transfer in the W/O microemulsion.

Preparation of Nanoiron by Water-in-Oil (W/O) Microemulsion for Reduction of Nitrate in Groundwater

Nanometer-sized iron particles with monodispersity and narrow size distribution were synthesized by modi-fied microemulsion system using environment-friendly non-ionic surfactants Span 80 and Tween 60 as mixed surfactants. The synthesized iron nanoparticles were characterized by using powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the synthesized particles were mainly composed of α-Fe with an average diameter of 80-90 nm. The chemical activity of the obtained iron nanoparticles was evaluated by the denitrification of nitrate in water. On neutral condition, complete denitri-fication of nitrate was achieved by freshly synthesized nanoiron within 30 min. Ammonia was the main product, with good material balance at the end of the reaction. Two possible reaction pathways for nitrate reduction by nanoiron have been proposed in this study.

The Acute Toxicity Test in Mice and Bacteriostasis in vitro of Yandureqing and Its Microemulsion

[Objective] The aim of this study is to evaluate the safety and bacteriostasis of Yandureqing(AEE)and its microemulsion(AEE-ME).[Method]The acute toxicity was tested in mice by intragastric administration,and median lethal dose(LD50)as well as its 95% confidence interval was calculated by modified Karber method;the bacteriostasis was investigated by cylinder plate method.[Result]LD50 of AEE in mice was 10.937 g/kg with the 95% confidence interval of 9.309-12.850 g/kg;and LD50 of AEE-ME in mice was 5.357 g/kg with the 95% confidence interval of 4.388-6.566 g/kg.The MICs of AEE to Escherichia coli O149 from swine,Staphylococcus aureus,Salmonella pullorum and Streptococcus agalactiae were 10.00,20.00,20.00 and 10.00 mg/ml,respectively;while the MICs of AEE-ME to the 4 kinds of bacteria mentioned above were 5.00,10.00,5.00 and 5.00 mg/ml in turn,and that to Pseudomonas aeruginosa is 20.00 mg/ml.[Conclusion]AEE is an actually nontoxic drug and AEE-ME belongs to the low toxic preparation.AEE and AEE-ME have obvious bacteriostasis,in which AEE-ME is superior to AEE.

Preparation and characterization of 9-nitrocamptothecin self-emulsifying microemulsion injection

Aim To prepare a self-emulsifying microemulsion of 9-nitrocamptothecin （9-NC ME） for intravenous injection and investi- gation of its pharmacokinetic profiles in normal SD rats. Methods 9-NC ME was optimized in terms of droplet size and lack of drug precipitation following aqueous dilution using a pseudo-ternary phase diagram. Physicochemical properties of 9-NC ME were evaluated. 9-NC ME was intravenously administered via tail vein in healthy rats. Results A stable microemulsion was formulated consisted of soybean oil as oil phase, EPC/Tween-80 as emulsifier, and anhydrous ethanol as co-emulsifier. The droplets of the microemulsion were spherical shape with mean diameter of 38.3 ± 4.0 nm after 1：20 dilution with 5% glucose injection. The pharmacokinetic parameters of 9-NC ME after intravenous administration in rats were t1/2 of 0.97 ± 0.14 h, A UC0-8 of 372.77 ±49.62 ng·h·mL^-1 and MRT of 1.40 ± 0.21 h which were 1.4-fold, 1.65-fold, and 1.4-fold more than those of 9-NC solution （P〈0.01）. Conclusion The results suggested that 9-NC ME was a promising drug delivery system and it was expected to provide a novel 9-NC injection for cancer patients.

Synthesis of Nanometer Cobalt Blue Pigment by Microemulsion Method and Control of Diameter of Particle

The nanometer cobalt blue pigments were prepared by microemulsion method. Using dynamic light scattering(DLS) test method, the influences of water content on the size of liquid drop of microemulsion and the liquid drop of microemulsion on the final diameter of nanometer particle were studied in the course of preparation. Accordingly, the method to control the diameter of nanometer particle by changing water content was established. The nanometer cobalt blue particles were confirmed by XRD and TEM. Color parameters of pigments were determined. The quantum size effect of the pigments was discussed.

Phase behavior of TXs/toluene/water microemulsion systems for solubilization absorption of toluene

Triton Xs （TXs） surfactants/cosurfactant/water/oil （toluene） microemulsion systems for enhancing toluene solubilization were proposed and its potential was investigated for toluene removal from gas stream. The results indicated that TX-100 was superior to other TXs surfactants in removing toluene without cosurfactant. The efficiency of cosurfactants for improving toluene solubilization capacity follows the order： amine 〉 alcohol 〉 acid. According to the factor analysis, the linear cosurfactants are better than the branched ones. The effects of hydrophile-lipophile balance （HLB）, salt （NaCl） concentration and temperature on the formation of microemulsion system were also discussed. The results suggested that the optimum value of HLB was 15, the effect of NaCl concentration on the system was inconspicuous and the lower temperature enhanced the solubilization capacity. Nonionic surfactant-based microemulsions had a significant absorption enhancement for toluene, indicated by as much as 82.72% of toluene in phase composition diagram, which will have a great prospect in air pollution treatment.

A study of the mechanism of enhancing oil recovery using supercritical carbon dioxide microemulsions

Supercritical carbon dioxide （scCO2） microemulsion was formed by supercritical CO2, H20, sodium bis（2-ethylhexyl） sulfosuccinate （AOT, surfactant） and C2HsOH （co-surfactant） under pressures higher than 8 MPa at 45 ℃. The fundamental characteristics of the scCO2 microemulsion and the minimum miscibility pressure （MMP） with Daqing oil were investigated with a high-pressure falling sphere viscometer, a high-pressure interfacial tension meter, a PVT cell and a slim tube test. The mechanism of the scCO2 microemulsion for enhancing oil recovery is discussed. The results showed that the viscosity and density of the scCO2 microemulsion were higher than those of the scCO2 fluid at the same pressure and temperature. The results of interfacial tension and slim tube tests indicated that the MMP of the scCO2 microemulsion and crude oil was lower than that of the scCO2 and crude oil at 45 ℃. It is the combined action of viscosity, density and MMP which made the oil recovery efficiency of the scCO2 microemulsion higher than that of the scCO2 fluid.

Water solubility enhancements of PAHs by sodium castor oil sulfonate microemulsions

Water solubility enhancements of naphthalene(Naph), phenantherene(Phen) and pyrene(Py) in sodium castor oil sulfonate(SCOS) microemulsions were evaluated. The apparent solubilities of PAHs are linearly proportional to the concentrations of SCOS microemulsion, and the enhancement extent by SCOS solutions is greater than that by ordinary surfactants on the basis of weight solubilization ratio(WSR). The log K em values of Naph, Phen, and Py are 3 13, 4 44 and 5 01 respectively, which are about the same as the log K ow values. At 5000 mg/L of SCOS conccentration, the apparent solubilities are 8 80, 121, and 674 times as the intrinsic solubilities for Naph, Phen, and Py. The effects of inorganic ions and temperature on the solubilization of solutes are also investigated. The solubilization is improved with a moderate addition of Ca 2+ , Na +, NH + 4 and the mixture of Na +, K +, Ca 2+ , Mg 2+ and NH + 4. WSR values are enhanced by 22 0% for Naph, 23 4% for Phen, and 24 6% for Py with temperature increasing by 5℃. The results indicated that SCOS microemulsions improve the performance of the surfactant enhanced remediation(SER) of soil, by increasing solubilities of organic pollutants and reducing the level of surfactant pollution and remediation expenses.

Kinetics of the Esterification Reaction Catalyzed by Lipase in W/O Microemulsions of Alkyl Polyglucoside

A novel kinetic mechanism of esterification reaction of 1-hexanoic acid with 1-butanol, catalyzed by lipase, was studied in water-in-oil microemulsions. The microemulsions were formed by alkyl polyglucoside C10G1.54/1-butanol / cyclohexane/phosphate buffer solution. The result shows that when the ratio of mol concentration of 1-butanol to 1-hexanoic acid is about 3.0, the initial rate V0 get the maximum values. This phenomenon was explained by the modified fishlike phase diagrams.

Catalytic spectrophotometric determination of trace selenium in microemulsion after separation and enrichment by SDG

A new catalytic spectrophotometric method was developed for the determination of trace amount of Se（Ⅳ） in microemulsion medium. The method is based on the catalytic effect of traces of Se（Ⅳ） on the oxidation of 2＇,4＇-dichlorophenylfluomne （p-CPF） by potassium bromate with HNO3 as an activator in the presence of nonionic microemulsion medium. Under optimum conditions, the calibration graph is linear in the range of 0.4-15 μg·L^-1 of Se（Ⅳ） at 480 nm. The detection limit achieved is 9.86 × 10^-10μg·L^-1. Samples were dissolved and the obtained trace Se（Ⅳ） was separated and enriched by sulphydryl dextrane gel （SDG）. The method has been applied for determination of trace selenium with satisfactory results.

Studies on the Microscopic Mechanism of the Thermodynamic Stability of Pesticide Microemulsion

The cryo-fracture electron microscope was used to study the micro-structure of pesticide mi-croemulsions. The hydromechanical radius (Rh) and the distribution (fRh) of pesticide microemulsions were determined by photo-correlation spectroscopy. This study showed that the Rh was significantly greater when the ratio of surfactants to water (w/w) decreased to 20/31 from 27/26, and a bicontinuous structure was formed when the ratio dropped to 15/36. These results explained the relationship between pesticide properties and the microscopic structure, and provided a good method for studying the microscopic structure of pesticide formulations.

Physicochemical Properties and Evaluation of Microemulsion Systems for Transdermal Delivery of Meloxicam

Microemulsion systems, composed of water, isopropyl myristate （IPM）, polyoxyethylene sorbitan trioleate （Tween 85 ）, and ethanol, were investigated as transdermal drug delivery vehicles for a lipophilic model drug（ meloxicam）. The purpose of this study was to investigate the physicochemieal properties of the tested microemulsion and to find the correlation between the physicoehemical properties and the skin permeation rate of the microemulsion. Pseudo-ternary phase diagram of the investigated system at a constant surfactant/cosurfactant mass ratio （ Km = 1 ： 1 ） was constructed by titration at 20℃, and the five fommlations were selected for further research in the o/w microemulsion domains. The values of electrical conductivity and viscosity showed that the selected systems were bicontinuous or non-spherical o/w microemulsion, and the electrical conductivity and viscosity were increased with increasing the content of water. These results suggest that the optimum formulation of microemulsion, containing 0. 375 meloxicam, 5% isopropyl myristate, 25% Tween 85. 25% ethanol, and water, showed the maximum permeation rate. It had a high electrical conductivity, small droplet size, and proper viscocity.

High Solids-Content Nanosize Polymeric Microlatexes Made by Microemulsion Copolymerization at Ambient Temperature

The microemulsion copolymerizations of acrylic acid (AA),acrylamide (AM),N-methylol acrylamide (NMA),methylmethacrylate (MMA),butyl acrylate (BA) and acrylonitrile (AN) initiated by the redox initiator ammonium persulfate (APS) and N,N,N′,N′-tetramethylethylenediamine (TMEDA) at ambient temperature were investigated.With this process high solids-content (44.0 wt%) and small (less than 50 nm) particle diameter copolymer latexes were attained.The effects of surfactants,the mechanical stabilities and application properties as an environmentally friendly self-crosslinking pigment printing binder with multifunctional groups were studied.

Percutaneous absorption and brain distribution facilitation of borneol on tetramethylpyrazine in a microemulsion-based transdermal therapeutic system

In this study, we show that the percutaneous absorption and brain distribution of tetramethylpyrazine(TMP) is enhanced when combined with borneol(BN) in a microemulsionbased transdermal therapeutic system(ME-TTS). The formulation of the TMP and BN microemulsion(TEM-BN-ME) was optimized in skin permeation studies in vitro following a uniform experimental design. Male Sprague-Dawley rats were used for the in vivo pharmacokinetic and tissue distribution studies of TMP-BN-ME-TTS. In the pharmacokinetic study, the TMP-BN-ME-TTS treated rats had significantly higher( P < 0.05) C max and AUC of TMP than the TMP-ME-TTS treated rats, indicating that BN improves the rate and extent of TMP percutaneous absorption. In the tissue distribution study, the AUC of TMP in brain was significantly higher in the TMP-BN-ME-TTS group( P < 0.05), indicating that BN facilitates the distribution of TMP in brain. In summary, BN enhanced the percutaneous absorption and brain distribution of TMP in a microemulsion-based transdermal therapeutic system.

Synthesis and characterization of CePO_4 nanowires via microemulsion method at room temperature

Uniform CeVO4 nanowires with diameter of about 25 nm were synthesized by the water-in-oil microemulsion method at room temperature from cerous chloride, sodium orthophosphate, sodium chloride, cyclohexane, Triton X-100 and cetyltrimethyl ammonium bromide （CTAB）. The crystal structure and morphology of the nanowires were characterized by XRD and TEM, respectively. The UV-vis absorption was detected by UV-vis spectrophotometer techniques. The results showed that as-prepared nanowires with the hexagonal phase have obvious quantum confinement effect and semiconductor characteristics. Little sodium chloride could play a positive role on the formation of CePO4 nanowires at room temperature. The size of the nanowires can be controlled through the joining of sodium chloride. C 2009 Yi Bin Yin. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Preparation and Characterization of CeO_2-ZrO_2 Solid Solution Ultrafine Particles Using Reversed Microemulsion

Ce0.6Zr0.4O2 solid solution ultrafine particle was prepared in the cyclohexane/water/OP-10/n-hexanol reversed microemulsion. The quasi-ternary phase diagram investigations showed that the system has narrow W/O type microemulison region, so it is the proper system to prepare Ce0.6Zr0.4O2 solid solution ultrafine particle. Some physical-chemical techniques such as TG/DTA, XRD, BET, and HRTEM are used to characterize the resultant powders. The results show that the fluorite cubic Ce0.6Zr0.4O2 solid solution is obtained at 400 ℃. The surface area is （146.7 m^2·g^-1）, which is higher than the surface area for sol-gel prepared sample （59.5m^2·g^-1）. HRTEM images indicated that the Ce0.6Zr0.4O2 solid solution ultrafine particle is well-crystallized, narrow size distribution, less agglomeration, within mean size of 5 -7 nm.

Selenium Nanoparticles Prepared from Reverse Microemulsion Process

Selenium nanoparticles were prepared by a reverse microemulsion system. Sodium selenosulfate was used as selenium source. The results showed that hydrochloric acid concentration and reaction temperature had great influence on the morphology of products. The crystalline selenium nanowires and amorphous selenium nanorods were obtained in given condition.