Percolative conduction in microemulsion type systems

Lagourette, B.; Peyrelasse, J.; Boned, Christian; Clausse, Marc

doi:10.1038/281060b0

Cited by 170 publications

(90 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…There exists a critical point of V 0 c (0.15vol.%) in the k~V curve. When V 5 V 0 c , the conducting behavior of the system could be ascribed to electrophoretic movement of the dispersed globules, as suggested by Peyrelasse et al 11 When V > V 0 c , the conducting behavior may result from a progressive interlinking and clustering processes of aqueous droplets, similar to the conducting behavior of the nonionic microemulsion reported by Lagourette et al 12 The results also suggest that water aggregates or water clusters are really present in the ternary solvent system.…”

supporting

confidence: 67%

Formation of a Novel Type of Reverse Microemulsion System and Its Application in Synthesis of the Nanostructured La_0.95Ba_0.05MnAl₁₁O₁₉ Catalyst.

Teng

Tian

et al. 2004

ChemInform

View full text Add to dashboard Cite

In the study, a novel microemulsion system, consisting of water, iso-propanol and n-butanol, was developed to synthesize the nanostructured La 0.95 Ba 0.05 MnAl 11 O 19 catalyst with high surface area and catalytic activity for methane combustion.Recently, catalytic combustion has attracted considerable attention due to its potential application for burning natural gas in gas turbines with extremely low levels of NO x emissions. 1 The main challenge in the area is to select and synthesize catalytic materials with high thermal stability and high activity. 4 However, nanostructured hexaaluminate catalysts are very difficult to synthesize, due to serious agglomeration and growth of the particles. In this work, a novel reverse microemulsion system was developed, which consisted of water, hydrophilic iso-propanol and half-hydrophobic n-butanol (W/iP/ nB). The nanostructured La 0.95 Ba 0.05 MnAl 11 O 19 catalyst was also synthesized in the system. The novel reverse microemulsion system could be potentially reused for preparation of the catalyst, and the preparation procedure is also simplified.Typically, the system was composed of 5-20 vol.% water, 5-20 vol.% iso-propanol and 60-90 vol.% n-butanol. To prepare the microemulsion, the appropriate amounts of water, iso-propanol and n-butanol were mixed and then stirred until the emulsion became transparent. The La 0.95 Ba 0.05 MnAl 11 O 19 catalysts were synthesized by hydrolysis of Ba(iso-OPr) 2 and Al(iso-OPr) 3 in the reverse microemulsion system, which consisted of an aqueous solution of stoichiometric La(NO 3 ) 3 and Mn(NO 3 ) 2 /iso-propanol/n-butanol. ‡ The stoichiometric amounts of Al(iso-OPr) 3 and Ba(iso-OPr) 2 were dissolved in iso-propanol, and the alkoxide solution was added to the ternary solvent system to hydrolyse and polycondense. The obtained sample was directly transferred to an autoclave for removing the solvent with supercritical drying (290 °C, 6.0 MPa). After drying, the sample was calcined at 1200 °C for 2 h. The structure property and phase behavior of the water in the system were investigated by means of FT-IR §, NMR ¶, electric conductivity (EC) ∑, laser light scatting granulometer **. The morphology, crystal structure and texture property of the catalyst were characterized by TEM, XRD and N 2 -adsorption etc. † †. The catalytic activity over the catalyst for methane combustion was measured in a fixed reactor which is described elsewhere. 5 As shown in Fig. 2, d H2O at V = 0.02 is ca. 4.49, and d H2O gradually shifts to low field with increasing V. d H2O is electron density of H 1 in H 2 O, which denotes the polarization behavior of water molecules. The larger the value of d H2O , the stronger the polarization and the hydrogen-bonding interaction of the water molecules are. 6 This also indicates that the hydrogen bonds of water become stronger with increasing of water content in the ternary system. It has been reported that ethanol molecules exist as selfassociated aggregates through hydrogen bonds between ethanol molecules in nonpolar solvents...

show abstract

supporting

confidence: 67%

Formation of a Novel Type of Reverse Microemulsion System and Its Application in Synthesis of the Nanostructured La_0.95Ba_0.05MnAl₁₁O₁₉ Catalyst.

Teng

Tian

et al. 2004

ChemInform

View full text Add to dashboard Cite

show abstract

“…These suspensions are usually also good anti-settling systems. It was experimentally found [14,16] that for aa >> ac the conductivity just above this threshold can be described by the scaling law…”

Section: Chain Formationmentioning

confidence: 99%

“…Conductivities of ion-conducting emulsions were measured by Meredith and Tobias [4,6], Pearce [13], Bhattacharya et al [15], Lagourette [16] (who also determined the frequency dependency), Fang et al [17] (who found a very good w Also at the Koninklijke/Shell-Laboratorium, Shell Research B.V., 0021-891X/92 9 1992 Chapman & Hall affirmation of Bruggeman's symmetric theory), and Turner [18]. In this last investigation a simple theory was developed based on the calculation of the distances between ion-conducting spheres; it agrees well with the experimental results for high volume fractions.…”

Section: Introductionmentioning

confidence: 99%

The conductance of suspensions with conducting particles

et al. 1992

View full text Add to dashboard Cite

The conductance of conductive ceramics, graphite and metal suspensions in aqueous KOH solutions was measured with the impedance technique using a four-electrode cell. The measurements were carried out for volume fractions up to high viscosities with particles of different sizes. A wide frequency range was used to investigate also the effect of particle-surface polarisation on the conductance. The results have been analysed in terms of the asymmetric and symmetric theories of Bruggeman and the GEM theory for a wide volume-fraction range of suspended particles. Depending on the suspended material, particle size and electrolyte properties, the suspensions reveal flocculation or chain formation. In case of chain formation, sometimes a decrease of the polarisation resistivity is found due to shortcircuiting by direct particle-particle contact. The conductivities of the particles phase, calculated from measured values, are orders lower than predicted from conductivity data of the pure materials. This is attributed to the occurrence of a constriction resistance and film resistance between the particles in the case of flocculation or chain formation as well as to poor wetting of the particles.

show abstract

“…26,91 At the percolation threshold, the water-in-oil droplets form nano-clusters favorable to the SDS counter-ion mobility. The deviation from the linearity observed for higher water content in the presence of certain oils has been ascribed to the formation of bicontinuous structures, generally observed before the pseudo-phase inversion.…”

Section: Conductivitymentioning

confidence: 99%

“…The measurement of electrical conductivity is a very efficient method to study the global structure of microemulsions, especially in the case of w/o systems. 26,27 The electrical conductivity undergoes a significant change over many orders of magnitude when the volume fraction of the dispersed aqueous pseudo-phase is increased above a certain value. The sharp increase is a consequence of the percolative behavior of formed nanostructures in the system.…”

Section: Introductionmentioning

confidence: 99%

Microemulsions with renewable feedstock oils

2012

View full text Add to dashboard Cite

In this paper we discuss the influence of chemical structures of renewable feedstock oils (RFOs) on the domains of existence and the nano-structures of microemulsions. We compare the results to those of classical microemulsions containing classical n-alkanes. First, the domains of microemulsions obtained from the melt of water, sodium dodecyl sulfate (SDS) as surfactant, 1-pentanol as co-surfactant and different RFOs (or RFO melts) in pseudo-ternary phase diagrams are presented. A surfactantco-surfactant mass ratio of 1 : 2 is kept constant and the RFO (or RFO melt) is considered as a pseudo-constituent. Two different fatty methyl ester (FAME) biodiesels from rapeseed and cuphea oils, rapeseed oil, "TBK" biodiesel from rapeseed oil, limonene, and different mixtures of limonene to FAME-rapeseed biodiesel and FAME-rapeseed biodiesel to FAME-cuphea biodiesel are used as RFOs or RFO melts. Second, conductivity data are shown along an experimental path having a constant RFO or RFO melt : (surfactant-co-surfactant) mass ratio, whereas the water content is varied. All obtained data are then compared to data from previous studies with a series of n-alkanes (from n-hexane to n-hexadecane). As the main conclusion it is found that RFOs or RFO melts can easily substitute n-alkanes. From the chemical structure of the oils, it appears that not only the polarity of the oil plays an important role but also does the absolute size of the oil molecules. In all cases microemulsion systems exhibit percolative behavior.

show abstract

Percolative conduction in microemulsion type systems

Cited by 170 publications

References 17 publications

Formation of a Novel Type of Reverse Microemulsion System and Its Application in Synthesis of the Nanostructured La_0.95Ba_0.05MnAl₁₁O₁₉ Catalyst.

Formation of a Novel Type of Reverse Microemulsion System and Its Application in Synthesis of the Nanostructured La_0.95Ba_0.05MnAl₁₁O₁₉ Catalyst.

The conductance of suspensions with conducting particles

Microemulsions with renewable feedstock oils

Contact Info

Product

Resources

About

Percolative conduction in microemulsion type systems

Cited by 170 publications

References 17 publications

Formation of a Novel Type of Reverse Microemulsion System and Its Application in Synthesis of the Nanostructured La0.95Ba0.05MnAl11O19 Catalyst.

Formation of a Novel Type of Reverse Microemulsion System and Its Application in Synthesis of the Nanostructured La0.95Ba0.05MnAl11O19 Catalyst.

The conductance of suspensions with conducting particles

Microemulsions with renewable feedstock oils

Contact Info

Product

Resources

About

Formation of a Novel Type of Reverse Microemulsion System and Its Application in Synthesis of the Nanostructured La_0.95Ba_0.05MnAl₁₁O₁₉ Catalyst.

Formation of a Novel Type of Reverse Microemulsion System and Its Application in Synthesis of the Nanostructured La_0.95Ba_0.05MnAl₁₁O₁₉ Catalyst.