title: Cross-diffusion in a water-in-oil microemulsion loaded with malonic acid or ferroin. Taylor dispersion method for four-component systems.
abstract: We describe an improved Taylor dispersion method for four-component systems, which we apply to measure the main- and cross-diffusion coefficients in an Aerosol OT water-in-oil microemulsion loaded with one of the reactants of the Belousov-Zhabotinsky (BZ) reaction, water(1)/AOT(2)/R(3)/octane(4) system, where R is malonic acid or ferroin. With [H(2)O]/[AOT] = 11.8 and volume droplet fraction phi d = 0.18, when the microemulsion is below the percolation transition, the cross-diffusion coefficients D(13) and D(23) are large and positive ( D(13)/ D(33) congruent with 14, D(23)/ D(33) congruent with 3) for malonic acid and large and negative for ferroin ( D(13)/ D(33) congruent with -112, D(23)/ D(33) congruent with -30) while coefficients D(31) and D(32) are small and negative for malonic acid ( D(31)/ D(33) congruent with -0.01, D(32)/ D(33) congruent with -0.14) and small and positive for ferroin ( D(31)/ D(33) congruent with 5 x 10(-4), D(32)/ D(33) congruent with 8 x 10(-3)). These data represent the first direct determination of cross-diffusion effects in a pattern-forming system and of the full matrix of diffusion coefficients for a four-component system. The results should provide a basis for modeling pattern formation in the BZ-AOT system.
authors.affiliation: Department of Chemistry and Volen Center for Complex Systems, MS 015, Brandeis University, Waltham, Massachusetts 02454, USA.
authors.forename: Vladimir K
authors.initials: VK
authors.lastname: Vanag
authors.forename: Federico
authors.initials: F
authors.lastname: Rossi
authors.forename: Alexander
authors.initials: A
authors.lastname: Cherkashin
authors.forename: Irving R
authors.initials: IR
authors.lastname: Epstein
mesh_terms: D004058:Diffusion; D004143:Dioctyl Sulfosuccinic Acid / Q000737:chemistry*; D004655:Emulsions / Q000737:chemistry; D008314:Malonates / Q000737:chemistry*; D009795:Octanes / Q000737:chemistry; D009821:Oils / Q000737:chemistry*; D010618:Phenanthrolines / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D004655:Emulsions; D008314:Malonates; D009795:Octanes; D009821:Oils; D010618:Phenanthrolines; D014867:Water; D004143:Dioctyl Sulfosuccinic Acid; C001635:ferroin; C030290:malonic acid