Study of the Soret Effect in Hydrocarbon Chain/Aromatic Compound Mixtures

Abstract

We studied the thermal diffusion behavior of equimolar mixtures of hydrocarbon chains in cyclohexane, p-xylene and o-xylene experimentally and by reverse nonequilibrium molecular dynamics.The hydrocarbon chains heptane, 2,3-dimethylpentane, 2,4-dimethylpentane, 2-ethyl 3 methyl butadiene and 2,4 dimethylpentadiene -1,3 with the same number of carbon atoms were considered in order to conserve the mass contribution and to investigate the shape influence on the Soret coefficient. Compared to the experimental data, the simulation results show the same trend. With increasing degree of branching the Soret coefficient becomes larger. The negative Soret coefficient of the hydrocarbon chains indicates the enrichment in the warm side. We were able to find a empirical correlation between the properties of the pure components and the Soret coeffcients of the mixture.

Soret motion in non-ionic binary molecular mixtures

“…4. A roughly linear dependence on φ 1 has been reported for mixtures of benzene, toluene, and cyclohexane [13]; more complexe variations occur for flexible alkane chains, sugars, and polar molecules such as acetone [14][15][16][17][18]. Both the linear variation with composition and the dependence on the Hamaker constants agree with numerical simulations of a Lennard-Jones binary liquid [32].…”

“…Here we describe finite-curvature corrections that arise from the modified van der Waals potential (16). Inserting the vertical distance z = r − R in (13) and performing the integral one finds where the finite size of the bead is accounted for by…”

“…1. First, molecular mixtures generally comprise comparable volume fractions of their components and thus cannot be treated in the low-dilution limit [13][14][15][16][17][18]. Second, in charged systems macroscopic hydrodynamics works well, since both the Debye length and the solute size are large compared to the solvent molecular structure [6][7][8]; this continuum approximation is less obvious for short-ranged dispersion forces [19].…”

Advances in Thermodiffusion and Thermophoresis (Soret Effect) in Liquid Mixtures

“…Experimental data are rather abundant in various combinations of binary hydrocarbon mixtures, e.g., (Perronace et al, 2002;Polyakov et al, 2006Polyakov et al, , 2009Leahy-Dios et al 2008). In some particular cases, benchmark experimental data are available obtained using very different methods with minimum uncertainty (Platten, 2006).…”

Investigação da influência do tamanho de partícula na termodifusão de colóides magnéticos positivamente carregados

“…Vários outros tipos de sistemas físicos, mais complexos que soluções iônicas, também são utilizados em experimentos de termodifusão: nanopartículas [34][35][36], micelas [25,37,38], misturas líquidas binárias [39][40][41], polímeros sintéticos [23,42], biopolímeros [43,44], biomoléculas e proteínas [40,43,45,46] A distância focal f T da lente é determinada a partir da equação [100,101]:…”