TY  - JOUR
AU  - Sehnem, André Luiz
AU  - Niether, Doreen
AU  - Wiegand, Simone
AU  - Figueiredo Neto, Antônio Martins
TI  - Thermodiffusion of Monovalent Organic Salts in Water
JO  - The journal of physical chemistry  / B
VL  - 122
IS  - 14
SN  - 1520-5207
CY  - Washington, DC
PB  - Soc.
M1  - FZJ-2018-03552
SP  - 4093 - 4100
PY  - 2018
AB  - The ionic Soret effect induced by temperaturegradients is investigated in organic electrolytes (tetramethylammoniumand tetrabutylammonium hydroxides) dispersed in waterusing a holographic grating experiment. We report the influences oftemperature and salt concentrations on the Soret, diffusion, andthermal diffusion coefficients. Experimental results to the thermaldiffusion coefficient are compared with a theoretical description forthermodiffusion of Brownian particles in liquids based in thethermal expansion of the liquid solution. It is observed that theobtained thermal diffusion coefficients for the organic electrolytespresent a similar temperature dependence as the theoretical prediction. Comparing the experimental results for the organic andcommon inorganic salts it is proposed an additional physical mechanism as the cause to the different thermal diffusioncoefficients in both types of salt. We propose that the temperature dependence of hydration free energy gives rise to a force termthat also leads to ion migration in a temperature gradient. We describe the thermal diffusion results as a competition betweenthermal expansion and hydration effects. The specific structure each type of ion cause in water molecules is considered in the heatof transport theory to describe thermal diffusion of electrolytes. A qualitative agreement is seen between our results and theclassical heat of transport theory.
LB  - PUB:(DE-HGF)16
C6  - pmid:29558136
UR  - <Go to ISI:>//WOS:000430641900040
DO  - DOI:10.1021/acs.jpcb.8b01152
UR  - https://juser.fz-juelich.de/record/848302
ER  -