TY - JOUR
T1 - Densities and interfacial tensions for fatty acid methyl esters (from methyl formate to methyl heptanoate) + water demixed mixtures at atmospheric pressure conditions
AU - Pozo, Irene del
AU - Cartes, Marcela
AU - Llovell, Fèlix
AU - Mejía, Andrés
N1 - Publisher Copyright:
© 2018 Elsevier Ltd
PY - 2018/6
Y1 - 2018/6
N2 - Experimental determination of mass densities and interfacial tensions (IFT) at liquid-liquid equilibrium (LLE) for methyl ester (FAME) demixed aqueous family (from methyl formate to methyl heptanoate) are reported as a function of temperature at atmospheric pressure (101.3 kPa). Mass density determinations are carried out in a vibrating tube densimeter, whereas a spinning drop tensiometer is used for performing IFT measurements. Furthermore, the IFT data have been correlated by using a simplified version of the Square Gradient Theory (SSGT) as applied to the Non-Random Two Liquids (NRTL) activity coefficient model. Based on the experimental results, the mass densities of both aqueous and methyl ester bulk phase decrease with temperature, whereas the IFT increases with the temperature and reaches a maximum value, which is related to the maximum tie line in the LLE. For higher temperatures, IFT starts to decrease with temperature. The correlation approach of IFT (SSGT + NRTL) was found to be suitable for correlating the IFT of the mixtures as a function of temperature and also provides a route to explore other interfacial properties, such as interfacial concentration profiles, which are difficult to measure. Considering the results from the calculated interfacial profiles along the interfacial region, the components (FAMEs and water) neither exhibit surface activity nor adsorption activity and the interfacial width decreases with temperature, as it was expected.
AB - Experimental determination of mass densities and interfacial tensions (IFT) at liquid-liquid equilibrium (LLE) for methyl ester (FAME) demixed aqueous family (from methyl formate to methyl heptanoate) are reported as a function of temperature at atmospheric pressure (101.3 kPa). Mass density determinations are carried out in a vibrating tube densimeter, whereas a spinning drop tensiometer is used for performing IFT measurements. Furthermore, the IFT data have been correlated by using a simplified version of the Square Gradient Theory (SSGT) as applied to the Non-Random Two Liquids (NRTL) activity coefficient model. Based on the experimental results, the mass densities of both aqueous and methyl ester bulk phase decrease with temperature, whereas the IFT increases with the temperature and reaches a maximum value, which is related to the maximum tie line in the LLE. For higher temperatures, IFT starts to decrease with temperature. The correlation approach of IFT (SSGT + NRTL) was found to be suitable for correlating the IFT of the mixtures as a function of temperature and also provides a route to explore other interfacial properties, such as interfacial concentration profiles, which are difficult to measure. Considering the results from the calculated interfacial profiles along the interfacial region, the components (FAMEs and water) neither exhibit surface activity nor adsorption activity and the interfacial width decreases with temperature, as it was expected.
KW - Densities
KW - Liquid-liquid systems
KW - Methyl esters + water mixtures
KW - Simplified Square Gradient Theory
KW - Spinning drop tensiometry
UR - http://www.scopus.com/inward/record.url?scp=85042413308&partnerID=8YFLogxK
U2 - 10.1016/j.jct.2018.02.010
DO - 10.1016/j.jct.2018.02.010
M3 - Article
AN - SCOPUS:85042413308
SN - 0021-9614
VL - 121
SP - 121
EP - 128
JO - Journal of Chemical Thermodynamics
JF - Journal of Chemical Thermodynamics
ER -