Subtle Effects of Aliphatic Alcohol Structure on Water Extraction and Solute Aggregation in Biphasic Water/ n -Dodecane
Organic phase aggregation behavior of 1-octanol and its structural isomer, 2-ethylhexanol, in a biphasic n-dodecane water system is studied with a combination of physical measurement, small-angle X-ray scattering (SAXS), and atomistic molecular dynamic simulations. Physical properties of the organic phases are probed following their mixing and equilibration with immiscible water phases. Studies reveal that the interfacial tension decreases as a function of increasing alcohol concentration over the solubility range of the alcohol with no evidence for a critical aggregate concentration (cac). An uptake of water into the organic phases is quantified, as a function of alcohol content, by Karl Fischer titrations. The extraction of water into dodecane was further assessed as a function of alcohol concentration via the slope-analysis method sometimes employed in chemical separations. This provides a qualitative understanding of solute (water/alcohol) aggregation in the organic phase. The physical results are supported by analyses of SAXS data that reveals an emergence of aggregates in n-dodecane at elevated alcohol concentrations. The observed aggregate structure is dependent on the alcohol tail group geometry, consistent with surfactant packing parameter. The formation of these aggregates is discussed at a molecular level, where alcohol-alcohol and alcohol-water H-bonding interactions likely dominate the occurrence and morphology of the aggregates.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Workforce Development for Teachers and Scientists (WDTS)
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1368082
- Journal Information:
- Langmuir, Vol. 33, Issue 15; ISSN 0743-7463
- Publisher:
- American Chemical Society
- Country of Publication:
- United States
- Language:
- English
Similar Records
Salt Effect Model for Aqueous Solubility of TBP in a 5 to 100% TBP/n-Dodecane-Nitric Acid-Water Biphasic System at 298.2 K
Alternative (Potentially Green) Separations Media: Aqueous Biphasic and Related Systems Extending the Frontier Final Report For Period September 1, 2002 January 31, 2007