Phase equilibrium investigation with ionic liquids and selectivity in separation of 2-phenylethanol from water Urszula Doman ´ ska a,b,⇑ , Marek Królikowski a , Maciej Zawadzki a , Agnieszka Wróblewska a a Department of Physical Chemistry, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland b Thermodynamic Research Unit, School of Chemical Engineering, University of KwaZulu-Natal, Howard College Campus, King George V Avenue, Durban 4001, South Africa article info Article history: Received 25 April 2016 Received in revised form 13 July 2016 Accepted 17 July 2016 Available online 18 July 2016 Keywords: Synthesis of [HMMOR][NTf 2 ] Physicochemical properties Binary LLE phase diagrams Ternary LLE phase diagrams Thermodynamic description abstract This work presents some important issues and topics related to possible extraction of 2-phenylethanol (PEA) from aqueous phase ‘‘in situ” during the biosynthesis with ionic liquids (ILs). It consists of a series of experimental phase equilibrium measurements in binary and ternary systems. Three ILs as extraction media are proposed for the extraction process based on phase equilibria in ternary systems {IL (1) + PEA (2) + water (3)} at temperature T = 308.15 K and ambient pressure. The systems are composed of the following ILs: 1-hexyl-1-methylmorpholinium bis{(trifluoromethyl)sulfonyl}imide, [HMMOR][NTf 2 ], 1-allyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}imide, [AMIM][NTf 2 ], and diethylmethylsul- fonium bis{(trifluoromethyl)sulfonyl}imide, [S 221 ][NTf 2 ]. A differential scanning calorimetry (DSC) was used to determine the thermal properties of the ILs. The synthesis of new [HMMOR][NTf 2 ] IL and its ther- mal and physicochemical properties as density, viscosity, surface tension were presented. The volume expansivity, as well as the surface thermodynamic functions, such as surface entropy and enthalpy have been derived from the temperature dependence of the surface tension values, as well as the critical tem- perature, parachor and speed of sound for all ILs were presented. The correlation of the liquidus curves in binary systems and tie-lines in ternary systems was undertaken with the NRTL equation. These results of solubility can be used to design future alternative technological processes of the extraction of PEA from fermentation broth. Ó 2016 Elsevier Ltd. 1. Introduction Ionic liquids (ILs) are organic salts with low melting points, low vapour pressure, good stability and high solvation properties [1,2]. ILs exist in the liquid phase in a wide range of temperature, which enable their use in many chemistry and biochemistry reactions [3,4]. ILs may be used as solvents, as co-solvents in the aqueous phase, or as biphasic systems [5]. They also have a broad spectrum of separation applications [6–10]. This generation of solvents pro- vides not only an environment for fragrance materials solubility, but also a highly efficient extraction medium for biocatalytic reactions [11–13]. During the last decade we worked in our Faculty on chemical synthesis of 2-phenylethanol (PEA) [14,15]. However, according to new directives of European Parliament, the fragrance materials must be determined from natural sources or from biosynthesis [16]. This work proposes to study a particular type of biosynthesis of PEA with fast extraction of PEA ‘‘in situ” with ILs. PEA is an important commercial flavour compound with a rose-like aroma [17–19,11]. PEA is included in the production of food, soft drinks, candy, ice cream, pudding, chewing gum and cookies. The natural PEA is usually produced by Saccharomyces cerevisiae yeast in water phase [17–19,11]. There are several examples in literature of using ILs as extraction solvents in the biosynthesis for extraction of PEA ‘‘in situ’ from aqueous phase [11–13,20]. The ionic liquids used in such a process have to be bio- compatible with the yeast [13], reveal non-miscibility with water and large or complete miscibility with PEA at low temperatures. The critical aspect in biosynthesis is that some ILs are toxic to the yeast and may be in the industrial waste processing and enter the aquatic ecosystems. In this paper we continue our investiga- tions concerned on applications of organic solvents [21] and of ILs in PEA extraction [22–27]. Recently, we measured the possibility of using hydrophobic ILs as 1-octylisoquinolinium bis{(trifluoromethyl)sulfonyl}imide, [OiQuin][NTf 2 ] [22], 1-hexylquinolinium bis{(trifluoromethyl)sulfo nyl}imide, [HQuin][NTf 2 ], 1-hexylisoquinolinium bis{(trifluorome thyl)sulfonyl}imide, [HiQuin][NTf 2 ] [23], and piperidinium-based ILs [23]. The 1-hexyl-3-methylpyridinium triflate, [HM 3 Py][CF 3 SO 3 ], and 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluoro phosphate, [EMIM][FAP] have shown complete miscibility with http://dx.doi.org/10.1016/j.jct.2016.07.025 0021-9614/Ó 2016 Elsevier Ltd. ⇑ Corresponding author at: Department of Physical Chemistry, Faculty of Chem- istry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland. E-mail address: ula@ch.pw.edu.pl (U. Doman ´ ska). J. Chem. Thermodynamics 102 (2016) 357–366 Contents lists available at ScienceDirect J. Chem. Thermodynamics journal homepage: www.elsevier.com/locate/jct