Abstract
This work presents an investigation on phase equilibria in partially miscible systems comprised of water, esters, and alkanols. Experimental liquid–liquid equilibria (LLE) were determined for ternaries of water+H2u–1Cu–1CO2CvH2v+1+CwH2w+1(OH) (u = 3,4; v = 2,3; w = 1–4) at 298.15 K and for the four corresponding water+ester binaries, in the temperature interval T = [283–328] K. The results reveal a complex behavior of the ternary LLE. The ester barely dissolves in the aqueous phase, even in the presence of alkanol (xmax,esterII ≈ 0.15). However, the organic phase contains high quantities of water when the compositions approach the plait point (xmax,waterI ≈ 0.75). Data modeling was carried out with a multiparametric model, obtaining an acceptable correlation with a maximum deviation in the compositions of sx = 0.031 for the system water(1)+propyl butanoate(2)+propan-1-ol(3). Estimations with COSMO-RS and UNIFAC differed from experimental values in all cases, especially in the systems containing propan-1-ol, since both models predict a nonreal immiscibility at 298.15 K in the binary water+propan-1-ol. Therefore, the simulation of the extractive process using UNIFAC was not adequate.
Highlights
Characterization of liquid−liquid equilibria (LLE) in heterogeneous systems is essential for the design of extraction/ decantation operations in the chemical industry.1,2 For specific conditions, the experimental information can reveal (a) the liquid phases formed, (b) the amount of material in each phase, and (c) the proportion of each component in each phase
This work focuses on the experimentation and analysis of these systems using four esters and four alkan-1-ol, whose practical utility is discussed with a new modeling procedure
The water is dissolved in significant proportions in the organic phase, reaching up to x1I ≈ 0.75 in some cases
Summary
Characterization of liquid−liquid equilibria (LLE) in heterogeneous systems is essential for the design of extraction/ decantation operations in the chemical industry. For specific conditions, the experimental information can reveal (a) the liquid phases formed, (b) the amount of material in each phase, and (c) the proportion of each component in each phase. The experimental information can reveal (a) the liquid phases formed, (b) the amount of material in each phase, and (c) the proportion of each component in each phase These three factors influence the consideration of these items, because they determine the composition of the products generated and their influence in the design of above the aforementioned operations. Esterification of a carboxylic acid with alkanol is a biphasic chemical reaction in liquid state, as the aforementioned immiscibility between the reaction products, ester and water, can split the system into two phases (Figure 1) In this case, the reagents act as cosolvents, and the separation of the system into phases will depend on the alcohol, the acid used and its composition, in addition to other factors such as the temperature or the catalyst employed
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