Phase Separation of Alcohol (1-Propanol, 2‑Propanol, or tert-Butanol) from Its Aqueous Solution in the Presence of Biological Buffer MOPS

Buffering-out is a new finding phase-separation phenomenon. It can minimize the drawback of the conventional salting-out method, which will cause corrosion of the equipment at high concentrations of ionic salts. To develop this new separation process, phase equilibrium data are essentially needed. In the present study, the density measurements method was used to determine the phase boundaries of solid–liquid equilibrium (SLE), and the cloud-point method was used to determine the phase boundaries of liquid–liquid equilibrium (LLE) and solid–liquid–liquid equilibrium (SLLE). The phase compositions of coexistence phases for alcohol (1-propanol, 2-propanol, or tert-butanol)–water + 3-(N-morpholino)­propanesulfonic acid (MOPS), including at LLE and at SLLE, were then measured at 298.15 K with an analytical method. The experimental tie-line data were also accurately correlated by the nonrandom two-liquid (NRTL) model. A conceptual process flowsheet was also proposed for the recovery of 1-propanol from its aqueous solution with the aid of MOPS.