**2. Materials and Methods**

This section describes the DSC procedure used for phase diagram construction and outlines the methodologies employed for static layer freeze crystallization, suspension freeze crystallization, and for separation efficiency studies.

### *2.1. Di*ff*erential Scanning Calorimetry (DSC)*

The solid–liquid equilibrium of binary [DBNH][OAc] and water solution was investigated to obtain phase diagram data that cover both [DBNH][OAc]- and water-enriched solutions. Thermal analyses were conducted by DSC (3, Mettler Toledo (Schwerzenbach, Switzerland)) equipped with an intra-cooler. Individual samples, with a mass of ca. 10 mg, were placed in 25 μL aluminum crucibles that were subsequently sealed before being placed in the experimental chamber with a N2 flux regulated atmosphere. As low heating and cooling rates offer better information about the thermal behavior of the samples, i.e., whether the ionic liquid is a crystal or a glass formation [20], a heating and cooling rate of 1 K/min was chosen for all experiments.
