As part of the experimental work of my thesis, I prepared a natural deep eutectic solvent (NADES) composed of fructose and citric acid, to which water was added (hereinafter referred to as the water-containing DES solvent, abbreviated as FCH). I successfully synthesized FCH using three methods: utilizing an ultrasonic (UZ) homogenizer at room temperature, using a UZ homogenizer with continuous cooling of the solvent in an ice bath, and through a mixing and heating method. More diluted aqueous solutions of the deep eutectic solvent composed of fructose and citric acid were prepared in two different ways: in the first method, I added all the intended water to fructose and citric acid before their mixing/homogenization, while in the second method, I added a portion of the water at the beginning of FCH preparation, and then further diluted FCH with the remaining amount of water. I measured the refractive index, specific conductivity, density, viscosity, sound velocity and calculated adiabatic compressibility of the prepared solvents at 25 °C. I compared the obtained values for differently prepared samples of these solvents and investigated whether the method of adding water (adding all water immediately at the beginning or adding a portion of water at the start of preparation and diluting the prepared FCH with the remaining water) truly influences the physicochemical properties of the DES, as suggested by a recent entry in scientific literature.
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