How green additives affect the water heating profile under ultrasound irradiation: a methodological study

The use of ultrasound irradiation (US) has grown up in the recent years, resulting in a significant number of researches. The US effect is dependent of different parameters, as the probe diameter, amplitude, frequency, kind of solvents, etc. When a solution is sonicated, the energy transferred, although induced by mechanical effects, is ultimately lost as heat. ¹Thus, ultrasonic processing usually results in a temperature increase, unless cooling is provided. The calorimetric method is generally used to measure the heat dissipated in a volume of liquid, which consider the heat capacity of this liquid (Cp) by which the acoustical energy is absorbed. ² At the present work, we studied the behavior of sonicated water when two independent additives are employed, ionic liquids and deep eutectic solvents. The dissipated power was calculated by the calorimetric method, which involves the solvent heat capacity, mass and temperature variation: P (W) = CpMdT/dt. From the heating ramps were obtained from the slope, dT/dt and R2. The graph 1 shows the variation of the dissipated power of the pure water and the water doped with the additives, as a function of the amplitude increase. These data show an interesting result when DES was employed, as the dissipated power increased considerably. On the other hand, when the IL was added no significant difference was observed. Thus, DES have enormous potential as additive, due to their tunable physicochemical properties.