Effects of water temperature on ultrasonic desalination and estimated chloride reduction of sea sand

Abstract Ultrasonic desalination has emerged as a promising physical technique for chloride removal from sea sand; however, the influence of water temperature on its performance remains insufficiently elucidated under practical operating conditions, as the water temperature during the process varies seasonally and is often not actively controlled. In this study, we examined the effects of water temperature on ultrasonic desalination performance using a laboratory-scale system under low (10–15 °C), ambient (~ 25 °C), and elevated (30–35 °C) temperatures. The residual estimated chloride content was evaluated against the (≤ 0.04%). The results indicated that under the tested laboratory conditions, ultrasonic power was the primary factor influencing estimated chloride reduction, while water temperature modulated the mass-transfer stability. The residual estimated chloride content generally decreased with increasing ultrasonic power across the tested temperatures. Ambient temperature exhibited the most stable and monotonic reduction, achieving residual estimated chloride levels as low as 0.014–0.017%. In contrast, low-temperature conditions showed non-monotonic behavior and greater variability, requiring extended treatment time to satisfy the same criterion. Elevated-temperature conditions achieved desalination performance comparable to that of ambient conditions only at the highest power level tested, indicating limited benefit from additional heating. These preliminary findings suggest that ultrasonic desalination can effectively lower estimated chloride concentrations under representative seasonal temperatures without active temperature regulation, provided operating times are suitably adjusted.