Progressive Freezing-Melting Method for Removal Boron from Simulated Seawater

Desalination plays a crucial role in addressing water scarcity and promoting sustainable development. However, the high boron content in seawater poses a major challenge. This study of progressive freezing-melting method for removing boron from simulated seawater reveals the effects of freezing duration, freezing temperature, initial concentration and melting method on the boron removal rate. Experimental results demonstrated that the progressive freezing-melting method effectively removal boron from simulated seawater. After freezing the simulated seawater at -5 degree celsius for 48 h, an average freezing volume of 11.5% was achieved, with a boron removal rate exceeding 96.1%. Extending the freezing duration, reducing the freezing temperature, and increasing the initial concentration all resulted in decreased boron removal rates during progressive freezing. In order to obtain purer ice bodies, melting techniques were employed to further increase boron removal rate. Ultrasonic melting and oscillation melting can remove more than 85.2% of the boron in the ice at 30% of the mass of the melted ice. Compared with natural melting, ultrasonic melting and oscillation melting can better promote the removal of boron from ice. After subjecting boron-containing simulated seawater with an initial concentration of 12 mg/L to progressive freezing-melting, the recovered ice exhibited a boron concentration below 0.050 mg/L. This study is expected to fill the research gap of boron removal from seawater desalination by the progressive freeze-melt method and provide data reference for the frozen seawater desalination process, which not only contributes to environmental sustainability, but also has great potential due to its high efficiency in seawater boron removal.