Thermal Redox Desalination of Seawater Driven by Temperature Difference

Abstract

Millions of people suffer from the crisis of lacking sufficient freshwater, particularly for the regions or occasions without proper electricity supply. Therefore, desalination of seawater with low power and renewable energy has become an important issue. Here, we proposed an electrolyte-based thermal redox desalination (ETRD) device powered by temperature difference, where two electrodes are in contact with circulating [Fe(CN)6]3-/4- redox electrolytes at different temperatures sandwiching two salt streams in between. A single ETRD device operating at temperature difference of 60 K, with a large Seebeck coefficient of 1.82 mV K-1 and a high potential difference of 113 mV, enables a maximum power density of 188.8 mW m-2 released and salt removal rate of 9.77 μg cm-2 min-1 with reusability and stability. Besides, seawater can be spontaneously desalinated to freshwater standard while generating electricity. This work shows that ETRD device can realize triple functions including low-grade heat utilization, seawater desalination, and energy supply.