Hydrogen has various applications in different sectors, for instance in chemical industries for fertilizer production and the power sector for generation of electricity. In this work, a new application of hydrogen is explored, for desalination. A membrane-free chemical approach to remove salt ions from saline water at room temperature is developed. Accordingly, a thermodynamically uphill desalination process is carried out using H2 and O2 gases. In this approach, solid phase sodium and chloride ion trapping redox materials, respectively, are reacted with hydrogen and oxygen gases to trap the ions from the salt water. The proof of concept for this chemical desalination approach, on a redox material, is validated by several methods, including physical characterization of the salt trapping materials, and analysis of the desalinated solution employing ion selective electrode and ion chromatography techniques. Electrochemical analysis suggests that salt ion trapping is driven by the electrochemical reactions of the reactant gasses. Even though electrochemical desalination systems are efficient, they face challenges in scalability due to electrode surface area constraints and electrolyte resistance; in contrast, the proposed membrane-free chemical desalination approach utilizes hydrogen and oxygen gases as direct redox agents for desalination to address these challenges. This approach can make the process potentially scalable and compatible with off-grid operations. Furthermore, the theoretical energy consumed by this process, including chemical desalination and salination, is calculated as approximately 6.72kWh/m3 (for brackish water). This work represents a contribution to the field of water purification, demonstrating the potential application of hydrogen for desalination via chemical reactions.
Tiwari et al. (Mon,) studied this question.