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A New Design of Flow-through System for Dual-ions Electrochemical Deionization
1  Singapore University of Technology and Design


Seawater desalination is a leading way for tackling the global freshwater shortage challenge. However, existing desalination technologies have their own limits, including high energy consumption or low ion removal capacity, which is not sufficient for desalting high-concentration saline water with low cost. In our recent research efforts, we have designed a new flow-through system with a new concept of dual-ions electrochemical deionization technology, which consists of BiOCl for chloride ion Faradaic electrode on the negative side, sodium manganese oxide (Na0.44MnO2) as sodium ion Faradaic electrode on the positive side. It utilizes a redox reaction to individually absorb chloride ions and sodium ions concurrently. Under positive electric current operations, the two ions are released to flow NaCl water electrolyte. Upon switch to negative electric current, the chloride ions are extracted into the negative electrode from flowing NaCl solution while sodium ions are electrochemically captured into the positive electrode. The novel dual-ions Faradaic deionization delivers a stable and reversible salt absorption/desorption capacity of 68.5 mg g-1 when operated at a current density 100 mA g-1, which makes over twice salt absorption of the previous reported best performance (31.2 mg g-1) obtained by a hybrid capacitive deionization system. The electric charge efficiency is up to 0.977 during salt desorption process and 0.958 during absorption process. Owing to ion intercalation process in the salt removal process, energy will be recovered during discharge process. Our research will supply a new method for desalination flow-through system.