Simultaneous Sea Sand Desalination and Resources Recovery Using the Bipolar Membrane Electrodialysis

Objective To achieve the simultaneous recovery of fresh water, acid and alkali resources through desalination of sea sand, Method it is expected to utilize the principle of water molecule dissociation and ion transmembrane migration at the action of an electric field, taking sea sand as the treatment object, to construct a bipolar membrane electrodialysis reactor and conduct experiments on the simultaneous recovery of desalinated sea sand through bipolar membrane electrodialysis. Result With sand-to-water ratio in quality of 1:1 and current density of 10 mA/cm², Cl^- removal efficiency in the sea sand was 98% ± 1% in the BMED, so that Cl^- content in desalinated sea sand reached the standard of sand for construction (GB/T 14684－2022). Meanwhile, a stream of fresh water with pH = 8.43 ± 0.30 and conductivity as 2.30 ± 0.49 mS/cm was recovered from the desalination chamber. A stream of acid solution with H⁺ concentration of 0.057 mol/L was recovered from the acid production chamber. A stream of alkali solution with OH^- concentration of 0.025 mol/L was recovered from the alkali production chamber. Conclusion BMED is a promising method for simultaneous sea sand desalination and resources recovery.