Desalination and Li+ enrichment via formation of cyclopentane hydrate

Abstract

Hydrate-based desalination is an attractive and energy-effective method. In order to obtain high water recovery and purity, the desalination and Li+ enrichment performance were examined using single-stage desalination via graphite-promoted cyclopentane (CP) hydrate formation. LiCl, LiBr and LiI aqueous solutions with concentration ranging from 0.01 to 0.6 mol/L were used as brine. The rate for CP hydrate formation is determined by concentration, independent of the type of used salts. Halide ions were found to have the different capability in hindering CP hydrate-based desalination, with an order of Cl− < Br− < I−. The desalination efficiency was improved with increased concentration. Water recovery of 40% can be obtained in 1 h reaction, demonstrating the high efficiency of hydrate-based desalination. The desalination efficiency remains constant at around 70% over 24 h reaction, which can be dramatically enhanced by multi-stage desalination. The graphite powder, as the promoter for hydrate formation shows impressive recycling stability. The finding in this study would be of great help for developing effective desalination processes to produce fresh water and enrich high-value salts via CP hydrates.