Separation of magnesium and lithium from brine using a Desal nanofiltration membrane

Owing to the high ratio of Mg2+ to Li+ in most of the salt lake brines in China, it is difficult to extract lithium. Therefore, the separation efficiency of a nanofiltration membrane was investigated in this study. Operating conditions such as operating pressure, inflow water temperature, pH, and Mg2+/Li+ ratio were investigated. Relationship between the rejection rates of magnesium and lithium was established. Moreover, the extractions of lithium from salt lake brines were also evaluated. The results indicate that the separation of magnesium and lithium was highly dependent on the Mg2+/Li+ ratio, operating pressure, and pH. When the Mg2+/Li+ ratio was <20, the competitive coefficient was sensitive to the Mg2+/Li+ ratio. The permeate flux of membrane for the East Taijiner brine was higher than that for the West Taijiner brine.