Extracting Lithium Using the Steric Bulk of an Aminimide Functional Group

An aminimide is a zwitterionic group containing a cationic nitrogen bonded to an anionic nitrogen. The goal of this project was to use the steric bulk and electronic properties of the aminimide to block other species in a brine solution such as potassium, and selectively pick up lithium. To test this, polymethacrylate beads which contain carboxyl groups were modified to the desired aminimide. Three different aminimide groups were tested, a trimethylaminimide, aminopyridiniumaminimide, and a triethylaminimide. The modified beads would be introduced to a solution containing lithium and the lithium concentration was measured before and after exposure to the beads using atomic absorption spectroscopy. Our realistic brine solution contained 10,000 ppm K, 200 ppm Li. Only the aminopyridiniumaminimide and the triethylaminimide exhibited selectivity. The aminopyridiniumaminimide took up 43.9 ppm Li, while the triethylaminimide took up 59.35 ppm Li