Method for extracting and separating light rare earth elements by using dual-functional ionic liquid

The invention belongs to the technical field of rare earth separation and ionic liquid extraction and particularly relates to a method for extracting and separating light rare earth elements by usingdual-functional ionic liquid. The method comprises the following steps: taking an aqueous solution containing light rare earth elements as a raw material solution, combining 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester with N-octyl pyridine chloride salt, adding sodium hydroxide and adjusting, retaining negative ions of 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester and positive ionsof N-octyl pyridine chloride salt, combining the negative ions of 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester with the positive ions of N-octyl pyridine chloride salt to synthesize dual-functional ionic liquid, mixing the dual-functional ionic liquid with acidic raw material liquid, mixing and extracting, centrifuging to obtain an organic phase loaded with rare earth and extraction raffinate, carrying out back ex