The DES, composed of a mixture of tri-n-octylphosphine oxide (TOPO) and lactic acid (LA) in a 1:2 mol proportion, was successfully immobilized on the PU nanofibers by electrospinning.After optimizing the electrospinning machine parameters, the fibers were made of PU with 10, 20, and 30 weight% DES.All DES-PU nanofibers exhibited stability without any significant swelling or loss of materials during equilibrations.The extraction data of La, Ce, Nd and Eu in TOPO-LA DES loaded nanofibers as a function of HNO3 concentration exhibited faster kinetics, a decrease in the extraction of a given lanthanide with an increase in the concentration of HNO3, and an increase in the extraction of La3+ to Eu3+.It was observed that lanthanides could be completely deloaded with > 2 M HNO3 from TOPO-LA DES-loaded PU nanofibers.Among different leaching agents including hydrophilic DESs tested, HNO3 was found to be the best leachant of REEs from Kerala sand.The REEs extraction from leach liquor (0.5 M HNO3) showed that Th is extracted with high efficiency (95%) and Ce, La, and Nd are extracted with moderate efficiency (35-50%) in the presence of a large excess of Fe3+ ions.Th was found to sorb efficiently from 4 HNO3 also.