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Solid-liquid extraction of terbium from phosphoric acid medium has been studied using the commercially available macroporous bifunctional phosphinic acid resin, Tulsion CH-96. The parameters studied include equilibration time, acid concentration, amount of resin, metal concentration, temperature, loading, elution, regeneration, and recycling. In the wide range of phosphoric acid concentration 0.01-7.8 M the percent extraction of terbium decreases from 98.9% at 0.01 M to 16.0% at 1 M due to an ion-exchange mechanism and increases to 36% at 7.8 M due to a coordination mechanism. The percent extraction increases with an increase in weight of the resin from 2.7% at 0.05 g to 80.7% at 1.2 g. Under the studied experimental conditions, the loading of Tulsion CH-96 for terbium was determined to be 3.52 mg per gram of resin. The percent extraction of terbium increases with the increase in temperature, indicating the endothermic nature of the extraction process. Screening of various eluants suggested 1 M (NH4)2CO3 as the best with an efficiency of 99.8%. The extraction behavior of commonly associated metals with terbium such as yttrium, holmium, erbium, dysprosium, ytterbium, and lutetium has been studied as a function of phosphoric acid concentration to determine the separation factors and possible separation. [ABSTRACT FROM AUTHOR]