Novel diisobutyl diamide grafted polymer resin for uranium recovery from mild nitric acid medium

Abstract

A novel diisobutyl diamide (DIBDA) grafted resin was synthesized by chemically grafting the amidic functionalities onto a commercially available styrene-divinylbenzene polymer resin. The resin was characterized using standard techniques such as FTIR, solid-state 13-C CP/MAS NMR, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The sorption behavior of uranium and competing metal ions was systematically evaluated in both batch and column modes. Optimal uranium uptake was achieved from a dilute nitric acid medium at pH  2–3 in the presence of 2.0 M nitrate ions. More than 98 % uranium was stripped efficiently in a single step using 0.25 M HNO₃. Column studies using a feed containing 0.1 g/L U and a 6 mL resin bed volume yielded a strip solution with uranium concentration exceeding 1.2 g/L, corresponding to a concentration factor above 12. The resin exhibited excellent selectivity for uranium over common matrix elements such as Fe, Y, Ca, Al, and Na. Kinetic studies and sorption isotherm modelling revealed the significant role of amidic functional groups in the selective and efficient sorption of U(VI).