Metal organic framework doped amine-functionalized polymeric beads for selective removal of Uranium (VI) from alkaline leach liquor: Batch and column study

Abstract

In this work, a diethylenetriamine (DETA) functionalized metal organic framework (ZIF-67) incorporated polyacrylonitrile (PAN) bead (MFB) was developed to capture U efficiently from simulated medium and alkaline leach liquor. The synthesized beads were characterized using suitable analytical methods. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to understand the U uptake mechanism. The process of adsorption was inherently heat-absorbing and spontaneous in nature. The Langmuir sorption capability (Q_m) was 835 mg/g, at pH 7 and, 298 K. Surface- grafted abundant amine (–NH₂) groups introduce significant coordinative interaction with the U species in aqueous medium. The adsorbent is reusable and structurally robust with >85 % U removal after five consecutive regeneration cycles. The performance of the continuous adsorption columns was simulated by a fundamental adsorption-diffusion model and the relevant transport parameters were evaluated. For real life alkaline leach liquor with U concentration 825 mg/L and 100 to 500 kg of adsorbent, the adsorption column had a breakthrough life of 46 to 108 days with constant flow rate of 500 L/day. This study showed that the synthesized MFB is an excellent adsorbent that is inexpensive, non-toxic, recyclable,environmentally compatible, and selective towards U removal from alkaline leach liquor.