Sorption of Uranium on a Bifunctional Polymer of Diethylenetriaminepentaacetic Acid Cross-Linked Β-Cyclodextrin in the Presence of Humic Acid: Kinetics, Isotherms, and Thermodynamics

Abstract

Humic acid (HA) plays an important role in the migration and transformation of uranium in natural waters. To effectively remove uranium in the presence of HA, a bifunctional polymer, diethylenetriaminepentaacetic acid cross-linked β-cyclodextrin (DTPA-β-CD), was synthesized by polycondensation reaction. The sorption performance of DTPA-β-CD in functions of pH, ionic strength, contact time, initial time, and temperature were explored batch wise. Experimental results showed that DTPA-β-CD could concurrently sorb uranium and HA around pH of 3.0. The sorption strongly depended on pH and on ionic strength, demonstrating outer-sphere surface complex in nature. Two sorption kinetics well followed pseudo-second-order model. Sorption isotherm accorded with Sips model. Increasing temperature facilitated uranium and restrained HA sorption. This work demonstrated that DTPA-β-CD was a promising material for sorbing uranium in the presence of HA.