Adsorption of U(VI)-CO3/Ca-U(VI)-CO3 by Amidoxime-functionalized Hydrothermal Carbon

Abstract

Hydrothermal carbon adsorption materials possess the advantages of simple preparation process, mild synthesis conditions and easy surface modification. In this UO 2 2+ speciation as a function of CO 3 2concentration, soluble starch used as carbon source, acrylonitrile was grafted onto starch molecule through ring opening under the catalysis of cerium ammonium nitrate. Subsequently, amidoxime hydrothermal carbon spheres (AO-HTC) were successfully synthesized by hydrothermal reaction and hydroxylamine hydrochloride reduction. Meanwhile, static and dynamic adsorption experiments were performed to investigate the effects of solution pH, carbonate and calcium ion concentration on the adsorption performance of AO-HTC for uranium. And the dynamic adsorption process of AO-HTC for uranium was also studied by Yoon-Nelson and Thomas models. The results show that the adsorption capacity of AO-HTC, the volume of penetration point as well as saturation point in the penetration curve also decreases gradually with the increase of pH, carbonate concentration and calcium concentration. The maximum adsorption capacity (q o) and the required time (τ) of adsorbate through 50% of 5% AO-HTC column are several times higher than that of pure soil column. Therefore, the research highlights that AO-HTC would act as an excellent permeable-reactive barriers (PRB) medium and expected to remediate uranium-contaminated soil and groundwater.