Green Hydrogel-Biochar Composite for Enhanced Adsorption of Uranium

Zeinab F Akl; Elsayed G Zaki; Shimaa M ElSaeed

doi:10.1021/acsomega.1c01559

Green Hydrogel-Biochar Composite for Enhanced Adsorption of Uranium

ACS Omega. 2021 Dec 8;6(50):34193-34205. doi: 10.1021/acsomega.1c01559. eCollection 2021 Dec 21.

Authors

Zeinab F Akl¹, Elsayed G Zaki², Shimaa M ElSaeed^{2

3}

Affiliations

¹ Egyptian Atomic Energy Authority (EAEA), P.O. Box 11762 Cairo, Egypt.
² Egyptian Petroleum Research Institute (EPRI), P.O. Box 11727 Cairo, Egypt.
³ National Committee of Women in Science (ASRT), 11334 Cairo, Egypt.

Abstract

Uranium is the backbone of the nuclear fuel used for energy production but is still a hazardous environmental contaminant; thus, its removal and recovery are important for energy security and environmental protection. So far, the development of biocompatible, efficient, economical, and reusable adsorbents for uranium is still a challenge. In this work, a new orange peel biochar-based hydrogel composite was prepared by graft polymerization using guar gum and acrylamide. The composite's structural, morphological, and thermal characteristics were investigated via Fourier transform infrared (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) methods. The composite's water absorption properties were investigated in different media. The performance of the prepared composite in adsorbing uranium (VI) ions from aqueous media was systematically investigated under varying conditions including solution's acidity and temperature, composite dose, contact time, and starting amount of uranium. The adsorption efficiency increased with solution pH from 2 to 5.5 and composite dose from 15 to 50 mg. The adsorption kinetics, isotherms, and thermodynamics parameters were analyzed to get insights into the process's feasibility and viability. The equilibrium data were better described through a pseudo-second-order mechanism and a Langmuir isotherm model, indicating a homogeneous composite surface with the maximum uranium (VI) adsorption capacity of 263.2 mg/g. The calculated thermodynamic parameters suggested that a spontaneous and endothermic process prevailed. Interference studies showed high selectivity toward uranium (VI) against other competing cations. Desorption and recyclability studies indicated the good recycling performance of the prepared composite. The adsorption mechanism was discussed in view of the kinetics and thermodynamics data. Based on the results, the prepared hydrogel composite can be applied as a promising, cost-effective, eco-friendly, and efficient material for uranium (VI) decontamination.