Decorated xanthan gum/alginate mingled hydrogel beads@La(III)-MOFs@reduced graphene oxide@graphene quantum dots nanohybrid for adsorptive capture and recovery of U(VI)

Abstract

Uranium as an example of radionuclide toxic heavy metal has shown serious impacts on human and living systems causing well-known sever diseases and therefore, proper attention should be directed and given to safely store and remove uranium hazardous species from the environment especially water resources by finding effective approaches for remediation and capturing uranium from water or wastewater. Therefore, the present investigation is designed to fabricating and combining of xanthan gum and alginate mingled hydrogel beads with reduced graphene oxide (rGO)/graphene quantum dots (GQDs) and lanthanum 1,4-benzene di-carboxylate (La-MOFs) in a single nanocomposite (La-BDC/rGO/GQDs@mingled hydrogel) for direct application in adsorptive capturing of U(VI) from water. The assembled nanocomposite was found into crystalline structure as well as characterized and detected with multiple correlated active functional groups to the constituting units from the FT-IR analysis, while the HR-TEM analysis showed uniformly distributed particles with 25.3 nm as the average nanocomposite size. The effectiveness behavior of La-BDC/rGO/GQDs@mingled hydrogel nanocomposite in adsorptive capturing of uranyl ions (50 and 100 mg/L) was explored and optimized in a number of experimental conditions and revealed to the optimum pH = 7.12, nanocomposite dose = 20 mg and reaction time = 30 min. The adsorptive capture interaction of U(VI) by La-BDC/rGO/GQDs@mingled hydrogel nanocomposite perfectly fitted with the linear and nonlinear pseudo-second order expressions giving 0.96 and 0.93 as well as the linear and nonlinear Freundlich isotherm expressions yielded 0.997 and 0.997 correlation factors, respectively. The computed thermodynamic parameters provided good evidence for the endothermic capture type of U(VI) interaction with La-BDC/GQDs-rGO@mingled hydrogel. The nanocomposite was subjected to more than three regeneration processes with satisfactory results. Finally, La-BDC/rGO/GQDs@mingled hydrogel nanocomposite achieved excellent capture percentage of U(VI) from sea, tap and wastewaters providing 91.19 %, 90.78 % and 91.53 % from 100 mg/L concentration to deliver a direct confirmation for its potential superior performance in adsorptive capturing of U(VI) from contaminated waters.