Highly Efficient Removal of Uranium(VI)\nfrom Wastewater by Polyamidoxime/Polyethyleneimine Magnetic Graphene\nOxide

Abstract

Highly efficient\nremoval\nof U­(VI) from mine radioactive wastewater has received a lot of attention.\nHerein, the polyamidoxime/polyethyleneimine magnetic graphene oxide\n(mGO-PP) adsorbent was successfully prepared by in situ polymerization\nof acrylonitrile on magnetic GO (mGO) covalently modified with polyethylenimine\n(PEI). The mGO-PP\nwas characterized by Fourier transform infrared (FT-IR), scanning\nelectron microscopy, transmission electron microscopy, vibrating sample\nmagnetometer, and X-ray photoelectron spectroscopy (XPS). The maximum\nadsorption capacity of mGO-PP toward U­(VI) was 606.06 mg/g at 298\nK and pH 6.0. The removal of U­(VI) by mGO-PP for U­(VI) was a monolayer\nchemisorption based on the study of the batch experiment. The calculated\nthermodynamic parameters indicated that the removal of U­(VI) by mGO-PP\nwas a spontaneous and endothermic process. The adsorption mechanism\nof mGO-PP toward U­(VI) was explored by FT-IR and XPS analyses. Furthermore,\nthe removal rate of U­(VI) by mGO-PP is 93.68% and the <i>K</i>_d value for U­(VI) is 444.73 L/g in actual mine radioactive\nwastewater, and the residual U­(VI) concentration (6.37 μg/L)\nin wastewater was lower than the maximum permissible concentration\nof uranium in drinking water (30 μg/L) (World Health Organization).\nThis indicated that the mGO-PP composite is a promising adsorbent\nfor efficient removal of U­(VI) from practical mine radioactive wastewater.