Redox Behavior of Uranium at the Nanoporous Aluminum Oxide-Water Interface: Implications for Uranium Remediation

• Published in: Environmental science & technology Vol. 46; no. 13; pp. 7301 - 7309
• Main Authors: Jung, Hun Bok, Boyanov, Maxim I, Konishi, Hiromi, Sun, Yubing, Mishra, Bhoopesh, Kemner, Kenneth M, Roden, Eric E, Xu, Huifang
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 03.07.2012; American Chemical Society (ACS)
• Subjects: Adsorption; Aluminum; aluminum oxide; Aluminum Oxide - chemistry; Applied sciences; Biological and physicochemical properties of pollutants. Interaction in the soil; Bioremediation; Carbonates - chemistry; Chemical compounds; Decontamination. Miscellaneous; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental Restoration and Remediation; Environmental science; ENVIRONMENTAL SCIENCES; Exact sciences and technology; nanopores; Nanostructures - chemistry; Nanostructures - ultrastructure; Oxidation; Oxidation-Reduction; Pollution; Pollution, environment geology; Porosity; porous media; Radioactive Pollutants - chemistry; Radioactive Pollutants - isolation & purification; sediments; sodium bicarbonate; soil; Soil and sediments pollution; Sorption; Uranium; Uranium - chemistry; Uranium - isolation & purification; uranium, sorption, redox reaction, nanopore, bioremediation, aluminum oxide, subsurface; Water - chemistry; X-Ray Absorption Spectroscopy; Aluminium oxide; Oxidation reduction; Radioactive pollution; Porous medium; Immobilization; Desorption; Radioisotope; Soil pollution; Sediments; Heavy metal; Actinide; Trace element; Pore size; Microporosity; Uranium; Adsorption; Decontamination; Size effect; Surface area; Alumina; Nanoporosity
• ISSN: 0013-936X; 1520-5851; 1520-5851
• DOI: 10.1021/es2044163

Sorption–desorption experiments show that the majority (ca. 80–90%) of U(VI) presorbed to mesoporous and nanoporous alumina could not be released by extended (2 week) extraction with 50 mM NaHCO3 in contrast with non-nanoporous α alumina. The extent of reduction of U(VI) presorbed to aluminum oxides was semiquantitatively estimated by comparing the percentages of uranium desorbed by anoxic sodium bicarbonate between AH2DS-reacted and unreacted control samples. X-ray absorption spectroscopy confirmed that U(VI) presorbed to non-nanoporous alumina was rapidly and completely reduced to nanoparticulate uraninite by AH2DS, whereas reduction of U(VI) presorbed to nanoporous alumina was slow and incomplete (<5% reduction after 1 week). The observed nanopore size-dependent redox behavior of U has important implications in developing efficient remediation techniques for the subsurface uranium contamination because the efficiency of in situ bioremediation depends on how effectively and rapidly U(VI) bound to sediment or soil can be converted to an immobile phase.