The effect of water chemistry on adsorption and desorption of U(VI) on nano-alumina

It is demonstrated that nanoparticles are ubiquitous in subsurface sediments; therefore, investigation of the adsorption and desorption of U(VI) on nanoparticles plays vital role in the understanding of the fate and transport of U(VI) in sub-sediment at their initial sources. The nano-alumina was synthesized by self-assemble method and was characterized by TEM, XRD and potentiometric titration. The characteristic results revealed the presence of nanoscale space confinement effect of nano-alumina. The batch adsorption of U(VI) on nano-alumina was carried out under various water chemistry such as reaction time, pH, ionic strength, initial U(VI) concentration and temperature. The maximum adsorption capacity of nano-alumina and alpha-alumina calculated from Langmuir model at pH 4.5 and T = 298 K are 92.59 and 59.88 mg/g, respectively. Approximately 35% and 5% of U(VI) are desorbed from alpha-alumina and nano-alumina at 48 h in the presence of 0.01 M NaHCO3 solution, which indicate that the nano-alumina presents the strong chemical affinity for U(VI) as compared to alpha-alumina. This study implies that nano-alumina could be as a promising adsorbent to remove the U(VI) from aqueous solutions.