Plasma-grafted polyamine/hydrotalcite as high efficient adsorbents for retention of uranium (VI) from aqueous solutions

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 342; pp. 103 - 111
• Main Authors: Cheng, Wen, Wan, Tian, Wang, Xinhong, Wu, Wei, Hu, Baowei
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.06.2018
• Subjects: Adsorption; EXAFS; Modeling; Plasma; Polyanime/hydrotalcite; Uranium; Plasma; Polyanime/hydrotalcite; Uranium; Adsorption; Modeling; EXAFS
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2018.01.100

[Display omitted] •U(VI) adsorption decreased with increasing ionic strength at pH 2.0–5.0.•Release of U(VI) from hydrotalcite was irreversible by desorption experiment.•U(VI) sorption can be satisfactorily fitted by surface complexation modeling. The high efficient adsorbent of polyamine/hydrotalcite (PANI/HT) composites has been fabricated by plasma-grafting techniques. In this study, the effect of environmental factors on the adsorption of U(VI) on PANI/HT was investigated by EXAFS, modeling and theoretical calculations. The characteristic results indicated that the large layer spacing of PANI/HT provided the massive interlayer ion exchange capacity for U(VI). The batch results illustrated that no effect of ionic strength on U(VI) adsorption at pH > 5.0 was observed, moreover the U-N and U-Si shells were observed at pH 5.0 and 7.0 by the EXAFS analysis, respectively, indicating that inner-sphere surface complexation dominated U(VI) adsorption at pH > 5.0. The desorption results showed that release of U(VI) from PANI/HT was irreversible, which indicated that the PANI/HT presented the large layer spacing to fix uranyl into cage space of the adjacent octahedral. The adsorption behaviors of U(VI) on PANI/HT can be well fitted by double layer modeling with ion exchange and inner-sphere surface complexation. According to theoretical calculations, the binding energies of U(VI) with carbonate (15.49 kcal/mol) were significantly higher than that of U(VI) with hydroxyl (8.35 kcal/mol), indicating that U(VI) was easily combined with carbonate compared to hydroxyl groups at high pH. These observations revealed that PANI/HT can be used as an excellent adsorbent for retardation of uranium species into sub-environments.