Memory effect induced the enhancement of uranium (VI) immobilization on low-cost MgAl-double oxide: Mechanism insight and resources recovery

• Published in: Journal of hazardous materials 2021-01, Vol.401, p.123447, Article 123447
• Main Authors: Chen, Meiqing, Li, Shuaishuai, Li, Liping, Jiang, Lu, Ahmed, Zubair, Dang, Zhi, Wu, Pingxiao
• Format: Article
• Language: English
• Subjects: Immobilization mechanism; Memory effect; MgAl-double oxide; Removal; Uranium
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2020.123447

[Display omitted] •MgAl-LDO-500 could fast capture U(VI) (15 min) with superior ability (1098.90 mg g−1).•MgAl-LDO-500 had well adaptability for pH, coexistence ions and water matrices.•Memory effect was the key immobilization mechanism except for surface complexation.•MgAl-LDO-500 had promising potential to extract uranium from seawater. It remains challenging to develop high-performance technologies for uranium (U(VI)) removal/recovery from wastewater/seawater. In this study, MgAl-double oxide (MgAl-LDO-500) was fabricated by calcining MgAl-layered double hydroxide (MgAl-LDH) at 500 ℃ in air. It showed excellent performance in U(VI) removal with an equilibrium time of 15 min and the maximal adsorption capacity of 1098.90 mg g−1. MgAl-LDO-500 also showed good adaptability in a wide range of pH (from 3 to 10), coexisting ions and different water matrices for U(VI) immobilization. It was found that the anion form of U(VI) intercalated into the layer of MgAl-LDO-500 and caused recombination of layered structures. A series of characterizations (XRD, SEM, FTIR, XPS) proved that memory effect and surface complexation were the key mechanism for the enhancement of U(VI) immobilization on MgAl-LDO-500. Due to the remarkable memory effect, the performance of MgAl-LDO-500 for U(VI) immobilization was superior to MgAl-LDH and other high-cost materials. Besides, the fixed-bed column experiments illustrated that the removal rate achieved 99 % before 1500 BV at initial U(VI) concentration of 20 μg L−1, and the breakthrough volumes (BVs) were 4500 BVs. These results confirm that MgAl-LDO-500 is a promising material for extracting U(VI) from seawater and wastewater.