Highly efficient and reusable Mg–Fe layered double hydroxides anchored in attapulgite for uranium uptake from wastewater

Micro/nano interface adsorption is an effective strategy for separating uranium from aqueous solutions. However, their undesirable capture efficiency and poor cycling stability limit their practical application. In this study, we developed a clay-based micro-adsorbent constructed using attapulgite (ATP) and Mg-Fe layered double hydroxides (Mg-Fe LDHs) for uranium uptake from wastewater. The surface charge affinity between ATP and Mg-Fe LDHs contributed to the robust heterostructure of the ATP@Mg-Fe LDHs adsorbent, thereby enabling a uniform distribution of Mg-Fe LDHs on the ATP surface. Thus, the aggregation behavior of Mg-Fe LDHs was significantly reduced and stellated with an improved dispersion performance of this ATP@Mg-Fe LDHs micro-composite in an aqueous solution. The uranium adsorption capacity was 670.21 mg/g, which is the maximum among previously reported clay-based adsorbents. Notably, a satisfying performance was achieved for the adsorbent stability; the uranium adsorption efficiency remained as high as 97% after eight cycles of adsorption-desorption. The ATP@Mg-Fe LDHs adsorbent for separating UO22+ from water is a promising system that combines efficiency, capacity, selectivity, and reusability, and has potential for scaled-up applications.