Atomic-layered Mn clusters deposited on palygorskite as powerful adsorbent for recovering valuable REEs from wastewater with superior regeneration stability

The control of dispersity and size of metal particles deposited on substrate surface are always the major challenges for fabricating the efficient and stable metallic nanoparticles-decorated composite. Herein, we proposed a simple liquid-phase atomic layer deposition (L-ALD) method to obtain an atomic-layered MnO2 nanoparticles loaded palygorskite nanorod (MnO2@Pal), involving two-step procedures comprised of the solid-liquid interfacial reaction between organic manganese precursor and surface hydroxyl groups of palygorskite, and then a calcination treatment to activate surface Mn, which is used as a powerful adsorbent for recovery of REE ions from wastewater. The results show that MnO2@Pal has a desirable adsorption capacity of 66.80, 45.17 and 48.78 mg/g for different REEs of Ce3+, Eu3+ and Dy3+ respectively, rapid adsorption rate (achieve above 85% capacity within 20 min) and low residual concentration (below 1.0 ppm). Full kinetic and isotherm analysis as well as thermodynamic study were also undertaken. Exciting, the MnO2@Pal exhibited an outstanding regeneration stability that almost no loss on adsorption capacity after 7 consecutive cycles accompanied by near 100% desorption ratio, overcoming the consistent deficiency for such kind composite adsorbent. These results provide a promising surface modification method for fabricating stable metal-modified composite.

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