Robust phosphate capture over inorganic adsorbents derived from lanthanum metal organic frameworks

- A superior phosphate scavenger was designed deriving from La-MOF.
- The adsorbent has a hierarchical structure of microsphere-nanorod-nanoparticle.
- A high adsorption capacity and a high P/La ratio were obtained concurrently.
- The adsorbent exhibits a much higher adsorption capacity of over 170 mg P/g.

Excessive phosphate in water can cause severe water quality problems owing to its somatotrophic effect on microorganisms. Herein, a superstructural phosphate scavenger, La-MOF-500, composed of La2O2CO3, is rationally designed by derivation from lanthanum metal organic frameworks (La(1,3,5-BTC)(H2O)6) by calcination. La-MOF-500 has a hierarchical micro/nano structure of microsphere-nanorod-nanoparticle: urchin-like microsphere is comprised of many nanorods and the individual nanorod was formed by piling up plentiful thin nanoparticles. The hierarchical micro/nano structure provides La-MOF-500 with an intriguing phosphate capture capacity of 173.8 mg P/g and a high utilization of lanthanum active sites, simultaneously, which was a challenge in previous research. Moreover, La-MOF-500 exhibits a good tolerance of foreign species. Even in the water from Songhua River (China), La-MOF-500 can remove phosphate to be less than 10 μg P/L. This development is expected to be meaningful for practical water purification.

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