Thermoresponsive Amphoteric Metal-Organic Frameworks for Efficient and Reversible Adsorption of Multiple Salts from Water

Ranwen Ou; Huacheng Zhang; Jing Wei; Seungju Kim; Li Wan; Nhi Sa Nguyen; Yaoxin Hu; Xiwang Zhang; George P Simon; Huanting Wang

doi:10.1002/adma.201802767

Thermoresponsive Amphoteric Metal-Organic Frameworks for Efficient and Reversible Adsorption of Multiple Salts from Water

Adv Mater. 2018 Jul 10:e1802767. doi: 10.1002/adma.201802767. Online ahead of print.

Authors

Affiliations

¹ Department of Chemical Engineering, Monash University, Clayton, Victoria, 3800, Australia.
² Department of Materials Science and Engineering, Monash University, Clayton, Victoria, 3800, Australia.

PMID: 29989209
DOI: 10.1002/adma.201802767

Abstract

Regenerable, high-efficiency salt sorption materials are highly desirable for water treatment. Here, a thermoresponsive, amphoteric metal-organic framework (MOF) material is reported that can adsorb multiple salts from saline water at room temperature and effectively release the adsorbed salts into water at elevated temperature (e.g., 80 °C). The amphoteric MOF, integrated with both cation-binding carboxylic groups and anion-binding tertiary amine groups, is synthesized by introducing a polymer with tertiary amine groups into the cavities of a water-stable MOF such as MIL-121 with carboxylic groups inside its frameworks. The amphoterized MIL-121 exhibits excellent salt adsorption properties, showing stable adsorption-desorption cycling performances and high LiCl, NaCl, MgCl₂ , and CaCl₂ adsorption capacities of 0.56, 0.92, 0.25, and 0.39 mmol g^-1 , respectively. This work provides a novel, effective strategy for synthesizing new-generation, environmental-friendly, and responsive salt adsorption materials for efficient water desalination and purification.

Keywords: amphoteric; desalination; metal-organic frameworks; regenerable salt adsorbents; thermoresponsive.