Issue 34, 2023

Design of a robust and strong-acid MOF platform for selective ammonium recovery and proton conductivity

Abstract

Metal–organic frameworks (MOFs) are potential candidates for the platform of the solid acid; however, no MOF has been reported that has both aqueous ammonium stability and a strong acid site. This manuscript reports a highly stable MOF with a cation exchange site synthesized by the reaction between zirconium and mellitic acid under a high concentration of ammonium cations (NH4+). Single-crystal XRD analysis of the MOF revealed the presence of four free carboxyl groups of the mellitic acid ligand, and the high first association constant (pKa1) of one of the carboxyl groups acts as a monovalent ion-exchanging site. NH4+ in the MOF can be reversibly exchanged with proton (H+), sodium (Na+), and potassium (K+) cations in an aqueous solution. Moreover, the uniform nanospace of the MOF provides the acid site for selective NH4+ recovery from the aqueous mixture of NH4+ and Na+, which could solve the global nitrogen cycle problem. The solid acid nature of the MOF also results in the proton conductivity reaching 1.34 × 10−3 S cm−1 at 55 °C by ion exchange from NH4+ to H+.

Graphical abstract: Design of a robust and strong-acid MOF platform for selective ammonium recovery and proton conductivity

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Article information

Article type
Edge Article
Submitted
30 May 2023
Accepted
31 Jul 2023
First published
01 Aug 2023
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2023,14, 9068-9073

Design of a robust and strong-acid MOF platform for selective ammonium recovery and proton conductivity

G. Hatakeyama, H. Zhou, T. Kikuchi, M. Nishio, K. Oka, M. Sadakiyo, Y. Nishiyama and T. Yamada, Chem. Sci., 2023, 14, 9068 DOI: 10.1039/D3SC02743K

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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