Issue 2, 2023

Effective strategies toward imine-linked cationic covalent organic frameworks for rapid and selective removal of 99TcO4 from water: insights from DFT and MD calculations

Abstract

Effective removal of radioactive 99TcO4 is crucial for both the management of spent nuclear fuel and nuclear-related environmental remediation. Recently, cationic covalent organic frameworks (cationic COFs) have received extensive attention as efficient anion-scavenging materials for capturing radioactive 99TcO4. Herein, three kinds of imine-linked cationic COFs (named as DBBT, DBTFP and PITFP) with eclipsed (AA) and staggered (AB) structures were built and modeled to eliminate 99TcO4 from radioactive wastewater. The adsorption performance and interaction mechanism were systematically investigated by density functional theory (DFT) calculations and molecular dynamics (MD) simulations. The anion-exchange process is driven by the electrostatic interaction between 99TcO4 and positively charged groups of cationic COFs. The adsorption ability of DBBT is better than that of DBTFP and PITFP with a higher elimination ratio of 99TcO4. The straight channels of DBBT-AA make both the adsorption dynamics and selectivity better than DBBT-AB. The carbonyl group in DBTFP has a slightly negative influence on the adsorption of 99TcO4. The adverse effect of small pore size can be observed for PITFP, though more adsorption sites are an advantage. The increasing concentration of 99TcO4 will significantly accelerate the adsorption, however, full elimination of 99TcO4 is not observed owing to the hard desorption of inner-layer counter-anions. Our study provides an insightful understanding for the adsorption process of 99TcO4 at the molecular level and will facilitate the development of cationic COFs with outstanding performance for 99TcO4 elimination.

Graphical abstract: Effective strategies toward imine-linked cationic covalent organic frameworks for rapid and selective removal of 99TcO4− from water: insights from DFT and MD calculations

Supplementary files

Article information

Article type
Paper
Submitted
21 Nov. 2022
Accepted
25 Dec. 2022
First published
26 Dec. 2022

Environ. Sci.: Nano, 2023,10, 611-624

Effective strategies toward imine-linked cationic covalent organic frameworks for rapid and selective removal of 99TcO4 from water: insights from DFT and MD calculations

C. Zhao, X. Ma, X. Wei, W. Liu, L. Sun and Y. Ai, Environ. Sci.: Nano, 2023, 10, 611 DOI: 10.1039/D2EN01049F

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