Effective strategies toward imine-linked cationic covalent organic frameworks for rapid and selective removal of 99TcO4− from water: insights from DFT and MD calculations. Issue 2 (10th January 2023)

• Record Type: Journal Article
• Authors: Zhao, Chaofeng; Ma, Xinjie; Wei, Xin; Liu, Weiwei; Sun, Lu; Ai, Yuejie
• Is Part Of: Environmental science. Volume 10:Issue 2(2023)
• Page Start: 611
• Page End: 624
• Publication Date: 2023-01-10
• Subjects: Environmental sciences -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/d2en01049f
• Languages: English
• ISSNs: 2051-8153

Abstract

Abstract : The dynamic behavior and anion exchange mechanism of 99 TcO4 − on imine-linked cationic COFs are elucidated to provide theoretical basis for developing novel cationic COFs materials for environmental remediation. Abstract : Effective removal of radioactive 99 TcO4 − 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 99 TcO4 − . 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 99 TcO4 − 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 99 TcO4 − 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 99 TcO4 − . 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 99 TcO4 − . The adverse effect of small pore size can be observed for PITFP, though more adsorption sites are an advantage. The increasing concentration of 99 TcO4 − will significantly accelerate the adsorption, however, full elimination of 99 TcO4 − is not observed owing to the hard desorption of inner-layer counter-anions. Our study provides an insightful understanding for the adsorption process of 99 TcO4 − at the molecular level and will facilitate the development of cationic COFs with outstanding performance for 99 TcO4 − elimination.