A novel ionic-liquid-mediated covalent organic framework as a strong electrophile for high-performance iodine removal

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-05, Vol.488, p.150913, Article 150913
• Main Authors: Fu, Jie, Liu, Jia-Ying, Zhou, Yue-Ru, Zhang, Lei, Wang, Shuang-Long, Qin, Song, Fan, Maohong, Tao, Guo-Hong, He, Ling
• Format: Article
• Language: English
• Subjects: Covalent organic frameworks; Electrophiles; Gas adsorption; Ionic liquids
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2024.150913

[Display omitted] •Ionic liquid Solution Process (ILSP) was employed to prepare ionic covalent organic frameworks.•Strong electrophilic ionic liquid cations have the ability to regulate the iodine adsorption activity of sulfonic sites in COF.•The adsorption kinetics k80% of optimal COF-Bmim absorbent is 2.69 g·g−1·h−1, an increase of 400 %.•DFT studies reveal a positive correlation between the local polarity of adsorption sites and adsorption performance. The research on the adsorption and conversion of non-polar gases (carbon dioxide, hydrogen, iodine, etc.) has attracted global attention. Extensive work has revealed the intuitive impact of the heteroatom effect on the adsorption performance of covalent organic framework (COF) adsorbents for non-polar gases. However, more influencing factors must be studied to more precisely design and construct target-specific COF adsorbents. In this work, an underlying influencing factor, local polarity, is discovered, which is defined as the polarity of the functional moiety. Due to the substitution of strong electrophile, the electron cloud distribution of the COF framework is regulated, and the local polarity that better matches the adsorption of target electrophilic gas (iodine) has been observed. The local polarity of COF has been controlled through several strong electrophilic ionic liquids, dramatically improving adsorption performance. The saturated adsorption capacity increases from 1.5 to 5.2 g·g−1, and the adsorption kinetics index k80% value increases from 0.51 to 2.69 g·g−1·h−1. The insight would support precise chemical regulation of target-specific COF in energy and environment science.