Amine-Functionalized Metal-Organic Frameworks and Covalent Organic Polymers as Potential Sorbents for Removal of Formaldehyde in Aqueous Phase: Experimental Versus Theoretical Study

Porous materials have been identified as efficient sorbent media to remove volatile organic compounds. To evaluate their potential as adsorbents, the adsorptive removal of formaldehyde (FA) in aqueous environments was investigated using four materials, two water-stable metal–organic frameworks (MOFs) of UiO-66 (U6) and U6-NH2 (U6N) and two covalent organic polymers (COPs) with amine-functionality, CBAP-1-EDA (CE) and CBAP-1-DETA (CD). U6N exhibited the highest removal capacity of 93% (0.56 mg g–1) of the tested materials [e.g., CE (81.1%, 0.53 mg g–1) > CD (67.2%, 0.43 mg g–1) > U6 (66.9%, 0.42 mg g–1)], which was 2 times higher than that of the reference sorbent, activated carbon (AC: 50%, 0.30 mg g–1). The results of Fourier transform infrared and powder X-ray diffraction analyses confirmed the interactions between FA molecules and the amine components of the materials (U6N, CD, and CE). According to density functional theory calculations, the formation of hydrogen bonds between FA molecules and amine c...