(2019) Environmental Research_Adsorption properties of advanced functional materials against gaseous formaldehyde

Vikrant K., Cho M., Khan A., Kim K.-H., Ahn W.-S., Kwon E.E.

(Academic Press Inc.) Environmental Research ISSN: 139351 Vol.178 Issue. Article No.108672 DOI: 10.1016/j.envres.2019.108672

Intense efforts have been made to eliminate toxic volatile organic compounds (VOCs) in indoor environments, especially formaldehyde (FA). In this study, the removal performances of gaseous FA using two metal-organic frameworks, MOF-5 and UiO-66-NH₂, and two covalent-organic polymers, CBAP-1 (EDA) and CBAP-1 (DETA), along with activated carbon as a conventional reference material, were evaluated. To assess the removal capacity of FA under near-ambient conditions, a series of adsorption experiments were conducted at its concentrations/partial pressures of both low (0.1–0.5 ppm/0.01–0.05 Pa) and high ranges (5–25 ppm/0.5–2.5 Pa). Among all tested materials at the high-pressure region ㅐ (e.g., at 2.5 ppm FA), a maximum adsorption capacity of 69.7 mg g−1 was recorded by UiO-66-NH2. Moreover, UiO-66-NH2 also displayed the best 10% breakthrough volume (BTV10) of 534 L g⁻¹ (0.5 ppm FA) to 2963 L g−1 (0.1 ppm FA). In contrast, at the high concentration test (at 5, 10, and 25 ppm FA), the maximum BTV10 values were observed as: 137 (UiO-66-NH2), 144 (CBAP-1 (DETA)), and 36.8 L g−1 (CBAP-1 (EDA)), respectively. The Langmuir isotherm model was observed to be a better fit of the adsorption data than the Freundlich model under most of the tested conditions. The superiority of UiO-66-NH2 was attributed to the van der Waals interactions between the linkers (framework) and the hydrocarbon “tail” (FA) coupled with interactions between its open metal sites and the FA carbonyl groups. This study demonstrated the good potential of these advanced functional materials toward the practical removal of gaseous FA in indoor environments. © 2019 Elsevier Inc.

The authors acknowledge the support made by the R&D Center for Green Patrol Technologies through the R&D for Global Top Environmental Technologies funded by the Ministry of Environment (MOE 2018001850001 ) as well as a grant from the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (Grant No: 2016R1E1A1A01940995 ). KHK also acknowledges support from the Korea Ministry of Environment ( 2015001950001 ) as part of “The Chemical Accident Prevention Technology Development Project” and the support of “ Cooperative Research Program for Agriculture Science and Technology Development (Grant No: PJ012521032018 )” Rural Development Administration , Republic of Korea.