Abstract
Geosmin, a metabolite of gram-positive bacteria actinomycetes and fungi, is a bicyclic alcohol detected by humans as earthy and mud taste at very low concentrations (from 5 to 50 ng/L, depending on the matrix) [1]. Therefore, for the aquaculture sector, the presence of this compound implies high production costs due to the low acceptance by the consumers.
Covalent organic frameworks (COFs) are porous crystalline materials with long-range order [2,3], which, due to their small pore size (1−5 nm), tuneable structure, and large surface area, have been demonstrated as efficient materials for the capture of different molecules from water, e.g., different types of pharmaceuticals [3,4]. In this work, different COFs with varying pore size and functional groups were tested for their capacity to adsorb geosmin. The conditions were optimized for the material to be able to adsorb concentrations of geosmin far above the detection limit of humans. In addition, geosmin desorption was studied and optimized to allow for the reuse of the COF adsorbent.
Among the tested materials, the COF with best efficiency could adsorb 78 mg of geosmin /g of COF, reaching equilibrium after an incubation of only 30 s. TpBD-Me2 was selected for further characterization. Additionally, geosmin could be removed from each COF by a simple incubation in organic solvent. At least five cycles of reuse were demonstrated without significant efficiency loss.
However, COFs are powders as synthesized and should not be used directly in water as their recovery would be extremely difficult and their release into the environment could lead to some ecotoxicity [5]. To overcome this, TpBD-Me2 was supported on alumina pellets, keeping high adsorption capacity for geosmin.
Acknowledgments
This work was developed under the project Blue Bioeconomy ERA-NET DIGIRAS (BLUEBIO/0002/2019) (2020-2023), as well as the project Charm (PTDC/QUI-OUT/2095/ 2021) funded by the FCT − Fundação para a Ciência e Tecnologia. L.R.-L. acknowledges funding to FCT (Fundação para a Ciência e Technologia) for the Scientific Employment Stimulus Program (2020.04021.CEECIND).
References
[1] V. Liato, M. Aïder, Chemosphere 2017, 181, 9.
[2] K. T. Tan, S. Ghosh, Z. Wang, F. Wen, D. Rodríguez-San-Miguel, J. Feng, N. Huang, W. Wang, F. Zamora, X. Feng, A. Thomas, D. Jiang, Nat. Rev. Methods Prim. 2023, 3, 1.
[3] S. P. S. Fernandes, V. Romero, B. Espiña, L. M. Salonen, Chem. – A Eur. J. 2019, 25, 6461.
[4] S. P. S. Fernandes, A. Mellah, P. Kovář, M. P. Sárria, M. Pšenička, H. Djamila, L. M. Salonen, B. Espiña, Molecules 2020, 25, 3132.
[5] M. P. Sárria, A. Vieira, Â. Lima, S. P. S. Fernandes, I. Lopes, A. Gonçalves, A. C. Gomes, L. M. Salonen, B. Espiña, Environ. Sci. Nano 2021, 8, 1680.
[6] A. Hafuka, T. Nagasato, H. Yamamura, Int. J. Environ. Res. Public Health 2019, 16, 1907.
[7] A. Asghar, Z. Khan, N. Maqbool, I. A. Qazi, M. A. Awan, J. Nanomater. 2015, 2015, 1.
[8] M. Antonopoulou, E. Evgenidou, D. Lambropoulou, I. Konstantinou, Water Res. 2014, 53, 215.