Innovative formaldehyde adsorption with optimized deep eutectic solvents: An experiment and multilevel computational chemistry approach.

Formaldehyde, a hazardous gas that is exposed to everyone every day, has been proven to pose an elevated risk of respiratory problems, allergies, and chronic diseases. Adsorption technologies have proven to be a straightforward and labor-saving method to reduce indoor formaldehyde levels. Currently, extensive research has been conducted utilizing Deep Eutectic Solvents (DES) as adsorbents for harmful gases, yet the adsorption and conversion mechanisms for formaldehyde remain unclear. In this study, we highlighted the adsorption and transformation mechanisms of formaldehyde with DES employing quantum chemical and molecular dynamics calculations. Initially, thermodynamic software (CosmoTherm) was employed to calculate the logarithmic activity coefficients (LAC) of formaldehyde and determine the solid-liquid equilibrium (SLE) for 416 combinations of DES. On the basis of the eutectic point and LAC of DES, potential formaldehyde adsorbents were screened. In the second step, the DES screened out has a good formaldehyde adsorption capacity through the experiment. Finally, the reactive sites, reaction pathways, van der Waals interactions, and hydrogen bonds of DES of L-cysteine/diethanolamine (CYS-DEA) and formaldehyde were studied through a theoretical approach. This study comprehensively elucidates the screening of formaldehyde adsorbents, experimental adsorption, and adsorption mechanisms. Significantly shortens the development cycle of DES as formaldehyde adsorbents.