Abstract

Micro(nano)plastics, MPs/NPs, serve as a pathway for the transport of arsenicals in waters and soils; even their occurrence in the atmosphere could present significant environmental implications due to the persistence and mobility of both pollutants, but their atmospheric-phase interactions remain unexplored. In this work, we use density functional theory (DFT) calculations to study the interaction between atmospheric arsenicals [arsine (AsH3), arsenic trioxide (As2O3), and dimethylarsinic acid (DMA)] with NPs: polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polyamide (PA), polyvinyl chloride (PVC), and polystyrene (PS). The adsorption process is exothermic and occurs via physisorption, where NPs retain their surface polarity for subsequent co-uptake. The adsorption Gibbs free energies ranged from 7.5 to -11.2 kcal/mol, depending on arsenic polarity and NP composition (negative values stand for spontaneous adsorption); the adsorption process is dominantly enthalpy-controlled for As2O3 and DMA, whereas entropy-limited for AsH3. DMA showed the highest binding affinity and the highest adsorption rate on polar NPs (PA, PET, PVC). Thermodynamic profiles indicate enhanced adsorption at lower atmospheric temperatures when exothermicity outweighs entropic penalties. Energy decomposition analyses reveal a dual stabilization mechanism involving non-directional, dispersiondriven entrapment and directional electrostatic interactions modulated by steric effects. Complementary ATRFTIR and SEM/EDS analyses provide qualitative experimental support for the physisorption-driven adsorption mechanism predicted by the computational results. This work highlights the role of NPs as potential vectors for long-range atmospheric transport of pollutants.