The Fate of Microplastics in Bursting Bubbles: Interfacial Hydrodynamics and the Aerosolization Potential of a Bio-inspired Foam System

Abstract The transport of marine microplastics across the air-sea interface represents a critical uncertainty in global pollution cycling. Herein, a high-precision T-junction microfluidic platform was employed to reconstruct the lifecycle of bio-inspired microbubbles, either pristine or laden with microplastics, to systematically investigate their evolution and collapse dynamics under varying gas-to-liquid and solid-to-liquid ratios. Characterization of microbubble rafts devoid of microplastics revealed two distinct bursting modes: rapid shrinking (RS) and collective bubble collapse (CBC). Moreover, experimental results from microbubble rafts laden with microplastics demonstrate that the solid-to-liquid ratio acts as a key parameter, driving the transition from fluid-dominated drainage to granular-dominated jamming. At high solid-to-liquid ratios such as γ = 0.01, microplastics irreversibly accumulate at the gas-liquid interface driven by lateral capillary forces, forming a rigid armored shell that exhibits Pickering stabilization and retards film drainage. Crucially, contrary to the prevailing assumption of unhindered ejection, our results demonstrate a distinct suppression of microplastic release during the bursting of armored microbubbles. This retention is mechanically attributed to the dissipation of bursting energy by the jammed particle network and the lack of a sufficient bulk liquid reservoir to sustain the inertial Worthington jet required for heavy particle ejection. At low solid-to-liquid ratios such as γ = 2×10 − 3 , the experimental results indicate an effective decoupling between microbubble and microplastics. These findings suggest that the ocean surface microlayer may act as a selective retention zone rather than a continuous emitter under specific hydrodynamic conditions.