Experimental Evaluation of Microplastic Removal Mechanisms in Aquatic, Soil, and Air-Relevant Systems

Microplastics (MPs) are widely detected in aquatic, terrestrial, and atmospheric environments, raising increasing concerns regarding ecosystem impacts and potential human exposure. Although numerous studies have examined microplastic occurrence, comparatively fewer investigations have experimentally evaluated remediation strategies across multiple environmental matrices. In this laboratory-based study, the effectiveness of selected physicochemical and nature-based treatment approaches for microplastic removal was investigated in representative water, soil, and air-relevant systems. Polyethylene (PE), polypropylene (PP), and polystyrene (PS) particles (50–500 µm) were introduced into controlled experimental systems simulating freshwater microcosms, agricultural soil matrices, and airborne particle chambers. Removal efficiencies and physicochemical changes were analysed using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), particle size analysis, and mass-balance measurements. Results indicated that removal efficiency depends strongly on both polymer type and environmental matrix. In aquatic systems, combined adsorption–oxidation treatments (biochar + UV/H₂O₂) achieved the highest removal efficiencies (85 ± 4%). Soil systems were dominated by stabilisation and extraction processes, where biochar amendment reduced microplastic mobility (68 ± 6%) and soil washing physically extracted particles (76 ± 5%). In the air-flow chamber experiments, electrostatic capture demonstrated higher removal efficiency (82 ± 3%) than HEPA filtration (69 ± 4%). These findings illustrate how physicochemical interactions, radical-mediated oxidation, and physical capture mechanisms influence microplastic removal across environmental systems. The results provide experimental insight into system-specific mitigation strategies and highlight the potential value of combining oxidative and sorptive processes for improved microplastic control.