Microplastics Removal by Sustainable PVA/Bentonite Membranes: Morphological and Structural Evidence of the Retention...

The increasing presence of microplastics (MPs) in aqueous matrices has driven the search for efficient and sustainable technologies for their removal. In this context, this work investigates the development of green polymeric membranes based on poly-(vinyl alcohol) (PVA) reinforced with bentonite clay nanoparticles (ArNPben), aiming to establish relationships between structure, properties, and performance in microplastic filtration. The membranes were produced by the solvent evaporation phase inversion method, employing PVA at different concentrations (6-10% w/v), citric acid as a cross-linking agent, and glycerol as a plasticizer, with the incorporation of bentonite (1-5% w/w). Characterization was performed using morphological, spectroscopic, and thermal techniques (SEM, FTIR, TGA, and DSC), associated with the evaluation of transport behavior and retention efficiency. The results demonstrated that the controlled incorporation of bentonite promotes structural reorganization of the polymer matrix, directly affecting hydraulic permeability, stability, and interaction with particles. A critical dispersion limit of the inorganic phase was observed, where low concentrations favor the formation of homogeneous and functionally efficient structures, while higher concentrations induce structural heterogeneity and increased resistance to transport. The formulation containing 6% (w/v) PVA and 1% (w/w) bentonite showed the best overall performance, combining structural stability and permeation capacity, achieving an average PM removal efficiency of 99.78 ± 0.13% in tests conducted under controlled pressure. Evidence obtained by FTIR and TGA confirmed the retention of polymeric material on the surface of the membranes after use. The results highlight the potential of the developed hybrid membranes as a sustainable and technically viable alternative for application in water treatment systems contaminated by microplastics, contributing to the advancement of technologies based on materials with low environmental impact.