Functionalized Nanofibers for Removing Emerging Contaminants from Air and Water: Mechanisms, Strategies, and Challenges

Abstract

The growing occurrence of emerging contaminants (ECs) in air and water, including nanoplastics, per- and polyfluoroalkyl substances (PFAS), volatile organic compounds (VOCs), pathogenic microorganisms, and inorganic nanoparticles, has intensified the need for advanced and selective filtration technologies. In this context, polymer nanofiber-based membranes have emerged as promising platforms for the removal of ECs due to their high specific surface area, interconnected porosity, tunable morphology, and versatility for surface functionalization. However, efficient removal cannot be achieved solely through size-exclusion mechanisms, requiring a deeper understanding of the physicochemical interactions governing particle and solute capture. This review provides a comprehensive analysis of the fundamental mechanisms involved in air and water filtration using polymer nanofiber-based membranes, emphasizing the transition from geometry-dominated to interaction-driven collection processes as contaminant size decreases. Surface functionalization is highlighted as a key strategy for improving filtering selectivity and enhancing the removal efficiency of emerging pollutants. Strategies based on charged functional groups, hydrophobic domains, bioinspired coatings, catalytic interfaces, and high-affinity adsorbents, including metal–organic frameworks (MOFs), are discussed in relation to their dominant interaction mechanisms and contaminant-specific performance. By integrating filtration fundamentals, functionalization strategies, and application-specific requirements, this review proposes a unified framework linking contaminant characteristics, dominant removal mechanisms, and nanofiber design principles. Critical challenges associated with fouling, regeneration, long-term stability, scalability, sustainability, and additive leaching are also assessed. Ultimately, rational surface functionalization represents a key pathway toward the development of nanofiber-based filtration systems with enhanced selectivity removal efficiency and applicability to emerging contaminants.