From structural engineering to functional integration: A comprehensive review of 3D architectures for microplastics...

Microplastics (MPs) and nanoplastics (NPs) have emerged as persistent environmental pollutants that pose serious ecological and health concerns due to their high environmental mobility, physicochemical stability and strong affinity with co-existing organic and inorganic pollutants. Despite significant technological evolution in remediation technologies, conventional adsorptive systems remain constrained by poor selectivity, inefficient capture of nanoscale plastic contaminants, limited mass-transfer accessibility, and challenging post-separation recovery. In this context, three-dimensional (3D) porous architectures like foams, sponges, aerogel and hydrogel, have emerged as highly promising adsorptive platforms for MPs/NPs remediation. Their hierarchically interconnected pore networks, high specific surface area, tunable interfacial chemistry, and robust structural integrity collectively facilitate efficient adsorption and recovery performance. This review comprehensively summarizes recent advances in adsorbent materials, including carbonaceous materials, biomaterials, metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and functional nanoparticles, together with their rational integration into hierarchically engineered 3D porous architectures for enhanced MPs/NPs capture and separation. The fundamental mechanistic pathways governing MPs/NPs sequestration within 3D porous architectures are systematically elucidated, with emphasis on steric entrapment, pore-confined adsorption, hydrophobic interactions, electrostatic forces, hydrogen bonding, and π-π interactions that collectively regulate adsorption affinity and selective capture performance. In addition, diverse fabrication strategies, including freeze drying, gas foaming, pyrolysis-assisted carbonization, sol-gel processing, electrospinning, 3D printing, and hydrothermal synthesis, are systematically discussed for the development of structurally tunable 3D porous architectures. Particular emphasis is placed on recently developed 3D architectures derived from synthetic polymers, biopolymers, carbon-based materials, MOFs/COFs, and functional nanoparticles, highlighting their structural diversity, multifunctional integration, and emerging potential for efficient MPs/NPs remediation. Finally, current challenges and future perspectives associated with scalable fabrication, selective nanoscale plastic capture, adsorbent regeneration, and practical environmental applicability are briefly discussed.