Polymer Sorbents for Wastewater Treatment: Structure–Performance Relationships and Adsorption Mechanisms

ABSTRACT Industrial effluents containing heavy metals, synthetic dyes, per‐ and polyfluoroalkyl substances (PFAS), pharmaceuticals, and endocrine‐disrupting compounds remain a major challenge for wastewater treatment. Conventional adsorbents, including activated carbon and zeolites, often show limitations in selectivity, regeneration, or adsorption capacity for complex wastewater systems. Polymer sorbents offer an alternative because their chemical structure and surface functionality can be tailored for specific separation and adsorption applications. This review examines studies published between 2021 and 2025, with particular attention to the relationship between polymer structure and adsorption performance. The discussion considers the effects of crosslinking density, pore architecture, and functional‐group modification on adsorption behavior across different classes of polymer sorbents. Representative examples include molecularly imprinted polymers for selective recognition, poly(ionic liquid)‐based materials for PFAS removal, stimuli‐responsive hydrogels with swelling‐dependent transport properties, and magnetic polymer nanocomposites that combine adsorption with straightforward separation. The review also discusses regeneration efficiency, structural stability during repeated adsorption–desorption cycles, and the balance between mechanical strength and biodegradability. Although substantial progress has been reported at the laboratory scale, pilot‐scale investigations and studies involving multi‐component wastewater remain relatively limited. Recent work applying machine learning to polymer design is briefly considered as a promising direction for accelerating material development. By bringing these aspects together, this review provides an updated overview of current polymer sorbent technologies and identifies priorities for future research and practical wastewater treatment applications, with the aim of supporting informed material‐selection decisions by treatment‐plant operators, regulators, and technology managers.