Layer cellulose-based sandwich sponge with directionally aligned channels for rapid removal of polystyrene nanoplastics and TBBPA

Nanoplastics can adsorb organic pollutants and facilitate their transport in water environments, thereby increasing potential risks to ecosystems and human health. However, most porous adsorbents have an even structure, making it difficult to combine rapid pollutant capture with stable retention. Herein, a layer cellulose-based sandwich (PCP) sponge with directionally aligned channels was fabricated through directional freezing and chemical cross-linking of cellulose fibers with chitosan and polyvinyl alcohol. The aligned porous channels promote solution transport, while chitosan provides positively charged sites favorable for capturing polystyrene (PS) nanoplastics. The layered architecture integrates macropore-mediated transport, interfacial adsorption, and physical interception within a single material. PCP sponge removed up to 99.88% of 100 nm PS nanoplastics within 10 min at room temperature. In coexistence experiments, an apparent tetrabromobisphenol A (TBBPA) removal efficiency of more than 80% was also observed. After 10 adsorption-desorption cycles, the removal efficiency of PS still remains above 94.85%, and the pore structure remains intact under acidic, saline, and repeated cycling conditions. This study proposes a sustainable strategy for raw materials, which convert biomass resources into high-performance multifunctional adsorbents, providing a promising solution for the simultaneous removal of nanoplastics and coexisting organic pollutants from complex water environments.