Dual-target, high-capacity removal of microplastics and dyes from water using a recyclable sponge monolith

Abstract

Microplastics, in combination with ubiquitous dye pollutants, pose a complex environmental challenge through synergistic interactions that enhance contaminant mobility and amplify ecological risks. To address this, we fabricate a monolithic, recyclable chitin/activated carbon sponge (CT/AC) via a scalable, crosslinker-free cryo-assembly method. This integrated sponge enables dual-target removal of microplastics and multiple dyes, overcoming the limitations of powdered adsorbents and flocculation processes by allowing direct retrieval without secondary release. The sponge exhibits exceptional co-removal performance, achieving record-high adsorption capacities of 1177.17 mg g⁻¹ for 5 µm polystyrene (PS) microplastics, and 1038.86, 911.23, and 734.47 mg g⁻¹ for rhodamine B, malachite green, and Congo red, respectively, even under challenging conditions (e.g., high ionic strength, particulate interference, and humic acid). Life cycle assessment (LCA) confirms a low carbon footprint, attributable to renewable feedstocks and energy-efficient fabrication. Furthermore, the spent sponge is sustainably upcycled into graphene via flash Joule heating (FJH), enabling a closed-loop solution for advanced wastewater decontamination.