Dual-functional ionic liquid-modified PBAT-based biodegradable spherical adsorbent for high-efficiency treatment of dye wastewater

This study successfully prepared a porous spherical PBAT-g-IL/MMT composite adsorbent (PIMMT) for treating toxic, refractory dye wastewater through a one-step melt blending process combined with non-solvent-induced phase separation. Ionic liquids perform a dual function in this process. ILs enhance PBAT hydrophilicity through radical grafting and form intercalation structures with MMT via ion exchange, providing rapid transport pathways for pollutant molecules. This research aims to develop a biodegradable adsorbent material that combines highly efficient adsorption performance, good hydrophilicity and structural tunability. The effects of initial dye concentration, pH, temperature, contact time, and adsorbent dosage were systematically investigated. Under optimal conditions, the best sample PIMMT8 demonstrated high removal efficiency for cationic dyes methylene blue (MeB) and auramine O (AO), achieving maximum adsorption capacities (Q max ) of 145.85 mg g −1 and 191.07 mg g −1 respectively. Adsorption kinetics conformed to the pseudo-second-order model (R 2  > 0.99), while isotherm data better aligned with the Freundlich model (R 2  > 0.99), indicating multi-layer adsorption. The adsorbent demonstrated excellent reusability, maintaining removal efficiencies above 85 % for both MeB and AO after six adsorption-desorption cycles. Furthermore, the study innovatively employed a combined alcohol-alkali hydrolysis process to achieve resource recovery of the adsorbent, successfully recovering monomers such as terephthalic acid and adipic acid. This research not only fills a gap in the study of PBAT/MMT composites for dye adsorption but also provides novel insights for designing wastewater treatment materials that combine high adsorption efficiency, environmental friendliness, and resource recycling properties.