Incorporation of biomass-derived carbon dots and hydrochar into electrospun polylactic acid membranes: A sustainable zero-waste approach to highly efficient methylene blue, malachite green and neutral red dye removal.

Recently, biomass-derived carbon dots (CDs) and hydrochar have gained widespread attention for environmental remediation. However, hydrochar is commonly regarded as carbon waste (CW) generated in the manufacture of CDs, and only a few reports have focused on the simultaneous application of CW and CDs. Herein, we propose a sustainable zero-waste approach for efficient dye removal by incorporating CDs and CW into electrospun membranes. CDs and CW were obtained via the one-step solvothermal carbonization of apple peels. The prepared CDs with an average size of 7.36 nm were first added to the electrospinning solution to obtain electrospun polylactic acid (PLA)/CDs fibers, followed by CW-integration via ultrasonication. The optimized PLA/CDs/CW composite exhibited high dye adsorption capacities of 141.99, 130.52, and 110.83 mg/g for neutral red, methylene blue, and malachite green, respectively. These dye adsorption capacities are significantly higher than those of the CD-loaded (70.15 mg/g for MB) or CW-loaded (52.34 mg/g for MB) composites, and are attributable to the rational loading of CDs and CW. Furthermore, the optimized composite exhibited remarkable chemical stability, stable reusability, and the ability to adsorb multiple dyes concurrently. This work provides new perspectives on the development of biomass-derived carbonaceous materials for environmental preservation and remediation.