Design and Evaluation of a Biochar-Integrated Supramolecular Fibrous Framework for Efficient Microplastics Removal from Aqueous Environments

Abstract

Current wastewater treatment plants are unable to capture the microplastics (MPs), highlighting the need for sustainable, low-cost, and eco-friendly remediation methods. This study focuses on the design of supramolecular fibrous frameworks produced via the self-assembly of chitin (Ct) and cellulose (Cel) fibers, combined with municipal solid waste (MSW) derived biochar (BC), for MP removal. MSW-BC was prepared via the pyrolysis at 550 °C. Ct was dispersed in 5% acetic acid and combined with Cel and BC at a 10:1:1 ratio. All three components were combined and homogenized for 30 min. Following blending, the mixture was frozen at −19 °C for 24 h. The frozen mixture was oven-dried at 70 °C for 72 h. Fourier transform infrared (FTIR) spectroscopy confirmed successful integration of the three components, revealing characteristic O–H/N–H stretching (3300-3250 cm−1), C–H stretching (2890 cm−1), amide I and II bands (1650-1625 cm−1 and 1550 cm−1), and C–O–C/C–O stretching vibrations (1157 and 1010 cm−1), indicative of strong hydrogen bonding and intermolecular interactions between the biopolymer matrix and BC surface. MP removal performance was assessed on packed-bed column experiments using a 50 mL polyethylene (PE) MP solution (1 mg/L). Under optimum conditions (10 cm bed height, 2.5 mL/min flow rate), the quartz-only control removed 42.14% of MPs, while the quartz/Ct-Cel-BC column achieved 95.30% removal. Therefore, incorporating BC may have improved physical entrapment due to its porous structure and fibrous framework. Removal efficiency increased with greater bed height and lower flow rate, which may be due to longer residence times and greater contact time between MPs and the adsorbent surface. Overall, the integration of MSW-BC into a Ct-Cel supramolecular fibrous framework yielded a multifunctional, cost-effective adsorbent with excellent PE MP removal efficiency.