Lignin-Derived Magnetic Activated Carbons for Effective Methylene Blue Removal

Large-scale environmental remediation of polluted water requires an effective and recyclable adsorbent produced from an abundant, low-cost, and renewable feedstock via a simple processing procedure. In this work, we demonstrate that lignin-derived magnetic activated carbons (mACs) uniquely satisfy these five criteria for (i) high-performance adsorption, (ii) high regeneration efficiency, (iii) feedstock economic and environmental viability, (iv) single-step processing, and (v) large-scale production. The mACs are synthesized via an efficient cocarbonization and activation with simultaneous impregnation of ferric sulfate. The Langmuir model closely fits the adsorption of methylene blue (MB) by mACs within the temperature range of 298–323 K, where the adsorption capacity increases as temperature increases. This capacity increased from 55.0 mg g–1 to 220.2 mg g–1 with the presence of magnetic nanoparticles. In addition, the magnetite nanoparticles on the activated carbon surface significantly improve its recycling ability with a removal percentage above 95% after four cycles for 5:1 mAC.