High-efficiency removal of methcathinone from water using a novel DES modified magnetic biochar nanocomposite

Deep eutectic solvent (DES), an environmentally friendly solvent, has drawn the growing interest of the academic community due to its distinctive physicochemical properties and widespread applications. In this work, magnetic biochar modified with DES (DES-MBC) has been fabricated and utilized to efficiently remove methcathinone from water. Batch experiments and density functional theory (DFT) simulations were utilized to explore the adsorption performance and mechanism of DES-MBC. Under optimal conditions, the removal rates of DES-MBC were highly remarkable with 93.26% and 95.85% in water containing methcathinone of 0.5 mg·L−1 and 1.0 mg·L−1, respectively. DFT simulations revealed that DES incorporation lowered the HOMO-LUMO energy gap (ΔEgap) and introduced additional reaction sites (e. g. hydroxyl groups and quaternary amino groups) which could react with methcathinone to increase the adsorption capacity of DES-MBC. Combining the results of experiments and simulations, the main removal mechanism between methcathinone and DES-MBC were electrostatic interaction, hydrogen bond and π-π interaction. In conclusion, DES modification was an effective strategy to enhance the adsorption capacity for methcathinone from water in practical applications. This study will contribute to the deep and extensive understanding of the microscopic adsorption mechanism so as to help optimize and develop more excellent adsorbents.