A mechanism study of methylene blue adsorption on seaweed biomass derived carbon: From macroscopic to microscopic scale

Biomass based active adsorbent can be prepared by activation process to adsorb dyes. In this study, using macroalgae as raw material, the biomass based activated carbon material was prepared by NaOH activation method to adsorb methylene blue. The activated adsorbent with high specific surface area (1238.491 m2 g−1) was characterized by BET, XRD, FTIR and XPS. The effects of impregnation ratio, amount of adsorbent, pH and contact time on the adsorption activity of biochar on MB were evaluated. The adsorption kinetics, molecular dynamics and density functional theory were discussed. The maximum MB removal efficiency of SWAC reached 98.56 % at 30 °C and pH = 5 which is due to its large specific surface area and mesoporous slit structure. MD simulation shows that MB molecules were adsorbed on carbon layer through face-to-face stacking. DFT calculation and subsequent electron structure analysis suggested that a synergistic effect of π-π stacking, cation-π interaction, and electrostatic interaction could help stabilize adsorbed MB molecules. And an excellent adsorption capacity SWAC is due to its graphitic N sites for high electronegativity.