Activation and adsorption mechanisms of methylene blue removal by porous biochar adsorbent derived from eggshell membrane

Eggshell membrane as carbon source prepared porous biochar adsorbent. The affinity of adsorbents to methylene blue (MB) been researched in the adsorption equilibrium experiment. The effects of pH value, adsorbent dosage, temperature and adsorption time on the adsorption activity of porous biochar were discussed. It is shown that the porous biochar has a good affinity with MB at pH=9, and the adsorption capacity reaches 110.38 mg·g -1 . The adsorption isotherm model is consistent with the Langmuir adsorption model, and its dynamic behavior follows the second-order kinetic process. Furthermore, there are physical and chemical adsorptions such as hydrogen bonding, electrostatic attraction and ligand exchange during the adsorption process on porous biochar. Therefore, ESM can be used as a biomass carbon material to remove organic dyes from wastewater. The preparation process of eggshell membrane adsorbent • Eggshell membrane-derived porous biochar adsorbent was prepared by slow pyrolysis and subsequent acid treatment. • The carbonization temperature of the biochar was 300°C, different from the previous ultra-high temperature. • The relevant kinetic and isothermal models have been established. • Adsorption mechanisms have been described.