Sorption Characteristics of Methylene Blue on Medulla Tetrapanacis Biochar and its Activation Technology

As a simple and low-cost sorbent, biochar can effectively remove inorganic and organic pollutants, but the sorption performance of biochar from different biomass sources on pollutants varies greatly. Finding a biochar material with higher sorption capability and activating methods of biochar to further improve the sorption performance should be very important and basic for the promotion of biochar. In this paper, the plant-based biochar (PBC) produced by Medulla tetrapanacis and activated PBCs treated with HCl, NaOH, and KCl were used as sorbents to remove methylene blue (MB). The PBCs were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS), and BET-N2. The effects of the PBC, HCl-PBC, NaOH-PBC, and KCl-PBC on the removal of MB under different contact times, concentrations, pH, and temperature were tested, respectively. Compared with reported biochar samples, the sorption capacity of PBC on MB is the largest, and the method of activated PBC using KCl works best. The maximum sorption capacity of KCl-PBC is increased by 98.71%, reaching 228.62 mg/g, and is much larger than that of PBC (114.87 mg/g). The activation mechanism of the biochar is dredging the pores and dissolving impurities. The PBC and activated PBCs derived from Medulla tetrapanacis are promising and effective sorbent materials for environmental protection.