Biomass activated carbon derived from golden needle mushroom root for the methylene blue and methyl orange adsorption from wastewater

Removing textile dye by activated carbon adsorption from wastewater has become a focus issue owing to its easy operation, rapid adsorption ability, and relatively high removal efficiency. Biomass-based activated carbon is an excellent candidate due to its renewability and easy accessibility, but the biomass resources like peel and stem are usually with relatively long growth cycle and the removal efficiency within a wide pH range is relatively low. Thus, a biomass carbon source with a short growth cycle and activated carbon with high removal efficiency within a wide pH value needs to be explored. In this study, golden needle mushroom root-based activated carbon (GNMACs) activated by H₃PO₄ was successfully prepared, characterized, and applied in methylene blue (MB) and methyl orange (MO) removal. The carbonization temperature (400 °C ∼ 600 °C), the GNMACs dosage (5 mg ∼ 25 mg), and the dye solution pH (4 ∼ 12) were controlled. The results indicated the optimal adsorption performance can be achieved with the carbonization temperature of 550 °C and the adsorbent dosage of 20 mg. The GNMACs carbonized at 550 ℃ possessed a porous structure with the mesopore volume of 1.095 cm³/g, the specific surface area of 802.987 m²/g, and the average pore diameter of 5.87 nm. Within a wide pH range from 4 to 12, GNMACs removed MB with an efficiency above 98.57 % and MO with an efficiency above 98.77 %. Additionally, the adsorption process of MB and MO onto GNMACs followed the pseudo-second-order kinetic model and the Redlich-Peterson isothermal adsorption model, with adsorption capacities of 816.04 mg/g and 286.99 mg/g, respectively. The adsorption was facilitated by hydrogen bonding, electrostatic attraction, π-π interaction, and pore filling. The results indicated the GNMACs can be used as an adsorbent to remove MB and MO from the wastewater.