Hydrothermal conversion of bamboo shoot shell to biochar: Preliminary studies of adsorption equilibrium and kinetics for rhodamine B removal

Abstract Hydrothermal carbonization is an efficient way in transforming biomass into hydrochar while most studies have been dedicated to bio-oil production with rare studies focusing on the use of hydrochar. Here, biochar was derived from hydrochar pyrolysis at various temperatures using agricultural waste of bamboo shoot shells as the raw materials, and the microstructure of biochar varied with temperature, and the removal performance for rhodamine B (RhB) at 0, 25, and 40 °C were studied in detail. The results indicated that BHC-800 obtained at pyrolysis temperature of 800 °C showed well-developed pores with surface area of 513 m2/g. Significantly, the maximum adsorption capacity of RhB on BHC-800 at 25 °C is up to 85.8 mg/g with isotherms fitted well to Freundlich model. Adsorption kinetics indicated that the adsorption equilibrium time for RhB on BHC-800 was of about 20 min with the data fitted better to the pseudo-second-order kinetics. This work indicated that biochar from the hydrochar pyrolysis holds promise as adsorbents to efficiently remove RhB dyes from water.