Characteristics and adsorption of methylene blue on activated carbon derived from enzyme-pretreated Camellia oleifera shells

Activated carbon is a porous material extensively utilized in water treatment field . In this study, an efficient activated carbon (E-AC) adsorbent was prepared from agricultural by-product Camellia oleifera shells (COS) by enzymatic pretreatment combined with phosphoric acid activation. The enzymatic pretreatment was beneficial for increasing the volume of mesopores and loosening the structure of the synthesized activated carbon, which ultimately led to an increased adsorption capacity of E-AC. The characteristics and adsorption performances of E-AC were thoroughly investigated. The results showed that E-AC exhibited a high adsorption capacity of 1249.01 mg/g on methylene blue (MB), and the adsorption process was a spontaneous endothermic process. The adsorption kinetics aligned closely with the pseudo-second-order kinetic model (R 2 > 0.99), and the adsorption mechanisms could be a combination of hydrogen bonding, π-π conjugation, electrostatic attraction, and physical adsorption. Additionally, E-AC exhibited good reusability, with a consistent MB removal rate of 91.14 % even after five cycles. This study offered an approach for obtaining high-quality activated carbon from COS and contributed to sustainable development strategies.