Hydrothermal carbonization of shrimp shell with glucose remarkably impacts pore development in activation

Herein, hydrothermal carbonization treatment of shrimp shells or together with glucose at 200 ºC plus subsequent activation with K₂C₂O₄ at 800 ºC was conducted, aiming to understand the retainment of organics and development of pore structures of resulting activated carbon. The results indicated that the organics in shrimp shells were highly unstable and the activation formed activated carbon with a mass yield of 5.6 %. Hydrothermal carbonization resulted in the leaching of some organics but promoted the aromatization of others, which in overall enhanced the resistivity of remaining organics towards cracking in activation, increasing the yield of activated carbon to 10.3 %. However, the leaching of a significant portion of aliphatic organics also decreased the specific surface area to 1128.1 m²/g (1593.2 m²/g from direct activation of shrimp shells. The co-hydrothermal carbonization of shrimp shells with glucose further increased activated carbon yield and enhanced the specific surface area of the activated carbon (1326.6 m²/g), due to additional aliphatic organics formed. Additionally, direct activation of shrimp shells formed activated carbon with dominant micropores (89.6 %), while hydrothermal carbonization of shrimp shells plus activation formed mainly mesopores (71.7 %). The presence of glucose in co-hydrothermal carbonization not only rendered micropores to dominate (80.3 %) but also retained appreciable amount of mesopores, forming activated carbon of superior capacity for the adsorption of methylene blue. Leaching of organics via the hydrothermal carbonization, promoted the formation of mesopores/macropores while suppressed the generation of micropores. Additionally, hydrothermal carbonization treatment resulted in wrapping of SiO₂ with organics, deterring further removal of SiO₂ via solid phase reactions with K₂C₂O₄.