Preparation, Pore Structure Development, and Properties of Bamboo Parenchyma Cell-Derived Activated Carbon by Phosphoric Acid Activation

Abstract Bamboo parenchyma is rich in lignocellulosic macromolecules, including cellulose, hemicellulose, and lignin, whose structural transformation plays a critical role during chemical activation processes. In this study, bamboo parenchyma cells were employed as a lignocellulosic precursor to prepare porous activated carbon via phosphoric acid activation, followed by silver loading to introduce antibacterial functionality. The activation process induced dehydration, depolymerization, and aromatization of cellulose, hemicellulose, and lignin, accompanied by crosslinking reactions that governed the formation of hierarchical pore structures. The obtained phosphoric-acid-activated carbon (PPAC) exhibited a predominantly microporous structure with a high specific surface area of 1534 m2 g–1 and a micropore volume of 0.260 cm3 g–1. TG–MS–FTIR analysis further revealed stepwise gas evolution and a phosphorus–oxygen reaction cycle associated with the transformation of lignocellulosic macromolecules during thermal activation. After silver loading, Ag nanoparticles were uniformly dispersed on the carbon surface with a maximum loading of 19.36 wt %. Although the specific surface area decreased to 525 m2 g–1, the composite material displayed excellent antibacterial activity. Antibacterial tests demonstrated that PPAC/Ag achieved nearly 100% inhibition against Escherichia coli and Staphylococcus aureus and maintained stable antibacterial performance after five reuse cycles. This work highlights the crucial role of lignocellulosic macromolecule transformation in pore structure formation during phosphoric acid activation and provides insights into the design of functional carbon materials derived from biomass for water purification and bio-protection applications.