Sustainable fabrication of hierarchical porous graphitic carbon from banana peduncle via self-template and self-activation for high-performance sorption of phthalate easters

In this study, we propose a simple and sustainable strategy to fabricate hierarchical porous graphitic carbon (HPGC) through the direct pyrolysis of banana peduncle, in which the naturally occurring potassium-rich components allow it to act as carbon source, template, and self-activator all in one. During pyrolysis, the formation of KCl and K 2 CO 3 enabled simultaneous carbonization and self-template/self-activation of banana peduncle, eliminating the need for exogenous chemicals. The resulting HPGC exhibited high graphitization, hydrophobicity, and a large specific surface area of 1686.30 m 2 g −1 , with a hierarchical pore structure dominated by micropores (peaking at 0.86 nm) and narrow mesopores (<4.0 nm). HPGC achieved exceptional sorption capacities of 730.63 and 833.44 mg g −1 for dimethyl phthalate and diethyl phthalate, respectively, within 2 h, significantly outperforming most reported sorbents. The superior performance is attributed to the developed pore structure and large surface area, which provided abundant sorption sites through pore-filling and surface coverage. Meanwhile, the hydrophobic π-conjugated carbon framework of HPGC facilitated the sorption via hydrophobic effects, π-π electron donor–acceptor interactions, and π-π stacking. Additionally, hydrogen bonding may be involved, but with minor contribution. Thermodynamic parameters indicated that the sorption process was spontaneous and exothermic, driven primarily by hydrophobic effects, resulting in an entropy gain in systems. The stronger sorption of diethyl phthalate compared with dimethyl phthalate was attributed to stronger hydrophobic interaction with HPGC. This work highlights a novel, cost-efficient, and environmental-friendly approach to synthesizing high-performance porous carbon for phthalate easters removal, offering significant potential for large-scale applications in water remediation.