Synthesis and Physicochemical Characterization of Acid- and Base-Activated Carbon Derived from Black Plum Seed Shells

Abstract

Biomass-derived activated carbon offers several advantages over traditional sources, including low cost, renewability, and reduced environmental footprint. A wide range of agricultural residues such as rice husk, coconut shells, corn cobs, and palm kernel shells have been successfully utilized as precursors for activated carbon production. The synthesis of activated carbon from black plum (Vitex doniana) seed shells through carbonization followed by chemical activation using phosphoric acid (H₃PO₄) and sodium hydroxide (NaOH) was carried out. The influence of activation methods on the physicochemical properties of the resulting materials was carried out. Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed the presence of key surface functional groups, including hydroxyl, carbonyl, and aromatic structures, with enhanced oxygenated functionalities observed in the acid-activated carbon. Scanning Electron Microscopy (SEM) showed a transformation from a relatively dense and poorly developed surface in the unmodified raw sample to highly porous structures in the activated carbon, with NaOH activation inducing more extensive pore networks. X-ray diffraction (XRD) patterns indicated predominantly amorphous carbon structures with slight improvements in structural ordering upon activation, particularly for the sodium hydroxide modified carbon. Both surface chemistry and morphology were enhanced through chemical activation, with phosphoric acid favoring functional group development and sodium hydroxide promoting pore formation.