Research Article

Investigation of Structural, Thermal, Magnetic and Functional Properties of Sustainable Carbon Materials from Calcined Coconut Shell Charcoal

Abstract

The effect of calcination of the coconut-shell charcoal on thermal, structural, chemical, morphological, textural, vibrational and magnetic properties has been investigated. The TG/DTA results indicated that moisture and volatile contents were removed up to about 200 °C, unstable ones were decomposed between about 200 and 450 °C, and a thermally stable carbon framework was formed above approximately 600 °C. The XRD patterns showed broad reflections near 28° and 45° in 2θ, which confirmed the amorphous-to-turbostratic nature of the carbon. The crystallites average size was 4 nm before calcination and 6 nm after calcination. FTIR analysis showed the presence of hydroxyl, aliphatic C–H, carbonyl, aromatic C=C and C–O bands, and the decrease in their intensities following calcination, suggested deoxygenation and dehydration. The SEM study indicated that the surface was irregular, rough, fractured and porous with many interconnected cavities, cracks, grooves and natural channels. The BET analysis was employed to study the surface area, pore volume, pore diameter and the pore size distribution, and the hysteresis behavior observed reveals the presence of mesoporous nature along with the microporous regions. Raman spectra exhibited the typical D and G bands at 1350 and 1580 cm⁻¹, respectively, and the changes in the intensity ratios of these bands after calcination indicated carbonization, aromatization, defect formation and partial graphitic ordering. VSM analysis results indicated that the magnetic reactivity of the charcoal changed because of the calcination, which could have been due to the reorganization of the organic carbon matrix and/or the possible concentration or modification of the inorganic mineral phases. In summary, the process of calcination transformed coconut-shell biomass into a carbon material with thermal stability along with chemical reorganization and porous structure that may have some degree of order and functionality for use in adsorption, catalysis, electrochemistry and energy-related applications.