Charcoal ash derived from mature-wood twigs of neem (<i>Azadirachta indica</i>): an economical, accessible material with multifaceted application potential

Abstract In this study, discarded neem ( Azadirachta indica ) mature-wood twigs are charred at 473 K to yield charcoal ash. Material characterizations reveal that the charcoal ash is composed of various minerals and organic functionalities and has a flaky, macroporous surface consisting of protrusions. Elementary property analyses are performed, and neem mature-wood twig charcoal ash is compared characteristically with similar wood-derived, organic, and bottom ashes. The inherently gray color of charcoal ash (∼50 % absorbance and ∼50 % reflectance) changes to reddish gray when the ash solution is ultrasonicated and to golden yellow upon subsequent filtration; the emission peaks are spectrally identified as 706.32 and 577.26 nm, respectively. Thermal testing is conducted, and the following parameters are determined: thermal emissivity = 0.830–0.924; phase-transition temperature = 652.75 K; decomposition temperature = 886.85 K; enthalpy of fusion = 2,760.77 J g −1 ; enthalpy of crystallization = −3,708.41 J g −1 . The electrically conductive nature of charcoal ash is demonstrated in its solution and powdered forms, with the conductivity ranging 7–10 mS m −1 and the electrical continuity being sustained over a distance of at least 4√2 cm. Hence, this study aims to provide guidance for customizing abundantly available plant waste into valuable materials for varied target applications.