Abstract
Leaching pine bark with deionized water effectively reduced its total ash content by removing a portion of the inorganic elements, particularly the water-soluble potassium (K) and sodium (Na). As a result, biocarbon derived from leached pine bark contained lower levels of both ash and carbon, compared to biocarbon derived from untreated pine bark. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) confirmed that the content of total and individual inorganic elements in the leached bark biocarbon was considerably reduced relative to the untreated counterpart. X-ray diffraction (XRD) analysis identified calcium carbonate as the dominant mineral phase in both biocarbons; however, its peak intensity was notably weaker in the leached bark biocarbon, indicating a lower content of this mineral phase. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) revealed calcium-rich grains on the surface of the untreated bark biocarbon, which were largely absent in the leached bark biocarbon. Fourier transform infrared (FTIR) spectroscopy showed similar spectral profiles for both biocarbons, though the leached bark biocarbon exhibited reduced peak intensities corresponding to C=O and C–O–C stretching vibrations. This reduction is likely due to the removal of water-soluble extractives and polysaccharides during leaching, resulting in the formation of fewer oxygenated functional groups during carbonization and a reduced carbon content. Copyright © 2026, AIDIC Servizi S.r.l.