Abstract:

The generation of agricultural residues from Adonidia merrilli and Dacryodes edulis continually and the need for sustainable resource utilization have intensified research into biomass characterization for energy and material applications. However, limited information exists on the chemical structure and functional groups present in the seed residues of Adonidia merrilli (Christmas palm) and Dacryodes edulis (African pear), despite their abundance as agro-waste. This study aimed to characterize the functional groups present in these seed residues using Fourier Transform Infrared (FTIR) spectroscopy in order to understand their chemical composition and potential utilization pathways. Seed residues of Adonidia merrilli and Dacryodes edulis were collected, cleaned, air-dried, ground, and sieved to obtain uniform particle sizes. The prepared samples were analyzed using FTIR spectroscopy within the spectral range of 4000–500 cm⁻¹. The spectra obtained were interpreted to identify characteristic absorption bands corresponding to different functional groups and to compare the chemical composition of the two biomass residues. The FTIR spectra revealed the presence of several important functional groups in both samples, including hydroxyl (–OH), carbonyl (C=O), aliphatic C–H, aromatic C=C, ether (C–O), and amide (N–H) groups. These functional groups indicate the presence of lignocellulosic components such as cellulose, hemicellulose, and lignin within the biomass structure. For Christmas Palm, the 3334.3cm-1 wave number indicates hydroxyl groups, common in alcohols, phenols, or moisture presence, The peak at 2918.5 cm-1 and 2850.8 cm-1 both indicates an Aliphatic C-H stretching vibrations, typical for Alkanes or fatty acids, the peak at 1644.9 cm-1 is indicative of Alkenes, 1438.8 cm-1 and 1367.9 cm-1 shows a functional group belonging to the CH2 and CH3, 1260.9 cm-1 and 1177.8 cm-1 has a mood vibration of stretching. For African Pear, 3280 cm-1: likely represents O-H stretching, 2922 cm-1 and 2856 cm-1: typical for C-H stretching in alkanes, 1710 cm-1 indicates C=O stretching, 1148 cm-1: likely indicative of C-O stretching, 1438 – 1334 cm-1: suggest deformation, 700 – 995 cm-1: out-of-plane bending vibrations, The 2079.9 cm-1 and 2009.0 cm-1 indicates the presence of unsaturated bonds such as alkynes or nitriles. The spectral patterns showed similarities between the two residues, although variations in peak intensities suggested differences in their chemical composition. The identified functional groups are known to influence the physicochemical behavior and thermal reactivity of biomass materials. The findings demonstrate that Adonidia merrilli and Dacryodes edulis seed residues contain functional groups typical of lignocellulosic biomass, indicating their potential suitability for bioenergy production, bio-based materials, and other value-added applications. The study highlights and supports the sustainable utilization of these biomass resources in energy and environmental engineering applications.