Widi Astuti, Irene Nindita Pradnya, Triastuti Sulistyaningsih, Luluk Arvi Cahyaning Suwandi, Afifah Sagita Fitria Wati, Erwan Adi Saputro, Zulfa Ajrina Fitri
Moringa oleifera stem (MOS) waste contains 30.61% cellulose, 27.37% hemicellulose, and 20.78% lignin, making it a promising precursor for biochar and activated carbon (AC) production. However, the high lignin and cellulose contents may contribute to significant tar formation during pyrolysis, resulting in pore blockage and reduced carbon material quality. This study investigates the coupled effects of lignocellulosic composition (i.e., cellulose, hemicellulose, and lignin) and pyrolysis temperature on the surface chemistry, microstructural characteristics, and adsorption performance of the resulting AC. Pyrolysis of MOS powder was carried out in a muffle furnace under limited air conditions at 2 target temperatures: 500 °C (denoted as MOSbc-500) and 600 °C (denoted as MOSbc-600). Chemical activation was subsequently performed using potassium hydroxide (KOH) at a mass ratio of 3:1 (KOH:biochar) in a muffle furnace under limited air conditions at 800 °C. Surface morphology was examined using SEM equipped with EDX, while the surface functional groups were characterized via FTIR spectroscopy. The pore structure was analyzed through N2 adsorption-desorption measurements. The results indicate that the surface of MOSbc-600 appears cleaner than that of MOSbc-500, suggesting reduced tar deposition at the higher pyrolysis temperature. The AC derived from MOSbc-600 (denoted as MOSac-600) exhibited higher oxygen-containing functional groups compared to that derived from MOSbc-500 (denoted as MOSac-500). Moreover, MOSac-600 demonstrated a higher BET surface area (1221.56 m2/g) and an average mesopore diameter of 3.42 nm, contributing to a high methyl violet (MV) adsorption capacity of 29.94 mg/g at pH 11. Equilibrium adsorption data were best described by the Langmuir isotherm model. These findings suggest that MOS-derived AC is a low cost, high removal efficiency, and environmentally sustainable adsorbent with significant potential for wastewater treatment applications. © 2026, Walailak University. All rights reserved.
Departement of Chemical Engineering, Universitas Negeri Semarang, Semarang, Indonesia; Department of Chemistry, Universitas Negeri Semarang, Semarang, Indonesia; Department of Chemical Engineering, Universitas Pembangunan Nasional “Veteran” Jawa Timur, Surabaya, Indonesia; School of Agriculture, Food, and Ecosystem Sciences, Faculty of Science, The University of Melbourne, VIC, Australia
