Dewi Selvia Fardhyanti, Maulida Zakia, Irene Nindita Pradnya, Haniif Prasetiawan, Alifyan Syauqi
Coffee husks, which contain a high lignocellulosic content, can be effectively converted into bio-oil through the pyrolysis process. However, the resulting bio-oil contains 34% phenolic compounds, which could potentially cause significant damage to engines if used as a direct substitute for diesel fuel. This study utilized a liquid-liquid extraction technique to isolate phenolic compounds from bio-oil. Phenol was extracted from coffee husk bio-oil using a NaOH solution and 80% methanol, followed by phase separation and gas chromatography analysis to determine component concentrations. Various temperatures and stirring speeds were tested, and phenolic concentrations in the extract and raffinate phases were analyzed. Higher stirring speeds increase the Kd value by enhancing phenol transfer into the extract phase through reduced diffusion distances and improved contact between liquid phases, thereby boosting extraction efficiency. Additionally, phenol extraction yield increases with temperature, as higher temperatures enhance solvent diffusion, but excessive heat may reduce yield due to solvent properties. The highest yield of 91.76% was achieved at 50°C and a stirring speed of 250 rpm. © 2026 American Institute of Physics Inc.. All rights reserved.
Department of Chemical Engineering, Faculty of Engineering, Universitas Negeri Semarang, Semarang, 50229, Indonesia
