Optimal Bio-Oil Production Using Triplochiton scleroxylon Sawdust Through Microwave-Assisted Pyrolysis

Abstract

This study aims to optimize bio-oil production through microwave pyrolysis of Triplochiton scleroxylon sawdust (Ayous). After a physicochemical characterization of the sawdust, response surface methodology via centered composite design was used to investigate the influence of pyrolysis factors on bio-oil yield and determine the optimal pyrolysis conditions. The studied pyrolysis factors were microwave power (W), irradiation time (min), and biochar (%) as wave absorber. Finally, the bio-oil produced under optimal conditions was characterized by GC–MS. It emerges from this study that Ayous biomass has physicochemical properties that can be valorized for bio-oil production, with a high volatile matter content (63.2 ± 2%) and low ash content (2.8 ± 0.3%). The optimization study of bio-oil yield shows that all factors have significant effects with a statistical significance level of 5% (p < 0.05) on the measured parameters. The optimal bio-oil yield of 44.82% is obtained at optimal conditions: microwave power of 576 W, irradiation time of 28 min, and a biochar (wave absorber) input of 3.18%. The bio-oil produced under optimal conditions has a pH of 4.6 ± 0.7 and a water content of 25 ± 1.2%. Compound identification of this bio-oil by GC–MS identified families of compounds including alkanes (13.90%), esters (5.88%), alcohols (1.10%), and high molecular weight phenolic compounds (58%). The produced bio-oil can be used as biofuel or in industrial applications. Nevertheless, further processing steps are needed to lower the water content and acidity of the oil.