Characterization of Rice Husk Pyrolysis Products for Potential Renewable Energy Applications

Abstract

Converting agricultural waste into value-added products offers a promising strategy for sustainable waste management and reducing dependence on fossil resources. This study investigates the slow pyrolysis of rice husk at 550 °C, with emphasis on product distribution and the physicochemical characteristics of the resulting biochar, bio-oil, and gaseous fraction. The process produced 50.88 ± 0.51 wt.% biochar, 38.18 ± 1.05 wt.% bio-oil, and an estimated gas yield of 10.94 ± 1.50 wt.%, calculated by mass difference. Gas chromatography (GC) identified carbon dioxide (17.251% of the reported GC composition) as the dominant detected gaseous component, followed by carbon monoxide, methane, and hydrogen. Gas chromatography–mass spectrometry (GC-MS) showed that the bio-oil contained esters (31.33%), fatty acids (24.48%), phenolic compounds (22.88%), hydrocarbons (9.97%), ketone/aromatic carbonyl compounds (7.84%), and other oxygenated compounds (2.28%) based on relative GC peak areas. Brunauer–Emmett–Teller (BET) analysis showed that the biochar had a specific surface area of 77.05 m² g⁻¹, a total pore volume of 0.052 cm³ g⁻¹, and an average BJH pore diameter of 69.527 Å (6.95 nm), indicating a predominantly mesoporous textural structure. These results demonstrate the potential of rice husk as a feedstock for integrated production of a carbonaceous solid, condensable liquid products, and combustible gas components. Further application-specific testing is required to establish the performance of the individual fractions in energy and environmental applications.