The phenolic compounds were primarily originated from the degradation of the lignin component in risk husk (by cleavage
of the aryl ether linkages in lignin). The furan derivatives and the acids were formed primarily from the cellulose and hemicellulose components of rice husk [21]. A large quantity of esters were obtained from the liquefaction of rice husk with ethanol as solvent, which may be ascribed to the esterification reactions between fatty acid and ethanol [14]. Fatty acid can also be partly degraded through decarboxylation at hydrothermal conditions to produce long-chained hydrocarbons [30].