Abstract
Bio-oil is often extracted from biomass using liquid solvent or supercritical carbon dioxide. However, extraction using these methods has several disadvantages. In this study, expanded hexane with carbon dioxide is examined as a new extraction solvent. The objective of this study is to develop a new technique for the extraction of bio-oil from biomass using expanded hexane with carbon dioxide; rice bran is used as the raw biomass. The extraction was carried out at 25— 27°C, 5.0—5.3 MPa, and 0.78—0.94 mole fraction of carbon dioxide in expanded hexane. At 26°C, 5.1 MPa, 0.87 of mole fraction of carbon dioxide, the oil yield was 1.6 times greater than that with normal liquid hexane because of the low viscosity and high permeability of expanded hexane. Furthermore, the phosphorus concentration in the extracted oil was 9.5 ppm. This was very low, compared with that in rice bran,in which it is approximately 350 ppm. This was because the solvent power of expanded hexane to extract neutral lipid decreased slightly while that to extract polar components decreased significantly. As a result, expanded hexane with carbon dioxide could extract the phosphorus-free bio-oil in high yield under mild conditions.
Highlights
Rice bran is the byproduct of milling paddy rice to produce refined rice
Extraction using expanded hexane with CO2 was studied as a new method to recover bio-oil from rice bran for biodiesel production
It was found that the solubility of bio-oil and the phosphorus concentration decreased with increase in mole fraction of CO2
Summary
Rice bran is the byproduct of milling paddy rice to produce refined rice. During milling, approximately 73.5% of white rice, 3.5% of broken rice, 15% of husk, and 8% of rice bran are obtained from paddy (Pandey and Shrivastava, 2018). Since rice bran contains 15–25 wt% oil and is one of the most abundant byproducts of the rice industry, it is an important biomass for producing bio-oil It must be stabilized immediately upon production, primarily because of the presence of lipase, an enzyme that rapidly hydrolyzes oil to free fatty acids (FFA) and glycerol. Supercritical carbon dioxide has many advantages, including tunable solvent properties, rapid mass transfer, facile removal of the solvent, and production of solventfree crude lipids (Halim et al, 2012). This process can be used to extract impurity-free rice bran oil or other bio-oil in high yields. It requires high pressure at 20—40 MPa and temperature of 40—60°C to obtain yields comparable with that by hexane extraction (Tomita et al, 2014)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
