Location: Bio-oils Research Unit
Title: Biodiesel Derived from a Feedstock Enriched in Palmitoleic Acid, Macadamia Nut Oil Author
Submitted to: Energy and Fuels
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 30, 2009
Publication Date: April 8, 2010
Citation: Knothe, G.H. 2010. Biodiesel Derived from a Feedstock Enriched in Palmitoleic Acid, Macadamia Nut Oil. Energy and Fuels. 24:2098-2103. Interpretive Summary: This research evaluated oil from the macadamia nut as a possible source of biodiesel. Biodiesel is produced from vegetable oils such as soybean oil or other sources such as animal fats and waste frying oils. Biodiesel has advantages such as renewability, domestic origin, biodegradability, safer handling, lower sulfur content, and reduced exhaust emission when compared to petroleum diesel. However, problems related to behavior at low temperatures and storage stability affect biodiesel. One possible method of improving these biodiesel properties is to change its composition. In this work, an oil with a different composition than most other vegetable oils, macadamia nut oil, was used as a model to produce biodiesel, so that the properties of this kind of biodiesel could be studied. The results show that the component that makes the biodiesel from macadamia nut oil unique would need to be present in even greater amounts for more desirable property improvement. These results are of interest to all parties interested in biodiesel and the improvement of its properties, including producers, users, researchers, and plant breeders.
Technical Abstract: Numerous vegetable oils, animal fats or other feedstocks have been investigated for obtaining biodiesel, defined as the mono alkyl esters of vegetable oils and animal fats. While biodiesel is competitive with petrodiesel, technical problems facing biodiesel include cold flow and oxidative stability. Most biodiesel fuels largely contain five fatty acids: palmitic, stearic, oleic, linoleic, and linolenic in varying amounts in their fatty acid (FA) profiles. Depending on the major fatty acids present, biodiesel from different feedstocks face these technical problems with varying severity. As previous work indicates, enrichment of other fatty acids such as decanoic or palmitoleic acid (PA) in the FA profile may be advantageous to address the technical issues facing biodiesel. In this work, a feedstock moderately enriched in PA (approximately 16-20%), macadamia nut oil (MNO), was selected for producing the corresponding biodiesel fuel and investigating its fuel properties. Methyl esters of MNO were prepared by conventional transesterification with sodium methoxide. Fuel properties such as cetane number, kinematic viscosity, oxidative stability, cold flow as well as lubricity are discussed in light of biodiesel standards. The approximately 15% content of saturated fatty esters in MNO affects cold flow. The 1H-NMR spectrum of macadamia methyl esters is also reported.