Sunflower Acid Oil

About This Product

Sunflower acid oil is produced from the soapstock generated when crude sunflower oil is neutralised with caustic soda during chemical refining. Acidulating that soapstock with sulphuric acid releases the fatty acids, which separate as an oil layer and are drawn off. It is supplied as a brown viscous liquid and is a by-product of refining rather than a manufactured product. As a residue stream it is classified as waste-based feedstock under RED II and comparable schemes, the main reason it is bought for fuel rather than industrial use. Its composition follows the parent oil, so it is dominated by linoleic acid with oleic, palmitic and stearic making up the balance. The high linoleic fraction gives a high iodine value and therefore poor oxidation stability in the finished ester, but keeps saturated content low so cold flow is good. Compared with soybean and rapeseed acid oil it is paler and carries fewer phosphatides, reducing the pretreatment burden ahead of hydrotreating. Free fatty acid content is high, so acid esterification rather than alkali transesterification is the route, and residual sulphate is controlled for catalyst protection. It is converted to biodiesel by acid esterification and to renewable diesel by hydrotreating, and is also used in industrial soap manufacture and as feed energy. Bio Green Fuels supplies sunflower acid oil to specification on free fatty acid, iodine value, moisture and impurities, sulphur and residual sulphate, and unsaponifiable matter.