Okra (Hibiscus esculentus) seed oil for biodiesel production

Biodiesel was derived from okra (Hibiscus esculentus) seed oil by methanol-induced transesterification using an alkali catalyst. Transesterification of the tested okra seed oil under optimum conditions: 7:1 methanol to oil molar ratio, 1.00% (w/w) NaOCH3 catalyst, temperature 65 °C and 600 rpm agitation intensity exhibited 96.8% of okra oil methyl esters (OOMEs) yield. The OOMEs/biodiesel produced was analyzed by GC/MS, which showed that it mainly consisted of four fatty acids: linoleic (30.31%), palmitic (30.23%), oleic (29.09%) and stearic (4.93%). A small amount of 2-octyl cyclopropaneoctanoic acid with contribution 1.92% was also established. Fuel properties of OOMEs such as density, kinematic viscosity, cetane number, oxidative stability, lubricity, flash point, cold flow properties, sulfur contents and acid value were comparable with those of ASTM D 6751 and EN 14214, where applicable. It was concluded that okra seed oil is an acceptable feedstock for biodiesel production.