Comparative analysis of biodiesels from calabash and rubber seeds oils

Abstract

Physicochemical properties of biodiesel from vegetable oils depend on the inherent properties of the oil-producing seeds. The purpose of this study is to investigate the physicochemical properties of biodiesels extracted from calabash and rubber seeds oils, as well as their combined oil mixtures with a view to ascertaining the most suitable for biodiesel production. Calabash and rubber seeds oils were separately extracted through the use of a mechanical press with periodic addition of water. Biodi esels were produced from each category of the oils by transesterification of the free fatty acid (FFA) with alcohol under the influence of a catalyst in batch process. The physicochemical properties of the biodiesels were investigated and comparatively analysed. The results obtained indicated an average of 1.40 wt% FFA for biodiesel produced from the purified calabash oil, which has a specific gravity of 0.920, pH of 5.93, flash point of 1160 C, fire point of 1380 C, cloud point of 700 C, pour point of-40 C, moisture content of 0.82 wt% and specific heat capacity of 5301 J/kg K. Conversely, the results obtained for biodiesel produced from the purified rubber oil showed an average of 33.66 wt% FFA, specific gravity of 0.885, pH of 5.51, flash point of 1450 C, fire point of 1700 C, cloud point of 100 C, pour point of 40 C, moisture content of 1.30 wt% and specific heat capacity of 9317 J/kgK. However, results obtained for biodiesel produced from the combined oil mixtures indicated an average of 19.77 wt% FFA content, specific gravity of 0.904, API gravity of 25.036, pH value of 5.73, flash point of 1570 C, Fire point of 1800 C, cloud point of 90 C, pour point of 50 C, moisture content of 0.93 wt% and specific heat capacity of 6051 J/kg.K. Biodiesel produced from calabash seed oil is superior in quality to rubber seed oil, particularly in terms of its low FFA and moisture contents.