Statement of the Problem: Madagascar is widely renowned for its unique biodiversity. Particularly, there are nine species of Millettia (Fabaceae) in Madagascar, including one introduced Millettia pinnata L. or Karanja, and eight endemic Malagasy species. While M. pinnata (Mp) is a famous tree for biodiesel production, no studies have ever been done on Malagasy Millettia species. The purpose of this study is to compare the physicochemical characteristics of oils extracted from MP seeds with those of two endemic Malagasy species: M. capuronii (Mc) and M. taolanaroensis (Mt).
Methodology & Theoretical Orientation: Millettia seeds were collected in the eastern part of Madagascar. Solvent extraction was used. Oil refraction indices were determined according to the NF T60-212 standard (AFNOR 1984). ANOVA was used to compare the differents parameters.
Findings: The MP oil is canary yellow with an unpleasant smell, the MC oil is pale green and its smells like a passion fruit. Mt oil is orange-yellow with a similar Mc smell. Mc seeds have the highest oil yield (48.3±1.39%), followed by Mt (43.8±0.51%) and Mp seeds have the lowest oil yield (36.2±0.73%), the difference was significant. In terms of density: Mp oil (D=0.918±0.0004g.cm-3) is denser than Mc oil (0.874±0.0007g.cm-3) and Mt oil (0.864±0.0008 g.cm-3). A significant difference was observed in the values of the refraction indexes (RI); Mp oil has the highest RI (1.475 ±0.0003) compared to Mc oil (1,463 ±0.0015) and Mt (1.46 ±0.0005). The cetane indices are respectively IC=54.62 for MP, IC=65.41 for Mc and IC=66.36 for Mt which are above the minimum standard required (IC=48) by ASTM D 976. The calorific powers are respectively 40.31MJ.kg-1 for MP, 41.85MJ.kg-1 for Mc and 42.12MJ.kg-1 for Mt.
Conclusion & Significance: These results showed that Malagasy Millettia species have characteristics close to biodiesel (gasoil), and have an interesting potential for biofuel production.
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