Biodiesel potentials of two phenotypes of Cyperus esculentus unconventional oils

Abstract

Two varieties of Cyperus esculentus, identified by their phenotype (black or yellow) were collected from Benin. To investigate their biodiesel profiles, the roots were extracted with hexane. Physicochemical properties and fuel profiles of obtained oils (YCE and BCE, respectively Yellow C. esculentus and Black C. esculentus) were determined by following standards methods. Although the major physicochemical properties (Iodine value: YCE: 72.89± 0.00 vs BCE: 79.73± 0.00 g I2/100 g-oil and Saponification value: YCE: 178.54 ± 0.6 vs BCE: 178.09 ± 0.13 mg KOH/g-oil) were relatively closed, slight difference were observed with their fatty acids profiles. Major fatty acids were oleic acid (YCE: 63.50 ± 0.15 vs BCE: 63.42 ± 0.11 g / 100 g- oils) and palmitic acid (YCE: 16.50 ± 0.26 vs BCE: 15.94 ± 0.11 g / 100 g- oils). These profiles should be correlatived with the density (≈0.89 g.cm-3 at 40°C), the viscosity (≈24 mm2s-1 at 40°C) and the cetane number (YCE: 60.47vs BCE: 59.01) of the oils. Their calorific values (YCE: 36361vs BCE: 37452 KJ/Kg) indicate that they could be used for biodiesel purposes. However, C. esculentus oils should be treated before their conversion in biodiesel in order to reduce their high level in minerals. Key words: Cyperus esculentus, unconventional oils, fuel profiles, physicochemical properties, phenotype.