Investigation of the Fatty Acid Profile in Some Macroalgae in Relation to the Environmental Conditions for Biodiesel Production

Abstract

In this study, fatty acids profile was determined in four algal species; namely Ulva fasciata (Chlorophyta), Corallina mediterranea, Corallina officinalis and Pterocladiella capillacea (Rhodophyta) which were collected from two sites (Abu-Qir Bay and Eastern Harbor) located on the Egyptian Mediterranean Sea during the four seasons in the period (2011-2012). In addition, nutrient content in the algal species (total nitrogen and phosphorus) and the environmental conditions of the ambient sea water were measured to find out their effect on the algal fatty acids content. The nitrogen content in algal species was almost equal in both sites. In contrast, the phosphorus content was higher in Abu-Qir (0.33-1.71%) than in Eastern Harbor (0.21-0.74%). The fatty acids profile showed different correlations with water’s physico-chemical properties. The fatty acids profile of the four algal species revealed high content of SFAs against MUFA and PUFA in both sites. Consequently, the algae were screened to define the suitable site, season and species for the highest quality and quantity of biodiesel production. Biodiesel physical properties; the Degree of Unsaturation (DU), Long Chain Saturation Factor (LCSF), Cold Filter Plugging Point (CFPP), Iodine Value (IV), Saponification Value (SV), the Cetane Number (CN), Kinematic viscosity (υ), density (ρ), the Higher Heating Value (HHV), C18:3% (wt%) and double bond Db ≥4(wt%) were calculated. All the investigated algae showed biodiesel properties that follow the standard values set for optimum biodiesel, with the green alga U. faciata collected from Abu-Qir during winter, as the best choice for producing biodiesel; whereas, the extracted fatty acids from Corallina officinalis is more suitable to be used for production of blenders, which can be added to the petroleum diesel in order to increase its quality, oxidative stability and octane number.