Özet:

The green algae Ulva faciata was subjected to different physical pretreatments comprising thermal and mechanical techniques at different experimental conditions to state the most appropriate method of cell disruption for increasing the quantity of the extracted lipid and hence improve the quality of the produced biodiesel with low cost. Thermal pretreatment was autoclaving of either wet or dry algal biomass, while mechanical pretreatments include microwave and ultrasonication at different time intervals. The control was the alga without pretreatment extracted at optimum conditions: 60 min, 55oC, shaking speed at 250 rpm, < 0.16 mm particle size with 25:1 v/w solvent to solid ratio. The results showed that the quantity of extracted lipids in case of using all physical pretreatments increased the Total fatty acids yield significantly by about 2-folds of the control for wet algae in hydrothermal treatment with optimum time of treatment 40 minutes, and 1.4 folds for dry algae in thermal pretreatment of the dried alga for 60minutes autoclaving period. The sharp increase by 2.2 folds of extracted lipids was recorded by microwave pretreatment for radiation period (5 min), while ultrasonication showed 2.1-fold increase in lipid yield at 15minutes ultrasound exposure time. Concerning the physical properties of the produced biodiesel after all physical pretreatments, the results indicated that the produced biodiesel had very high quality as all its properties are almost complied with the ASTM D6751 and EN14214 standards. These results were confirmed statistically where all physical pretreatments had high significant effect on fatty acids yield and Biodiesel properties.

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