Direct extraction and conversion of microalgal lipid to biodiesel in one step process is developed to initiate an efficient method in biofuel production. The method that is called as in-situ process has been applied in the biodiesel production from microalgae Chlorella vulgaris lipid by involving sonication assisting. Various parameters that affect the in-situ transesterification were investigated to find the optimum conditions including power of sonication, co-solvent use, and biomass amount. The experiment was performed by acidic catalyst H2SO4. The use of sonication in 25kHz/270W yielded the highest biodiesel product. The apply of co-solvent n-hexane significantly increased the yield biodiesel rather than no co-solvent. The biodiesel yield of 10.39 % obtained when the process was accompanied by the n-hexane as co-solvent with increasing level as 47% rather than without co-solvent. The in situ process in the ratio biomass-methanol 3:50 that assisted by sonication for 60 mins produced the highest biodiesel, which was 20.31 % w/w. The yield was higher than assisting with reflux or a combination of reflux-sonication. The component of biodiesel yielded in the process consisting of 7,10,13-hexadecatrienoic methyl ester; pentadecanoic acid, 14-methyl-methyl ester; 9,12,15-octadecatrienoic acid-methyl ester; and eicosanoic acid-methyl ester. The combine of reflux-sonication exhibited a low biodiesel product. The disadvantage method from the combination may inhibit on lipid extraction or FAME transformation, the exact cause needs to be looked for in the future.

Original languageEnglish
Pages (from-to)162-171
Number of pages10
Issue number1
Publication statusPublished - 15 Mar 2024


  • Biodiesel
  • in-situ transesterification
  • microalgae Chlorella vulgaris
  • sonication


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