Chlorella vulgaris'den Biyodizel Üretim Verimliliğinin Arttırılması İçin Transesterifikasyon Koşullarının Optimizasyonu

Abstract

Biodiesel production from microalgae species Chlorella vulgaris was optimized using in-situ transesterification with acid (H2SO4) and base (NaOH) catalysts. Response Surface Methodology (RSM) based on a Central Composite Design (CCD) was applied to investigate the effects and interactions of in-situ transesterification parameters; alcohol: biomass ratio (v/w), temperature, catalyst concentration (%) (catalyst:biomass), and reaction time on the responses of fatty acid methyl ester (FAME) content, specifically C18:1 (%), C18:2+C18:3 (%), and C16+C18 (total area). The study aimed to increase biodiesel yield by enhancing C18:1 (%) and total C16+C18 content while reducing C18:2 + C18:3 (%) content in the FAME composition. For H2SO4 catalyst, the optimum conditions were determined as 5:1 (v/w biomass), 85% catalyst concentration by weight, 60°C reaction temperature, and 72 minutes reaction time. The FAME content obtained from the quadratic response surface model under these optimum conditions was calculated as 49.71% for C18:1 and 1.40% for C18:2+C18:3, and a total area of 2.09556E+09 for C16+C18. These theoretical results were in agreement with the experimental results of 49.52±0.11% for C18:1, 1.80±0.31% for C18:2+C18:3, and 2.08830E+09±1.70E+05 for the total area of C16+C18. The FAME yield under these conditions was calculated as 67.28%. For NaOH catalyst, the optimum conditions were determined as 39:1 (v/w biomass), 58% catalyst concentration by weight, 36°C reaction temperature, and 64 minutes reaction time. The FAME content obtained from the quadratic response surface model under these optimum conditions was calculated as 48.46% for C18:1 and 3.03% for C18:2+C18:3, and a total area of 1.75019E+09 for C16+C18. These theoretical results were in agreement with the experimental results of 47.98±0.09% for C18:1, 3.54±0.50% for C18:2+C18:3, and 1.74773E+09±1.54E+05 for the total area of C16+C18. The FAME yield under these conditions was calculated as 38.68%. These results showed that H2SO4 catalyst had better performance in terms of FAME composition and reaction yield compared to NaOH catalyst. In the second part of the study, all the in-situ transesterification conditions were kept the same except for the source of Chlorella vulgaris biomass to compare their FAME compositions by using these two different sources of biomass. Biodiesel products obtained from the first source were high in C18 fatty acids, while biodiesel products obtained from the second source had a high in C16 fatty acids. This study confirms that an efficient production of high-quality FAME composition from microalgae Chlorella vulgaris could be possible through optimized in-situ transesterification.