Synthesis of microalgae-based methyl ester using calcium glyceroxide catalyst derived from duck eggshells and crude glycerol in the n-hexane co-solvent system

Abstract

Abstract The synthesis of microalgae-based methyl ester has attracted the interest of researchers since microalgae have a high lipid content and can proliferate. Chlorella vulgaris, with its 63% lipid content on a dry basis, holds promise for methyl ester production. Heterogeneous catalysts, particularly calcium glyceroxide (Ca[O(OH)2C3H5]), play a crucial role in ester manufacturing due to their high catalytic activity. The synthesis of the calcium glyceroxide catalyst involves duck eggshells as a calcium source and crude glycerol. Optimal methyl ester production is achieved by employing n-hexane as a co-solvent for efficient microalgae oil dissolution. This research focuses on synthesizing and characterizing the calcium glyceroxide catalyst derived from duck eggshells and crude glycerol, emphasizing its application in manufacturing microalgae-based methyl esters with n-hexane as the co-solvent. Methyl ester synthesis variables include a 55°C reaction temperature, a 1.5% microalgae-derived catalyst, and a 9:1 methanol to microalgae ratio. FTIR functional group analysis identifies hydroxyl (O-H) groups from crude glycerol bound to calcium at 3345.71 cm−1, along with C-H group vibrations from crude glycerol bound to calcium at 2941.80 cm−1. SEM morphological analysis reveals aggregate formation on the calcium glyceroxide catalyst, indicating potential active sites. Utilizing the calcium glyceroxide catalyst for methyl ester synthesis yields a promising 62.42% yield. GC characterization demonstrates a methyl ester purity of 72.09%, with methyl palmitate as the predominant component at 30.927%. This study underscores the efficient use of the synthesized calcium glyceroxide catalyst for microalgae-based methyl ester production, showcasing its potential for sustainable biodiesel synthesis.