Pramesti, I.N. et al. 2026. Ultrasonic-Assisted Synthesis of Methyl Ester Sulfonate (MES) from Coconut Oil via Transesterification and Sulfonation Using Eggshell-Derived CaO Catalyst . Al-Kimia. 14, 1 (Jun. 2026). DOI:https://doi.org/10.24252/al-kimia.v14i1.62602.