Green metrics evaluation of pumpkin ( <i>Cucurbita moschata</i> ) peel ash as palm oil transesterification catalyst

Abstract A base catalyst has been prepared from pumpkin peel ash for the synthesis of fatty acid methyl ester (FAME) from palm oil using the ultrasonication method. This catalyst was prepared by burning the pumpkin peel in the open air and calcinating at 800 °C for 2.5 h. Preparation of FAME was performed at ambient temperature, using proportions of palm oil:methanol of 1:6 mol, and catalyst mass variations of 1%, 2%, 3%, 4%, 5% and 6% (w/w). The obtained catalyst was characterized by Fourier transform infrared, X‐ray diffraction, Brunauer–Emmett–Teller and scanning electron microscopy with energy dispersive X‐ray analysis. The characterization results showed the presence of potassium‐based oxides and carbonates which could be used as a base for the transesterification catalysis. The resulting FAME was characterized using 1 H‐nuclear magnetic resonance and the conversion value was calculated to reach 96.94% at a 5% catalyst mass variation. Additionally, the transesterifications were evaluated using green metrics to determine their environmental impact using Environmental Assessment Tool for Organic Synthesis software and an Andraos spreadsheet. The results confirmed that the study presented here displays noteworthy advancements in sustainability and efficiency. The catalyst holds the benefit of being a waste material, relatively cheap, easy to prepare, efficient and environmentally benign. Thus, it is a promising candidate as a ‘green catalyst’ in large‐scale biodiesel production.