Biodiesel production from waste cooking oil using biochar derived from chicken manure as a porous media and catalyst

Abstract

In this study, we introduce a low-cost, efficient, porous catalytic material produced from chicken manure by pyrolysis (i.e., chicken manure biochar) for converting waste cooking oil into fatty acid methyl esters (FAME, i.e., biodiesel) via transesterification. Chicken manure can be pyrolysed at different temperatures (350, 450, 550, and 660 °C), and the properties of the resulting biochar are dependent on the temperature at which the biochar is made. The biochar in our study contained a large amount of inorganic compounds (mostly CaCO3) that expedite the catalytic activity during the transesterification of waste cooking oil. Compared to SiO2, the chicken manure biochar lowered the transesterification reaction temperature at which the highest FAME yield (95%) was achieved (350 °C). However, despite the catalytic effect of CaCO3 in the chicken manure biochar, undesirable thermal cracking of FAME occurred. To avoid this, the mass ratio of silica to chicken manure biochar was optimised. The optimal mass ratio of silica to chicken manure biochar was found to be less than 0.8. This study suggests an environmentally benign biodiesel production process that recycles organic waste such as chicken manure.