Two-Step Biodiesel Production from Black Acid Oil Waste Using Calcium Oxide from Charcoal Ash as a Catalyst

Jindaporn Jamradloedluk1,#

Somsuk Trisupakitti2,#,Email

1Solar Energy and Energy Resources Research Unit, Faculty of Engineering, Mahasarakham University, Kantharawichai District, Maha Sarakham 44150, Thailand.

2Chemistry Department, Faculty of Science and Technology, Rajabhat Maha Sarakham University, Mueang District, Maha Sarakham 44000, Thailand.

#These authors contributed to this work equally.

Abstract

Black acid oil is a liquid waste from the production of coconut oil. Here we used this waste to synthesize biodiesel by two-step reaction: esterification and transesterification. Charcoal ash was calcined to obtain a CaO-based catalyst. The black acid oil was heated to evaporate and esterified to reduce the amount of Free Fatty Acid (FFA) to less than 2% before transesterification. The results showed that calcium oxide (CaO) from charcoal ash incineration increased with increasing temperature and calcination time at 1000 oC and 240 min, the maximum calcium oxide content was 85%. FFA in black acid oil decreased from 82% to 1.8% from esterification using a 18:1 v/v methanol:oil ratio, catalyst concentration as 5% w/w, 60 oC and 180 min. Transesterification at a 12:1 v/v methanol:oil ratio, catalyst concentration as 3% w/w, 60oC and 60 min gave the highest yield of biodiesel equal to 81%. Properties of the biodiesel obtained from black acid oil in the transesterification lay within the specified standards, except for the viscosity value, which is higher than the standard value.

Two-Step Biodiesel Production from Black Acid Oil Waste Using Calcium Oxide from Charcoal Ash as a Catalyst