Waste Cooking Oil Purification with Various Adsorbents for Synthesizing Biodiesel

Abstract

This study aims to: (1) activate rice husk ash (ASP), coconut shell ash (ATK), and wood charcoal (AK) to become adsorbents and characterize them; (2) purify waste cooking oil (WCO) using ASP, ATK, and AK adsorbents; (3) making biodiesel from the purified WCO and characterizing their quality. This work uses experimental techniques, starting with preparing adsorbents by activating with KOH and characterizing activated ASP, ATK, and AK adsorbents using SEM and FTIR. The adsorbents were then used to purify WCO. Biodiesel was made from purified WCO by transesterification using an H2SO4 catalyst in ethanol. The process was carried out at 60°C for 12 hours. Then biodiesel layer was heated to 70°C to evaporate the ethanol. The biodiesel products were tested according to Indonesian National Standard (SNI). The results showed that peaks of the activated ASP, ATK, and AK adsorbents have alcohol groups (-OH), and other functional groups. Activated adsorbents have many pores when compared to adsorbents before activation. Biodiesel synthesized using activated ASP adsorbent has a higher flash point than using activated ATK and AK adsorbents and fulfils SNI specifications.