Ethyl esters from waste oil: Reaction data of non-catalytic hydroesterification at pressurized conditions and purification with sugarcane bagasse ash

Abstract

The reaction data of hydroesterification of waste oil, under pressurized conditions, were collected and the adsorption of compounds from ester mixture by sugarcane bagasse ash was evaluated. The reactions were conducted in a continuous reactor to evaluate of the effect of temperature and residence time. In the hydrolysis, the evaluated variables promoted an increase in free fatty acid (FFA) formation. However, at the highest temperature evaluated (320 °C), the equilibrium was reached after 12 min, obtaining 91.68% of FFA. Temperature and residence time increased the FFA conversion, although at 300 °C the conversion was stabilized after 10 min and ester yield after 20 min, thereby obtaining a 96.42% of FFA conversion with 74% of ester content. In the adsorption, the percentage of adsorbent and contact time varied for the FFA removal and polar compounds (PC). The adsorption equilibrium was reached with 12.5 wt% of ash and after 8 h 33.22% of FFA and 56.31% of PC were absorbed. Adsorption in four successive beds was also evaluated, changing the adsorbent mass every 8 h, maintaining the same adsorbate. The results indicated the removal of 43.89% of FFA and 73.08% of PC after the 4th bed.