Bioresource Technology 2016-01-01

Glycerin esterification of scum derived free fatty acids for biodiesel production.

Erik Anderson, Min Addy, Qinglong Xie, Huan Ma, Yuhuan Liu, Yanling Cheng, Nonso Onuma, Paul Chen, Roger Ruan

Index: Bioresour. Technol. 200 , 153-60, (2015)

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Abstract

Scum is an oily waste stream of the wastewater treatment process that can be used to produce biodiesel. Combining acid hydrolysis and solvent extraction, a free fatty acid and acyl-glycerol rich product was produced. Free fatty acids (FFAs) present were converted to acyl-glycols via a high temperature (238°C) glycerin esterification process known as glycerolysis. The inorganic catalysts zinc aluminum oxide and sodium sulfate were tested during glycerolysis to compare the reaction kinetics of converting FFA to acyl-glycerols. It was concluded that the zinc-based catalyst increased the reaction rate significantly, from a "k" value of 2.57 (uncatalyzed) to 5.63, completing the reaction in 60min, half the time it took the uncatalyzed reaction (120min). Sodium sulfate's presence however slowed the reaction, resulting in a "k" value of 1.45, completing the reaction in 180min. Use of the external catalyst Zn-Al2O3 showed the greatest catalytic potential, but also assumes additional costs. Copyright © 2015 Elsevier Ltd. All rights reserved.