Liquid Lipase-Catalyzed Esterification of Oleic Acid with Methanol for Biodiesel Production in the Presence of Superabsorbent Polymer: Optimization by Using Response Surface Methodology

Hoang Nguyen,Dinh Huong,Chien-Chung Chien,Chia-Hung Su,Horng-Yi Juan

doi:10.3390/en11051085

Abstract

Liquid lipase-catalyzed esterification of fatty acids with methanol is a promising process for biodiesel production. However, water by-product from this process favors the reverse reaction, thus reducing the reaction yield. To address this, superabsorbent polymer (SAP) was used as a water-removal agent in the esterification in this study. SAP significantly enhanced the conversion yield compared with the reaction without SAP. The lipase-catalyzed esterification in the presence of SAP was then optimized by response surface methodology to maximize the reaction conversion. A maximum conversion of 96.73% was obtained at a temperature of 35.25 °C, methanol to oleic acid molar ratio of 3.44:1, SAP loading of 10.55%, and enzyme loading of 11.98%. Under these conditions, the Eversa Transform lipase could only be reused once. This study suggests that the liquid lipase-catalyzed esterification of fatty acids using SAP as a water-removal agent is an efficient process for producing biodiesel.

Highlights

Extensive energy consumption and environmental pollution have stimulated the development of renewable energy sources
Biodiesel is commonly produced from edible feedstocks such as soybean, sunflower, and rapeseed oils [5,6,7,8]; the use of these feedstocks for biodiesel production is restricted because of their high cost and competition with demand for the food supply [9,10,11]
Inedible and waste oils have been developed as potential feedstocks for biodiesel production [12,13,14,15]

Summary

Introduction

Extensive energy consumption and environmental pollution have stimulated the development of renewable energy sources. A renewable fuel derived from vegetable oil, is increasingly considered a promising alternative to petrodiesel because of its superior combustion properties, compatibility with diesel engines, and environmental benefits [1,2,3,4]. Biodiesel is being produced globally to reduce the consumption of petrodiesel. Inedible and waste oils have been developed as potential feedstocks for biodiesel production [12,13,14,15]. These inedible and waste oils usually contain a high level of free fatty acids, which must be esterified into biodiesel before the transesterification [16,17]. The esterification of fatty acids for biodiesel production has been widely investigated [18,19,20]

Methods

Results

Conclusion