Influence of free fatty acid content in biodiesel production on non-edible oils

Abstract

The use of alternative feedstock as waste cooking oils (WCO) and bovine tallow for biodiesel production has some advantages. It is cheaper than edible vegetable oils and it is a way to valorize a sub-product. Nevertheless, these oils possess some contaminants, specially free fatty acid (FFA) content, which can reduce the quality and yield of biodiesel production. This problem was solved by testing different operating conditions and different transesterification procedure and equipments for each stage of processing. Technological assessment of process was carried out to evaluate their technical benefits, limitations and quality of final product. In this work biodiesel was produced by an alkali-catalyzed transesterification and by a two step esterification/alkali-catalysed transesterification in cases which FFA content has above 3%. Evaluation of quality from raw materials and final biodiesel was performed according to standard EN 14214. Results show that all parameters analyzed meet the standard and legislation requirements. This evidence proves that in those operational conditions the biodiesel produced from WCO and bovine tallow can substitute petroleum-based diesel.