title: Esterification of sludge palm oil as a pretreatment step for biodiesel production.
abstract: Acid esterification of sludge palm oil, having 50 mas.% free fatty acids, i.e., 50 g of dominant free fatty acid per 100 g of oil, was investigated with the objective of determining conditions for the efficient reduction of free fatty acids. The influences of sulphuric acid dosage and molar ratio of methanol to oil were studied, with the final intention to obtain feedstock with a free fatty acids content acceptable for biodiesel production by alkali-transesterification. Esterification was performed using different molar ratios of methanol to oil (3:1, 6:1 and 9:1) and varying the amount of H2SO4 catalyst (0.92 mas.%, 1.84 mas.% and 4.60 mas.%). Under the applied conditions, the sulphuric acid dosage of 4.60 mas.% resulted in the satisfactory decrease of the feedstock's free fatty acids for 6:1 and 9:1 molar ratios of methanol to oil. Thus, taking into account the economic reasoning, it can be concluded that approximately 5 mas.% of H2SO4 with 6:1 molar ratio of methanol to oily feedstock, might be regarded as the dosage necessary for satisfactory pretreatment of the feedstock to be further subjected to the alkaline transesterification. Finally, the effort to consolidate the information on acid esterification available in literature was made, contributing to knowledge on sustainable biodiesel production using the low-grade and low-cost sources.
authors.affiliation: University of Novi Sad, Faculty of Technology, Novi Sad, Serbia biljana@tf.uns.ac.rs.
authors.forename: Biljana
authors.initials: B
authors.lastname: Škrbić
authors.affiliation: University of Novi Sad, Faculty of Technology, Novi Sad, Serbia.
authors.forename: Zlatica
authors.initials: Z
authors.lastname: Predojević
authors.affiliation: University of Novi Sad, Faculty of Technology, Novi Sad, Serbia.
authors.forename: Nataša
authors.initials: N
authors.lastname: Đurišić-Mladenović
mesh_terms: D056804:Biofuels / Q000032:analysis*; D004951:Esterification; D000073878:Palm Oil; D010938:Plant Oils / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods; D018505:Waste Management / Q000379:methods*
chemical_list: D056804:Biofuels; D010938:Plant Oils; D000073878:Palm Oil
keywords: Sludge palm oil; catalyst dosage; esterification; free fatty acids; molar ratio of methanol to oil; sulphuric acid