TY - JOUR AB - Acid esterification of sludge palm oil, having 50mas.% free fatty acids, i.e. 50g of dominant free fatty acid per 100g 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 (0.92mas.%, 1.84mas.% and 4.60mas.%). Under the applied conditions, the sulphuric acid dosage of 4.60mas.% 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 5mas.% 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. AD - Univ Novi Sad, Fac Technol, YU-21000 Novi Sad, Serbia AN - WOS:000358519900005 AU - Skrbic, B. AU - Predojevic, Z. AU - Durisic-Mladenovic, N. DA - Aug DO - 10.1177/0734242x15587546 IS - 8 J2 - Waste Manage Res KW - sludge palm oil LA - English N1 - Sp. Iss. SI PY - 2015 SN - 0734-242x SP - 723-729 ST - Esterification of sludge palm oil as a pretreatment step for biodiesel production T2 - Waste Management & Research TI - Esterification of sludge palm oil as a pretreatment step for biodiesel production UR - ://WOS:000358519900005 VL - 33 ID - 11892 ER -