royalsocietypublishing.org/journal/rsos Research Cite this article: Akinfalabi S-I, Rashid U, Arbi Nehdi I, Yaw Choong TS, Sbihi HM, Gewik MM. 2020 Optimization and blends study of heterogeneous acid catalyst-assisted esterification of palm oil industry by-product for biodiesel production. R. Soc. open sci. 7: 191592. http://dx.doi.org/10.1098/rsos.191592 Received: 25 September 2019 Accepted: 19 November 2019 Subject Category: Chemistry Subject Areas: green chemistry/energy Keywords: palm fatty acid distillate methyl ester, response surface methodology, methyl ester-petro diesel blends, FTIR, TGA Author for correspondence: Umer Rashid e-mail: umer.rashid@upm.edu.my; umer.rashid@yahoo.com This article has been edited by the Royal Society of Chemistry, including the commissioning, peer review process and editorial aspects up to the point of acceptance. Electronic supplementary material is available online at https://doi.org/10.6084/m9.figshare.c. 4779473. Optimization and blends study of heterogeneous acid catalyst-assisted esterification of palm oil industry by-product for biodiesel production Shehu-Ibrahim Akinfalabi 1 , Umer Rashid 1 , Imededdine Arbi Nehdi 3,4 , Thomas Shean Yaw Choong 2 , Hassen Mohamed Sbihi 3 and Mohamed Mossad Gewik 3 1 Institute of Advanced Technology, and 2 Department of Chemical and Environmental Engineering, Engineering Faculty, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia 3 Department of Chemistry, College of Science, King Saud University, Riyadh 11451, Saudi Arabia 4 Chemistry Department, El Manar Preparatory Institute for Engineering Studies, Tunis El Manar University, P.O. Box 244, Tunis 2092, Tunisia UR, 0000-0001-6224-413X The optimum conditions to produce palm fatty acid distillate (PFAD)-derived-methyl esters via esterification have been demonstrated with the aid of the response surface methodology (RSM) with central composite rotatable design in the presence of heterogeneous acid catalyst. The effect of four reaction variables, reaction time (30–110 min), reaction temperature (30–70°C), catalyst concentration (1–3 wt.%) and methanol : PFAD molar ratio (3 : 1–11 : 1), were investigated. The reaction time had the most influence on the yield response, while the interaction between the reaction time and the catalyst concentration, with an F-value of 95.61, contributed the most to the esterification reaction. The model had an R 2 -value of 0.9855, suggesting a fit model, which gave a maximum yield of 95%. The fuel properties of produced PFAD methyl ester were appraised based on the acid value, iodine value, cloud and pour points, flash point, kinematic viscosity, density, ash and water contents and were compared with biodiesel EN 14214 and ASTM D-6751 standard limits. The PFAD methyl ester was further blended with petro-diesel from B0, B3, B5, B10, B20 and B100, on a volumetric basis. © 2020 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.