RSM/ANN based modeling of methyl esters yield from Anacardium occidentale kernel oil by transesteriﬁcation, for possible application as transformer ﬂuid Chinedu Matthew Agu a, * , Charles Chukwudozie Orakwue b , Matthew Chukwudi Menkiti b , Albert Chibuzor Agulanna c , Florence Chidinma Akaeme b a Chemical Engineering Department, Michael Okpara University of Agriculture, Umudike, Nigeria b Chemical Engineering Department, Nnamdi Azikiwe University, Awka, Nigeria c Materials and Energy Technology Department, Projects Development Institute (PRODA), Emene Industrial Area, Enugu, Nigeria ARTICLE INFO Keywords: Modeling Response surface methodology Anacardium occidentale kernel Artiﬁcial neural network Methyl esters Gas chromatography (GC) ABSTRACT This study is on the modeling of methyl esters production process; obtained by the transesteriﬁcation of Ana- cardium occidentale kernel (AOK) oil (AOKO), using artiﬁcial neural network (ANN) and response surface meth- odology (RSM). AOKO was obtained from the kernels/seeds of Anacardium occidentale tree. The oils were extracted from the kernels using solvent extraction method. The physicochemical properties of AOKO and Ana- cardium occidentale kernel oil methyl esters (MAOKO t ) were determined using standard methods. Fatty acids composition was determined using gas chromatography (GC). At modeling conditions of temperature (65  C), mole ratio (7:1), catalyst concentration (2.5 wt %), stirring speed (600 rpm) and time (150 min), the RSM pre- dicted and validated methyl ester yields were 94.82%, and 94.70%, respectively; while ANN predicted and validated yields were 93.21% and 93.33%, respectively. The physicochemical characterization results of AOKO and MAOKO t samples, show that their respective viscosity, dielectric strength (DS), pour and ﬂash points were (20.01 and 10.97 mm 2 s -1 ), (25.34 and 38.60 kV), (11 and 5  C), and (270 and 288  C). These results indicated the MAOKO t sample’s potential use as transformer ﬂuid. The GC result indicated that MAOKO t was unsaturated. Finally, on the basis of the gotten model results, ANN was adjudged as a better predictive model, when compared to RSM. 1. Introduction Recently, technological developments are focused on vegetable oil raw materials for both domestic and industrial applications. This is attributed to their applicability as bio-oils for industrial production of products like biodiesel, biolubricant, bio-transformer ﬂuids, etc., since they serve as substitute for non-renewable hydrocarbons (petroleum). This technological advancement also helps in attaining the desired global food demand/security and healthy life, for and ever growing world population; since oil seeds also provide the desired raw materials for food and pharmaceutical industries [1]. In other words, the beneﬁts of bio-oils over petroleum cannot be overemphasized because of their portability, availability, renewability, higher combustion efﬁciency, higher biode- gradability, high ﬂash point, inherent lubricity, as well as lower sulfur and aromatic contents [2,3]. As a result of afore mentioned beneﬁts, the demand for seeds and nuts for bio-oils extraction for industrial needs have increased. This has resulted in increased planting/cultivation of oil seeds/nuts, as well as trees/plants with high oil seeds bearing potentials, so as to meet the ever increasing market demand [4]. Globally, several seeds and nuts are a major source of oil for different purposes, because of their oil yields. For instance, oils from Elaeis guineensis (palm), Jatropha curcas, Sesamum indicum L. (sesame), Coco snucifera (coconut), Glycine max (soybean), Arachis hypogaea Linn. (Groundnut) and Terminalia catappa L. kernel, etc., have been recently used as raw materials for different bio-products due to their high oil yields. Hence, there is need to evaluate the utilization po- tentials of Anacardium occidentale kernels oil. Anacardium occidentale commonly known as “Cashew nut” is native to tropical America, speciﬁcally North and Northeast regions of Brazil [5,6]. The world production of cashew nut is estimated at about 2 billion tons * Corresponding author. E-mail addresses: eduetal@yahoo.com, agu.chinedum@mouau.edu.ng (C.M. Agu). Contents lists available at ScienceDirect Current Research in Green and Sustainable Chemistry journal homepage: www.elsevier.com/journals/ current-research-in-green-and-sustainable-chemistry/2666-0865 https://doi.org/10.1016/j.crgsc.2021.100255 Received 25 October 2021; Received in revised form 25 December 2021; Accepted 28 December 2021 Available online 3 January 2022 2666-0865/© 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by- nc-nd/4.0/). Current Research in Green and Sustainable Chemistry 5 (2022) 100255