Contentslistsavailableat ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel FullLengthArticle Theoptimizationofoilextractionfrommacroalgae, Rhizoclonium sp.by chemicalmethodsforefcientconversionintobiodiesel Boonyawee Saengsawang a ,PrakashBhuyar b ,NumchokManmai a ,VinothKumarPonnusamy c , Rameshprabu Ramaraj a ,YuwaleeUnpaprom d, ⁎ a School of Renewable Energy, Maejo University, Chiang Mai 50290, Thailand b Biotechnology Laboratory, Faculty of Industrial Sciences & Technology, Universiti Malaysia Pahang, 26300 Pahang, Malaysia c Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, 807, Taiwan d Program in Biotechnology, Faculty of Science, Maejo University, Chiang Mai 50290, Thailand GRAPHICALABSTRACT ARTICLEINFO Keywords: Rhizoclonium sp. Transesterifcation FAME Responsesurfacemethodology(RSM) ABSTRACT Optimization of biodiesel production from freshwater macroalgae, Rhizoclonium sp. was investigated in this study.Biodieselproductionprocessparameterssuchaschemicalsolventextraction,hexane:etheranddiferent extractiontechniqueswereoptimizedbyusingtheresponsesurfacemethodologybasedonthecentralcomposite design. Optimization of the transesterifcation process was conducted by varying two factors each at three diferentlevelsandthisrequiredatotalofthirteenruns.Aquadraticmodelwascreatedtopredictthebiodiesel yieldwheretheR 2 valuewasfoundtobe0.97,whichindicatesthesatisfactoryaccuracyofthemodel.Basedon the results, the optimum process parameters for transesterifcation of the macroalgae Rhizoclonium sp. oil mixtureatanagitationspeedof300rpmoveraperiodof180minwasfoundtobeahexane:ethermolarratio 1:1(40mL),NaOHcatalystconcentrationof1wt%andreactiontemperatureof45°C.Finally,aprocessopti- mizationfoundhighestmacroalgaeoilbysimpletreatmentwas0.376 ± 0.14gandultrasonictreatmentwas 6.044 ± 0.81 g is the highest of biodiesel weight. For transesterifcation reaction frommacroalgaeoil,atri- glyceride was mixed with 0.25 g methanol converted to biodiesel into methyl esters. The biodiesel weight https://doi.org/10.1016/j.fuel.2020.117841 Received23February2020;Receivedinrevisedform18March2020;Accepted10April2020 ⁎ Correspondingauthor. E-mail address: yuwalee@mju.ac.th (Y.Unpaprom). Fuel 274 (2020) 117841 Available online 16 April 2020 0016-2361/ © 2020 Published by Elsevier Ltd. T