Contents lists available at ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel Full Length Article Bioethanol production from the comparison between optimization of sorghum stalk and sugarcane leaf for sugar production by chemical pretreatment and enzymatic degradation Numchok Manmai a,b , Yuwalee Unpaprom c , Vinoth Kumar Ponnusamy d, ⁎ , Rameshprabu Ramaraj b, ⁎ a Department of Forestry, National Chung Hsing University, Taichung 402, Taiwan b School of Renewable Energy, Maejo University, Chiang Mai 50290, Thailand c Program in Biotechnology, Faculty of Science, Maejo University, Chiang Mai 50290, Thailand d Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung City 807, Taiwan GRAPHICALABSTRACT ARTICLEINFO Keywords: Agriculture wastes Chemical pretreatment Enzymatic hydrolysis and Bioethanol production Central composite design (CCD) ABSTRACT This work reports the comparison of optimized pretreatment models on total sugar (TS) production from su- garcane leaf (SL) with sorghum stalk (SS) utilization to decompose the lignocellulosic biomass into oligo- saccharide(OS).Theaccumulationvariableswereexaminedinthepretreatmentmodel,includingpretreatment time (1–3 days), concentrations of sodium hydroxide (NaOH) from 1 to 2% (w/v), and heating temperatures from 30 to 40 °C. TS productions were optimized by using response surface methodology (RSM) on central composite design (CCD) models. These models indicated excellent determination coefcients (R 2 )rangedfrom 0.9820 to 0.9900 and are signifcant. Process optimization showed that the highest TS yield was achieved of 32.612g/Land38.977g/LforNaOHpretreatmentatcondition(2)%(w/v)NaOHatthetemperatureof40°C for3days.Afterpretreatment,thebiomasswasdegradedusingacellulaseenzymetoformthefermentablesugar for ethanol production by Saccharomyces cerevisiae TISTR5020. The maximum bioethanol yield of https://doi.org/10.1016/j.fuel.2020.118262 Received23March2020;Receivedinrevisedform1May2020;Accepted27May2020 ⁎ Corresponding authors. E-mail addresses: kumar@kmu.edu.tw (V.K. Ponnusamy), rrameshprabu@gmail.com, rameshprabu@mju.ac.th (R. Ramaraj). Fuel 278 (2020) 118262 0016-2361/ © 2020 Elsevier Ltd. All rights reserved. T