Lin K.-SMdlovu N.VChan H.-YKEVIN CHIA-WEN WUWu J.C.-SHuang Y.-T.JEFFREY CHI-SHENG WU2022-03-222022-03-22202109205861https://www.scopus.com/inward/record.uri?eid=2-s2.0-85119428069&doi=10.1016%2fj.cattod.2021.11.017&partnerID=40&md5=e1f6161d053e67b43441515428f50a9bhttps://scholars.lib.ntu.edu.tw/handle/123456789/598212The hydrophobic and spherical PDVB-x-MeCN (x: molar ratio of p-styrene sulfonate/divinylbenzene; x = 0.0, 0.1, 0.3, 0.5, and 1.0) catalyst was synthesized via polymerization and the ion-exchange process. Moreover, the hydrophobic property of PDVB-x-MeCN with high contact angles (> 124.0?) was directly observed with a contact angle analyzer. The most appropriate x value of PDVB-x-MeCN for free fatty acid (FFA) removal and biodiesel production was 0.5, which was identified with gas chromatography (GC). During a 6-h transesterification-esterification, FFA removal and biodiesel yield of PDVB-0.5-MeCN reached 83.2% and 83.3%, respectively, at a ratio 45/1 (v/v) of methanol/palmitic acid mixture, approaching that of the Amberlyst 15 ones (83.4%). On the basis of these results, waste oils containing FFA can be transesterified efficiently from triglycerides and FFA into biodiesel. ? 2021 Elsevier B.V.BiodieselEsterificationFatty free acid removalPolymer-based solid acidic catalystTransesterificationCatalystsContact angleEstersGas chromatographyHydrophobicityIon exchangeMolar ratioPalmitic acidStyreneAcidic catalystsBiodiesel productionFree acidsFree fatty acidMesoporous polymersPolymer basedSolid acid catalystsTransesterifications[SDGs]SDG11journal article10.1016/j.cattod.2021.11.0172-s2.0-85119428069