Continuous biodiesel production from acidic oil using a combination of the acid-, alkali-catalyzed membrane and GO/PVDF separation membrane

An integrated process of esterification with phosphotungstic acid/poly (ether sulfone) (PWA/PES) membrane, transesterification with alkalized polysulfone (APSF) membrane and Graphene Oxide/poly (vinylidene fluoride) (GO/PVDF) separation membrane was carried out to produce biodiesel from acidic oil. At the first step, the PWA/PES membrane was introduced to catalyze the esterification reaction. The morphology, maximum pore size, porosity and catalytic esterification performance of PWA/PES membrane were investigated. After the esterification, products and reactants without reaction were put into the GO/PVDF separation membrane to soybean oil and other substances. The permeation mixture flux and soybean oil rejection of the GO/PVDF separation membrane is 597.89 L/m(2).h and 98.02%, respectively. At the second step, the APSF membrane was added to catalyze the transesterification reaction in which the soybean oil reacted with methanol. The results showed that the esterification conversion was 98.6% and transesterification conversion was 91.2%. The main parameters of the biodiesel product obtained meet the Chinese Standard (GB/T 20828) and European Standard (EN 14214). (C) 2021 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.