Purification of bioethanol fermentation broth using hydrophilic PVA crosslinked PVDF-GO/TiO_(2) membrane

The presence of impurities in the bioethanol fermentation broth should be removed to mitigate any possible ineffective refining processes as well as to enhance bioethanol production. In this study, a prefiltration process was carried out for separating fermentation yeast cells and residual substrates using a microfiltration membrane. Hydrophilic polyvinylidene fluoride-graphene oxide/titanium dioxide(PVDF-GO/TiO_(2)) membrane with polyvinyl alcohol(PVA) surface-coating modification was fabricated and characterized. Membrane modification attempts have succeeded in increasing the hydrophilicity as indicated by contact angle decline from 72.10° to 34.83° and affinity towards water leading to higher water permeability. The performance evaluation showed that 90.77% of unwanted by-products(yeast cells and residual substrate) can be removed. This high rejection is also followed by a high and stable flux performance at 40.20 L·m^(-2)·h^(-1) where the flux was increased by 13 times compared to that of the neat membrane. The PVA-coated PVDF-GO/TiO2showed the best anti-biofouling performance with a flux recovery ratio after 5 days incubation(FRR5d) of 93.55%. This membrane material has excellent prospects in future membrane development for either in-situ application or as a pre-filtration in the fermentation process to separate living cells and residual substrates before being further processed in the refining processes.