Removal of furfural and HMF from monosaccharides by nanofiltration and reverse osmosis membranes

Ethanol can be produced from lignocellulosic biomass through fermentation. However, some inhibitory compounds are also generated, and can substantially reduce the efficiency of ethanol production. In the present work, two commercial nanofiltration (NF) membranes and two commercial reverse osmosis (RO) membranes were utilized to remove the model fermentation inhibitors, furfural and 5-hydroxymethyl-2-furaldehyde (HMF), from the synthetic xylose-glucose-furfural-HMF model solution. The influences of operating parameters such as pH, pressure, temperature and solute concentration in feed on the separation performance of the tested membranes were investigated. The selectivities of furfural and HMF from monosaccharides by NF/RO membranes were compared to evaluate the feasibility of simultaneous inhibitor removal and sugar concentration. Results showed that RO membranes are more efficient than NF membranes for retaining monosaccharides under all tested conditions. RO membranes are more suitable than NF membranes for sugar concentration and removal of some inhibitors from lignocellulose hydrolyzate simultaneously.