Recovery of saccharides from lignocellulosic hydrolysates using nanofiltration membranes: a review

Abstract

The use of lignocellulosic biomass as feedstock in the production of second generation of bioethanol has gained significant attention due to environmental sustainability concern and the rising issue of global waste. The biomass is typically hydrolysed to release the fermentable sugars that will further utilized in ethanol fermentation. However, bioethanol production from lignocellulosic biomass still struggling with the separation and purification of the biomass hydrolysates. The main obstacle is to deal with the inhibitory compounds that generated along with sugar molecules during hydrolysis process. Inhibitors such as acetic acid, formic acid, furfural and HMF are toxic for the downstream process of bioethanol production and must be removed prior to the fermentation step. Recently, nanofiltration membrane shows a great potential in biorefineries of small molecules like sugars. The optimum efficiency of this membrane technology is influenced by many factors such as transport mechanism, membrane materials, and the operating conditions such as temperature, pH, pressure, feed concentration. Thus, this paper will comprehensively review the effect of these parameters on the nanofiltration performance that mainly reflected by permeate flux and solute rejection. The present paper also outlines the challenges and outlook of membrane technology on saccharide recovery for improvement of the membrane productivity.