Sugar concentration and detoxification of clarified biomass hydrolysate by nanofiltration

• Nanofiltration used to concentrate sugars in solutions and in biomass hydrolysates.
• Nanofiltration used to remove hydrolysis degradation products.
• Selection of nanofiltration membrane may be guided by surface characterization.
• Membrane performance depends on membrane surface properties.

Development of efficient unit operations is critical in order to design economically viable processes for conversion of lignocellulosic biomass into chemicals and fuels. Here the use of nanofiltration membranes for concentration of sugars in a lignocellulosic biomass hydrolysate has been explored. In addition, simultaneous removal of compounds such as acetic acid, 5-(hydroxymethyl)furfural and furfural which are inhibitory to the microorganisms used in the subsequent fermentation step has also been investigated. Dead-end filtration experiments have been used to test a number of commercially available nanofiltration membranes under a range of operating conditions. Model feed streams as well as real hydrolysates have been tested. The results obtained here indicate that both concentration of sugars and removal of hydrolysis degradation products are feasible. However careful selection of the membrane and operating conditions are essential. The introduction of a nanofiltration step for concentration of sugars and removal of hydrolysis degradation products could enable the development of a continuous process for biomass hydrolysis.