Nanofiltration of biorefinery process streams containing sugars and impurities

Description

To use monomeric biomass sugars, e.g. derived from hydrolysis and sulphite processes, as raw material for further conversion some byproducts have to be removed. Mainly organic acids, furanaldehydes, and phenolic compounds have been identified as toxic for many fermentation processes. The separation of these impurities from the sugars by means of nanofiltration was investigated in more detail. The aim was to separate the stream in a way that sugars are concentrated in the retentate while impurities can be discharged with permeat. Different commercially available nanofiltration membranes were tested with a model compound solution on a lab-scale device. The model solution for the membrane screening contained acetic acid, HMF, sulfate, gluconic acid, glucose and xylose. Some of the tested membranes showed high retention of sugars but not sufficient flux for the impurities. Others exhibited a very low and even negative retention for impurities on the one hand, but on the other hand the retention of sugar was not sufficient. In all cases, high transmembrane pressure had to be applied to maintain sufficient flux. With the most promising membrane an extensive parameter study (Design of Experiments) was done to investigate a satisfying compromise between detoxification and sugar retention. Parameters under investigation were temperature, pH-value and the concentration of sugar and other components in the solution. Based on that, the separation behavior of the membrane can be predicted and possible operational windows - meeting defined purification targets - could be suggested.

Period	17 May 2018
Event title	Paper and Biorefinery Graz 2018
Event type	Conference
Location	AustriaShow on map