TY - JOUR
T1 - High performance separation of xylose and glucose by enzyme assisted nanofiltration
AU - Morthensen, Sofie Thage
AU - Luo, Jianquan
AU - Meyer, Anne S.
AU - Jørgensen, Henning
AU - Pinelo, Manuel
PY - 2015
Y1 - 2015
N2 - An integrated membrane system was investigated for the separation of mixtures of xylose and glucose. Separation of these sugars is extremely challenging due to their similar structure, size and charge. In order to enhance the xylose separation factor in nanofiltration (NF), we present an enzymatic process for converting glucose to gluconic acid followed by separation of xylose from gluconic acid by nanofiltration. Process conditions which favored the negative charge repulsions between gluconic acid and the NF270 membrane were examined. At the best conditions (9:1 feed molar ratio of xylose to gluconic acid, 0.15M total feed concentration, pH 9.5, 25°C and 4bar), we achieved a xylose separation factor of 34 and a throughput of 18.7Lm−2h−1. In comparison, the separation factor was only 1.4 for solutions of xylose and glucose at the same process conditions, thus demonstrating the huge potential of the integrated system. Full conversion of glucose to gluconic acid assisted by glucose oxidase (GOD) could be achieved by coupling a parallel reaction catalyzed by catalase (CAT), where H2O2 (GOD-inhibitor formed in the first reaction) was decomposed to water and oxygen. GOD has a high oxygen-demand and it was demonstrated that sufficient oxygen could be obtained by controlling the CAT-catalyzed reaction through initial H2O2 addition. The new strategy suggested in this study, integrating reaction and nanofiltration to enhance separation while obtaining another value-added stream, presents new options for separating compounds with similar molecular weights by nanofiltration.
AB - An integrated membrane system was investigated for the separation of mixtures of xylose and glucose. Separation of these sugars is extremely challenging due to their similar structure, size and charge. In order to enhance the xylose separation factor in nanofiltration (NF), we present an enzymatic process for converting glucose to gluconic acid followed by separation of xylose from gluconic acid by nanofiltration. Process conditions which favored the negative charge repulsions between gluconic acid and the NF270 membrane were examined. At the best conditions (9:1 feed molar ratio of xylose to gluconic acid, 0.15M total feed concentration, pH 9.5, 25°C and 4bar), we achieved a xylose separation factor of 34 and a throughput of 18.7Lm−2h−1. In comparison, the separation factor was only 1.4 for solutions of xylose and glucose at the same process conditions, thus demonstrating the huge potential of the integrated system. Full conversion of glucose to gluconic acid assisted by glucose oxidase (GOD) could be achieved by coupling a parallel reaction catalyzed by catalase (CAT), where H2O2 (GOD-inhibitor formed in the first reaction) was decomposed to water and oxygen. GOD has a high oxygen-demand and it was demonstrated that sufficient oxygen could be obtained by controlling the CAT-catalyzed reaction through initial H2O2 addition. The new strategy suggested in this study, integrating reaction and nanofiltration to enhance separation while obtaining another value-added stream, presents new options for separating compounds with similar molecular weights by nanofiltration.
KW - Nanofiltration
KW - Xylose
KW - Glucose oxidase
KW - Catalase
KW - Gluconic acid
U2 - 10.1016/j.memsci.2015.05.025
DO - 10.1016/j.memsci.2015.05.025
M3 - Journal article
VL - 492
SP - 107
EP - 115
JO - Journal of Membrane Science
JF - Journal of Membrane Science
SN - 0376-7388
ER -