Experiment on and modeling of purification of fructooligosaccharides using ceramic nanofiltration membranes

High-purity fructooligosaccharides (FOS) with high economic value have been widely used in the food and medical fields. The use of ceramic nanofiltration (NF) membranes with narrow pore-size distributions have been proven to be a promising strategy for purifying FOS. The preliminary screening of membranes according to the retention rate of each membrane itself is more scientific than basing it only on the molecular weight cut-off. In addition, the yield, purity, membrane flux, and washing water volume of the product should be considered comprehensively. Here, the concentration of FOS feed should be controlled within 100 g·L⁻¹, with the suggested settings for transmembrane pressure, cross-flow velocity, and operating temperature being 0.7 MPa, 1.2 m·s⁻¹, and 60 °C, respectively. The model analysis showed that the NF membrane with a high separation factor and low non-prebiotic sugar rejection rate can obtain a high FOS yield and purity with less leachate addition. Moreover, the ceramic NF membrane can maintain a stable separation performance during the separation process, and the pure water flux can be recovered after cleaning, which has good application prospects in the FOS purification industry.