Abstract
Glucosamine hydrochloride (GAH) and N-acetyl glucosamine (NAG) are chitin derivatives. Owing to their excellent biological activity, they have long been used as pharmaceuticals and nutraceuticals. However, both of them exist simultaneously in chitin hydrolyzate or fermentation production. The aim of this study is to identify the feasibility of separating GAH and NAG by nanofiltration on the basis of appropriate adjustments of physical conditions. One commercial spiral nanofiltration membrane (QY-5-NF-1812) was used. Experiments were carried out in full recycle mode and the membrane separation performance was investigated at various mass ratios (mass ratios of GAH to NAG were from 1:14 to 1:2), pressures (4–22 bar), temperatures (15–35 °C), and electrolytes (NaCl, MgSO4, and MgCl2). The influence of temperature on molecular characteristics that play an important role in the separation process was also studied. Owing to the steric-hindrance effect, electrostatic effect, and different solute permeability, the GAH separation factor increased with increasing GAH concentration. Furthermore, upon temperature increasing, the permeability difference between GAH and NAG decreased, thus decreasing the GAH separation factor. Simultaneously, with increasing temperature, the polarities and calculated molecular diameters for both GAH and NAG increased evidently. The calculated reflection coefficients for both GAH and NAG can be well fitted by the steric-hindrance pore (SHP) model, suggesting that steric-hindrance effect played an important role on the separation process. Furthermore, owing to Donnan repulsion and solute diffusion effects, three electrolytes had noticeable effects on nanofiltration separation efficiency. The nanofiltration separation efficiency of GAH and NAG was significantly affected by their physical properties in this system, and the mechanisms for GAH and NAG separation were elucidated. The current study could provide a certain basis for the nanofiltration separation of GAH and NAG on an industrial scale.
Highlights
Glucosamine hydrochloride (GAH) and N-acetyl glucosamine (NAG) are chitin derivatives
The slope deviation from linearity occurs at the higher pressures, in the case of GAH:NAG with 1:14 because of the concentration polarization exacerbated owing to NAG accumulation at the membrane surface by the driving pressure
Feed flux increases with increasing GAH:NAG ratio
Summary
Glucosamine hydrochloride (GAH) and N-acetyl glucosamine (NAG) are chitin derivatives. Owing to their excellent biological activity, they have long been used as pharmaceuticals and nutraceuticals. Both of them exist simultaneously in chitin hydrolyzate or fermentation production. The aim of this study is to identify the feasibility of separating GAH and NAG by nanofiltration on the basis of appropriate adjustments of physical conditions. Glucosamine hydrochloride (GAH) and N-acetyl glucosamine (NAG) are widespread (Chen et al 2012). Given that GAH and NAG have significant biological activity and can be used as ligands in coordination chemistry (Tao et al 2014), both of them have long been used as pharmaceuticals and nutraceuticals to treat. Nanofiltration (NF) technology is a good approach for separation due to their advantages, including lower energy consumption, sustainable processing and relatively easy scale-up over other filtration procedures (Kolfschoten et al 2011; Aroon et al 2010)
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