Cleaner strategy for the scouring and bleaching of flax rove with enzymes in supercritical carbon dioxide
2019
Zhang, Juan | Qiao, Yan | Zu, Xiuxia | Zheng, Huanda | Gao, Shihui | Zheng, Laijiu
A novel and eco-friendly approach was developed for the scouring and bleaching of flax roves with xylanase, cellulase and mixed enzymes (xylanase and cellulase) in supercritical carbon dioxide fluid (SC-CO2). The results showed that significant improvements in the whiteness and residual gum content of flax roves were achieved in SC-CO2 since xylanase hydrolysed xylan into low molecular oligosaccharides, xylobiose and xylose by hydrolyzing and cleaving β-1,4-glucosidic bonds of xylan. Simultaneously, the hydrolysis reaction of lignin through the hydrophobic and electrostatic interactions at β-O-4 linkages could be effectively facilitated by the catalyst of cellulase in SC-CO2. Furthermore, the whiteness and residual gum content of flax roves were notably influenced by the dosage of enzyme, enzyme ratio, scouring and bleaching temperature, pressure, time and CO2 flow. An optimized enzymatic process for the scouring and bleaching of flax roves was recommended with a dosage of enzyme 3%, an enzyme ratio of 2: 1 (xylanase: cellulase), a system temperature of 50 °C, a pressure of 20 MPa, a CO2 flow of 30 g/min for 90 min in SC-CO2. The whiteness value of flax roves reached to 42.3%, and the value of residual gum content was decreased to 16.95% in the optimum condition.
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