Evaluation of Aqueous Ammonia Degumming of Ramie Fiber and Recyclability of Black Liquor

In this study, the effects of aqueous ammonia on the fiber properties were evaluated, and its potential for application in recycling degumming was also investigated. The results show that the degumming rate of fibers could reach 86.83% after treatment with aqueous ammonia (at 170.6 °C for 164 min with an ammonia concentration of 11.67%), while 98% of cellulose was retained. When the black liquor was cycling reused in degumming, the residual gum rate of the fibers was less than 5%, with significant removal of noncellulosic substances after the third cycle of degumming. The degummed fibers exhibited a 1.7-fold increase in tenacity and a 1.5-fold increase in breaking elongation compared with the raw fiber. Additionally, approximately 18% of the ammonia was recovered from the black liquor after three cycles of reusing. To summarize, the recycling degumming of ramie fibers using aqueous ammonia offers the advantages of being a recyclable solvent with high degumming efficiency, thus enhancing the potential application of natural fibers.