Evaluation of recycling degumming and solvent recovery of ramie with high-boiling glycol solvent

Abstract

The high-boiling alcohol degumming paves an innovative approach to the environment-friendly and high-efficiency preparation of ramie fiber, while it remains challenging to the high reagent cost and discharge of black liquor. In this work, the possibility of glycol recycling degumming and solvent recovery was investigated, and the influence of recycling times of degumming liquid on fiber structure and physical properties, recovery rate of solvents and functional groups in black liquor solids was appraised. The results revealed that each cycle of degumming removed all the wax and pectin in ramie, achieved above 95.5 % of cellulose, and reached 71.3 ∼ 73.5 % of fiber yield, 4.9 ∼ 6.0 dtex of linear density, 5.5 ∼ 8.7 cN/dtex of tenacity, respectively, which fulfilled the requirement of spinning process. Hence, it suggested that degumming solution could be reused at least five times in the recycling degumming process of ramie, of which the first, second and third cycles of degumming gained the best physical properties of fiber. Furthermore, solvent recovery rate reached 99.41 % after the first degumming, and still as high as 98.93 % after the fifth cycle of degumming, indicating a superior solvent recovery. A relatively complete structure of lignin was contained in the black liquor solid, and the contents of lignin and hemicellulose gradually accumulated with the increase of the number of degumming cycles. To sum up, the recycling degumming of ramie with glycol has the prominent feasibility of reducing reagent cost, environmental pollution, and realizing resource recycling, which raised the application prospects of natural fiber isolation.