Energy-Efficient Enzymatic–Ultrasonic Degumming of Ramie for Improved Eco-friendly Textile Fiber Properties

Cotton remains the most widely utilized natural fiber due to its excellent absorbency; however, its high-water demand and vulnerability to climate change have driven the search for sustainable cellulose alternatives. Ramie fiber (Boehmeria nivea L. Gaudich) offers excellent mechanical strength but requires efficient degumming to remove non-cellulosic gums. This study proposes an integrated degumming method combining ultrasonication (40 °C, 42 kHz) for 30 min with enzymatic hydrolysis using pectinase and xylanase (30–40 °C, 24–72 h (h)), followed by bleaching. Ultrasonication enhanced enzyme accessibility, reducing the residual gum and the yellowness index by 4.43% and 14.77%, respectively. The integration ultrasonication–degumming–bleaching processes achieved the highest tensile strength (1171.03 MPa). The synergistic degumming of 40 °C for 72 h achieved the highest yield with the lowest residual gum (8.78%). Prolonged enzymatic incubation yielded finer, cleaner fibers with improved crystallinity (from 39.06 to 42.64%), increased cellulose content (+ 18.57%), and reduced lignin (− 8.90%) and hemicellulose (− 2.69%). Energy consumption for the combined ultrasonic–enzymatic process was 27.1% lower than the conventional chemical method. This energy-efficient degumming has potential for sustainable textile fiber processing.