Evaluation of natural hemicellulose additive from waste resource of Lanzhou lily for eco-friendly water-based lubricant

The development of functional, cost-effective, and environmentally benign additives is critical for enhancing the lubricity of water-based fluids. This study proposes hemicellulose, isolated from abundant lily stem waste, as a novel bio-based lubricant additive, leveraging its natural abundance, non-toxicity, and unique polysaccharide structure capable of forming protective tribo-films. Through alkaline extraction and ethanol precipitation, hemicellulose was obtained with a xylose content of 52.13 % (High-performance anion-exchange chromatography) and molecular weight of 124 kDa (Gel permeation chromatography). Rheological tests of hemicellulose solutions demonstrated concentration-dependent viscosity enhancement, from 0.95 mPa·s (0.5 wt.%) to 2.31 mPa·s (2 wt.%) at 50 s^-¹. Tribological evaluations showed that 2 wt.% hemicellulose reduced the friction coefficient by about 50 % (20–80 N) and decreased wear rate by one order of magnitude at 60–80 N compared to water, while extended effective lubrication to load of 100 N without performance degradation. Surface analysis (Scanning electron microscope / X-ray photoelectron spectroscopy / Transmission electron microscope) confirmed a thin (about 10 nm), dense boundary film via hemicellulose adhesion, effectively preventing metal-to-metal contact. This work validates hemicellulose as a sustainable, high-performance lubricant additive and offers a promising pathway for agricultural waste valorization in eco-friendly lubrication systems.