Separation of high polymerization-degree cellulose and high-quality lignin from bamboo by integrated alkali-deep...

The bamboo cellulose was mostly produced by traditional alkaline pulping, which was energy-intensive and caused a sharp decline in the degree of polymerization of cellulose, and the lignin was severely condensed with poor quality. Hence, an alkaline pretreatment followed by deep eutectic solvent process was proposed to produce high polymerization-degree cellulose and high-quality lignin simultaneously. The results showed that 57.21 % of bamboo hemicellulose and 60.70 % of ash were removed after alkali treatment at 70 °C. And cellulose content increased from 53.55 % to 66.37 %, which also broke the tight and stubborn characteristics of the dense structure. After that, Cellulose pulp with high α-cellulose (82.15 %) and high degree of polymerization (DP = 1280) can be obtained after mild DES cooking (110 °C, 50 min). Furthermore, the isolated lignin exhibited a narrow molecular weight distribution, enhanced thermal stability, and reduced condensation degree. In brief, this integrated biorefining approach gave a novel route to produce value-added cellulose and lignin products.