Acidic deep eutectic solvent treatment for viscosity control and reactivity enhancement of bamboo dissolving pulp

This work demonstrated a green process using deep eutectic solvent (DES) treatment for properties improvements of bamboo dissolving pulp. Results showed that an acidic DES, namely choline chloride-oxalic acid, was the most effective compared to other acidic, alkaline and neutral DESs. Upon the optimum acidic DES treatment (pulp to DES ratio 1:10, 60 degrees C and 30 min), the pulp viscosity was reduced from 715 mL/g of original pulp to 466 mL/g, while the pulp reactivity increased from 43.0 to 88.1%. The positive results were mainly ascribed to a synergy during the DES treatment: (1) a large number of activated protons (H+) from the acidic DES depolymerized the cellulose chain and destroyed the fiber structure; (2) the vigorous hydrogen bonding competitions between fibers and DES (Ch(+) and Cl-) facilitated the fiber swelling and reaction efficiency, thus increasing fiber accessibility/reactivity. DES also featured a high recyclability/reusability after serval reuses. Therefore, this work offers a sustainable and effective alternative for production of premium bamboo dissolving pulp. [Graphics]

Automated summary

This study demonstrated a green process using deep eutectic solvent (DES) treatment to improve the properties of bamboo dissolving pulp. The results showed that the most effective DES was an acidic one called choline chloride-oxalic acid. Under the optimal treatment conditions, the viscosity of the pulp decreased and the reactivity increased. The positive results were attributed to the depolymerization of cellulose chain and improved fiber swelling and reaction efficiency during DES treatment.