Chlorine dioxide removes lignin for high-purity cellulose

Chlorine dioxide (ClO 2 ) is a strong oxidative free radical. Under its oxidative action, lignin was effectively degraded at temperatures between 50 and 80 °C. However, excessively high temperatures can lead to energy waste and enhance chlorination by-reactions, resulting in the formation of harmful substances. Therefore, this study constructed a high-concentration chlorine dioxide oxidation method, whereby lignin in pulp was effectively removed at room temperature (25 °C). Through efficient recycling of chlorine dioxide, the remaining ClO 2 does not increase costs, and the physicochemical properties of the pulp before and after treatment indicate that high concentrations of ClO 2 at room temperature do not damage the fibers. Using a ball-milling device, a nanocellulose membrane with good air permeability was prepared. Molecular dynamics simulations demonstrate that the reaction between lignin molecules and ClO 2 molecules is primarily guided by van der Waals interactions, with a lesser contribution from electrostatic forces. This finding provides a novel method for fiber purification at room temperature and proposes a feasible approach for the valorization of cellulose.