Preparation of Highly Reactive Lignin by Ozone Oxidation: Application as Surfactants with Antioxidant and Anti-UV Properties

Enhancement of lignin reactivity plays a critical role in the chemical modification of lignin. In the current study, a simple, green, and effective method, of ozone oxidation, was developed to improve the reactivity of enzymatic lignin through the formation of carboxyl groups. The resultant ozonate of enzymatic lignin (OzEL) indicated a higher reactivity of esterification. We report the ozonated enzymatic lignin grafted to polyethylene glycol (OzEL-PEGs) afforded satisfactory water solubility, good surface activity, and good emulsifying properties. The remaining phenolic hydroxyl groups in OzEL-PEGs also maintain excellent antioxidant and UV absorbing properties. This ozone oxidation process provides an effective and green method for the preparation of highly reactive lignin, which can be applied in the manufacture of a multifunctional lignin polymer.