Lignocellulosic nanofibrils isolate via laccase/TEMPO-mediated oxidation for stabilizing pickering emulsions
Wangfang Deng, Yidong Zhang, Liqiu Hu, Nizam Puthiyaveettil Azeez, Chunlin Xu, Martti Toivakka
Abstract
Abstract Lignin-containing cellulose nanofibrils (LCNF) have garnered significant attention in academia and industry due to their high output, low manufacturing costs, and minimal environmental impact. In this work, we demonstrate a TEMPO/laccase/O 2 (TLO) system in water to oxidize the thermomechanical pulp (TMP), followed by homogenization to prepare LCNF. The morphology, nanostructure, and residual lignin content of LCNF could be tailored by controlling the TLO oxidation time, enabling the regulation of its crystallinity, hydrophobicity, and rheological properties. As the oxidation time increased from 24 to 96 h, the carboxylate content of LCNF gradually increased from 0.3 to 1.1 mmol/g, while the lignin content of LCNF decreased from 30.1 to 20.7%. The results of SEM, TEM, UV–Vis, and FTIR confirmed the presence of lignin in LCNF, demonstrating that fibrous network structures coexisted with lignin, which increases the amphiphilic balance of LCNF. The obtained oxidized LCNF showed enhanced emulsification ability compared to unoxidized LCNF, stabilizing the Pickering emulsion with a relatively narrow distribution of droplet size around 3.8 – 7.6 µm and maintaining emulsion stability for over 7 days. This work presents a green pathway for achieving sustainable production of LCNF and provides practical guidance for potential applications of LCNF-based Pickering emulsions in foodstuff, cosmetic, and pharmaceutical formulations.