Extraction of Cellulose Nanofibrils (CNFs) from Pomelo Peel via a Green and Simple Method

Abstract

Pomelo is cultivated worldwide due to its unique taste. Most of the pomelo peel is discarded, thus, wasting the beneficial ingredients contained in it. In order to effectively utilize these ingredients, a green and low-consumption method has been reported here to extract the cellulose nanofibrils (CNFs) from the pomelo peel by employing the sequential alkaline treatment, bleaching, acid hydrolysis, and ball milling. The results demonstrate that the impurities in the pomelo peel, such as hemicellulose and lignin, are gradually removed. The obtained CNFs still maintain their natural cellulose structure. The degree of crystallinity and thermal stability of CNFs are noted to be significantly improved as compared to the raw pomelo peel. The CNF diameter is observed to range between 6 and 47 nm. Compared with 10–17.5% NaOH/KOH and 60–65% HNO3/H2SO4 used in previous studies, the developed method requires a low concentration of the alkali solution and bleaching agent. Further, the lemon juice, used as an acidolysis agent, is inexpensive and environmentally friendly. The ball milling purifies the CNFs and effectively reduces the size of CNFs without consuming a significant amount of energy. This study lays a foundation for an effective use of the agricultural solid waste based on pomelo peel.

Keywords

• pomelo peel
• extraction
• cellulose nanofibrils
• lemon juice hydrolysis