Mineralization and physicochemical characteristics of Lycium barbarum L. leaf cellulose detected using the basic alkali/acid extraction

Abstract

This study aimed to depict the mineral deposition on the cellulose extracted from mineral-rich Lycium barbarum L. leaves by the basic base/acid treatment. Alkali treatment made the cellulose fluffy, and the leaf phytoliths changed to liquid silicon, depositing onto the fluffy cellulose in crystalline forms, with the mineral content (mainly Si, Ca, and Al) reaching 9.41 % in cellulose after 24 h alkali treatment. Acid treatment decreased the deposited minerals affecting the cellulose crystallinity. Sulfuric acid (SA) mainly eroded the cellulosic amorphous zone and the attached minerals, and crystallized minerals (mainly quartz-SiO2) remained in the crystalline zone, increasing the cellulose crystallinity (66.8 %). Hydrofluoric acid (HF) indiscriminately removed nearly all minerals regardless of crystalline and amorphous zones, thus lowering the crystallinity. Further application research showed that the ability of the SA-refining cellulose to stabilize emulsion (89.8 %) was much stronger than that of the HF counterpart (62.6 %), and the mineral-relevant cellulose crystallinity determined the emulsion stability. These findings might help in understanding the impact of the basic extraction on cellulosic mineralization and quality and shed light on the development of novel functional cellulose.

Keywords

• Cellulose extraction
• Crystallinity
• Crystal mineralization
• High-mineral cellulose
• Pickering emulsion