Study of the microwave-assisted hydrothermal extraction of polysaccharides from agave fiber: production of hollow cellulose fibers

This research work demonstrated that the extraction components from natural fibers (NFs) during microwave-assisted hydrothermal treatment is a selective and controllable method, since the process and the extraction mechanism depend on the dielectric heating (DH) of the lignocellulosic components of NFs, mainly hemicellulose, and cellulose. DH causes hemicellulose degradation, which allows its extraction from the internal part of NFs to the reaction medium (water). Moreover, the cellulose fraction showed high thermal stability; in this regard, the treated fiber (MW-NF) increased its crystallinity percentage from 80.91 to 96.23%, and the thermal degradation temperature shifted from 182 to 240 °C, maintaining its fibrillar morphology even when the fibers present a hollow aspect. Furthermore, a direct relationship between time/energy and extraction percentage was established, which allowed controlling of the final properties of the treated NFs. Graphical abstract