Preparing lignin-rich microcrystalline cellulose from spruce chemithermomechanical pulp fiber by Fe3+ enhanced high temperature liquid water treatment

摘要

A kind of lignin-rich microcrystalline cellulose (MCC) with short rod structure was successfully prepared from spruce chemithermomechanical pulp (CTMP) fibers via Fe3+ enhanced high temperature liquid water (HTLW) treatment process. During this process, hemicelluloses were selectively removed, while lignin and cellulose were partially dissolved. The alpha-cellulose content of as-prepared MCC specimens increased significantly. XRD analysis indicated that the MCC specimens exhibited higher crystallization index than original specimen and was cellulose I type. GPC and 2D NMR analyses indicated that lignin suffered strengthened depolymerization and condensation effects under the catalytic effect of Fe3+ during treatment process. These resulted in the decreased molecular weight and polydispersity index (PDI), also hindered the further dissolution of lignin component from as-prepared MCC specimens. A relatively small repose angle indicated that the as-prepared MCC exhibited a desirable fluidity comparable to the commercial MCC product. TG analysis also showed that MCC specimens exhibited better thermal stability than commercial MCC product, which might be used as a filler to enhance the thermal performance of composites. Besides, this kind of lignin-rich MCC is also expected to be used in the field of medicinal food aid and feed additive.