posted on 2015-02-25, 00:00authored byJin Gu, You-Lo Hsieh
Rice straw holocellulose was TEMPO-oxidized
and mechanically defibrillated
to produce holocellulose nanofibrils (HCNFs) at 33.7% yield (based
on original rice straw mass), 4.6% higher yield than cellulose nanofibril
(CNF) generated by the same process from pure rice straw cellulose.
HCNFs were similar in lateral dimensions (2.92 nm wide, 1.36 nm thick)
as CNF, but longer, less surface oxidized (69 vs 85%), and negatively
charged (0.80 vs 1.23 mmol/g). HCNFs also showed higher affinity to
hydrophobic surfaces than CNFs while still attracted to hydrophilic
surfaces. By omitting hemicellulose/silica dissolution step, the two-step
2:1 toluene/ethanol extraction and acidified NaClO2 (1.4%,
pH 3–4, 70 °C, 6 h) delignification process for holocellulose
was more streamlined than that of pure cellulose, while the resulting
amphiphilic HCNFs were more hydrophobic and self-assembled into much
finer nanofibers, presenting unique characteristics for new potential
applications.