Impact of Carboxymethylation Pretreatment on Bleached Rice Hull Nanofiber by Grinding

Abstract

Rice hull is a agricultural byproducts that can be a raw material for cellulose nanofiber. We produced cellulose nanofiber from rice hulls through chlorine dioxide bleaching followed by carboxymethylation and nano-grinding. We investigated the degree of pre-treament by zeta-potential, and 1H-NMR spectroscopy. The characterstics of cellulose nanofiber was measured by particle size and water holding ability. BRAfter bleaching, lignin in rice hull was removed and the lignin content of bleached rice hull decreased from 25.8% to not detected level. With carboxymethylation pretreatment, zeta potential of bleached rice hull was increased from –47.2 mV for no pretreated to –49.1 mV - –55.8 mV with different degree of carboxymethylation. Size of cellulose nanofibril was 2.5-122.6 nm and 160-866 nm in length. With increasing carboxymethylation in pretreat¬ment led to thinner width of cellulose nanofibril. Water holding properties of cellulose nanofibril varied from 940% to 2000% with different DS of pretreatment and different number of grinding.