Fractional and Structural Characterization of Ball Milled and Enzyme Lignins from Oil Palm Empty Fruit Bunch Fiber

The pure milled lignin (PML), hemicellulose rich milled lignin (HRML), pure enzyme lignin (PEL), lignin rich enzyme lignin (LREL), and solubilized lignin during enzyme treatment (SLET) fractions were obtained by 90% and 50% dioxane-water extractions from 6 days' ball milled oil palm empty fruit bunch fiber and the subsequently 3 days' cellulase-treated fiber residues, respectively. The purification was performed with a two-step precipitation method instead of traditional ether precipitation. The five lignin fractions were compared using spectroscopic and degradative techniques. The pure milled lignin and pure enzyme lignin fractions showed a very low content of associated polysaccharides (2.84-2.98%), and contained a large proportion of noncondensed syringyl units with some amounts of noncondensed guaiacyl units and fewer p-hydroxyphenyl units. They are composed mainly of β-O-4 ether bonds together with small amounts of β-5 carbon-carbon linkages. The lignin fractions also appeared to be very closely associated with hydroxycinnamic acid and glucuronic acid or 4-O-methylglucuronic acid. Glucuronic acid or 4-O methylglucuronic acid and over 83% of p-coumaric acid were identified to be esterified to lignin, and over 53% of ferulic acid was found to be linked to lignin by ether bonds

Isolation and Characterization of Organosolv Lignins From Wheat Straw

Delignification of wheat straw with aqueous methanol, ethanol, l-propanol, n-butanol, dioxane, and acetone in the presence of acid catalyst (0.02 N H2SO4) at low temperature (75°C) for 2 h was studied. The effect of ethanol-water ratios on the yield of dissolved lignin is also reported here. There was no significant difference in the organosolv lignin yields among the various organic solvents used, which accounted for 24-28% of the total amount of acidic chlorite lignin present in wheat straw. Increase of ethanol-water volume ratio from 40/60 to 70/30 resulted in raising lignin yields from 25 to 31%, while the reverse yield from 31 to 24% appeared in the increase of volume ratio from 70/30 to 90/10. The isolated organosolv lignin fractions contained low amounts of polysaccharide sugars (4.5-5.3%) and had low average molecular weights (1190-1650 Da), which corresponded with the ball-milling lignin, enzyme lignin, and alkali lignin obtained from wheat straw. The predominant components of the alkali nitrobenzene oxidation products were found to be vanillin and syringaldehyde. The yield of vanillin was slightly higher than that of syringaldehyde in all the nitrobenzene oxidation products of the isolated organosolv lignin preparations

Chemical Composition, Fiber Morphology, and Pulping of P. Bolleana Lauche

The chemical composition and fiber morphology of the P. bolleana Lauche was assessed for its suitability for pulping and papermaking. The P. bolleana Lauche used in this study contained a low amount of lignin, but higher quantities of cellulose and hemicelluloses. It was found that morphological indices of P. bolleana Lauche were adequate for pulping and papermaking. The pulping of this wood was carried out using conventional kraft and soda pulping process under varying conditions. The results indicated that at higher sulfidity (24%-32%) with lower EA (14-16%), higher yields, and viscosity of pulping were obtained with an acceptable kappa number. Kraft pulp of P. bolleana Lauche obtained at given conditions (EA 14-16%; sulfidity 24-32%) provided paper sheets with greater tensile strength, burst index and tear index, at the same beating degree

IMPACT OF HOT COMPRESSED WATER PRETREATMENT ON THE STRUCTURAL CHANGES OF WOODY BIOMASS FOR BIOETHANOL PRODUCTION

As an initial step in an alternative use of woody biomass to produce bioethanol, this work was aimed at investigating the effect of hot compressed water (HCW) pretreatment within the temperature range 100 to 200 °C in a batch-type reactor on the structural changes of Tamarix ramosissima. The untreated and pretreated solid residues were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), solid-state cross polarization/magic angle spinning (CP/MAS), 13C NMR spectroscopy, and thermogravimetric analysis (TGA), as well as chemical methods. The results showed that HCW pretreatment solubilized mainly hemicelluloses and resulted in enriched cellulose and lignin content in the pretreated solids. It was found that the deposition of lignin droplets on the residual surfaces was produced during pretreatment under the hot water conditions above 140 °C. In addition, the removal of hemicelluloses and lignin re-localisation as a result of condensation reactions under the severe pretreatment condition may lead to an increase in cellulose crystallinity and thermal stability of biomass solid residues, thus consequently influencing the downstream digestibility of biomass for sugars and bioethanol production