Integrated Forest Biorefinery:Value-added Utilization of Dissolved Organics in the Prehydrolysis Liquor of Prehydrolysis Kraft (PHK) Dissolving Pulp Production Process

The concept of integrated forest biorefineries(IFBRs) has gained significant interest.The prehydrolysis kraft(PHK) dissolving pulp production process is a suitable example of IFBR concept for the production of dissolving pulp and utilization of dissolved hemicelluloses,acetic acid,and lignin in the prehydrolysis liquor(PHL).This review paper highlights recent progress related to the recovery and utilization of dissolved organics(e.g.,hemicelluloses,acetic acid,and lignin) in the PHL of the PHK dissolving pulp production process.Integrated multi-step recovery and separation processes have been developed for this purpose to accommodate the complex nature of the PHL.Potential products,including xylan-based compounds,acetic acid,and lignin,are also discussed in detail.

Effect of Acetic Acid Prehydrolysis on Unbleached Bamboo Pulp Production

Bamboo was used as raw material for unbleached pulp production.An acetic acid prehydrolysis process was employed before the pulping process.The effect of acetic acid prehydrolysis on pulp properties was investigated.The results showed that some components,such as hemicellulose and extractives,were degraded or dissolved in the prehydrolysis process prior to kraft pulping.SEM images of the substrate after treatment indicated that the parenchyma cell wall was thinner,and the size of pores between fiber bundle cell walls was larger.The pulping results showed that acetic acid prehydrolysis could improve the pulp quality and make the pulp easier to bleach.The brightness of the pulp reached 59.6%ISO with a single oxygen delignification step.The acetic acid prehydrolysis decreased pulp viscosity and fiber length,but not significantly.The amount of parenchyma cells in the pulp was reduced,which was beneficial for papermaking and improving mechanical strength of paper.This procedure has good potential for unbleached pulp production.

Wet oxidation of activated carbon for enhanced adsorptive removal of lignin from the prehydrolysis liquor of kraft-based dissolving pulp production in an integrated forest biorefinery

Prehydrolysis is a key step for the production of kraft-based dissolving pulp.The pre-hydrolysis liquor mainly contains hemicellulosic components.Lignin can also be released into the pre-hydrolysis liquor,which hinders the purification and utilization of these hemicellulosic components.In this work,wet oxidation of activated carbon with nitric acid was employed to enhance the adsorptive removal of lignin from the pre-hydrolysis liquor.Under mild oxidation conditions(2%nitric acid solution),the oxidization of activated carbon resulted in significant enhancement of lignin removal.Adsorption isotherms showed that the specific surface area and the amount of carboxyl groups were affected by the oxidation treatment.The selective removal of lignin fitted well with the pseudo-second order kinetics model.

Synthesis of Amino Silicone Resins by Three-Step Method and Characterization

Amino silicone resins were synthesized through a three-step method using （3-aminopropyl） triethoxysilane （APTES）, methyltrimethoxysilane （MTMS） and end-capping agents, The products were characterized by Fourier transformed infrared spec- troscopy （FT-IR）, nuclear magnetic resonance （ 1 H NMR）, element analysis and gel permeation chromatography （GPC）. The results of 1 H NMR indicate that the chemical shift signal of acid-catalyzed products is weak at δ3.4 （attributing to alkoxy）. FT-IR shows that there is a vibration peak of Si-OH at 3 100-3 600 cm 1 and the intensity of the peaks is most weak at 6h. The results show that this method cannot only effectively reduce the residue of alkoxy groups and Si-OH groups, but also obtain the products with sufficient amino group. It concludes that this resin is suitable as modifier in the silicone rubber.