Jinhao Huang

Improving Rheology and Enzymatic Hydrolysis of High-Solid Corncob Slurries by Adding Lignosulfonate and Long-Chain Fatty Alcohols

The effects of lignosulfonate (SXSL) and long-chain fatty alcohols (LFAs) on the rheology and enzymatic hydrolysis of high-solid corncob slurries were investigated. The application of 2.5% (w/w) SXSL increased the substrate enzymatic digestibility (SED) of high-solid corncob slurries at 72 h from 31.7 to 54.0%, but meanwhile it increased the slurrys yield stress and complex viscosity to make the slurry difficult to stir and pump. The smallest molecular weight (MW) SXSL fraction had the strongest enhancement on SED. The SXSL fraction with large MW had a negative effect on rheology. n-Octanol (C8) and n-decanol (C10) improved the rheological properties of high-solid slurry and are strong enough to counteract the negative effect of SXSL. Furthermore, C8 and C10 clearly enhanced the enzymatic hydrolysis of high-solid corncob slurries with and without SXSL. A mechanism was proposed to explain the observed negative effect of SXSL and the positive effect of LFAs on the rheological properties.

Using polyvinylpyrrolidone to enhance the enzymatic hydrolysis of lignocelluloses by reducing the cellulase non-productive adsorption on lignin

Polyvinylpyrrolidone (PVP) is an antifouling polymer to resist the adsorption of protein on solid surface. Effects of PVP on the enzymatic hydrolysis of pretreated lignocelluloses and its mechanism were studied. Adding 1g/L of PVP8000, the enzymatic digestibility of eucalyptus pretreated by dilute acid (Eu-DA) was increased from 28.9% to 73.4%, which is stronger than the classic additives, such as PEG, Tween and bovine serum albumin. Compared with PEG4600, the adsorption of PVP8000 on lignin was larger, and the adsorption layer was more stable and hydrophilic. Therefore, PVP8000 reduced 73.1% of the cellulase non-productive adsorption on lignin and enhanced the enzymatic hydrolysis of lignocelluloses greatly.

Enhancing enzymatic hydrolysis of xylan by adding sodium lignosulfonate and long-chain fatty alcohols.

Sodium lignosulfonate (SXSL) and long-chain fatty alcohols (LFAs) could enhance the enzymatic hydrolysis of xylan, and the compound of SXSL and LFAs have synergies on the enzymatic hydrolysis. SXSL shows a strong enhancement in buffer pH range from 4.0 to 6.0. The enhancement increased with the SXSL dosage and the xylanase loading. The cellulose and lignin in corncob substrate could not only adsorb xylanase nonproductively, but also seriously reduce the accessibility of xylanase on xylan to impede the enzymatic hydrolysis of xylan. Cellulase could break the plant cell wall structure of corncob and make additives work better. The xylose yield of corncob at 72h increased from 59.4% to 73.7% by adding the compound of 5g/L SXSL and 0.01% (v/v) n-decanol, which was higher than that without cellulase and additives by 30.7%. Meanwhile, the glucose yield at 72h of corncob increased from 45.8% to 62.3%.

Aggregation of sodium lignosulfonate above a critical temperature

Abstract Single molecules of sodium lignosulfonate (NaLS) were prepared and their aggregation behavior was studied as a function of temperature. The molecular dispersity of the NaLS solutions were confirmed by dynamic light scattering (DLS), and the aggregation behavior was studied by DLS and static light scattering (SLS), fluorescence spectrometry (FS), and atomic force microscopy (AFM). It was demonstrated that NaLS molecules started to aggregate above a critical temperature and the aggregation behavior was related to their spherical microgel conformation and hydrophobic interaction. During the DLS measurement, when NaLS was dissolved in 1.2 mol·l-1 NaCl aqueous solution and then filtered with 0.45 μm syringe filter, the slow-mode diffusion (smD) corresponded to the polyelectrolyte effect and the original aggregates disappeared and the fast-mode diffusion (fmD) corresponded to the monomolecular NaLS (not yet aggregated) in the solution. When the temperature of the NaLS solution was raised to 38°C, the disappeared smD in DLS analysis appeared again, indicating that NaLS molecules started to form new aggregates. Due to the aggregation at 38°C, molecular weight (Mw) obtained from the SLS had a sharp increase, intensity ratio (I1/I3) of pyrene in FS suddenly decreased, and the adsorption of NaLS on a solid substrate and the corresponding roughness of the surface increased significantly.

A novel and highly efficient polymerization of sulfomethylated alkaline lignins via alkyl chain cross-linking method

Abstract A new family of water-soluble lignosulfonate polymers with ultrahigh molecular weight (Mw) was developed based on alkali lignin (AL) as starting material in a one-pot reaction in two steps: sulfomethylation of AL as raw material led to AL-S and this material was subsequently cross-linked via alkylation with 1,6-dibromohexane (alkAL-S). Gel permeation chromatography showed a significant increase of Mw from 5200 Da of AL-S to 201 000 Da of alkAL-S with high degree of alkylation. Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy and functional group analysis confirmed the efficient polymerization by a nucleophilic substitution reaction mechanism. Additionally, alkAL-S with high Mw showed unexpected viscosity-reducing effect, stability and good rheological properties on a low-rank coal-water slurry (CWS), which are even better than those obtained by naphthalene sulfonate formaldehyde (NSF) as additive. The adsorption properties of the new products were also characterized via a quartz crystal microbalance combined with dissipation monitoring (QCM-D method). Cross-linked structure, large steric hindrance from high Mw and suitable amphiphilic properties of alkAL-S polymers contribute together to the highly improved dispersion performances for CWS.

Preparation of Lignin/Sodium Dodecyl Sulfate Composite Nanoparticles and Their Application in Pickering Emulsion Template-Based Microencapsulation

Lignin is a vastly underutilized biomass resource. The preparation of water-dispersed lignin nanoparticles is an effective way to realize the high-value utilization of lignin. However, the currently reported preparation methods of lignin nanoparticles still have some drawbacks, such as the requirement for toxic organic solvent or chemical modification, complicated operation process, and poor dispersibility. Here, lignin/sodium dodecyl sulfate (SDS) composite nanoparticles (LSNPs) with outstanding water dispersibility and a size range of 70-200 nm were facilely prepared via acidifying the mixed basic solution of alkaline lignin and SDS. No harsh chemical was needed. The formation mechanism was systematically studied. Results indicated that the LSNPs were obtained by acid precipitation of the mixed micelles formed by the self-assembly of lignin and SDS. In addition, on the basis of the LSNP-stabilized Pickering emulsions, lignin/polyurea composite microcapsules combining the excellent chemical stability of a synthetic polyurea shell with the fantastic antiphotolysis and antioxidant properties of lignin were successfully prepared.

Bioinspired Engineering towards Tailoring Advanced Lignin/Rubber Elastomers

The pursuit of high volume and high value-added applications for lignin has been a long-term challenge. In this work, inspired by the energy sacrificial mechanism from biological materials, we developed high-performance lignin/carbon black (CB)/nitrile rubber (NBR) elastomers by constructing a dual-crosslinking network consisting of sulfur covalent bonds and dynamic coordination sacrificial bonds. Lignin was not only used for the substitution of half mass of CB in the NBR elastomer but also served as natural ligands for the Zn-based coordination bonds, providing a significant synergistic coordination enhancement effect. The mechanical performance of the elastomers can be easily manipulated by adjusting the proportion of non-permanent coordination bonds and permanent covalent bonds. Lignin/CB/NBR elastomers with a higher strength and modulus than CB-filled elastomers were obtained while maintaining excellent elasticity. The thermal stability and the high-temperature oil resistance of NBR elastomers were also improved by incorporation of lignin and metal coordination bonds. Overall, this work inspires a new solution for the design of high-performance lignin/rubber elastomers with a high lignin loading content.