Hongming Lou

Reducing non-productive adsorption of cellulase and enhancing enzymatic hydrolysis of lignocelluloses by noncovalent modification of lignin with lignosulfonate

Four fractions of one commercial sodium lignosulfonate (SXP) with different molecular weight (MW) and anionic polymers were studied to reduce non-productive adsorption of cellulase on bound lignin in a lignocellulosic substrate. SXP with higher MW had stronger blocking effect on non-productive adsorption of a commercial Trichoderma reesi cellulase cocktail (CTec2) on lignin measured by quartz crystal microgravimetry with dissipation monitoring. Linear anionic aromatic polymers have strong blocking effect, but they would also reduce CTec2 adsorption on cellulose to decrease the enzymatic activity. The copolymer of lignin and polyethylene glycol (AL-PEG1000) has strong enhancement in enzymatic hydrolysis of lignocelluloses, because it not only improves the cellulase activity to cellulose, but also blocks the non-productive cellulase adsorption on lignin. Apart from improving the cellulase activity to cellulose, the enhancements of enzymatic hydrolysis of lignocellulose by adding AL-PEG1000 and SXPs are the result of the decreased cellulase non-productive adsorption on lignin.

Properties of Different Molecular Weight Sodium Lignosulfonate Fractions as Dispersant of Coal‐Water Slurry

Four purified sodium lignosulfonate (SL) samples with different molecular weights were prepared by fractionation using ultrafiltration. The effect of the molecular weights of SL on the apparent viscosity of coal‐water slurry (CWS) was investigated by studying the adsorption amounts and the zeta potentials in the coal‐water interface. The results show that the adsorption behavior of the dispersants in the coal‐water interface is the key factor to affect the dispersing effect, that the higher adsorption amount and compact adsorption film help reduce the viscosity reduction of CWS, and that the zeta potential is also an important factor influenced by the sulfonic group and carboxy contents of the lignosulfonate molecule. Furthermore, SL with a molecular weight ranging from 10000 to 50000 has both a higher adsorbed amount and zeta potential on the coal surface and the best effect on reducing the viscosity of the coal‐water slurry.

Study on the stability of coal water slurry using dispersion-stability analyzer

Abstract Effect of modified lignin series and naphthalene series dispersants on the stability of coal water slurry (CWS) and sedimentation behavior of coal particles were investigated using Turbiscan Lab dispersion-stability analyzer. The results indicate that the sedimentation behavior of coal particles of CWS belongs to differential sedimentation and there is a conglobation between coal particles in CWS preparation. Stability of CWS prepared with lignin series dispersants is better than that prepared with naphthalene series, and the height and mean sedimentation rate of clarifying zone is about 68% of that of FDN when the dosage of additives is 1.0%. The Turbiscan Lab dispersion-stability analyzer can analyze the stability of CWS and also can be useful to investigate the stability mechanism of CWS.

Highly Efficient Inverted Perovskite Solar Cells With Sulfonated Lignin Doped PEDOT as Hole Extract Layer

UNLABELLED Sulfonated-acetone-formaldehyde (SAF) was grafted with alkali lignin (AL) to prepare grafted sulfonated-acetone-formaldehyde lignin (GSL). Considering the rich phenolic hydroxyl groups in GSL, we detected a hole mobility of 2.27 × 10(-6) cm(2) V(-1) s(-1) with GSL as a hole transport material by space-charge-limited current model. Compared with nonconjugated poly(styrene sulfonic acid), GSL was applied as p-type semiconductive dopant for PEDOT to prepare water-dispersed PEDOT GSL. PEDOT GSL shows enhanced conductivity compared with that of PEDOT PSS. Simultaneously, the enhanced open-circuit voltage, short-circuit current density, and fill factor are achieved using PEDOT GSL as a hole extract layer (HEL) in sandwich-structure inverted perovskite solar cells. The power conversion efficiency is increased to 14.94% compared with 12.6% of PEDOT PSS-based devices. Our results show that amorphous GSL is a good candidate as dopant of PEDOT, and we provide a novel prospective for the design of HEL based on lignin, a renewable biomass and phenol derivatives.

Lignin-based polyoxyethylene ether enhanced enzymatic hydrolysis of lignocelluloses by dispersing cellulase aggregates.

Water-soluble lignin-based polyoxyethylene ether (EHL-PEG), prepared from enzymatic hydrolysis lignin (EHL) and polyethylene glycol (PEG1000), was used to improve enzymatic hydrolysis efficiency of corn stover. The glucose yield of corn stover at 72h was increased from 16.7% to 70.1% by EHL-PEG, while increase in yield with PEG4600 alone was 52.3%. With the increase of lignin content, EHL-PEG improved enzymatic hydrolysis of microcrystalline cellulose more obvious than PEG4600. EHL-PEG could reduce at least 88% of the adsorption of cellulase on the lignin film measured by quartz crystal microbalance with dissipation monitoring (QCM-D), while reduction with PEG4600 was 43%. Cellulase aggregated at 1220nm in acetate buffer analyzed by dynamic light scattering. EHL-PEG dispersed cellulase aggregates and formed smaller aggregates with cellulase, thereby, reduced significantly nonproductive adsorption of cellulase on lignin and enhanced enzymatic hydrolysis of lignocelluloses.

Effect of the molecular structure of lignin-based polyoxyethylene ether on enzymatic hydrolysis efficiency and kinetics of lignocelluloses

Effect of the molecular structure of lignin-based polyoxyethylene ether (EHL-PEG) on enzymatic hydrolysis of Avicel and corn stover was investigated. With the increase of PEG contents and molecular weight of EHL-PEG, glucose yield of corn stover increased. EHL-PEG enhanced enzymatic hydrolysis of corn stover significantly at buffer pH 4.8-5.5. Glucose yield of corn stover at 20% solid content increased from 32.8% to 63.8% by adding EHL-PEG, while that with PEG4600 was 54.2%. Effect of EHL-PEG on enzymatic hydrolysis kinetics of cellulose film was studied by quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM). An enhancing mechanism of EHL-PEG on enzymatic hydrolysis kinetics of cellulose was proposed. Cellulase aggregates dispersed by EHL-PEG excavated extensive cavities into the surface of cellulose film, making the film become more loose and exposed. After the maximum enzymatic hydrolysis rate, the film was mainly peeled off layer by layer until equilibrium.

Polymerization reactivity of sulfomethylated alkali lignin modified with horseradish peroxidase.

Alkali lignin (AL) was employed as raw materials in the present study. Sulfomethylation was conducted to improve the solubility of AL, while sulfomethylated alkali lignin (SAL) was further polymerized by horseradish peroxidase (HRP). HRP modification caused a significant increase in molecular weight of SAL which was over 20 times. It was also found to increase the amount of sulfonic and carboxyl groups while decrease the amount of phenolic and methoxyl groups in SAL. The adsorption quantity of self-assembled SAL film was improved after HRP modification. Sulfonation and HRP modification were mutually promoted. The polymerization reactivity of SAL in HRP modification was increased with its sulfonation degree. Meanwhile, HRP modification facilitated SALs radical-sulfonation reaction.

Improving enzymatic hydrolysis of lignocellulosic substrates with pre-hydrolysates by adding cetyltrimethylammonium bromide to neutralize lignosulfonate.

Two pretreatment methods to overcome recalcitrance of lignocelluloses, sulfite pretreatment (SPORL) and dilute acid (DA), were conducted to pretreat softwood masson pine and hardwood eucalyptus for enzymatic hydrolysis. In the presence of corresponding pre-hydrolysates, adding moderate cetyltrimethylammonium bromide (CTAB) could enhance the enzymatic hydrolysis of the SPORL-pretreated substrates, but had no enhancement for the DA-pretreated substrates. The results showed that sodium lignosulfonate (SL) in pre-hydrolysates and CTAB together had a strong enhancement on the enzymatic hydrolysis of lignocelluloses. The compound of commercial lignosulfonate SXSL and CTAB (SXSL-CTAB) could enhance the substrate enzymatic digestibility (SED) of SPORL-pretreated masson pine from 27.1% to 71.0%, and that of DA-pretreated eucalyptus from 37.6% to 67.9%. The mechanism that CTAB increased the adsorption of SL on lignin to form more effective steric hindrance and reduced the non-productive adsorption of cellulase on lignin by neutralizing the negative charge of SL was proposed.

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.