Preparation of a high-performance conductive lignocellulose hydrogel by directly using non-detoxified bisulfite-pretreated corncob.

Biomass-based hydrogels have become a research hotspot because of their better biocompatibility. However, the preparation of biomass hydrogels is complicated, and they often need to be modified by introducing other substances. In this study, corncob pretreated with bisulfite (125-185 °C) was used as a raw material to prepare lignocellulose hydrogels. The results showed that directly using the pretreated sample without the washing step lowered the total hydrogel costs while preserving the lignosulfonate (LS) produced during pretreatment. The best tensile (54.1 kPa) and compressive (177.7 kPa) stresses were obtained for the hydrogel prepared from non-detoxified pretreated corncob at 165 °C (NCH-165). The sulfonic acid groups in LS could enhance the interaction between plant cellulose, thus improving its mechanical properties. The capacitor assembled from NCH-165 achieved an energy density of 236.1 Wh/kg at a power density of 499.7 W/kg and a high coulombic efficiency of more than 99 % after 2000 charge/discharge cycles. In conclusion, the present study simplifies the pathway for the preparation of flexible, conductive, and anti-freezing hydrogels by directly utilizing a non-detoxified bisulfite-pretreated corncob.

Laser damage properties of LiB3O5 crystal surface under UV laser irradiation.

LiB3O5 (LBO) crystal has a very high bulk laser damage threshold. Laser damage often occurs on the surfaces with a large number of processing defects during application. In this paper, the surface laser damage threshold, damage growth threshold, and damage growth curve of LBO crystal and fused silica under the same processing process have been comparatively studied by using a 355 nm pulsed laser. The surface laser damage performance of LBO crystal has been comprehensive evaluated. The results show that the laser damage threshold and damage growth threshold of LBO are about twice that of fused silica, and the damage growth coefficient is about 0.7 times that of fused silica. The detection and analysis of impurity defects and photothermal weak absorption defects show that the subsurface defects of LBO crystal are less than that of fused silica. Laser damage morphologies show that the damage process is related to strongly bonded chemical structure and anisotropic physical characteristics of LBO crystal. These characteristics together determine the high threshold damage performance of LBO crystal. The results of this study are of great guidance for the application of LBO crystal in high-power laser systems.

Lignocellulose hydrogels fabricated from corncob residues through a green solvent system.

It is still a challenge to find an effective solvent system that can simultaneously dissolve the cellulose and lignin in biomass residues to fabricate lignocellulose hydrogels (LHs). Herein, corncob residues from furfural production were pretreated with alkaline peroxide to regulate the lignin content. The lignin/cellulose composites with various lignin content were then dissolved and regenerated by a green and facile ZnCl2/CaCl2 solvent system. The inorganic salt solvents were served as linkers and flexible LHs were obtained. Substrate material containing 10.75% lignin shows the best compressive stress (76.71 kPa). Inspired by its superior ionic conductivity, the hydrogels were assembled into a solid-state electrolyte for a zinc-ion hybrid supercapacitor. This research develops a feasible, simple, and low-cost route for lignin-containing hydrogel preparation and offers insights into the high-value application of agro-industrial lignocellulosic wastes.

Deep eutectic solvent with bifunctional Brønsted-Lewis acids for highly efficient lignocellulose fractionation.

Green and low cost deep eutectic solvents (DESs) are promising to replace the solid acids and ionic liquids in biomass fractionation process. To enhance the lignocellulose pretreatment efficiency, an acidic DES that composed of Brønsted acid (ZnCl2) as hydrogen bond acceptor and Lewis acid (lactic acid) as hydrogen bond donator was designed. This bifunctional DES was used for the extraction of lignin from poplar sawdust. Under the optimal pretreatment condition, the ZnCl2-lactic acid DES could recover 95.2 wt% of lignin with a purity of 92.1%. The recovered lignin demonstrated a low polydispersity of 1.67 and small amount of ß-aryl-ethers. Moreover, the acidic DES had a good recyclability and reusability. Such performance was attributed to the presence of bifunctional acid sites, which help selectively cleave lignin-carbohydrate complex linkages. The acidity and polarity of Brønsted acid can be modulated by the Lewis acid, thus synergistically promote the lignin extraction and production.

Metal-organic framework promoting high-solids enzymatic hydrolysis of untreated corncob residues.

Metal-organic frameworks (MOFs) could serve as efficient matrixes to immobilize cellulase because of their high stability and porous morphology. Herein, the Zr-based MOFs (UiO-66 and UiO-66-NH2) assisted 20 wt% high-solids hydrolysis of untreated corncob residues (CRs) at low enzyme loading was investigated. Glucan hydrolysis yields increased to 60.55% and 71.47% by separately adding 4 g/L UiO-66 and UiO-66-NH2 at 5 FPU/g-glucan cellulase dosage. The maximum hydrolysis yield reached 90.01% at 10 FPU/g-glucan in the presence of 4 g/L UiO-66-NH2. Analysis of free protein concentration and cellulase activity suggested that MOFs effectively increased cellulase catalytic activity and stability, thus boosted CRs enzymatic hydrolysis efficiency. Additionally, UiO-66-NH2 immobilization gave a high catalytic activity because of the abundant anchor sites of NH2 groups. This research presents the promising future of MOFs' application in lignocellulosic biomass bioconversion and other areas requiring immobilized enzymes.

Generation of the periodically polarized structured light beams.

We report a kind of structured light beam with periodical polarization and phase singularities. It is generated from a setup consisting of conical refraction transformation and 4f-system. By this setup, the periodical structures are produced without any change of intensity distributions. We analyze both theoretically and experimentally the polarization and phase structures of the periodically structured light beam. The dependence of period is demonstrated on the length of crystal and the focal length. It is shown that the polarization of the input beam can be used to control the polarization and phase structures of the output beam.

Enhancement of high-solids enzymatic hydrolysis of corncob residues by bisulfite pretreatment for biorefinery.

Co-production of glucose, furfural and other green materials based on a lignocellulosic biorefinery is a promising way to realize the commercial application of corncob residues. An effective process was developed for glucose production using low temperature bisulfite pretreatment and high-solids enzymatic hydrolysis. Corncob residues from furfural production (FRs) were pretreated with 0.1g NaHSO3/g dry substrate at 100°C for 3h. Lignin was sulfonated and sulfonic groups were produced during pretreatment, which resulted in decreasing the zeta potential of the samples. Compared with raw material, bisulfite pretreatment of FRs increased the glucose yield from 18.6 to 99.45% after 72h hydrolysis at a solids loading of 12.5%. The hydrolysis residues showed a relatively high thermal stability and concentrated high derivatives. Direct pretreatment followed by enzymatic hydrolysis is an environmentally-friendly and economically-feasible method for the production of glucose and high-purity lignin, which could be further converted into high-value products.

Ethanol production from a biomass mixture of furfural residues with green liquor-peroxide saccarified cassava liquid.

BACKGROUND: As the most abundant renewable resources, lignocellulosic materials are ideal candidates as alternative feedstock for bioethanol production. Cassava residues (CR) are byproducts of the cassava starch industry which can be mixed with lignocellulosic materials for ethanol production. The presence of lignin in lignocellulosic substrates can inhibit saccharification by reducing the cellulase activity. Simultaneous saccharification and fermentation (SSF) of furfural residues (FR) pretreated with green liquor and hydrogen peroxide (GL-H2O2) with CR saccharification liquid was investigated. The final ethanol concentration, yield, initial rate, number of live yeast cells, and the dead yeast ratio were compared to evaluate the effectiveness of combining delignificated lignocellulosic substrates and starchy substrates for ethanol production. RESULTS: Our results indicate that 42.0 % of FR lignin removal was achieved on FR using of 0.06 g H2O2/g-substrate and 9 mL GL/g-substrate at 80 °C. The highest overall ethanol yield was 93.6 % of the theoretical. When the ratio of 0.06 g/g-H2O2-GL-pretreated FR to CR was 5:1, the ethanol concentration was the same with that ratio of untreated FR to CR of 1:1. Using 0.06 g/g-H2O2-GL-pretreated FR with CR at a ratio of 2:1 resulted in 51.9 g/L ethanol concentration. Moreover, FR pretreated with GL-H2O2 decreased the concentration of byproducts in SSF compared with that obtained in the previous study. CONCLUSIONS: The lignin in FR would inhibit enzyme activity and GL-H2O2 is an advantageous pretreatment method to treat FR and high intensity of FR pretreatment increased the final ethanol concentration. The efficiency of ethanol fermentation of was improved when delignification increased. GL-H2O2 is an advantageous pretreatment method to treat FR. As the pretreatment dosage of GL-H2O2 on FR increased, the proportion of lignocellulosic substrates was enhanced in the SSF of the substrate mixture of CR and FR as compared with untreated FR. Moreover, the final ethanol concentration was increased with a high ethanol yield and lower byproduct concentrations.