Numerical study on particle behavior in a Y-junction mixer for supercritical water hydrolysis.

In the continuous-type supercritical water hydrolysis process, rapid mixing of supercritical and subcritical streams is important to maximize yield and minimize degradation from over-reaction. This work investigated the particle behavior in a Y-junction mixer using large eddy simulation coupled with a discrete phase model, aiming to optimize the supercritical hydrolysis process for biomass conversion. A series of numerical simulations analyzed the influence of the mixer's orientation, flow directions, and flow rates on effective mixing and backflow prevention. The results demonstrated that the most effective mixing occurred in a vertically oriented Y-junction mixer with an upward-directed supercritical water inlet, aligning the momentum direction of natural and forced convection effectively. Consequently, over 80% of particles reached the temperatures close to the mixing temperature of supercritical and subcritical water within the Y-junction mixing zone, indicating enhanced mixing effectiveness and potential for efficient hydrolysis. This configuration also minimized backflow.

Eco-friendly and facile preparation of chitosan-based biofilms of novel acetoacetylated lignin for antioxidant and UV-shielding properties.

The development of eco-friendly, sustainable, biodegradable, and biocompatible green biopolymer composites is becoming increasingly important. In this study, acetoacetylated lignin (ATL) was obtained via an eco-friendly, facile one-step synthesis reaction, and chitosan (CS)-containing ATL films (CSL) were prepared. The chemical structural analysis of ATL confirmed that the acetoacetyl groups were successfully grafted onto kraft lignin (KL). ATL with adequate acetoacetyl groups exhibited enhanced molecular weight and antioxidant and ultraviolet (UV)-shielding properties. In particular, ATL, with a half maximal inhibitory concentration (IC50) of 23.8 µg·mL-1, exhibited superior antioxidant activity than butylated hydroxytoluene (38.3 µg·mL-1) and KL (50.0 µg·mL-1). When ATL was incorporated into the CS solution to prepare biofilms, the antioxidant activity, UV-shielding property, water resistance, and thermal stability of the CSL greatly improved. Notably, the UV-A and UV-B shielding properties of the 2 % CSL were 130 % and 78 % higher than those of the pure CS film, respectively. Therefore, ATL designed with lignin-derived multifunctional properties has potential applications as an antioxidant and UV-shielding bio-additive and shows significant prospects in food packaging and biomedical applications.

Synthesis of lignin-modified cellulose nanocrystals with antioxidant activity via Diels-Alder reaction and its application in carboxymethyl cellulose film.

Multifunctional polymers derived from renewable organic substances have received significant attention. In this work, the Diels-Alder "click" reaction was used to synthesize a renewable copolymer with the mechanical strength of cellulose nanocrystals (CNCs) and the natural antioxidant activity of lignin. Chemical structural analysis and molecular weight results confirmed that lignin was successfully attached to the CNCs. Phenolic hydroxyl groups were introduced into CNCs, resulting in good antioxidant activity with an IC50 value of 1.49 mg/mL, although a slight decrease in the crystallinity index and thermal properties was observed. Additionally, carboxymethyl cellulose (CMC) films containing lignin-modified CNCs were prepared by solution casting. The lignin-modified CNCs endowed film with antioxidant activity and also contributed to increasing the tensile strength by 70%. This indicated that the lignin-modified CNCs with good antioxidant activities and mechanical strength have promising applications in multifunctional materials.

A Novel Biosorbent From Hardwood Cellulose Nanofibrils Grafted With Poly(m-Aminobenzene Sulfonate) for Adsorption of Cr(VI).

Cellulose from different lignocellulosic biomass can be used to prepare various materials. In this work, the cellulose nanofibrils were produced from hardwood bleached kraft pulp. Then, a novel biosorbent from cellulose nanofibrils grafted with poly(m-aminobenzene sulfonate) (PABS) was prepared for effective detoxification and adsorption of Cr(VI) in an aqueous medium. 6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCNF) with a high aspect ratio was used as an adsorbent matrix. PABS, an amine-rich conductive polymer, was grafted onto TOCNF via a successive two-step reaction. The analyses of Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed the successful grafting reaction between TOCNF and PABS. The biosorbent from TOCNF-bonded PABS with the nitrogen content of 7.0% was synthesized. It exhibited excellent Cr(VI) adsorption capacity at a solution pH below 3, and almost 100% Cr(VI) can be removed. The adsorption of Cr(VI) on the biosorbent was described by a pseudo-second-order model and obeyed the Langmuir model. The Cr(VI) adsorption capacity of the biosorbent from TOCNF-bonded PABS was almost 10 times higher than that of TOCNF. It was interesting to note that part of Cr(VI) ions had been reduced to Cr(III) during the adsorption process. It indicated that the biosorbent from TOCNF grafted with PABS could detoxify and adsorb Cr(VI) synchronously.

Peracetic acid-induced kraft lignin solubilization and its characterization for selective production of macromolecular biopolymers.

This study was conducted to investigate the degradation characteristics of kraft lignin (KL) during peracetic acid (PAA) treatment, and to produce potentially valuable polymers of low molecular weight lignin by controlling the reaction conditions. For the peracetic acid treatment, acetic acid (AA) and hydrogen peroxide (HP) were directly mixed at ratios of 4:1, 1:1, and 1:4 (v/v) and employed as reaction media. After PAA treatment of kraft lignin at 80 °C, complete dissolution of the lignin and reduction in the molecular weight were observed. When the PAA reaction was performed at high HP concentration (1:4, v/v), the aromatic lignin skeleton opened and converted to a structure containing large amounts of carboxyl groups. On the other hand, the treatment at high AA concentration (4:1, v/v) decomposed lignin while maintaining its aromatic structure. Hence, we demonstrated that the selective production of lignin-derived polymers can be controlled depending on PAA and HP concentrations.

One-step silanization and amination of lignin and its adsorption of Congo red and Cu(II) ions in aqueous solution.

In this work, silanized and aminated lignin (SAL) was synthesized in one step and its adsorption of Congo red and Cu(II) ions in aqueous solution was explored. Lignin was subjected to amine-silanization with (3-aminopropyl) triethoxysilane (APTES). Structural characterization substantiated successful amine-silanzation of lignin and formation of multi-layer APTES intermolecular crosslinked structure. The prepared SAL (nitrogen content = 6.1%) exhibited enhanced molecular weight, thermal stability, and water- and organic solvent-resistance properties. Additionally, the present of the porous structure of particle surface and an increase in the specific surface area and zeta potential promoted the accessibility of contaminants to the effective adsorption sites of SAL. Adsorption experiments showed that both Congo red and Cu(II) ion could be completely removed at original pH value, and their adsorption involved electrostatic attraction and complexation, respectively. The adsorption isotherms and kinetics were well described by the Langmuir and pseudo-second-order equations, respectively. The results showed that SAL is a promising adsorbent for the treatment of effluents.

Characterization of solvent-fractionated lignins from woody biomass treated via supercritical water oxidation.

Crude supercritical lignin (SCL) extracted from hardwood (Quercus mongolica) treated via supercritical water (SCW) oxidation was subjected to sequential fractionation with four organic solvents; five lignin fractions (F1-F4 and FIN) were thus obtained. The molecular weight (MW) of the fractionated lignins gradually increased as fractionation proceeded. However, the content of methoxyl groups and phenolic hydroxyl groups tended to decrease with increasing molecular weight of the lignins. The functional groups of SCL and the fractionated lignins were very similar based on Fourier-transform infrared analysis. The syringyl/guaiacyl ratio (S/G ratio) of the fractionated lignins increased with an increase in the MW. The thermal stability decreased with decreasing MW of the fractionated lignins, and all fractions except for F1 had a maximum degradation temperature of around 360 °C. The glass transition temperature (Tg) of the fractions increased from 83 °C to 137 °C with increasing MW.

Sugar and ethanol production from woody biomass via supercritical water hydrolysis in a continuous pilot-scale system using acid catalyst.

The aim of this study were to efficiently produce fermentable sugars by continuous type supercritical water hydrolysis (SCWH) of Quercus mongolica at the pilot scale with varying acid catalyst loading and to use the obtained sugars for ethanol production. The SCWH of biomass was achieved in under one second (380°C, 230bar) using 0.01-0.1% H2SO4. With 0.05% H2SO4, 49.8% of sugars, including glucose (16.5% based on biomass) and xylose monomers (10.8%), were liberated from biomass. The hydrolysates were fermented with S. cerevisiae DXSP and D452-2 to estimate ethanol production. To prepare the fermentation medium, the hydrolysates were detoxified using activated charcoal and then concentrated. The ethanol yield of fermentation with S. cerevisiae DXSP was 14.1% (based on biomass). The proposed system has potential for improvement in yield through process optimization. After further development, it is expected to be a competitive alternative to traditional systems for ethanol production from woody biomass.

Phanerochaete chrysosporium Multienzyme Catabolic System for in Vivo Modification of Synthetic Lignin to Succinic Acid.

Whole cells of the basidiomycete fungus Phanerochaete chrysosporium (ATCC 20696) were applied to induce the biomodification of lignin in an in vivo system. Our results indicated that P. chrysosporium has a catabolic system that induces characteristic biomodifications of synthetic lignin through a series of redox reactions, leading not only to the degradation of lignin but also to its polymerization. The reducing agents ascorbic acid and α-tocopherol were used to stabilize the free radicals generated from the ligninolytic process. The application of P. chrysosporium in combination with reducing agents produced aromatic compounds and succinic acid as well as degraded lignin polymers. P. chrysosporium selectively catalyzed the conversion of lignin to succinic acid, which has an economic value. A transcriptomic analysis of P. chrysosporium suggested that the bond cleavage of synthetic lignin was caused by numerous enzymes, including extracellular enzymes such as lignin peroxidase and manganese peroxidase, and that the aromatic compounds released were metabolized in both the short-cut and classical tricarboxylic acid cycles of P. chrysosporium. In conclusion, P. chrysosporium is suitable as a biocatalyst for lignin degradation to produce a value-added product.

Evaluation of correlation between glucan conversion and degree of delignification depending on pretreatment strategies using Jabon Merah.

The main purpose of this study was to investigate the glucan conversion rate after enzymatic hydrolysis depending on the treatment methods and conditions with changes in the chemical composition of treated solid fraction of Jabon Merah. The glucan conversion rate (17.4%) was not significantly improved after liquid hot water treatment (1st step) even though most of the hemicellulose was dissolved into liquid hydrolysate. Subsequently, dilute acid, organosolv, and peracetic acid treatment (2nd step) was conducted under various conditions to enhance glucan conversion. Among the 2nd step treatment, the glucan conversion rate of organosolv (max. 46.0%) and peracetic acid treatment (max. 65.9%) was increased remarkably through decomposition of acid-insoluble lignin (AIL). Finally, the glucan conversion rate and AIL content were highly correlated, which was revealed by the R-squared value (0.84), but inhibitory factors including cellulose crystallinity must be considered for advanced glucan conversion from highly recalcitrant biomasses, such as Jabon Merah.

Levulinic acid production by two-step acid-catalyzed treatment of Quercus mongolica using dilute sulfuric acid.

The objectives of this research were to produce a levulinic acid by two-step acid-catalyzed treatment of Quercus mongolica and to investigate the effect of treatment parameter (reaction temperature range: 100-230°C; sulfuric acid (SA) concentration range: 0-2%) on the levulinic acid yield. After 1st step acid-catalyzed treatment, most of the hemicellulosic C5 sugars (15.6gg/100gbiomass) were released into the liquid hydrolysate at the reaction temperature of 150°C in 1% SA; the solid fraction, which contained 53.5% of the C6 sugars, was resistant to further loss of C6 sugars. Subsequently, 2nd step acid-catalyzed treatment of the solid fractions was performed under more severe conditions. Finally, 16.5g/100g biomass of levulinic acid was produced at the reaction temperature of 200°C in 2% SA, corresponding to a higher conversion rate than during single-step treatment.

Optimization of enzymatic hydrolysis conditions for extraction of pectin from rapeseed cake (Brassica napus L.) using commercial enzymes.

The aims of this study were to extract pectin from rapeseed cake (RSC) by enzymatic hydrolysis using commercial enzymes (Celluclast and Alcalase) and to investigate the effects of different reaction conditions, such as enzymatic hydrolysis time, enzyme-RSC ratio, and Celluclast-Alcalase ratio, on the degradation of RSC and pectin yield. RSC was treated using a combined extraction process that consisted of a fat removal process, enzymatic hydrolysis, and isopropanol/ethanol precipitation. After the fat removal process and enzymatic hydrolysis, defatted-RSC was suitably decomposed, and the loss of liberated reducing sugars was minimized when the hydrolysis condition reached a hydrolysis time of 270 min or an enzyme-RSC ratio of 1:50. Based on these results, various Celluclast-Alcalase ratios were applied. Alcalase led to the destruction of protein-carbohydrate complex in defatted-RSC, whereas Celluclast cleaved some linkages of carbohydrate slightly. As a result, the highest pectin yield was 6.85% at the Celluclast-Alcalase ratio of 1:4.

Effects of combination processes on the extraction of pectins from rapeseed cake (Brassica napus L.).

In this study, rapeseed cake (RSC) was used as a source of pectins due to its high carbohydrate content. Different combinations of treatments were applied to investigate the effect of combination processes on the extraction of pectin from RSC. The treatments chosen for combination were a fat removal process (FRP) (solvent extraction using an alcohol-benzene mixture), a chemical treatment (CT) (hydrolysis using 1% hydrochloric acid), and an enzymatic hydrolysis (EH). After the combined processes, pectins were extracted by isopropanol/ethanol precipitation and the residues were analysed by HPLC or an elemental analyser. The pectin yields and galacturonic acid contents were increased by FRP because 72.13% of the total fat was removed; additionally, EH had a similar effect. However, CT decreased the yields because the treatment was too harsh and the galacturonic acid broke down. Pectin yields and galacturonic acid contents were highest in the combination process FRP/EH (6.23% and 64.23%, respectively).

Antifungal efficacy of environmentally friendly wood preservatives formulated with enzymatic-hydrolyzed okara, copper, or boron salts.

Okara, an organic waste product obtained from soy milk production, was used with copper chloride or sodium borate to formulate new wood preservatives as a substitute for expensive wood preservatives, such as copper-azole-based preservatives and ammoniacal copper quaternary. Before formulating the preservatives, okara was hydrolyzed by enzymes (cellulase, pectinase, and protease) to augment penetration and fix the biocide salts of the preservatives into wood blocks. The preservatives were injected into wood blocks by vacuum pressure to measure the treatability of the preservatives. The treated wood blocks were placed in hot water for 3 d to measure leachability. The treatability and leachability of the preservatives were affected by the type and loading amount of enzymes and the addition of sodium borate into okara-based wood preservative formulations. The treatability and leachability of the preservatives formulated with copper chloride and okara hydrolysates were 63.38 and 3.15%, and those of the preservatives with copper chloride, okara hydrolysates, and sodium borate were 61.47 and 3.32%, respectively. Despite the hot water leaching, wood blocks treated with preservatives formulated with 2% cellulase, pectinase, and protease hydrolyzed okara, CuCl(2), and sodium borate showed only 1.98% average weight loss against Fomitopsis palustris over 12 weeks. Microscopic observation revealed how okara-based preservatives work in wood blocks. Okara has potential as a raw material for cost-effective and environmentally friendly wood preservatives.

Environmentally friendly wood preservatives formulated with enzymatic-hydrolyzed okara, copper and/or boron salts.

Novel biocides, such as copper azole (CuAz) and ammoniacal copper quaternary (ACQ), are extensively used as substitutes for chromate copper arsenate (CCA) in wood preservation. However, the expense of these biocides has necessitated the development of cost-effective and environmentally friendly wood preservatives. This study was conducted to investigate the effectiveness against decaying fungi of the preservatives formulated with enzymatic-hydrolyzed okara (OK), which is an organic waste produced from the manufacture of tofu, CuCl(2) (CC) and/or Na(2)B(4)O(7).10H(2)O (B). With the addition of NH(4)OH as a dissociating agent, the addition of OK facilitated the target retention of most of the OK/CC and OK/CC/B preservative formulations in wood blocks. The OK-based wood preservatives (OK-WPs) were stable against hot-water leaching. When compared with control and CC-treated wood blocks, the leached wood blocks treated with OK/CC and OK/CC/B formulations showed excellent decay resistance against both Postia placenta and Gloeophyllum trabeum, especially when OK was hydrolyzed by Celluclast at a loading level of 0.1 ml/g. Scanning electron microscopy (SEM) and SEM-energy dispersive X-ray (SEM-EDX) spectrometry analyses demonstrated that preservative complexes, such as OK-CC and OK-CC-B, existed in the wood blocks treated with OK/CC and OK/CC/B formulations. This study results support the potential application of OK-WPs as environmentally friendly wood preservatives capable of replacing CuAz and ACQ.