High Xylose Yields from Dilute Acid Pretreatment of Corn Stover Under Process-Relevant Conditions

Pretreatment experiments were carried out to demonstrate high xylose yields at high solids loadings in two different batch pretreatment reactors under process-relevant conditions. Corn stover was pretreated with dilute sulfuric acid using a 4-l Steam Digester and a 4-l stirred ZipperClave® reactor. Solids were loaded at 45% dry matter (wt/wt) after sulfuric acid catalyst impregnation using nominal particle sizes of either 6 or 18 mm. Pretreatment was carried out at temperatures between 180 and 200 °C at residence times of either 90 or 105 s. Results demonstrate an ability to achieve high xylose yields (>80%) over a range of pretreatment conditions, with performance showing little dependence on particle size or pretreatment reactor type. The high xylose yields are attributed to effective catalyst impregnation and rapid rates of heat transfer during pretreatment.     

Dilute Acid Pretreatment of Corncob for Efficient Sugar Production

Aqueous dilute acid pretreatments of corncob were conducted using cylindrical pressure vessels in an oil bath. Pretreatments were conducted in a temperature range of 160–190 °C with acid-solution-to-solid-corncob ratio of 2. The acid concentration (v/v) in the pretreatment solution was varied from 0% to 0.7%, depending on temperature. This gives acid charge on ovendry-weight corncob of 0–2.58%. It was found that optimal pretreatment temperature is between 160 and 170 °C based on total xylose and glucose yields and thermal energy consumption in pretreatment. At 170 °C and acid charge of 2.2% on cob, total glucose yield and xylose recovery were 97% and 75%, respectively, which resulted in an overall monomeric sugar recovery of about 88%. Xylose concentration in the hydrolysate was about 12%, with xylose-to-acetic-acid ratio of 8 and to furan (furfural and hydroxymethylfurfural) of about 15.     

Potential of Potassium Hydroxide Pretreatment of Switchgrass for Fermentable Sugar Production

Chemical pretreatment of lignocellulosic biomass has been extensively investigated for sugar generation and subsequent fuel production. Alkaline pretreatment has emerged as one of the popular chemical pretreatment methods, but most attempts thus far have utilized NaOH for the pretreatment process. This study aimed at investigating the potential of potassium hydroxide (KOH) as a viable alternative alkaline reagent for lignocellulosic pretreatment based on its different reactivity patterns compared to NaOH. Performer switchgrass was pretreated at KOH concentrations of 0.5–2 % for varying treatment times of 6–48 h, 6–24 h, and 0.25–1 h at 21, 50, and 121 °C, respectively. The pretreatments resulted in the highest percent sugar retention of 99.26 % at 0.5 %, 21 °C, 12 h while delignification up to 55.4 % was observed with 2 % KOH, 121 °C, 1 h. Six pretreatment conditions were selected for subsequent enzymatic hydrolysis with Cellic CTec2® for sugar generation. The pretreatment condition of 0.5 % KOH, 24 h, 21 °C was determined to be the most effective as it utilized the least amount of KOH while generating 582.4 mg sugar/g raw biomass for a corresponding percent carbohydrate conversion of 91.8 %.     

Effect of Novel Pretreatment of Steam Explosion Associated with Ammonium Sulfite Process on Enzymatic Hydrolysis of Corn Straw

Applied Biochemistry and Biotechnology - Effective pretreatment process to improve enzymatic saccharification and decrease inhibitors generation is a key operation involved in the lignocellulosic...     

Pretreatment of Reed by Wet Oxidation and Subsequent Utilization of the Pretreated Fibers for Ethanol Production

Common reed (Phragmites australis) is often recognized as a promising source of renewable energy. However, it is among the least characterized crops from the bioethanol perspective. Although one third of reed dry matter is cellulose, without pretreatment, it resists enzymatic hydrolysis like lignocelluloses usually do. In the present study, wet oxidation was investigated as the pretreatment method to enhance the enzymatic digestibility of reed cellulose to soluble sugars and thus improve the convertibility of reed to ethanol. The most effective treatment increased the digestibility of reed cellulose by cellulases more than three times compared to the untreated control. During this wet oxidation, 51.7% of the hemicellulose and 58.3% of the lignin were solubilized, whereas 87.1% of the cellulose remained in the solids. After enzymatic hydrolysis of pretreated fibers from the same treatment, the conversion of cellulose to glucose was 82.4%. Simultaneous saccharification and fermentation of pretreated solids resulted in a final ethanol concentration as high as 8.7 g/L, yielding 73% of the theoretical.     

Fed-Batch Enzymatic Saccharification of High Solids Pretreated Lignocellulose for Obtaining High Titers and High Yields of Glucose

1-Deoxynojirimycin (DNJ) is an efficient α-glucosidase inhibitor (α-GI) with potential applications in the prevention and treatment of diabetes. In this study, 16 Bacillus strains were screened for α-GI rate, and the strain HZ-12 with the highest α-GI rate was identified as Bacillus amyloliquefaciens through the analysis of physiological biochemical characteristics and 16S rDNA sequence. By LC-MS/Q-TOF analysis, the α-GI component produced by B. amyloliquefaciens HZ-12 was identified as DNJ. Soybean was used as the substrate for the solid-state fermentation; 870 mg/kg DNJ was produced by B. amyloliquefaciens HZ-12 after optimizing the fermentation conditions and media, which was 3.83-fold higher than the initial yield. Also, evaluations of nutraceutical enrichment in the form of anticoagulant activity, antioxidant activity, total nitrogen (TN), and total reducing sugars (TRS) of the B. amyloliquefaciens HZ-12 fermented soybeans were substantially higher than unfermented soybeans. This study provided a promising strain for high-level production of DNJ and produced nutraceutical enriched soybeans by fermentation.     

Pretreatment of Rice Straw Using a Butanone or an Acetaldehyde Dilute Solution Explosion for Producing Ethanol

Ethanol conversion from rice straw using butanone and acetaldehyde dilute solution explosions was evaluated based on the optimization of pure water explosion. To decrease residual inhibitor content, the exploded slurry was dried and investigated at different temperature. Using a 0.9-mol/L butanone solution explosion, with the explosion pressure set at 3.1 MPa, the residence time at 7 min, the dried rice straw-to-water ratio at 1:3 (w/w), and the exploded slurry drying temperuture at 90 °C for 8 h, the yields of total sugar, glucose, and xylose were 85%, 88%, 82% (w/w), respectively, and the ethanol productivity was 26.0 g/100 g rice straw dry matter. Moreover, 0.5-mol/L acetaldehyde dilute solution explosion improved the efficiency of enzymatic hydrolysis (EH) and simultaneous saccharification and co-fermentation (SSCF), and the residual inhibitors had negligible effects on EH and SSCF after detoxification by drying. The results suggested that compared with pure water explosions, the use of butanone and of acetaldehyde dilute solution explosions lowered the explosive temperature and improved the sugar yield, although relative crystallinity of the rice straw dry matter was increased after the explosion.     

Optimization of Dilute Sulfuric Acid Pretreatment to Maximize Combined Sugar Yield from Sugarcane Bagasse for Ethanol Production

Increasing fermentable sugar yields per gram of biomass depends strongly on optimal selection of varieties and optimization of pretreatment conditions. In this study, dilute acid pretreatment of bagasse from six varieties of sugarcane was investigated in connection with enzymatic hydrolysis for maximum combined sugar yield (CSY). The CSY from the varieties were also compared with the results from industrial bagasse. The results revealed considerable differences in CSY between the varieties. Up to 22.7 % differences in CSY at the optimal conditions was observed. The combined sugar yield difference between the best performing variety and the industrial bagasse was 34.1 %. High ratio of carbohydrates to lignin and low ash content favored the release of sugar from the substrates. At mild pretreatment conditions, the differences in bioconversion efficiency between varieties were greater than at severe condition. This observation suggests that under less severe conditions the glucose recovery was largely determined by chemical composition of biomass. The results from this study support the possibility of increasing sugar yields or improving the conversion efficiency when pretreatment optimization is performed on varieties with improved properties.     

Pretreatment of Rice Straw by a Hot-Compressed Water Process for Enzymatic Hydrolysis

Hot-compressed water (HCW) is among several cost-effective pretreatment processes of lignocellulosic biomass for enzymatic hydrolysis. The present work investigated the characteristics of HCW pretreatment of rice straw including sugar production and inhibitor formation in the liquid fraction and enzymatic hydrolysis of pretreated material. Pretreatment was carried out at a temperature ranging from 140 to 240 °C for 10 or 30 min. Soluble oligosaccharides were found to constitute almost all the components of total sugars in the liquid fraction. The maximal production of total glucose at 180 °C and below accounted for 4.4–4.9% of glucan in raw material. Total xylose production peaked at 180 °C, accounting for 43.3% of xylan in raw material for 10-min pretreatment and 29.8% for 30-min pretreatment. The production of acetic acid increased at higher temperatures and longer treatment time, indicating more significant disruption of lignocellulosic structure, and furfural production achieved the maximum (2.8 mg/ml) at 200 °C for both 10-min and 30-min processes. The glucose yield by enzymatic hydrolysis of pretreated rice straw was no less than 85% at 180 °C and above for 30-min pretreatment and at 200 °C and above for 10-min pretreatment. Considering sugar recovery, inhibitor formation, and process severity, it is recommended that a temperature of 180 °C for a time of 30 min can be the most efficient process for HCW pretreatment of rice straw.     

Soaking Pretreatment of Corn Stover for Bioethanol Production Followed by Anaerobic Digestion Process

The production of ethanol and methane from corn stover (CS) was investigated in a biorefinery process. Initially, a novel soaking pretreatment (NaOH and aqueous-ammonia) for CS was developed to remove lignin, swell the biomass, and improve enzymatic digestibility. Based on the sugar yield during enzymatic hydrolysis, the optimal pretreatment conditions were 1?% NaOH?+?8?% NH₄OH, 50°C, 48?h, with a solid-to-liquid ratio 1:10. The results demonstrated that soaking pretreatment removed 63.6?% lignin while reserving most of the carbohydrates. After enzymatic hydrolysis, the yields of glucose and xylose were 78.5?% and 69.3?%, respectively. The simultaneous saccharification and fermentation of pretreated CS using Pichia stipitis resulted in an ethanol concentration of 36.1?g/L, corresponding only to 63.3?% of the theoretical maximum. In order to simplify the process and reduce the capital cost, the liquid fraction of the pretreatment was used to re-soak new CS. For methane production, the re-soaked CS and the residues of SSF were anaerobically digested for 120?days. Fifteen grams CS were converted to 1.9?g of ethanol and 1337.3?mL of methane in the entire process.     

草鱼出血病病毒提纯中离心方法和离心参数的选择

为了有效地从鱼病组织中初提纯草鱼出血病病毒，我们探讨了各种离心方法和离心参数，结果表明最佳离心方法为角度离心(日立20PR-52D离心机，RPR 2-0之转头)，最佳离心参数为：转头温度是8℃，离心速度是16000转/分，离心时间是4．5小时。该离心方法和离心参数已成为我们实验室最常规使用的提纯该病毒的方法。     

On the Determination of Equilibrium Constant and Thermodynamic Parameters for the Association Process of Hydrogen Bond Complexes Using Relaxation Parameters

Abstract

A dielectric study of H-bond complexes of three acetates namely ethyl acetate, butyl acetate, and benzyl acetate with the proton donor (O-Cresol) has been made. The equilibrium constant and the thermodynamic parameters for the association process as well as the dielectric relaxation process have been determined from the dielectric data using an equation, proposed in our earlier paper. The results obtained being in agreement with the literature values thus support the validity of the proposed equation.     

溶胶-凝胶技术在织物化学镀活化预处理中的应用

以γ-氨丙基三乙氧基硅烷(KH-550)为先驱体,应用溶胶-凝胶技术在织物表面形成一层凝胶薄膜.由于该薄膜含有氨基和羟基等活性基团,能与钯离子起配位络合作用,阻止钯粒子的团聚,使钯以较高的活性完成织物化学镀.扫描探针显微镜(SPM)及扫描电子显微镜(SEM)观察了施镀前后织物的表面形态.与传统的前处理相比,无需SnCl2敏化,减少污染,缩短工艺流程,降低钯盐用量.     

ICP-AES测定钢铁中多元素的通用前处理法

通过探讨溶解酸与钢铁化学成分、金相组织之间的关系,提出了一种简单的电感耦合等离子体原子发射光谱(ICP-AES)测定钢铁中多元素的通用前处理方法。用高氯酸溶解并冒烟分解钢铁样品,稀盐酸或过氧化氢还原铬(Ⅵ),ICP-AES测定钢铁中磷、锰、铬、钼、镍、钒、铜、铝、钛、钴、镁、铈等常见元素;该方法与硝酸-盐酸溶解酸方法有良好的兼容性。     

Two-Step Pretreatment of Corn Stover Silage Using Non-ionic Surfactant and Ferric Nitrate for Enhancing Sugar Recovery and Enzymatic Digestibility of Cellulose

Corn stover silage (CSS) is regarded as a promising feedstock for bioethanol production. The two-step pretreatment using a sequential non-ionic surfactant and ferric nitrate pretreatment was investigated for improving the enzymatic hydrolysis of CSS. The first-step pretreatment using non-ionic surfactant (Tween-80, 2.0 wt.%) at 60 °C for 60 min achieved 30.48% the removal of lignin. Compared with the raw material, the cellulose content of first-step treated CSS increased by 15.86%. The second step using ferric nitrate resulted in 94.56% hemicellulose removal and achieved 72.53% cellulose purity at 130 °C for 30 min, while the yields of furfural and HMF were only 0.36 and 0.32 g/100 g dry material, respectively. The maximum enzymatic digestibility of the two-step treated CSS was 90.98% with a low cellulose dosage (15 FPU/g-glucan), which was approximately 32.07% higher than that of the first-step pretreatment only with Tween-80.

     

接枝共聚的接枝参数表述方法的探讨

介绍了接枝共聚物接枝参数，如单体转化率、接枝率、接枝效率、均聚物含量及接枝频率，概述了对这些参数在进行表述淀粉接枝共聚时出现的种各种表达形式。在此基础上，指出了这些其在表达上出现的混乱现象。     

Impact of Sample Pretreatment and Extraction Methods on the Bioactive Compounds of Sugar Beet (Beta vulgaris L.) Leaves

To find the most optimal green valorization process of food by-products, sugar beet (Beta vulgaris L.) leaves (SBLs) were freeze-dried and ground with/without liquid nitrogen (LN), as a simple sample pretreatment method, before ultrasound-assisted extraction (UAE) of polyphenols. First, the water activity, proximate composition, amino acid (AA) and fatty acid (FA) profiles, and polyphenol oxidase (PPO) activity of dried and fresh SBLs were evaluated. Then, conventional extraction (CE) and UAE of polyphenols from SBLs using water/EtOH:water 14:6 (v/v) as extracting solvents were performed to determine the individual and combined effects of the sample preparation method and UAE. In all the freeze-dried samples, the specific activity of PPO decreased significantly (p ≤ 0.05). Freeze-drying significantly increased (p ≤ 0.05) the fiber and essential FA contents of SBLs. The FA profile of SBLs revealed that they are rich sources of oleic, linoleic, and α-linolenic acids. Although freeze-drying changed the contents of most AAs insignificantly, lysine increased significantly from 7.06 ± 0.46% to 8.32 ± 0.38%. The aqueous UAE of the freeze-dried samples without LN pretreatment yielded the most optimal total phenolic content (TPC) (69.44 ± 0.15 mg gallic acid equivalent/g dry matter (mg GAE/g DM)) and excellent antioxidant activities. Thus, combining freeze-drying with the aqueous UAE method could be proposed as a sustainable strategy for extracting bioactive compounds from food by-products.     

Tailoring the Properties of Optical Force Probes for Polymer Mechanochemistry

The correlation of mechanical properties of polymer materials with those of their molecular constituents is the foundation for their holistic comprehension and eventually for improved material designs and syntheses. Over the last decade, optical force probes (OFPs) were developed, shedding light on various unique mechanical behaviors of materials. The properties of polymers are diverse, ranging from soft hydrogels to ultra-tough composites, from purely elastic rubbers to viscous colloidal solutions, and from transparent glasses to super black dyed coatings. Only very recently, researchers started to develop tailored OFP solutions that account for such material requirements in energy (both light and force), in time, and in their spatially detectable resolution. We here highlight notable recent examples and identify future challenges in this emergent field.