Effects of hot water extraction pretreatment on physicochemical changes of Douglas fir

Hot water extraction (HWE) is an autocatalytic pretreatment that can be effectively integrated into most of the conversion technologies for extracting hemicelluloses from woody biomass. The objective of this study was to understand the influence of pretreatment factors on removal of hemicelluloses from Douglas fir chips. Compositional change in biomass was analyzed with ion chromatography and further confirmed with Fourier transform infrared spectroscopy (FT-IR). Highest hemicellulose extraction yield (HEY) was estimated to be 67.44% at the optimum reaction time (79 min) and temperature (180 °C) by using response surface methodology (RSM). Experimental results show that the HEY increased from 19.29 to 70.81% depending on the reaction time (30–120 min) and the temperature (140–180 °C). Effects of the severity factor (SF) on the mass removal and compositional changes were also evaluated. Hygroscopicity and thermal stability of wood were improved after HWE pretreatment. Colorimetric analysis showed that temperature has a greater influence on color of the wood chips during HWE pretreatment than dwell time. HWE pretreatment shows great potential for extracting hemicelluloses and altering physicochemical properties of wood in an integrated biorefinery for diversification of product portfolio.     

N2 explosive decompression pretreatment of biomass for lignocellulosic ethanol production

This paper presents a novel biomass pretreatment method that uses high pressured N₂ and temperature to break the hemicellulose and lignin seal around the cellulose macro fibrils in the cell walls of the lignocellulosic biomass in order to open up the biomass structure for more efficient enzymatic hydrolysis. In this method the biomass is exposed to a high pressure using N₂ gas, and temperature. Under pressure, cells of the lignocellulosic biomass are filled with a solution saturated with nitrogen. When the pressure is then suddenly released, the feedstock is exposed to an explosive decompression and the dissolved nitrogen is released from the solution. Sudden change in the volume breaks the cell walls and opens the biomass structure resulting in increased surface area of the substrate for enzymatic hydrolysis. No catalysts or chemicals were added in the process thereby, making it economically and environmentally attractive. In this research, a range of different pressures (1–60 bar) and temperatures (25–175 °C) were applied to barley straw to evaluate the efficiency of the pretreatment. The pretreatment was followed by enzymatic hydrolysis and fermentation. Resulting glucose and ethanol concentrations were measured and the yields were considered as an estimate for the most suitable set of pretreatment conditions. The results indicate that the highest glucose yield and hydrolysis efficiency were gained at 150 °C and 10–30 bars. The fermentation efficiency was lower at higher temperatures. Nonetheless, the highest ethanol yield was still gained at the same conditions.     

样品处理方式对脱硝催化剂孔隙特征分析的影响研究

就压汞法测试板式脱硝催化剂时,样品处理方式对结果的影响进行了实验研究。选取北京某电厂在运脱硝催化剂为研究对象,选取3种不同的方法对样品进行处理,用压汞法测试其比孔容、孔径分布等孔隙参数,比较了不同处理方式对结果重现性的影响,对其原因及适用性进行了分析。     

脱磷转炉内成渣路线的理论研究

以CaO-SiO2-FeO三元渣系为基，利用正规溶液模型计算了不同碱度、炉渣组分对于脱磷转炉内磷分配比和终点磷含量的影响规律；同时，采用Factsage软件计算了不同脱磷渣系的液相线温度，考察了添加不同炉渣组元对于渣系液相线温度的影响规律。综合理论计算结果，得到脱磷转炉适宜的成渣路线为铁质成渣路线，脱磷初渣成分为15%CaO-44%SiO2-41%FeO，中期渣成分为53%CaO-25.5%SiO2-21.5%FeO,后期固磷渣成分为63.6%CaO-30.3%SiO2-6.1%FeO。可为脱磷转炉的生产操作提供参考。     

Valorization of Eucalyptus wood by glycerol-organosolv pretreatment within the biorefinery concept: An integrated and intensified approach

The efficient utilization of lignocellulosic biomass and the reduction of production cost are mandatory to attain a cost-effective lignocellulose-to-ethanol process. The selection of suitable pretreatment that allows an effective fractionation of biomass and the use of pretreated material at high-solid loadings on saccharification and fermentation (SSF) processes are considered promising strategies for that purpose. Eucalyptus globulus wood was fractionated by organosolv process at 200 °C for 69 min using 56% of glycerol-water. A 99% of cellulose remained in pretreated biomass and 65% of lignin was solubilized. Precipitated lignin was characterized for chemical composition and thermal behavior, showing similar features to commercial lignin. In order to produce lignocellulosic ethanol at high-gravity, a full factory design was carried to assess the liquid to solid ratio (3–9 g/g) and enzyme to solid ratio (8–16 FPU/g) on SSF of delignified Eucalyptus. High ethanol concentration (94 g/L) corresponding to 77% of conversion at 16FPU/g and LSR = 3 g/g using an industrial and thermotolerant Saccharomyces cerevisiae strain was successfully produced from pretreated biomass. Process integration of a suitable pretreatment, which allows for whole biomass valorization, with intensified saccharification-fermentation stages was shown to be feasible strategy for the co-production of high ethanol titers, oligosaccharides and lignin paving the way for cost-effective Eucalyptus biorefinery.     

Arabinosylated phenolics obtained from SO2‐steam‐pretreated sugarcane bagasse

A pentose‐rich hydrolysate fraction obtained by extraction of steam‐pretreated sugarcane bagasse was analysed with regard to dissolved phenolics. The liquid obtained after steam pretreatment (2% SO₂ (w/w) at 190 °C for 5 min) was divided into two parts: one containing dissolved compounds originating from hemicellulose (with xylose as the dominating compound), and the other containing predominantly dissolved compounds originating from lignin. Using nuclear magnetic resonance, the main dissolved compounds originating from lignin were identified as the glycosylated aromatics, 5‐O‐(trans‐feruloyl)‐L‐Arabinofuranose and 5‐O‐(trans‐coumaroyl)‐L‐Arabinofuranose, together with p‐coumaric acid and small amounts of more common free phenolics such as p‐hydroxybenzaldehyde, p‐hydroxybenzoic acid and vanillin. The phenolic compounds were analysed and quantified using reversed‐phase high‐performance liquid chromatography. The findings show that SO₂ steam explosion opened up new degradation pathways during lignin degradation. Copyright © 2012 Society of Chemical Industry     

Effect of sodium silicate pretreatment on phosphate layer: Morphology and corrosion resistance behavior

Phosphating is a widely adopted treatment in industry for many purposes. In this paper, carbon steel was pretreated with sodium silicate before phosphating. X‐ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical measurements were used to evaluate the pretreatment effect by sodium silicate on the phosphating layer. The results demonstrate that the phosphate layer pretreated by sodium silicate has a better corrosion resistance as compared with the un‐pretreated ones. More compact and uniform coatings composed of finer crystals were obtained with the pretreatment of sodium silicate.     

Enhanced saccharification of corn straw pretreated by alkali combining crude ligninolytic enzymes

BACKGROUND: This work investigated the monokaryogenesis of dikaryon strains of Trametes hirsuta by protoplasts regeneration for extracellular ligninolytic enzyme production. Saccharification of corn straw was enhanced by alkali pretreatment combining crude ligninolytic enzymes. RESULTS: Effectiveness of alkali pretreatment of corn straw on delignification was evaluated under different concentrations. About 45% lignin loss was achieved at the concentration of 1.5% NaOH. In addition, 79.0% sugar yield was obtained after combined pretreatment with NaOH and crude ligninolytic enzyme produced from monokaryotic strains of Trametes hirsuta. Scanning electron microscopy (SEM) images showed that the porosity and surface area increased significantly after combined pretreatment. The FTIR spectra indicated that great intensity changes occurred at the 890–900 cm^?1, 1509–1513 cm^?1 and 1595 cm^?1 bands. CONCLUSION: The proposed combined pretreatment removes lignin and enhances saccharification of corn straw effectively. Copyright © 2012 Society of Chemical Industry     

MBR工艺应用于城市污水处理的技术风险

对MBR工艺应用于城市污水处理中的技术风险进行了系统的分析,预处理的风险、处理能力降低的风险以及自动控制系统的风险是MBR工艺在应用时的主要技术风险。预处理应得到充分的重视,有效的预处理对于保持工艺性能非常关键。为了应对处理能力的降低,合理地设置调节池或膜组件对于保持处理能力非常重要,大型MBR污水处理厂还应准备一套传统工艺以应对峰值流量。小型MBR污水处理厂可以采用一套PLC控制系统,大型MBR污水处理厂应采用两套PLC控制系统,并且采用环状结构连通。