Manufacture of xylose-based fermentation media from corncobs by posthydrolysis of autohydrolysis liquors

Milled corncob samples were mixed with water and heated to obtain a liquid phase containing oligosaccharides, sugars, and acetic acid as main reaction products (autohydrolysis reaction). To hydrolyze the sugar oligomers to the correspondent monomers, sulfuric acid was added to the autohydrolysis liquors to reach 0.5–2 wt% of solution, and the reaction media were heated at 101.5–135°C. With this operational procedure, sugar solutions suitable as fermentation media (containing xylose as the major component) were obtained. The kinetics of the posthydrolysis step was characterized on the basis of experimental data concerning the time courses of the concentrations of xylooligosaccharides, xylose, furfural, and acetic acid. The concentrations of other reaction byproducts (glucose or arabinose) were also measured.     

玉米芯水解残渣热解焦气化反应性研究

利用热重分析仪研究了玉米芯及其酸水解残渣热解焦的气化反应性,重点考察了热解温度、升温速率、气化温度和气化介质(CO₂、H₂O)对残渣热解焦气化反应性的影响,并借助SEM观测了热解焦的表观形貌。结果表明,残渣热解焦的气化反应性较玉米芯热解焦有所下降;在热解温度550~850 ℃,残渣热解焦的气化反应性随热解温度提高而降低,在热解升温速率0.1 K/s下制取的热解焦,其气化反应性低于15.0 K/s下的热解焦;在气化温度850~950 ℃,提高气化反应温度和使用水蒸气作为气化介质能显著提高残渣热解焦的气化反应性;采用混合反应模型计算了残渣热解焦的气化反应动力学参数。     

玉米芯流化床快速热解制取生物油试验研究

本文在流化床上对玉米芯进行了快速热解制取生物油的试验研究.首先在非催化条件下考察了温度、气体流量、床高和物料粒径对热解产物产率的影响,得到了制取生物油的最优工况.在此工况下进行了催化热解试验,研究了FCC催化剂对热解产物产率和生物油品质的影响.结果表明,最优工况下生物油产率为56.8%.同未加催化剂相比,FCC催化剂的存在使得生物油中油组分和焦炭的产率降低,不凝结气体、水分和焦的产率增加.分级冷凝系统的应用较好的实现了重油、轻油和水的分离.对催化条件下第二级冷凝器收集的生物油分析表明,其油组分的氧含量和高位热值分别为13.64%和36.7 MJ/kg,具有很好的应用前景.     

Lactic acid production from cellulosic material by synergetic hydrolysis and fermentation

The hydrolysis process on corncob residue was catalyzed synergetically by the cellulase from Trichoderma reesei and the immobilized cellobiase. The feedback inhibition to cellulase reaction caused by the accumulation of cellobiose was eliminated efficiently. The hydrolysis yield of corncob residue was 82.5%, and the percentage of glucose in the reducing sugar reached 88.2%. The glucose in the cellulosic hydrolysate could be converted into lactic acid effectively by the immobilized cells of Lactobacillus delbrueckii. When the enzymatic hydrolysis of cellulose and the fermentation of lactic acid were coupled together, no glucose was accumulated in the reaction system, and the feedback inhibition caused by glucose was also eliminated. Under the batch process of synergetic hydrolysis and lactic acid fermentation with 100 g/L of cellulosic substrate, the conversion efficiency of lactic acid from cellulose and the productivity of lactic acid reached 92.4% and 0.938 g/(L·h), respectively. By using a fed-batch technique, the total concentration of cellulosic substrate and lactic acid in the synergetic process increased to 200 and 107.5 g/L, respectively, whereas the dosage of cellulase reduced from 20 to 15 IU/g of substrate in the batch process. The results of the bioconversion of renewable cellulosic resources were significant.     

玉米芯与低密度聚乙烯混合物在氢气气氛下的催化热解研究

本文研究了在氢气氛围及HZSM-5、H-Beta、NaY和TiO2催化剂作用下玉米芯与LDPE混合物(重量比2∶8)的共热解情况。通过催化热解所得油相液体的烃族分析及碳数分布发现:在催化剂作用下,油相液体的碳数分布变窄,共同热解所得气体产率最高的是H-Beta催化体系,液体产率最高的是NaY,残渣量最多的是TiO2催化体系。催化共热解所得油相液体的碳数分布主要集中在C4~C19之间,使用NaY可获得高品位的油相液体,其研究法辛烷值(RON)为97.5;水相液体中的主要物质是醋酸,加入催化剂后其含量明显增加。四种催化剂中,醋酸生成量最多的是NaY催化剂,其次是HZSM-5,最后是H-Beta和TiO2。其中在NaY催化体系作用下生成的水相液体组分中,醋酸含量为57.8%。     

玉米芯酸水解残渣的热解特性

在热重分析仪和管式炉热解装置上对玉米芯酸水解残渣（简称残渣）的热解过程进行了研究,并利用气相色谱（GC）,气相色谱-质谱联用(GC-MS)和扫描电镜(SEM)对热解产物进行了分析。热重分析结果表明,残渣的热裂解主要发生在280℃~ 450℃,仅在340.7℃有一个明显的失重峰。管式炉热解实验表明, 随着热解终温的升高,残渣的气相产物产率明显增加,而固相和液相产物产率均有所下降。GC分析结果表明,H₂和CH₄的产率随着热解终温的升高而升高,CO₂产率呈现下降趋势; 与玉米芯热解气相产物相比,残渣热解CO、H₂和CH₄的产率较高,CO₂产率较低。GC-MS结果表明,残渣热解焦油的主要成分为酚类物质和多环芳烃。SEM结果表明,随着热解终温的升高,残渣热解焦炭的表面结构趋于有序化。     

玉米芯粉对中性红的吸附脱色研究

本文研究了玉米芯粉对染料的吸附脱色情况,结果表明,玉米芯粉能有效吸附阳离子染料。以阳离子染料中性红为模型,考察了吸附剂用量、溶液浓度、溶液p H以及温度等对吸附平衡的影响,结果表明玉米芯粉吸附中性红符合拟二级动力学方程;不同温度下,该吸附过程符合Langmuir方程和Freundlich方程,qmax、KF受温度影响小;D-R等温方程拟合结果表明该吸附是以化学吸附为主;热力学参数计算结果表明玉米芯粉吸附中性红是一个熵减的自发放热过程。其他电解质的存在不利于吸附反应的进行。     

Correlation between the bath composition and nanoporosity of DC-electrodeposited Ni-Fe alloy

The outstanding mechanical strength of as-deposited DC-electrodeposited nanocrystalline (nc) Ni-Fe alloys has been the subject of numerous researches in view of their scientific and practical interest. However, recent studies have reported a dramatic drop in ductility upon annealing above 350°C, associated with a concomitant abnormal rapid grain growth. The inherent cause has been ascribed to the presence of a detrimental product or by product in the bath, which affects either the microstructure or causes defects in the concentration and/or distribution of the as-deposited films. The present work has been inspired by the observed abnormal behaviour of annealed electrodeposited nc Ni-Fe alloy, which has here been addressed by considering the relationship between the composition of the bath (iron-chloride, nickel-sulphate solution, saccharin and ascorbic acid) and deposition defects (e.g. grain boundary pores) in the case of an nc Ni-Fe (Fe 48 wt%) alloy. The current investigations have included X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) in both as-deposited and post-annealed conditions (300°C–400°C). XPS depth profiling with Ar ion sputtering showed a significant amount of C and O impurities entrapped in the foils during deposition. As such impurities are often overlooked in common analytical techniques, new scenarios may need to be rationalised to explain the observed drop in tensile ductility of the as-deposited Ni-Fe alloys.     

A Simple Method to Prepare Magnetic Modified Corncobs and its Application for Congo Red Adsorption

The purpose of this research is to use a simple method to prepare magnetic modified corncobs (MCBs) with good adsorption performances for Congo Red (CR). The adsorption was analyzed by Fourier transform infrared spectroscopy and x-ray diffraction. The maximal adsorption capacity of the MCB for CR was 198.2 mg/g and about 5.5-fold for unmodified corncob. Potassium ion was more positive effect onto adsorption than sodium ion. The dye uptake process obeyed the pseudo-second-order kinetic expression. The best-fitted data were obtained with the Langmuir model. The as-prepared magnetic modified sorbent had a potential in the dyeing industry wastewater treatment.     

Application of xylanase from thermomyces lanuginosus IOC-4145 for enzymatic hydrolysis of corncob and sugarcane bagasse

Xylanases have significant current and potential uses for several industries including paper and pulp, food, and biofuel. For the biofuel industry, xylanases can be used to aid in the conversion of lignocellulose to fermentable sugars (e.g., xylose). We investigated the thermophilic fungus Thermomyces lanuginosus was yielded for xylanase production and found that the highest activity (850 U/mL) was yielded after 96 h of semisolid fermentation. The enzyme was used for hydrolyzing agricultural residues with and without pretreatment. Such residues were characterized in relation to the maximum xylose content by total acid hydrolysis. The highest xylose yields realized by enzymatic hydrolysis were 24 and 52%, achieved by using 3000 U/g (dried material) of sugarcane bagasse and corncob, respectively, which received both alkali and thermal pretreatment.