Selective fast pyrolysis of biomass impregnated with ZnCl2: Furfural production together with acetic acid and activated carbon as by-products

Fast pyrolysis of biomass materials impregnated with ZnCl₂ offered a promising way to obtain a liquid product rich in furfural (FF) and acetic acid (AA), and the pyrolytic solids could be used as the precursors to prepare activated carbons (ACs). In this study, a lab-scale fast pyrolysis set was designed and used for the quantitative production of the three chemicals. The maximum FF was produced from the corncob impregnated with at least 15 wt% ZnCl₂ and at the pyrolysis temperature around 340 °C, with the yield of more than 8 wt% compared with only 0.49 wt% from the raw corncob. Meanwhile, AA of around 4 wt% could be obtained. The content of the FF and AA was over 50 wt% and 25 wt% on the water-free basis of the pyrolytic liquids. In addition, ACs were prepared from the pyrolytic solids, and they exhibited similar properties as those prepared from direct activation of ZnCl₂-impregnated biomass materials.     

廉价离子液体体系中玉米芯生成糠醛优化

采用廉价绿色离子液体[TEA][HSO4]作为溶剂,利用微波加热法辅助玉米芯水解并脱水制备糠醛.通过响应面法优化糠醛生成反应条件,有效转换玉米芯中的木糖,并得到82.2％糠醛收率.利用2-丁醇作为萃取剂对糠醛进行回收.重复4次萃取实验,从[TEA][HSO4]中回收99.7％糠醛.在2次[TEA][HSO4]的回收实验...     

Production of Ammonium Lactate by Fed-batch Fermentation of Rhizopus oryzae from Corncob Hydrolysate

IntroductionThere is an increased demand for lactic acid asa starting material for the synthesis of poly- lacticacid ( PLA) ,a biodegradable polymer,which cansubstitute for petrochemical derivatives.However,an optically pure L- ( + ) - lactic acid( LLA) is need-ed[1] .Industrial lactic acid fermentations are usual-ly carried out with bacteria,which produces a mix-ture of L- ( + ) - and D- ( - ) - lactic acid in a richmedium[2 ,3 ] .The rich nutrient supplements re-quired for bacterial ferm…     

微波消解-ICP-AES法测定玉米芯中的微量元素含量

采用微波消解处理样品,以电感耦合等离子体发射光谱法(ICP-AES)测定了我国北京、山东、吉林、云南、新疆、甘肃、山西、陕西、江苏、内蒙十个省区玉米芯中Zn,Mg,Mn,Sr,Fe,Pb,Cu和Se八种元素的含量。加入1.5 mL 68%的HNO₃以及0.5 mL HF作为消解剂,在400 W微波功率下3步即可完全将样品消解。测定上述八种元素的相对偏差及回收率分别为: 0.72%～4.16%,95.5%～104.5%;1.58%～3.66%,98.2%～103.5%;0.19%～4.58%,97.0%～103.2%;1.31%～4.90%,95.7%～104.1%;1.40%～4.01%,95.9%～104.6%;1.55%～4.28%,95.1%～104.5%;2.16%～5.00%,96.4%～103.5%;2.00%～4.99%,95.1%～101.3%。方法快速、简便、灵敏度高、准确性好,可多元素同时测定,且无损失和环境污染小。     

可磁力回收的Fe3O4纳米颗粒负载纤维素酶生物催化剂用于玉米芯降解

面对日益枯竭的化石能源和资源危机,科研工作者加速了对生物资源回收利用的研究.其中,作为生物资源主要成分的纤维素被证实是一种可以重新利用的原料,甚至可以作为工业产品潜在的前驱体.因此,回收利用富含纤维素的农作物副产品显得尤为重要.目前,多数纤维素资源并没有得到充分利用,例如玉米芯,全世界只有大约0.5％被利用.为了高效利用玉米芯资源,人们尝试各种分解方法将其主要成分纤维素和半纤维素转化成葡萄糖、木糖、糠醛以及酒精等.其中,最有效的策略是利用纤维素酶来分解玉米芯中的纤维素.然而,纤维素酶在实际应用过程中缺乏长久稳定性,将纤维素酶从反应体系中回收并重复利用非常困难.将纤维素酶负载到固体载体上是提高传统生物酶稳定性和可回收性的有效方法.固载纤维素酶在批生产处理和连续生产中比自由酶更具优势,可使生物酶催化剂从反应体系中分离出来变得容易和可操控.可以作为纤维素酶载体的物质有很多,例如浮石、静电纺丝的PAN纤维、纳米纤维膜、甲基丙烯酸甲酯共聚物和石墨烯等.一般来讲,任何含有表面功能基团从而提供了可以和纤维素酶形成强物理、化学作用的载体都可以采用.纳米尺寸的载体具有特殊性,一方面纳米颗粒提供了较大的比表面积从而可以拥有可观的负载能力,另一方面纳米颗粒可以轻易解决大颗粒载体应用中产生的反应底物和催化剂之间的扩散受阻问题.目前,纳米磁性颗粒已广泛用于负载蛋白质、多肽和生物酶.另外,用纳米磁性粒子作载体可方便地借助外加磁场实现生物酶催化剂的选择性分离回收,避免了传统载体所需的过滤或离心等单元操作,从而降低了生产成本,使生物酶催化技术实现连续化操作并用于规模化工业生产.本文通过水热法制备了颗粒均匀的纳米Fe3O4磁性颗粒,然后用3-氨丙基三乙氧基硅烷(KH550)化学修饰,再用戊二醛作交联剂将纤维素酶通过键合作用负载到修饰后的磁性载体上,从而高效制备了一种可磁力回收的生物酶催化剂.采用透射电镜和X射线衍射表征了磁性纳米粒子、修饰后的磁性纳米粒子以及制备的生物酶催化剂的粒径、外观形貌和品格结构,用红外光谱验证了磁性纳米颗粒上固载化纤维素酶的存在,用热重分析了固载化酶和自由酶的热稳定性,计算了制备的生物酶催化剂负载量和磁性粒子含量.对影响负载酶活性的多种因素进行了考察,合适的负载温度和pH值分别为40℃和6.0,戊二醛最佳添加浓度为2.0％,适宜的固载时间为4h.在最优负载条件下得到的固载化生物酶的活性可以保持自由酶活性的99.1％.经过15次重复使用后,固定化酶活性仍能保持91.1％.将制备的生物酶催化剂用于玉米芯分解制葡萄糖反应,预处理后的玉米芯最大分解率可达61.94％.     

Effect of aeration rate on production of xylitol from corncob hemicellulose hydrolysate

The effects of different aeration conditions on xylitol production from corncob hemicellulose hydrolysate by Candida sp. ZU04 were investigated. Batch fermentations were carried out in a 3.7-L fermentor at 30°C, pH5.5, and agitation of 300 rpm. It was found that the two-phase aeration process was more effective than the one-phase aeration process in xylitol production. In the first 24h of the aerobic phase, a high aeration rate was applied, glucose was soon consumed, and biomass increased quickly. In the second fermentation phase, aeration rate was reduced and an improved xylitol yield was obtained. The maximum xylitol yield (0.76 g/g) was obtained with an aeration rate of 1.5 vvm (KLa of 37 h⁻¹) for the first 24 h and 0.3 vvm (KLa of 6 h⁻¹) from 24 to 96 h.     

TEMPO-mediated oxidation of corncob holocellulose and its influences on paper properties

In this study, the agricultural by-products of corn production (corncobs) were ground into a powder form. Then, the powder was treated with sodium chlorite to remove the lignin, and the remaining holocellulose was optionally modified with 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)-mediated oxidation. The resulting product was examined using an elemental analysis, along with Fourier transform infrared spectroscopy (FTIR). The effects of the oxidation time and dosages of the TEMPO on the paper’s physical properties were investigated. The results indicated that the TEMPO-mediated oxidized corncob holocellulose had the ability to improve the properties of both paper and recycled paper. When 1.0% oxidized holocellulose was used, the resulting tensile index, burst index, and folding endurance were increased by 4.16%, 8.63%, and 50.71%, respectively, compared with the control paper. The SEM analysis indicated that the bonding between fibers was improved by adding oxidized corncob holocellulose. Compared with the control paper, it was determined that the proportion of mesopore within the fibers increased and the bonding of the C–O bonds increased in the paper with the oxidized corncob holocellulose. The results of this study may potentially provide guidance for the future high value-added application of corncobs as a paper strengthening agent.     

Adsorption of Procion Red MX‐5B and Crystal Violet Dyes from Aqueous Solution onto Corncob Activated Carbon

Textile and dyeing industries are considered as one of the main water utilizing industries and generate a huge amount of colored liquid effluents in their finishing and dyeing processes. In this paper, agricultural waste corncob has been chosen as a renewable source to produce activated carbon at 400 °C (corncob activated carbon, CCAC) for the removal of Procion Red MX‐5B (PR) and crystal violet (CV) from dye‐polluted effluent using a batch technique. The efficiency of CCAC in adsorbing CV and PR from the water has been carried out as a function of pH, adsorbent dose, contact time, agitation, and initial concentration. The Temkin, Langmuir, and Freundlich isotherm model equations were investigated to understand the adsorption mechanism of dye molecules. The Langmuir isotherm R² obtained was 0.9958 for CV and 0.9733 for PR. Maximum adsorption capacity obtained was 2.498 mg/g for CV and 2.86 mg/g for PR. Moreover, a pseudo‐second‐order kinetic equation with R² value of 0.9999 was found in this adsorption process. To identify the chemical and morphological characteristics and surface functional groups, nanocomposite of CCAC was characterized using field emission scanning electron microscopy and Fourier‐transform infrared spectrophotometry. The obtained results indicate that the prepared CCAC can be used as a promising low‐cost dye (CV and PR) removing adsorbent from aqueous solutions.