Comparison of ionic liquid,acid and alkali pretreatments for sugarcane bagasse enzymatic saccharification

BACKGROUND: Much attention has been given to applying ionic liquids (ILs) as an alternative pretreatment method for lignocellulosic biomass. This study aims to select the most suitable type of IL for pretreating sugarcane bagasse (SCB). The potential of ILs for pretreatment was evaluated and compared with conventional pretreatment media, acids and alkalis. The performance of the pretreatment media was evaluated based on the amount of reducing sugar produced from enzymatic saccharification, the energy requirement, and changes in the chemical structure and crystallinity index of the pretreated bagasse. RESULTS: 1‐ethyl‐3‐methylimidazolium acetate [EMIM]oAc was selected as the most suitable IL for SCB pretreatment. The optimum yields of reducing sugar obtained from [EMIM]oAc‐, alkali‐, and acid‐pretreated SCB were 69.5%, 92.8% and 41.3%, respectively. Although a lower yield of reducing sugar was obtained, [EMIM]oAc pretreatment required the least energy to pretreat 1 kg of SCB. Moreover, the percentage of SCB loss during [EMIM]oAc pretreatment was the lowest. [EMIM]oAc‐pretreated SCB also had the lowest crystallinity index (CI) with the most amorphous structure. CONCLUSION: [EMIM]oAc appears to be another option for pretreating SCB, and other issues such as the recyclability of [EMIM]oAc is worth investigating. Copyright © 2011 Society of Chemical Industry     

Impact of dilute acid pretreatment on the structure of bagasse for bioethanol production

Dilute acid pretreatment is a commonly used pretreatment method in the course of producing bioethanol from lignocellulosics and the structure variation of the lignocellulosics is highly related to the pretreatment process. To understand the impact of dilute acid pretreatment on the structure of bagasse, four different pretreatment conditions by varying heating time are considered where the bagasse and the pretreated materials are examined using a variety of analysis methods. The obtained results indicate that the thermogravimetric analysis (TGA) is able to provide a useful insight into the recognition of lignocellulosic structure. Specifically, the peak of the TGA of the pretreated materials moves toward the low temperature region, revealing that the lignocellulosic structure is loosened. However, the characteristic of crystal structure of cellulose remains in the pretreated materials. Increasing heating time enhances the pretreatment procedure; as a result, the average particle size of the investigated materials increases with heating time. This swelling behavior may be attributed to the enlarged holes inside the particles in that the surface area decreases with increasing heating time. In addition, when the heating time is increased to a certain extent (e.g. 15 min), some fragments are found at the surface and they tend to peel off from the surface. It follows that the dilute acid pretreatments have a significant effect on the bagasse structure. Copyright © 2009 John Wiley & Sons, Ltd.     

Production of active lipase by Rhizopus oryzae from sugarcane bagasse: solid state fermentation in a tray bioreactor

This study deals with production of lipase in solid state fermentation by Rhizopus oryzae from sugarcane bagasse. A tray bioreactor was designed for the extracellular enzyme production. Daily, lipase production was evaluated at several incubation temperatures. Furthermore, the influence of temperature and humidity of the cabinet, depth of solid bed, particle size, initial moisture content and supplementary substrate (olive oil) as carbon source was investigated. The obtained results showed that bioreactor temperature of 45 °C, humidity of 80%, solid bed depth of 0.5 cm, particle size in the range of 0.335–1 mm, substrate initial moisture content of 80% for the top tray and 70% for the middle tray and supplementary substrate of 8% (v/w) olive oil led to maximum lipase production. Under optimum fermentation conditions after 72‐h incubation, maximum lipase activities for the top, middle and bottom trays were 215.16, 199.36 and 52.64 U gds^?1, respectively.     

Fixed-Bed Pyrolysis of Hazelnut (Corylus Avellana L.) Bagasse: Influence of Pyrolysis Parameters on Product Yields

Fixed-bed slow pyrolysis experiments have been conducted on a sample of hazelnut bagasse to determine particularly the effects of pyrolysis temperature, heating rate, particle size and sweep gas flow rate on the pyrolysis product yields. The temperature of pyrolysis, heating rate, particle size and sweep gas flow rate were varied in the ranges 350–550° C, 10 and 50° C/min, 0.224–1.800 mm and 50–200 cm³/min, respectively. Under the various pyrolysis conditions applied in the experimental studies, the obtained char, liquid, and gas yield values ranged between 26 and 35 wt%, 23 and 34.40 wt%, and 25 and 32 wt%, respectively. The maximum biooil yield of 34.40% was obtained at the final pyrolysis temperature of 500°C, with a heating rate of 10° C/min, particle size range of 0.425–0.600 mm and a sweep gas flow rate of 150 cm³/min.     

羧甲基蔗渣木聚糖的合成与表征

以蔗渣木聚糖和一氯乙酸为主要原料,乙醇水溶液为溶剂,冠醚为催化剂,经碱活化、醚化反应两步合成了羧甲基蔗渣木聚糖。考察了物料摩尔比、反应时间、反应温度和溶剂中水含量等因素对合成工艺的影响,确定的较佳工艺条件:n(蔗渣木聚糖结构单元)∶n(氢氧化钠)∶n(一氯乙酸)=1∶3.25∶1.25,溶剂V(乙醇)∶V(水)=4∶1,45℃碱化2 h,70℃醚化3 h,所得羧甲基化产物的取代度可达0.59。用FTIR与SEM对原料和产物的结构进行了表征。热分析表明,反应后蔗渣木聚糖在234~312℃内分解量由总质量的46.27%降至30.58%。质量浓度为12 g/L的产物水溶液的表面张力为63.6 mN/m。     

甘蔗渣在烤烟漂浮育苗中的应用研究

以新鲜甘蔗渣为主要材料,研究了烤烟漂浮育苗基质配制技术。结果表明,添加复合肥和钙镁磷肥堆沤甘蔗渣腐熟速度较快,沤制7个月C/N值由182.35降至26.58。采用堆沤65%腐熟甘蔗渣 25%膨化珍珠岩 10%煤渣(磨成粉过3mm孔径筛)配制烤烟漂浮育苗基质,能使烤烟较好地出苗、生长和成苗,大田生长发育也优于其他方式育出的烟苗。     

Study of the Mechanical Properties of Fibers Extracted from Tunisian Agave americana L.

Agave americana L. fibers, the most abundant variety in Tunisia, have a quite important textile potential. This potential is demonstrated by studying the extraction of these fibers from leaves, their physical properties such us fineness or density and their mechanical behavior in tensile tests. In this work, results of a mechanical behavior study of fibers extracted from the Agave americana L. plant are presented. These results deal with the principal and mechanical characteristics of these fibers which are the strain at break, the elasticity modulus and the rupture facture. These results permitted to situate these fibers, compared to the other textile fibers, as materials that can be used in technical applications such as reinforcing composites or geotextile. In order to understand the mechanical properties of these fibers, a correlation study between the properties already cited and the fine structure was done. The obtained results showed that the mechanical properties of Agave americana L. fibers are closely related to the individual fibers deformations and to the natural matrix (lignin and gums) that are linked to these elementary fibers.     

低压蒸汽爆破处理对蔗渣浆化学组分的影响

本文对经低压蒸汽爆破处理的蔗渣浆进行了化学组分分析,重点探讨爆破处理后浆料的纤维素、半纤维素和木素含量的变化情况,同时对废液中的还原糖含量和有机酸含量进行了分析.     

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     

THERMAL ANALYSIS AND DRYING KINETICS OF OLIVE BAGASSE

ABSTRACT

The slow thermal decomposition of olive bagasse at temperatures ranging from 25 to 900° C, with particular stress on the moisture evaporation phenomena, is analyzed making use of thermogravimetry, derivative ihermogravimelry and differential scanning calorimetry. The results obtained demonstrate that Thermal Analysis techniques contribute for the characterization of iniernai moisture transfer processes. “ Drying curves” obtained from Thermal Analysis experiments were compared with thin-layer drying curves of olive bagasse at relatively high temperatures. The existence of a critical moisture content, which distinguishes two types of water liaisons, was demonstrated, and its value quantified at 17-18%.