Volume 4 Issue 2

Lignocellulosic materials such as agricultural residues have been recognized as potential sustainable sources of mixed sugars for fermentation to bioethanol. To obtain a high overall ethanol yield and achieve an economically feasible production process, the removal of lignin and hemicelluloses improves the accessibility of cellulosic material to hydrolytic enzymes and avoids the degradation products that are inhibitory to the yeast used in the subsequent fermentation. Technological advances, e.g., environmentally friendly removal of lignin and hemicelluloses from lignocellulosic biomass prior to fermentation of the librated glucose from cellulose into bioethanol, has the potential to provide for sustainable and cost effective production of biofuel.

The sustainable development of the chemical and energy industry is an indispensable component of our sustainable society. However, the traditional chemical and energy industry depends heavily on such non-renewable fossil resources as oil, coal, and natural gas. Its feedstock shortage and the resultant environmental and climatic problems pose a great threat for any type of sustainable development. Lignocellulosic materials are the most abundant renewable resources in the world, and their efficient utilization provides a practical route to address these challenges. The lignocellulosic feedstock bio-refinery is an effective model for the comprehensive utilization of lignocellulosic materials, and it will play vital role in the future development of chemical and energy industry.

Separation of solids from liquid swine manure and subsequent thermochemical conversion (TCC) of the solids fraction into oil is one way of reducing the waste strength and odor emission. Such processing also provides a potential means of producing renewable energy from animal wastes. Gravity settling and mechanical separation techniques, by means of a centrifuge and belt press, were used to remove the solids from liquid swine manure. The solid fractions from the above separation processes were used as the feedstock for the TCC process for oil production. Experiments were conducted in a batch reactor with a steady temperature 305 oC, and the corresponding pressure was 10.34 Mpa. Gravity settling was demonstrated to be capable of increasing the total solids content of manure from 1% to 9%. Both of the mechanical separation systems were able to produce solids with dry matter around 18% for manure, with 1% to 2% initial total solids. A significant amount of volatile solid (75.7%) was also obtained from the liquid fraction using the belt press process. The oil yields of shallow pit manure solids and deep pit manure solids with belt press separation were 28.72% and 29.8% of the total volatile solids, respectively. There was no visible oil product obtained from the deep pit manure solids with centrifuge separation. It is believed that it is the volatile solid content and the other components in the manure chemical composition which mainly determine the oil production.

Oxidative polymerization of two isolated lignans, secoisolariciresinol, and secoisolariciresinol diglucoside, as well as the lignan macromolecule, by a high redox potential Trametes hirsuta laccase was studied with different analytical methods. The reactivity of laccase with the different compounds was studied by an oxygen consumption measurement. The polymerization of laccase-treated lignans was evidenced by size exclusion chromatography, reversed phase - high performance liquid chromatography, and matrix-assisted laser desorption/ionisation - time of flight mass spectrometry. The data showed that the selected substrates could be oxidised by laccase. Secoisolariciresinol and secoisolariciresinol diglucoside were polymerized by laccase to a similar extent. The lignan macromolecule reacted to a lesser extent. Polymerization of the macromolecule proceeded mainly via its secoisolariciresinol diglucoside moieties. Furthermore, it was shown that ferulic acid can be linked to polymerized secoisolariciresinol via decarboxylation by laccase. This investigation showed that lignans can be enzymatically modified by Trametes hirsuta laccase.

Dhaincha (Sesbania aculeata) is one of the annual plants in Bangladesh that has potential as a fiber source. It is a crop generally cultivated for its nutritive value to soil. This paper describes the effect of harvesting age of dhaincha on chemical, morphological, pulp, and papermaking properties and its bleachability. Dhaincha is a short length fiber that can be used as a substitute to hardwood. Fiber length was found to increase slightly with increasing age of the plant. The alpha-cellulose content in dhaincha increased and pentosan decreased with increasing age. Dhaincha pulp was prepared from 2, 3, 4, 5, and 6 month old plants under identical cooking conditions. Pulp yield (43-45 %) and kappa number (26-30) did not follow direct correlation with plant age. But physical properties of unbleached pulp increased linearly with the increase of age. Bleachability of dhaincha pulp was quite poor. The bleachability of pulp was improved when the age of dhaincha was increased.

Direct dye with a high affinity for cellulose substrate was utilized as a cellulose anchor to promote retention of paper strengthening additives under various conditions associated with the wet end of a paper machine. Direct Red 28 (DR) was covalently linked to anionic polyacrylamide (A-PAM) via a condensation reaction using water-soluble carbodiimide. The DR-conjugated A-PAM (DR-A-PAM) demonstrated good retention efficiency, resulting in strength enhancement of handsheets. Anionic trash showed no interference with the performance of DR-A-PAM in the wet end, while the additive performance was sensitive to calcium ions. Surface plasmon resonance analysis gave useful information on the cellulose-anchoring ability of DR-A-PAM. Dye molecules were irreversibly adsorbed onto the cellulose substrate under aqueous conditions, while A-PAM possessed no significant affinity for cellulose. These results suggest that anionic DR moieties in DR-A-PAM molecules served as a cellulose-anchor, possibly due to multiple CH-π interaction between hydrophobic face of cellulose substrate and π-conjugated system of dye molecules. Such a unique interaction of direct dye and cellulose provides a new insight into the wet end system, and does not depend on conventional electrostatic attraction.

Municipal wastes have become a severe problem in developed and developing countries during the last century, paper being the main constituent. Not all of the waste paper can be recycled, and therefore alternative procedures for the use of the remaining material should be pursued. The aim of the present work was the application of cellulases for waste paper treatment and the subsequent glucose production and optimization of the conditions for such treatment. Glucose thereafter can be utilized for production of ethanol or other chemicals by specific microbial cultures. The work focused in the stabilization of cellulases by cross-linking or by the addition of specific crown ether based compounds to improve glucose production. The results indicated that enzymatic treatment of waste paper is of particular interest, since it may be an alternative way to carry out municipal wastes treatment and concomitant glucose production. By the application of the proposed procedure, the total amounts of municipal wastes can be greatly reduced and production of bioethanol can be achieved.

This experimental study was conducted to investigate the role of poly-vinyl-alcohol (PVA) treatment in improving the sliding wear behaviour of pure bamboo. The effects of dipping time in PVA solution and applied load on wear behaviour of bamboo samples were determined. The wear volume of bamboo was reduced when it was treated with PVA. The wear volume during sliding was increased with increasing of applied load, whereas the coefficient of friction was reduced on PVA treatment. Worn surfaces were observed by using SEM and discussed to explain the mechanism of wear.

Structural elements of the arylglycerol b-syringyl ether type are very frequent in hardwood lignins. A variety of crystalline dimeric lignin models representing different diastereomeric forms of structural elements in lignin of this type have been studied using X-ray crystallography. Bond distances and bond angles in the model compounds are in all probability nearly identical with those of the corresponding structural elements in lignins. Special attention was paid to the geometry of the b-O-syringyl linkage, since the reactivity of this linkage is of particular interest in connection with pulping reactions. The crystal structures of the model compounds suggest that two types of conformations are predominating; in both of them the aromatic rings are separated by ca. 4.5 Å (maximal distance 4.9-5 Å). Based on X-ray crystallographic data from four compounds a sequence of units (5 aromatic rings, 8 chiral C-atoms) attached to each other by b-syringyl ether linkages was constructed. The appearance of the resulting oligomer illustrates that stereoisomerism can be expected to influence the shape of the lignin molecules to a great extent.

Alkaline pre-extraction and hydrothermal hydrolysis were carried out with eucalyptus chips. Two methods were used to determine and calculate the extraction yield of five-carbon sugars. One is an indirect method, based on the difference of pentosan content between the chips before and after pre-extraction. The other method is to directly measure the content of five-carbon sugars in the extracting solution. The results indicated that there was a defined relationship between the two methods. For alkaline pre-extraction, a good logarithmic relationship was shown. There was a good linear relationship for hot water prehydrolysis. So the pentosan content of the extracted chips could be predicted from the results of the latter method, referring to the two relational expressions. In this study, a simple and rapid method of spectrophotometry was introduced, which will help in the evaluation of extraction yield of five-carbon sugars during biomass processing.