Volume 5 Issue 2

The influences of pulp type, content of acidic groups (i.e., sulfonic and carboxylic groups) in CTMP, kappa number (i.e., residual lignin content) of unbleached kraft pulp, and beating degree of bleached kraft pulp on the conductivity of polyaniline (PAn)-coated conductive paper were investigated. The amounts of PAn coated on chemical pulps were higher than those coated on high yield pulps, and the surface resistivities of conductive papers prepared from chemical pulps were lower than those prepared from high yield pulps. As the substrates for the production of PAn-coated conductive paper, bleached chemical pulps were better than unbleached chemical pulps. The conductivity had a significant positive linear correlation with the amount of PAn coated. The amount of PAn coated increased with increasing content of sulfonic groups in CTMP or decreasing kappa number of unbleached kraft pulp. We hypothesized that this might be associated with the ionizability of acidic groups and the inhibiting effect of lignin on aniline polymerization. The beating degree of pulp seemed to have an insignificant effect on the conductivity of PAn-coated conductive paper. As a whole, the interpretations of the influence of the chemical composition are based on proposed ideas and need to be confirmed by future experimental work.

Bio-oil is a promising alternative source of energy produced from fast pyrolysis of biomass. Increasing the viscosity of bio-oil during storage is a major problem that can be controlled by the addition of methanol or other alcohols. This paper reports the results of our investigation of the reactions of short chain alcohols with aldehydes and acids in bio-oil. The reaction of methanol with hydroxyacetaldehyde (HA) to form the acetal was catalyzed by the addition of 7 x 10-4 M strong acids such as sulfuric, hydrochloric, p-toluene sulfonic acid, and methanesulfonic acid. HA formed 2,2-dimethoxyethanol (DME), and at 60 oC the equilibrium was reached in less than one hour. Smaller amounts of DME were formed in the absence of strong acid. HA, acetaldehyde, and propanal formed their corresponding acetals when reacted with methanol, ethanol, 1-propanol or 1-butanol. Esters of acetic acid and hydroxyacetic acid were observed from reactions with these same four alcohols. Other acetals and esters were observed by GC/MS analysis of the reaction products. The results from accelerated aging experiments at 90 oC suggest that the presence of methanol slows polymerization by formation of acetals and esters from low molecular weight aldehydes and organic acids.

The continual expansion of urbanization and industrial activity has led to the accumulation of a large quantity of lignocellulosic residues throughout the world. In particular, large quantities of paper and bagasse are largely produced in Visakhapatnam. In this work we present the study of the degradability of these substrates with fungi. Three cultures of soil fungi were screened for their ability to degrade cellulose. Aspergillus flavus degraded the most, as shown by the highest CO2 release. Further, Aspergillus flavus was tested with the standard fungus Phanerochaete chrysosporium for cellulose degradation, which showed nearly equivalent potential.

Alkaline pretreatment with NaOH under mild operating conditions was used to improve ethanol and biogas production from softwood spruce and hardwood birch. The pretreatments were carried out at different temperatures between minus 15 and 100ºC with 7.0% w/w NaOH solution for 2 h. The pretreated materials were then enzymatically hydrolyzed and subsequently fermented to ethanol or anaerobically digested to biogas. In general, the pretreatment was more successful for both ethanol and biogas production from the hardwood birch than the softwood spruce. The pretreatment resulted in significant reduction of hemicellulose and the crystallinity of cellulose, which might be responsible for improved enzymatic hydrolyses of birch from 6.9% to 82.3% and spruce from 14.1% to 35.7%. These results were obtained with pretreatment at 100°C for birch and 5°C for spruce. Subsequently, the best ethanol yield obtained was 0.08 g/g of the spruce while pretreated at 100°C, and 0.17 g/g of the birch treated at 100°C. On the other hand, digestion of untreated birch and spruce resulted in methane yields of 250 and 30 l/kg VS of the wood species, respectively. The pretreatment of the wood species at the best conditions for enzymatic hydrolysis resulted in 83% and 74% improvement in methane production from birch and spruce.

Nanoparticles are widely used in the papermaking industry as retention/ drainage aids, usually in conjunction with a high mass cationic polyelectrolyte such as cationic starch. However, little convincing knowledge of their role and mechanism in the wet-end system is yet found. This work focused on the role of nanosilica on papermaking wet end system in response to some processing parameters (drainage, retention, and electrostatic force of the whole system). The observations indicated that the nanosilica performance is defined by interactions of nanosilica with the complex aqueous environment of wet end system. The interaction mechanism seems to rely on introduction of nanoparticles into a cationic starch-fines-fibers network, converting the fiber mat on the forming wire into a porous structure that is responsive to retention and drainage.

The anatomical, chemical, and physico-mechanical properties of the fibres of C. pangorei were investigated in this study. The results indicate that the rind region that is split and used in mat making contains compactly arranged fibrovascular bundles and a discontinuous patch of fibrous sheath. The frequency and the R/T ratio of the bundles were high in the rind region and were indicative of fibre strength. Lignin and cellulose, the major cell wall substances, were localized with heterochromatic, fluorescent, and natural dyes. The holocellulose content was high (82.2 %), and the lignin content was comparatively low (13.28 %) as analyzed by the method of Doree. Very thick walled, thick walled, very thin walled, and thin walled fibres were characterized when fibres were macerated, and their derived values indicated a high Slenderness and Runkell ratio that is indicative of tear resistance. The tenacity and percentage elongation of the split culm strands was also high, and this implies high strength of the fibre strands. The fibre of this mat sedge thus has favorable characteristics to be potentially utilized in the mat and silkmat industry. Furthermore the plant’s annual harvesting period, biomass, and appropriate fibre characteristics makes this sedge very attractive as an alternative fibre source in the miscellaneous plant fibre industry.

Phase transformations in microcrystalline cellulose (MCC) were studied following dissolution of 5, 10, and 20 wt. % MCC in the ionic liquid 1-butyl-3-methylimidazolium formate (BMIMFmO) and regeneration via water. BMIMFmO was found to be useful as a non-derivatizing solvent for cellulose without the need for any pre-treatment. Wide angle X-ray scattering indicated that a phase transformation from cellulose I to either a poorly crystalline form of cellulose I and/or cellulose II occurs during regeneration after dissolution in BMIMFmO. The dissolution time affected the resulting microstructure of the regenerated cellulose. Thermogravi-metric analysis showed that regeneration from the ionic liquid lowers the decomposition onset temperature and increases the char yield when compared with the as-received MCC.

The objectives of this research were to investigate surface characteristics and overlaying properties of medium density fiberboard (MDF) panels, as affected by thermal treatment of the fibers. MDF panels were manufactured from untreated rubberwood fibers and fibers treated at three different temperatures (120, 150, or 180°C) for 15 or 30 min. Contact angle measurements were obtained by using a goniometer connected with a digital camera and computer system. Roughness measurements, average roughness (Ra), mean peak-to-valley height (Rz), and maximum roughness (Ry), were taken from the sanded samples along and across the sandmarks using a fine stylus tracing technique. With the increasing thermal treatment temperature and time of the fibers, surface roughness of the panels decreased, while their wettability and adhesive bonding strength decreased. Statistical analyses showed significant differences in the surface roughness, contact angle, and adhesive bonding strength of the panels following thermal treatment. Based on the findings obtained from this study, the contact angle and surface roughness parameters of the MDF panels made from thermally treated rubberwood fibers can provide a good information on their ability to bond.

Corn stover and rice straw lignin samples received from ethanol pilot plants, along with softwood kraft lignin samples, were characterized using pyrolysis GC-MS, 13C CP/MAS NMR spectroscopy, and permanganate oxidation degradation. The lignins were then esterified using 1-methylimidazole as a catalyst in a pyridine-free reaction, and the thermal properties of the products were evaluated. Solid state NMR showed the rice straw lignin contained 18% residual polysaccharides. Pyrolysis GC-MS showed the softwood kraft, corn stover, and rice straw lignins to be G – type, H/G/S – type, and G/S – type, respectively. However, some discrepancy was apparent between the pyrolysis and permanganate oxidation studies as to the ratios of the monomeric make-up of the lignins. The kraft and rice straw lignins were determined to have high degrees of condensation, while the corn stover lignin was uncondensed. Little to no increase in solubility was noticed for corn stover or rice straw lignin esters in organic solvents. Glass transition temperatures (Tg) of the lignin derivatives were determined by a combination of differential scanning calorimetry, dynamic mechanical analysis, and parallel plate rheometry.

In recent years, increasing attention has been directed to the use of renewable resources, particularly of sugarcane bagasse. Considering the abundant availability of such lignocellulosic materials, relatively few attempts have been made regarding their utilization. Studies about properties and morphology, heavy metal adsorption, and membranes preparation have been conduced by this research group in order to use these materials. In this paper, cellulose fibers obtained from sugarcane bagasse were bleached and modified by hydrous niobium phosphate. Hybrids (cellulose/NbOPO4.nH2O) were prepared from metallic niobium dissolved in a fluoridric/nitric (10:1) mixture, to which cellulose sugarcane bagasse was added. Afterwards a concentrated orthophosphoric acid (85mL, 85% w/w) was added to precipitate hydrous niobium phosphate particles. This material was characterized by X-ray diffraction (XRD), thermogravimetry (TG/DTG), and differential scanning calorimetry (DSC) analyses, as well as scanning electronic microscopy (SEM) coupled to an energy dispersive spectrophotometer (EDS). Morphological studies of bleached cellulose revealed different sizes and arrangement of cells, showing that NbOPO4.nH2O was present in the cellulose structure. Thermal stability of the hybrid was observed up to approximately 200°C, and the cellulose decomposed at 300°C. These data will help finding new uses for these materials.