Volume 6 Issue 3

The safety of timber structure design based on the predicted Modulus of Rupture (MOR) of poplar lumber with nondestructive methods is presented in this paper. Dynamic(MOE) of poplar lumber was measured with three different nondestructive methods, and static MOE and MOR were obtained by a static bending test. The regression relationship between various MOE and MOR was evaluated to predict MOR with various MOE. Then timber construction design was conducted on poplar lumber based on measured and predicted MOR. Furthermore, reliability of timber structure design was analyzed with advanced first-order second-moment method. Results indicated that mean values of predicted MOR were slightly greater than those of measured MOR, but Coefficient of Variation (COV) of them were less than those of measured MOR. The reliability index of timber structure design based on predicted MOR, varying from 2.404 to 2.574, was less than that on measured MOR as 2.831.

Dynamic supply and demand equations for particleboard using a three-stage squares simulation (3SLS) were estimated. Empirical data included annual observations over the period of 1976 to 2006. The stationary character of the data was checked by applying the Augmented Dickey-Fuller (ADF) Test. The results revealed that in the demand function, variables such as particleboard price, the gross national product (GNP) in the previous year (lagged quantity), and the MDF price were significant at 0.05%. In the supply function, variables such as the price of medium density fiberboard (MDF), demand for particleboard in the previous year, the product/raw material price ratio in the previous year, and particleboard imports in the previous year were shown to be significant at 0.05%. Also price, income, and cross elasticities of demand for particleboard were calculated as -0.65, 0.32, and 1.63, respectively, indicating that this commodity is a necessary and normal good and MDF is a substitute for it.

Pulp and paper mills represent a major platform for the use of abundant, renewable forest-based biomass as raw material. The pulping processes produce a large amount of black liquor solids, which is currently burnt in a conventional Tomlinson recovery boiler for recovery of energy and inorganic chemicals. This combustion technology can recover chemicals with good efficiency, and steam and power can be produced for the mills. However, Black Liquor Gasification (BLG) can be used to substitute for the combustion process for potential higher energy efficiency, lower greenhouse gas emissions, and more safety. With BLG technology, current pulp and paper mills can be extended into future biorefineries. In this work, a thermodynamic equilibrium model using Gibbs free energy minimization approach and the software FactSage are utilized to analyze the thermodynamic equilibrium constraints of the complex multiple phase reactions and the effects of different operating conditions during black liquor gasification. The modeling results can help better understand the black liquor gasification process and be useful in process modeling and analysis of the future BLG-based biorefinery.

The aim of this work is to prove the suitability of a new alkaline and halo-tolerant bacterial laccase (SilA) produced by Streptomyces ipomoea CECT 3341 to enhance the conventional chemical bleaching process of an industrial eucalyptus kraft pulp. The laccase used for this study was a recombinant laccase obtained from cultures of E. coli BL21 (DE3) grown in LB liquid medium. The biobleaching experiment was carried out on Eucalyptus globulus kraft pulps using the above mentioned laccase and acetosyringone as natural mediator. Then, an alkaline extraction and further hydrogen peroxide steps were applied to evaluate the efficiency of the laccase-mediator system as a pretreatment in the bleaching sequences. Biobleached pulps showed a kappa number decrease and a brightness increase without decreasing the viscosity values significantly. Also, a reduction in the consumption of hydrogen peroxide was observed when the enzymatic treatment was applied to the pulp. CIE L*a*b* and CIE L*C* color coordinates measured in pulps demonstrated that among all treatments applied to pulps, the laccase-acetosyringone system presented the best optical properties even after an accelerated ageing process. Finally, it is also remarkable that during this treatment 64% of the laccase activity remained unaltered.

Lignocellulosic feedstocks are often prepared for ethanol fermentation by treatment with a dilute mineral acid catalyst that hydrolyzes the hemicellulose and possibly cellulose into soluble carbohydrates. The acid-catalyzed reaction scheme is sequential, whereby the released monosaccharides are further degraded to furans and other chemicals that are inhibitory to the subsequent fermentation step. This work tests the use of agricultural residues (e.g., plant waste) as starting materials for making activated biochars to adsorb these degradation products. Results show that both furfural and hydroxymethylfurfural (HMF) are adsorbed by phosphoric acid-activated and steam-activated biochars prepared from residues collected from cotton and linen production. Best results were obtained with steam-activated biochars. The activated biochars adsorbed about 14% (by weight) of the furfurals at an equilibrium concentration of 0.5 g/L, and by adding 2.5% of char to a sugar solution, with either furfural or HMF (at 1 g/L), 99% of the furans were removed.

It is possible to improve cellulase production by controlling fungal morphology. Farnesol, the first quorum-sensing molecule found in eukaryotic organisms, is reported to influence the morphology of fungi. In this work, farnesol was investigated for its effect on morphology and cellulase production of Penicillium decumbens. Scanning electron microscopy (SEM) revealed that farnesol promoted the growth of hyphae, making possible and facilitating a higher yield of cellulase secretion. Enhanced interaction with the substrate in fermentation led to greater cellulase production. These findings are associated with the subsequent cellulase production of the fungus. Compared with a control medium, exogenously added 1 mM farnesol resulted in 1.32-fold increase in maximal filter paper activity with no significant change in the activity per unit of protein. These results provide a novel way to improve the cellulase production, promoting the commercial application of cellulase.

The performance of kenaf powder (KP) filled recycled high density polyethylene (rHDPE) /natural rubber (NR) blends with and without a compatibilizer, were investigated. The composites with different filler loading (0 to 40 phr) were prepared with a Haake internal mixer. Increasing the KP loading in rHDPE/NR/KP biocomposites reduced the tensile strength and the elongation at break but increased the stabilization torque and the tensile modulus. The addition of MAPE as a compatibilizer increased the tensile strength, elongation at break, and modulus of the composites. This might be attributed to the enhanced adhesion between the filler and polymer matrix, as evidenced from the morphology, using scanning electron microscopy. The incorporation of compatibilizer also reduced the water absorption of the composites.

A quick, simple, and environmentally friendly sample preparation method for fatty acids analysis from chemical-grade cellulose was developed employing imidazolium based ionic liquids as solvents. A variety of imidazolium based ionic liquids were screened for their ability to dissolve chemical cellulose at different temperatures. Dissolution of chemical cellulose was observed to be dependent on the ionic liquids’ anions as well as temperature. The effect of ionic liquids on chemical cellulose was examined using FT-IR and TGA techniques, which showed no difference between the original and the regenerated cellulose except for the percentage mass residues in TGA profile which was high for regenerated cellulose, 15% compared to 8% of the original at 600 °C. Fatty acids extracted from cellulose were found to be predominant in the samples from different bleaching stages, with high levels in the oxygen delignification and low levels were observed in hypochlorite bleached samples. The number and levels of the identified fatty acids were observed to decrease with the bleaching sequence. The recoveries obtained using this method ranged from 90 – 107%.

In the papermaking process, the removal and control of dissolved and colloidal substances (DCS) is a key issue for reducing the usage of fresh water. Nano-size TiO2 is an excellent capturing and flocculating agent for DCS due to its large surface area and positive charge. The composition of dissolved and colloidal substances in a system and the removal of these substances by flocculation with nano-size TiO2 colloids were determined by gas chromatography and mass spectrometry (GC-MS). The samples were obtained from non-deinked pulp (non-DIP), deinked pulp (DIP), and whitewater. The research results indicated that the removal efficiencies of the DCS, which are associated with the molecular structures, were sequenced from large to small as follows: resin acids and sterols, benzene derivatives containing carboxyl, fatty acids, and the phthalic acid esters. Then, the mechanism of flocculation removal of DCS was considered. With hydrogen bonding between the surface hydroxyl (Ti4+-OH) and the functional groups containing oxygen, the nano-size TiO2 particles can capture dissolved substances (DS), and bridge colloidal substances (CS) and complexes to induce agglomerate flocculation. The flocculating removal efficiencies were influenced by the functional groups and alkyls of the DCS. Greater numbers and polarities of functional groups produced higher removal efficiencies. Long alkyl chains shield functional groups, thereby inhibiting the formation of hydrogen bonding, which results in a decrease in removal efficiencies.

The decay resistance, hardness, water absorption, and thickness swelling of a bagasse fiber/polypropylene composite were evaluated. Brown- (Coniophora puteana) and white-rot (Trametes versicolor) fungal treatments were applied for 8, 12, and 16 weeks according to BS 838:1961 with the kolle-flask method. The brown- and white-rotted, and control composite samples were immersed in distilled water at 2 h and 24 h to measure the water absorption and thickness swelling of samples according to the ASTM D 570-98 requirements. Results indicated that the both lowest (3.2%) and the highest (7.2%) weight loss were observed in the white-rotted composite samples for 8 and 16 weeks fungal exposure times, respectively. The highest hardness (77.6 Shore D) was noted in the control composite samples, and the lowest hardness (65.5 Shore D) was recorded in the white-rotted composite samples. The highest water absorption (10.5%) was observed in the brown-rotted composite samples for 8 weeks fungal exposure time and after 24 h immersion in distilled water, and the lowest (3.8%) was noted in the control composite samples after 2 h immersion in distilled water. The highest thickness swelling (6.3%) was observed in the control composite samples after 24 h immersion in distilled water, and the lowest thickness swelling (1.9%) was found in the white-rotted composite samples for 16 weeks fungal exposure time and after 2 h immersion in distilled water.